office

Mezzanine

2008-12-11T07:10:00.001-08:00

Overview
The floor often projects itself from the walls and does not completely close the view of the ceiling from ground floor. In short, the Mezzanine Floor and the ground floor share the same ceiling. There is a belief that a mezzanine floor is always located between the ground floor and the first floor but it is not unusual to have mezzanine floors in the upper floors of a building.
In Palladian architecture the mezzanine is a low upper floor, usually for servants and/or storage.
In stadiums, the "mezzanine" level is a term often used for premium or "club level" seating, typically just a few rows deep and hanging from the upper tier, affording an unobstructed view of the playing field.

Industrial Mezzanines
In industrial applications, mezzanine floor systems are semi-permanent floor systems typically installed within buildings, built between two permanent original stories. These structures are usually free standing and in most cases can be dismantled and relocated. Commercially sold mezzanine structures are generally constructed of three main materials; steel, aluminum, and fiberglass. The decking or flooring of a mezzanine will vary by application but is generally composed of b-deck underlayment and wood product finished floor or a heavy duty steel, aluminum or fiberglass grating.
The mezzanine is often used in shops and similar spaces for storage of tools or materials. The high roof of the shop is ideal for a mezzanine, and offices can be put either below or above it. Mezzanines are frequently used in industrial operations such as warehousing, distribution or manufacturing. These facilities have high ceilings, allowing unused space to be utilized within the vertical cube. Industrial mezzanine structures are typically either structural, roll formed, rack-supported, or shelf-supported, allowing high density storage within the mezzanine structure.

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Unit load

2008-12-11T07:08:00.000-08:00

Function
Most consumer and industrial products move through the supply chain in unitized or unit load form for at least part of their distribution cycle. Unit loads make handling, storage, and distribution more efficient. They help reduce handling costs and damage by reducing individual handling.
A typical unit load might consist of corrugated fiberboard boxes stacked on a pallet and stabilized with stretch wrap, straps or other materials. About 2 billion unit loads are in daily use in the United States (Ward 1993).

Unit Load Design
There are three kinds of unit load design: Component based, systems based, and standards compliant. These have different applications.

Component Based Design
Component based design is the outmoded ad-hoc method of unit load design. Components are sometimes over specified to get assured performance, or tested to get inexpensive economic performance.
Unit load storage and distribution systems consist of several interacting parts:
Packaging and labeling (with product),
Pallet, and
Handling/Storage Equipment
The distribution environment (shock, vibration, humidity, temperature, etc)
Considerable knowledge exists regarding the design of each of these components: their interactions have more recently been studied. When packaging, pallet, and handling systems are designed separately at different locations by different teams, the result might be inefficient unit load systems.
The consequences of independent component based design in the supply chain can include:
Unsafe WorkplacesProduct DamageHigh Packaging CostsReduced Handling EfficiencyWasted Natural ResourcesReduction of Environmental Quality

Systems Based Design
Systems Based Design is a proven process of unit load component cost optimization based on an understanding of how the pallet, packaging and material handling equipment interact during product distribution and storage to design the unit load component parts.
Very often a few inexpensive additions to the packaging can stabilize or stiffen a critical part and give good unit-load performance at a low cost.
Factors considered in unit load systems based design include:
Distribution Vibration and ResonanceLoad Bridging and DeformationUnit Load DeflectionsInterfacial friction and load stabilityCompression stress and product protectionVertical and horizontal stabilization

Standards-Compliant Design
Standards permit a unit load to be designed and tested to meet a written specification or test method. A unit load can be verified to comply with a standard and validated to determine that the unit load is indeed effective.
Unit loads move by an unpredictable mix of many types of vehicles and storage areas, the exact set is difficult to predict. Therefore, unit loads must be designed to travel by any such vehicles, and be stored in a wide variety of places. There are therefore many similarities in the requirements for long term storage and long distance transportation of unit loads.
Standards provide institutional memory of the many conditions in real logistic trains, and collect the best practices for design and testing unit loads. Standards also describe load requirements, so that logistic providers can plan to meet them.
Material based standards describe proven designs for particular circumstances. These are often used to describe unit load components such as pallets, strapping, seals, caps, retaining rings and battens.
Performance testing standards describe needs and allow flexibility in the choice of matierials. These are applied to particular unit load designs.
ASTM D4169 has standard test protocols for unit loads. These vary based on the value of the load, the expected hazards, and the distribution environment. This is a performance based standard.
Another standard for unit loads is MIL-STD-1660, a standard for ammunition unit loads. DOD unit loads generally use 40x48" pallets, which pack efficiently into ISO containers. They weigh less than 4000lbs (1800kg) to limit the stresses on handling equipment. They are weatherproof, and stack 16' (4.9m) high. They often use steel pallets, steel straps with notched seals, outdoor plywood, and plastic film. Interestingly, MIL-STD-1660 mandates that loads must never be less than the width of a pallet, while permitting some overhang. The markings are logmars bar codes and standard inventory numbers. The standard describes major parts of the logistic path, including storage, ship, air, truck, forklift and sling (i.e. ship-to-ship and parachute). There are auxiliary standards for ship-to-ship transfers, and amphibious transfers. There are tests for stacking, transport, sling, forklift and pallet jack, impact, drop tests, tip, water-retention (i.e. weather), and safe disassembly.
MIL-STD-1660 at first looks like ridiculous overdesign to commercial unit-load designers. However, similar marking standards, safety, stability, volumetric efficiency, weight limits and impact resistance are routinely needed in commercial logistics. Sling handling is routine for small ports and noncontainer transports. Weatherproofness could be optional. It's sometimes valuable, and the baggies are cheap. High, standardized stacking could be optional as well. It's expensive, but sometimes valuable for rackless and military customers.

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Pallet jack

2008-12-11T07:05:00.000-08:00

A pallet jack, also known as a pallet truck or pump truck, is a tool used to lift and move pallets.
The front wheels are mounted inside the end of the forks, and as the hydraulic jack is raised, the forks are separated vertically from the front wheels, forcing the load upward until it clears the floor. The pallet is only lifted enough to clear the floor for subsequent travel.

Types

Manual pallet jack
A manual pallet jack is a hand-powered jack.

Powered pallet jack
Powered pallet jacks are motorized to allow lifting and moving of heavier and stacked pallets. These generally contain a platform for the user to stand while hauling pallets around a warehouse or loading/unloading trucks. The powered pallet jack is generally moved by a throttle on the handle to move forward or in reverse and steered by swinging the handle in the intended direction. Some contain a type of dead man's switch rather than a brake to stop the machine should the user need to stop quickly or leave the machine while it is in use.

Operational limitations
Reversible pallets cannot be used.
Double-faced nonreversible pallets cannot have deckboards where the front wheels extend to the floor.
Enables only two-way entry into a four-way notched-stringer pallet, because the forks cannot be inserted into the notches

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Packaging and labeling

2008-12-11T07:03:00.000-08:00

The purposes of packaging and package labels
Packaging and package labeling have several objectives:
Physical protection - The objects enclosed in the package may require protection from, among other things, shock, vibration, compression, temperature, etc.
Barrier protection - A barrier from oxygen, water vapor, dust, etc., is often required. Permeation is a critical factor in design. Some packages contain desiccants or Oxygen absorbers to help extend shelf life. Modified atmospheres or controlled atmospheres are also maintained in some food packages. Keeping the contents clean, fresh, sterile and safe for the intended shelf life is a primary function.
Containment or agglomeration - Small objects are typically grouped together in one package for reasons of efficiency. For example, a single box of 1000 pencils requires less physical handling than 1000 single pencils. Liquids, powders, and granular materials need containment.
Information transmission - Packages and labels communicate how to use, transport, recycle, or dispose of the package or product. With pharmaceuticals, food, medical, and chemical products, some types of information are required by governments.
Marketing - The packaging and labels can be used by marketers to encourage potential buyers to purchase the product. Package design has been an important and constantly evolving phenomenon for several decades. Marketing communications and graphic design are applied to the surface of the package and (in many cases) the point of sale display.
Security - Packaging can play an important role in reducing the security risks of shipment. Packages can be made with improved tamper resistance to deter tampering and also can have tamper-evident features to help indicate tampering. Packages can be engineered to help reduce the risks of package pilferage: Some package constructions are more resistant to pilferage and some have pilfer indicating seals. Packages may include authentication seals to help indicate that the package and contents are not counterfeit. Packages also can include anti-theft devices, such as dye-packs, RFID tags, or electronic article surveillance tags, that can be activated or detected by devices at exit points and require specialized tools to deactivate. Using packaging in this way is a means of loss prevention.
Convenience - Packages can have features which add convenience in distribution, handling, stacking, display, sale, opening, reclosing, use, and reuse.
Portion control - Single serving or single dosage packaging has a precise amount of contents to control usage. Bulk commodities (such as salt) can be divided into packages that are a more suitable size for individual households. It is also aids the control of inventory: selling sealed one-liter-bottles of milk, rather than having people bring their own bottles to fill themselves.

Packaging types

Various household packaging types for foods
Packaging may be looked at as several different types. For example a transport package or distribution package is the package form used to ship, store, and handle the product or inner packages. Some identify a consumer package as one which is directed toward a consumer or household.
Packaging may discussed in relation to the type of product being packaged: medical device packaging, bulk chemical packaging, over-the-counter drug packaging, retail food packaging, military materiel packaging, pharmaceutical packaging, etc.

Pull open aluminum can
It is sometimes convenient to categorize packages by layer or function: "primary", "secondary", etc.
Primary packaging is the material that first envelops the product and holds it. This usually is the smallest unit of distribution or use and is the package which is in direct contact with the contents.
Secondary packaging is outside the primary packaging – perhaps used to group primary packages together.
Tertiary packaging is used for bulk handling, warehouse storage and transport shipping. The most common form is a palletized unit load that packs tightly into containers.
These broad categories can be somewhat arbitrary. For example, depending on the use, a shrink wrap can be primary packaging when applied directly to the product, secondary packaging when combining smaller packages, and tertiary packaging on some distribution packs.

Symbols used on packages and labels
Many types of symbols for package labeling are nationally and internationally standardized. For consumer packaging, symbols exist for product certifications, trademarks, proof of purchase, etc. Some requirements and symbols exist to communicate aspects of consumer use and safety. Recycling directions, Resin identification code (below), and package environmental claims have special codes and symbols.

Bar codes (below), Universal Product Codes, and RFID labels are common to allow automated information management.

"Wikipedia" encoded in Code 128
Shipments of hazardous materials or dangerous goods have special information and symbols (labels, plackards, etc) as required by UN, country, and specific carrier requirements.

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Forklift truck

2008-12-11T07:02:00.000-08:00

History
The middle 19th century through the early 20th century saw the developments that led to today's modern forklifts. The Pennsylvania Railroad in 1906 introduced battery powered platform trucks for moving luggage at their Altoona, Pennsylvania train station. World War I saw the development of different types of material handling equipment in the United Kingdom by Ransomes, Sims and Jeffries of Ipswich. This was in part due to the labor shortages caused by the war. In 1917 Clark in the United States began developing and using powered tractor and powered lift tractors in their factories. In 1919 the Towmotor Company and Yale & Towne Manufacturing in 1920 entered the lift truck market in the United States.
Continuing development and expanded use of the forklift continued through the 1920s and 1930s. World War II, like World War I before, spurred the use of forklift trucks in the war effort. Following the war, more efficient methods for storing products in warehouses were being implemented. Warehouses needed more maneuverable forklift trucks that could reach greater heights. New forklift models were made that filled this need.

Design types

The following is a list of the more common lift truck types. It is arranged from the smallest type of lift to largest:
Hand pallet truck
Walkie low lift truck (powered pallet truck, usually electrically powered)
Rider low lift truck
Towing tractor
Walkie stacker
Rider stacker
Reach truck (small forklift, designed for small aisles, usually electrically powered)
Electric counterbalanced truck
IC counterbalanced truck
Sideloader
Telescopic handler
Slip Sheet machine
Walkie Order Picking truck
Rider Order Picking truck (commonly called an "Order Picker"; like a small forklift, except the operator rides up to the load and transfers it article by article)
Articulated Very Narrow Aisle Counterbalanced trucks (commonly called "Flexi Truck")
Guided Very Narrow Aisle truck - 'Man Down' (a type of reach truck designed for aisles less than five feet wide) and 'Man Riser' Combination pickcle Picker/ Stacker truck
Truck Mounted Forklift / Sod Loader

Specialty trucks
At the other end of the spectrum from the counterbalanced forklift trucks are more 'high end' specialty trucks:
Articulated Counterbalance Trucks
These are, unlike most other lift trucks, front wheel steer, and are a hybrid VNA (Very Narrow Aisle) truck designed to be both able to offload trailers and place the load in narrow aisle racking. Increasingly these trucks are able to compete in terms of pallet storage density, lift heights and pallet throughput with Guided Very Narrow Aisle trucks.
Guided Very Narrow Aisle Trucks
These are rail or wide guided and available with lift heights up to 40' non top-tied and 98' top-tied. Two forms are available; 'man-down' and 'man-riser' where the operator elevates with the load for increased visibility or for multilevel 'break bulk' order picking. This type of truck, unlike Articulated Narrow Aisle Trucks, requires a high standard of floor flatness.
U.S. Military 10K-AT "Adverse Terrain"

Counterbalanced forklift components

Image of an electric forklift with component descriptions
A typical counterbalanced forklift contains the following components
The Truck Frame - is the base of the machine to which the mast, axles, wheels, counterweight, overhead guard and power source are attached. The frame may have fuel and hydraulic fluid tanks constructed as part of the frame assembly.
The Counterweight - is a heavy cast iron mass attached to the rear of the forklift truck frame. The purpose of the counterweight is to counterbalance the load being lifted. In an electric forklift the large lead-acid battery itself may serve as part of the counterweight.
The Cab - is the area that contains a seat for the operator along with the control pedals, steering wheel, levers, switches and a dashboard containing operator readouts. The cab area may be open air or enclosed, but it is covered by the cage-like overhead guard assembly.
The Overhead Guard - is a metal roof supported by posts at each corner of the cab that helps protect the operator from any falling objects. On some forklifts, the overhead guard is part of the frame assembly
The Power Source - may consist of an internal combustion engine that can be powered by LP gas, CNG gas, gasoline or diesel fuel. Electric forklifts are powered by either a battery or fuel cells that provide power to electric motors. The motors may be either DC or AC types.
Tilt Cylinders - are hydraulic cylinders that are mounted to the truck frame and the mast. The tilt cylinders pivot the mast to assist in engaging a load.
The Mast - is the vertical assembly that does the work of raising and lowering the load. It is made up of interlocking rails that also provide lateral stability. The interlocking rails may either have rollers or bushings as guides. The mast is either hydraulically operated by one or more hydraulic cylinders or it may be chain operated with a hydraulic motor providing motive power. It may be mounted to the front axle or the frame of the forklift.
The Carriage - is the component to which the forks or other attachments mount. It is mounted into and moves up and down the mast rails by means of chains or by being directly attached to the hydraulic cylinder. Like the mast, the carriage may have either rollers or bushings to guide it in the interlocking mast rails.
The Load Back Rest - is a rack-like extension that is either bolted or welded to the carriage in order to prevent the load from shifting backward when the carriage is lifted to full height.
Attachments - may consist of forks or tines that are the L-shaped members that engage the load. A variety of other types of material handling attachments are available. These include sideshifters, slipsheet attachments, carton clamps, multipurpose clamps, rotators, fork positioners, carpet poles, pole handlers, container handlers, roll clamps and many others.

Attachments
Below is a list of common forklift attachments:
Sideshifter - is a hydraulic attachment that allows the operator to move the tines (forks) and backrest laterally. This allows easier placement of a load without having to reposition the truck
Rotator - To aid the handling of skids that may have become excessively tilted and other specialty material handling needs some forklifts are fitted with an attachment that allows the tines to be rotated. This type of attachment may also be used for dumping containers for quick unloading.
Fork Positioner - is a hydraulic attachment that moves the tines (forks) together or apart. This removes the need for the operator to get out of the cab to manually adjust the tines for different sized loads.
Roll and Barrel Clamp Attachment - A mechanical or hydraulic attachment that is used for handling barrels, kegs, or paper rolls. This type of attachment also usually have a rotate function so that a vertically stored paper roll can be inserted into the horizontal intake of a printing press.
Pole Attachments - In some locations, such as carpet warehouses, a long metal pole is used instead of forks to lift carpet rolls. Similar devices, though much larger, are used to pick up metal coils.
Carton and Multipurpose Clamp Attachments - are hydraulic attachments that allow the operator to open and close around a load, squeezing it to pick it up. Products like cartons, boxes and bales can be moved with this type attachment. With these attachments in use, the forklift truck is sometimes referred to as a clamp truck.
Slip Sheet Attachment (Push - Pull) - is a hydraulic attachment that reaches forward, clamps onto a slipsheet and draws the slipsheet onto wide and thin metal forks for transport. The attachment will push the slip sheet and load off the forks for placement.
Drum Handler Attachment - is a mechanical attachment that slides onto the tines (forks). It usually has a spring loaded jaw that grips the top lip edge of a drum for transport. Another type grabs around the drum in a manner similar to the roll or barrel attachments.
Man Basket - a lift platform that slides onto the tines (forks); meant for hoisting workers. The man basket has railings and brackets for attaching safety harnesses.
Telescopic Forks - are hydraulic attachments that allow the operator to operate in warehouse design for "double-deep stacking", which means that two pallet shelves are placed behind each other without any aisle between them.

Forklift control and capabilities

a typical load capacity chart
‎
Forklift trucks are available in many variations and load capacities. In a typical warehouse setting most forklifts used have load capacities between one to five tons. Larger machines, up to 50 tons lift capacity are used for lifting heavier loads, including loaded shipping containers. [7]
In addition to a control to raise and lower the forks (also known as blades or tines), the operator can tilt the mast to compensate for a load's tendency to angle the blades toward the ground and risk slipping off the forks. Tilt also provides a limited ability to operate on non-level ground. Skilled forklift operators annually compete in obstacle and timed challenges at regional forklift rodeos.

General operations

A forklift transporting a pallet of potted plants in Durham, North Carolina.
Forklifts are rated for loads at a specified maximum weight and a specified forward centre of gravity. This information is located on a nameplate provided by the manufacturer, and loads must not exceed these specifications(In Canada it is 24" Load Center). In many jurisdictions it is illegal to remove or tamper with the nameplate without the permission of the forklift manufacturer.
An important aspect of forklift operation is that many have rear-wheel steering. While this increases maneuverability in tight cornering situations, it differs from a driver’s traditional experience with other wheeled vehicles. While steering, as there is no caster action, it is unnecessary to apply steering force to maintain a constant rate of turn.
Another critical characteristic of the forklift is its instability. The forklift and load must be considered a unit with a continually varying centre of gravity with every movement of the load. A forklift must never negotiate a turn at speed with a raised load, where centrifugal and gravitational forces may combine to cause a disastrous tip-over accident. The forklift are designed with a load limit for the forks which is decreased with fork elevation and undercutting of the load (i.e. load does not butt against the fork "L"). A loading plate for loading reference is usually located on the forklift. A forklift should not be used as a personnel lift without the fitting of specific safety equipment, such as a "cherry picker" or "cage".

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Pallet

2008-12-11T07:00:00.000-08:00

Overview
Containerization for transport has spurred the use of pallets because the containers have the clean, level surfaces needed for easy pallet movement. Most pallets can easily carry a load of 1,000 kg (about 2,000 lb). Today, over half a billion pallets are manufactured each year and about two billion pallets are in use across the United States alone.
Pallets make it easy to move heavy stacks. Loads with pallets under them can be hauled by forklift trucks of different sizes, or even by hand-pumped and hand-drawn pallet jacks. Movement is easy on a wide, strong, flat floor: concrete is excellent. A forklift truck can cost the same as a luxury automobile, but a good reconditioned hand-drawn pallet jack costs only a few hundred dollars. The greatest investment is thus in the construction of commercial or industrial buildings where the use of pallets could be economical. Passage through doors and buildings must be possible. To help this issue, some later pallet standards (the europallet and the U.S. Military 35x45.5") are designed to pass through standard doorways.
Organizations using standard pallets for loading and unloading can have much lower costs for handling and storage, with faster material movement than businesses that do not. The exceptions are establishments that move small items such as jewelry or large items such as cars. But even they can be improved. For instance, the distributors of costume jewelry normally use pallets in their warehouses and car manufacturers use pallets to move components and spare parts.
The lack of a single international standard for pallets causes substantial continuing expense in international trade. A single standard is difficult because of the wide variety of needs a standard pallet would have to satisfy: passing doorways, fitting in standard containers, and bringing low labor costs. For example, organizations already handling large pallets often see no reason to pay the higher handling cost of using smaller pallets that can fit through doors.

History

Development of commercial transport packaging

Pallets stacked for loading onto barges in North London
Skids and pallets were slowly introduced throughout the early 20th century; wooden boxes, crates, barrels and kegs were much more commonly used to unitize, protect, store and transport goods. The predecessor of the modern wooden pallet was a simple skid that consisted only of stringers fastened to a top deck. It first appeared in American factories in conjunction with the low lift truck. A crude low lift hand truck was invented in 1887 and a more durable, all-steel low lift truck design was introduced in 1909.
The high lift fork truck first appeared in 1915. With further modification in 1919, the truck could lift loads several feet high while other improvements included cantilever design and forks. The emergence of forks as well during the same period enabled lift trucks to handle a much greater range of materials.
Another development was the new capability of the mast of the fork lift to tilt both forward and back, independent of the lifting mechanism. These developments, along with the emergence of the double-faced pallet during the same time period, allowed for tiering of unit loads. As early as 1926, the essence of the modern lift truck had been developed. Now, pallets no longer were simply a means of moving materials within the plant. High lift trucks made possible vertical stacking of unit loads and a resulting dramatic improvement of warehouse and plant storage efficiencies.

Development of the pallet
The pallet was developed in stages. Spacers were used between loads to allow fork entry, progressing to the placement of boards atop stringers to make skids. Eventually boards were fastened to the bottom to create the pallet. The addition of bottom boards on the skid, which appeared by 1925, resulted in the modern form of the pallet. With the bottom deck, several problems common to the single faced skid were addressed. For example, the bottom boards provided better weight distribution and reduced product damage; they also provided better stacking strength and rigidity. Lift truck manufacturers promoted the idea of using more vertical area of a plant for stock storage.
In size, skids started narrow in order to pass through ordinary doors. As facilities were rebuilt, many organizations optimized their buildings for larger pallets in order to reduce labor costs.
The earliest referenced U.S. patent on a skid is Hallowell's 1924 "Lift Truck Platform." In 1939, Carl Clark patented a recognizably modern pallet, although with steel stringers.In World War II, palleted material handling was rapidly perfected in order to transfer Allied war materials. The patent activity picked up again after the war, as inventors claimed items they improvised for the war effort. The first four direction pallet was claimed in 1945 by Robert Braun.At the end of 1948, Sullivan Stemple claimed the basic idea of a pallet designed to be used with a fork lift; the pallet was to be stamped from steel During World War II, to reduce the resupply time of warships, the first modern disposable four-way block pallet was developed, and patented in early 1949 by Norman Cahners, a U.S. Navy Supply Officer in the ordnance depot at Hingham, Massachusetts. The first completely modern 2-direction stringer pallet was described in 1949 by Darling Graeme.

Impact of pallet on rail transport
Pallets and forklifts also provided much quicker turnaround of rail cars and ships. In 1931, three days were required to unload a boxcar containing 13,000 cases of unpalletized canned goods. When the same amount of goods were loaded into the railway trucks on pallets or skids, the identical task took only four hours. With the entry of the U.S. into World War II, the urgency for material handling reform changed almost overnight. Palletization was regarded as an enormous opportunity to help the U.S. armed forces do more with less. Palletized loads could handle more goods with fewer people, freeing up men for military duty; it also could increase warehouse storage capacity and throughput, reducing the need for additional warehouse capacity. Pallets were used somewhat in the European theater, but they were put to work extensively in the Pacific.

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Material handling equipment

2008-12-11T06:52:00.000-08:00

Storage and Handling Equipment
Storage and handling equipment is a category within the material handling industry. The equipment that falls under this description is usually non-automated storage equipment. Products such as Pallet rack, shelving, carts, etc. belong to storage and handling. Many of these products are often referred to as "catalog" items because they generally have globally accepted standards and are often sold as stock materials out of Material handling catalogs.

Engineered Systems
Engineered systems are typically custom engineered material handling systems. Conveyors, AS/RS, AGV and most other automated material handling systems fall into this category. Engineered systems are often a combination of products integrated to one system. Many distribution centers will optimize storage and picking by utilizing engineered systems such as pick modules and sortation systems.

Industrial Trucks
Industrial trucks usually refer to operator driven motorized warehouse vehicles. Industrial trucks assist the material handling system with versatility; they can go where engineered systems cannot. Forklift trucks are the most common example of industrial trucks but certainly aren't the extent of the category. Tow tractors and stock chasers are additional examples of industrial trucks.

Bulk Material Handling
Bulk material handling equipment is used to move and store bulk materials such as ore, liquids, and cereals. This equipment is often seen on farms, mines, shipyards and refineries. This category is also explained in Bulk material handling.

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Doorstop

2008-12-11T06:44:00.000-08:00

Usage

Holding Doors Open
A door may be held open by a door stop which is simply a heavy solid object, such as a brick, placed in the path of the door. These stops are predominantly improvised. Historically, lead bricks have been popular choices when available. However, as the toxic nature of lead has been revealed, this use has been strongly discouraged.
Another method is to use a door stop which is a small wedge of wood, rubber, plastic, cotton or another material. Manufactured wedges of these materials are commonly available. The wedge is kicked into position and the downward force of the door, now jammed upwards, onto the door stop provides enough static friction to keep it motionless.
A third strategy is to equip the door itself with a stopping mechanism. In this case, a short metal bar capped with rubber, or another high friction material, is attached to a hinge near the bottom of the door opposite the door hinge and on the side of the door which is in the direction that it closes. When the door is to be kept open, the bar is swung down so that the rubber end touches the floor. In this configuration, further movement of the door towards being closed increases the force on the rubber end, thereby increasing the frictional force which opposes the movement. When the door is to be closed, the stop is released by pushing the door slightly more open which releases the stop and allows it to be flipped upwards. A newer version of equipping the door with the stopping mechanism is to attach a magnet to the bottom of the door on the side which opens outward which then latches onto another magnet or magnetic material on the wall or a small hub on the floor. The magnet must be strong enough to hold the weight of the door, but weak enough to be easily detached from the wall or hub.

Preventing Damage by Doors
Another type of door stop is used to prevent doors from opening too far and damaging nearby walls. In this case a short length of rubber-tipped wood or metal is screwed into either the wall or the floor in the path of the door. If it is attached to the wall, it may be either a few inches above the ground, or at such a height as to meet the doorknob.
On occasion, stops are used that are fitted at the midpoint of the door, as part of the central door-hinge. Such a stop is known as a "hinge pin".

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Wide-angle lens

2008-12-11T06:38:00.000-08:00

Wide-angle lenses for 35 mm format
For a full-frame 35 mm camera with a 36 mm by 24 mm format, the diagonal measures 43.3 mm and by custom, the normal lens adopted by most manufacturers is 50 mm. Also by custom, a lens of focal length 35 mm or less is considered wide-angle.
Common wide-angle lenses for a full-frame 35 mm camera are 35, 28, 24, 21, 18 and 14 mm. Many of the lenses in this range will produce a more or less rectilinear image at the film plane (though some degree of barrel distortion is not uncommon here).
Extreme wide-angle lenses that do not produce a rectilinear image are called fisheye lenses. Common focal lengths for these in a 35 mm camera are 6 to 8 mm (which produce a circular image). Lenses with focal lengths of 14 to 16 mm may be either rectilinear or fisheye designs.
Wide-angle lenses come in both fixed-focal-length and zoom varieties. For 35 mm cameras, lenses producing rectilinear images can be found at focal lengths as short as 12 mm, including zoom lenses with ranges of 2:1 that also begin at 12 mm. .

Digital camera considerations

Apparent focal length in APS-sized digital cameras is increased by a crop factor.
As of 2007 most interchangeable-lens digital cameras have photosensors that are smaller than the film format of full-frame 35 mm camerasFor the most part, the dimensions of these photosensors are similar to the APS-C image frame size, i.e., approximately 24 mm x 16 mm. Therefore, the angle of view for any given focal length lens will be narrower than it would be in a full-frame camera because the smaller sensor "sees" less of the image projected by the lens. The camera manufacturers provide a crop factor (sometimes called a field-of-view factor or a focal-length multiplier) to show how much smaller the sensor is than a full 35 mm film frame. For example, one common factor is 1.5 (Nikon DX format and some others), although many cameras have crop factors of 1.6 (most Canon DSLRs), 1.7 (the Sigma DSLRs) and 2 (the Four-thirds-format cameras). The 1.5 indicates that the angle of view of a lens on the camera is the same as a 35 mm full-frame camera with a focal length of 1.5 times the focal length, which explains why the crop factor is also known as a focal-length multiplier. As examples, a 28 mm lens would produce on the DSLR the angle of view of a 42 mm lens (given a crop factor of 1.5) on a full-frame camera. So, to determine the focal length of a lens for a digital camera that will give the equivalent angle of view as one on a full-frame camera, the full-frame lens focal length must be divided by the crop factor. For example, to get the equivalent angle of view of a 28 mm lens on a full-frame 35 mm camera, from a digital camera with a 1.5 crop factor, one would use an 18 mm lens.
Lens manufacturers have responded to this problem by making wide-angle lenses of much shorter focal lengths for these cameras. In doing this, they limit the diameter of the image projected to slightly more than the diagonal measurement of the photosensor. This gives the designers more flexibility in providing the optical corrections necessary to economically produce high quality images at these short focal lengths, especially when the lenses are zoom lenses. Examples are 10 mm minimum focal length zoom lenses from several manufacturers. At 10 mm, these lenses provide the angle of view of a 15 mm lens on a full-frame camera when the crop factor is 1.5.
Construction

Cross-section of a typical short-focus wide-angle lens.

Cross-section of a typical retrofocus wide-angle lens.
There are two different varieties of wide-angle lens: short-focus lenses and retrofocus lenses.
Short-focus lenses are generally made up of multiple glass elements whose shapes are more or less symmetrical in front of and behind the diaphragm. As the focal length decreases, the distance of the rear element of the lens from the film plane or digital sensor also decreases. This makes short-focus wide-angle lenses undesirable for single-lens reflex cameras unless they are used with the reflex mirrors locked up. Short-focus lenses are widely used on large format view cameras.
The retrofocus lens solves this proximity problem through an asymmetrical design that allows the rear element to be further away from the film plane than its effective focal length would suggest. (See Angenieux retrofocus.) For example, it is not uncommon for the rear element of a retrofocus lens of 18 mm to be more than 25 mm from the film plane. This makes it possible to design wide-angle lenses for single-lens reflex cameras.

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Crash bar

2008-12-11T06:33:00.000-08:00

A crash bar is a mechanism for unlatching a door, consisting of a metal bar fixed horizontally to the front of the door and hinged. It is operated by pushing on it, which unlatches and opens the door. Many countries' building codes require them on all fire and emergency exits. They are so named because they can be operated by someone "crashing" into them; the alternate term "panic bar" implies a similar meaning.
Crash bars also refers to motorcycle engine guards. They are commonly made of tubular steel bent into a "U" shape and mounted to the sides of a motorcycle's lower frame. They primarily protect the bike's engine and body panels during slides or tipovers but also serve as a mount point for accessories like highway pegs, lights and, on police motorcycles, sirens, cameras and radar guns.

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Welding

2008-12-09T07:05:00.000-08:00

Processes

Arc
Main article: Arc welding
These processes use a welding power supply to create and maintain an electric arc between an electrode and the base material to melt metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is sometimes protected by some type of inert or semi-inert gas, known as a shielding gas, and filler material is sometimes used as well.

Power supplies
To supply the electrical energy necessary for arc welding processes, a number of different power supplies can be used. The most common welding power supplies are constant current power supplies and constant voltage power supplies. In arc welding, the length of the arc is directly related to the voltage, and the amount of heat input is related to the current. Constant current power supplies are most often used for manual welding processes such as gas tungsten arc welding and shielded metal arc welding, because they maintain a relatively constant current even as the voltage varies. This is important because in manual welding, it can be difficult to hold the electrode perfectly steady, and as a result, the arc length and thus voltage tend to fluctuate. Constant voltage power supplies hold the voltage constant and vary the current, and as a result, are most often used for automated welding processes such as gas metal arc welding, flux cored arc welding, and submerged arc welding. In these processes, arc length is kept constant, since any fluctuation in the distance between the wire and the base material is quickly rectified by a large change in current. For example, if the wire and the base material get too close, the current will rapidly increase, which in turn causes the heat to increase and the tip of the wire to melt, returning it to its original separation distance.
The type of current used in arc welding also plays an important role in welding. Consumable electrode processes such as shielded metal arc welding and gas metal arc welding generally use direct current, but the electrode can be charged either positively or negatively. In welding, the positively charged anode will have a greater heat concentration, and as a result, changing the polarity of the electrode has an impact on weld properties. If the electrode is positively charged, the base metal will be hotter, increasing weld penetration and welding speed. Alternatively, a negatively charged electrode results in more shallow welds.Nonconsumable electrode processes, such as gas tungsten arc welding, can use either type of direct current, as well as alternating current. However, with direct current, because the electrode only creates the arc and does not provide filler material, a positively charged electrode causes shallow welds, while a negatively charged electrode makes deeper welds. Alternating current rapidly moves between these two, resulting in medium-penetration welds. One disadvantage of AC, the fact that the arc must be re-ignited after every zero crossing, has been addressed with the invention of special power units that produce a square wave pattern instead of the normal sine wave, making rapid zero crossings possible and minimizing the effects of the problem.
Processes

Shielded metal arc welding
One of the most common types of arc welding is shielded metal arc welding (SMAW), which is also known as manual metal arc welding (MMA) or stick welding. Electric current is used to strike an arc between the base material and consumable electrode rod, which is made of steel and is covered with a flux that protects the weld area from oxidation and contamination by producing CO2 gas during the welding process. The electrode core itself acts as filler material, making a separate filler unnecessary.
The process is versatile and can be performed with relatively inexpensive equipment, making it well suited to shop jobs and field work An operator can become reasonably proficient with a modest amount of training and can achieve mastery with experience. Weld times are rather slow, since the consumable electrodes must be frequently replaced and because slag, the residue from the flux, must be chipped away after welding Furthermore, the process is generally limited to welding ferrous materials, though special electrodes have made possible the welding of cast iron, nickel, aluminium, copper, and other metals. Inexperienced operators may find it difficult to make good out-of-position welds with this process.
Gas metal arc welding (GMAW), also known as metal inert gas or MIG welding, is a semi-automatic or automatic process that uses a continuous wire feed as an electrode and an inert or semi-inert gas mixture to protect the weld from contamination. As with SMAW, reasonable operator proficiency can be achieved with modest training. Since the electrode is continuous, welding speeds are greater for GMAW than for SMAW. Also, the smaller arc size compared to the shielded metal arc welding process makes it easier to make out-of-position welds (e.g., overhead joints, as would be welded underneath a structure).
The equipment required to perform the GMAW process is more complex and expensive than that required for SMAW, and requires a more complex setup procedure. Therefore, GMAW is less portable and versatile, and due to the use of a separate shielding gas, is not particularly suitable for outdoor work. However, owing to the higher average rate at which welds can be completed, GMAW is well suited to production welding. The process can be applied to a wide variety of metals, both ferrous and non-ferrous.
A related process, flux-cored arc welding (FCAW), uses similar equipment but uses wire consisting of a steel electrode surrounding a powder fill material. This cored wire is more expensive than the standard solid wire and can generate fumes and/or slag, but it permits even higher welding speed and greater metal penetration.
Gas tungsten arc welding (GTAW), or tungsten inert gas (TIG) welding (also sometimes erroneously referred to as heliarc welding), is a manual welding process that uses a nonconsumable tungsten electrode, an inert or semi-inert gas mixture, and a separate filler material. Especially useful for welding thin materials, this method is characterized by a stable arc and high quality welds, but it requires significant operator skill and can only be accomplished at relatively low speeds.
GTAW can be used on nearly all weldable metals, though it is most often applied to stainless steel and light metals. It is often used when quality welds are extremely important, such as in bicycle, aircraft and naval applications.A related process, plasma arc welding, also uses a tungsten electrode but uses plasma gas to make the arc. The arc is more concentrated than the GTAW arc, making transverse control more critical and thus generally restricting the technique to a mechanized process. Because of its stable current, the method can be used on a wider range of material thicknesses than can the GTAW process, and furthermore, it is much faster. It can be applied to all of the same materials as GTAW except magnesium, and automated welding of stainless steel is one important application of the process. A variation of the process is plasma cutting, an efficient steel cutting process.
Submerged arc welding (SAW) is a high-productivity welding method in which the arc is struck beneath a covering layer of flux. This increases arc quality, since contaminants in the atmosphere are blocked by the flux. The slag that forms on the weld generally comes off by itself, and combined with the use of a continuous wire feed, the weld deposition rate is high. Working conditions are much improved over other arc welding processes, since the flux hides the arc and almost no smoke is produced. The process is commonly used in industry, especially for large products and in the manufacture of welded pressure vessels. Other arc welding processes include atomic hydrogen welding, carbon arc welding, electroslag welding, electrogas welding, and stud arc welding.

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Steelmaking

2008-12-09T07:00:00.000-08:00

Steelmaking is the second step in producing steel from iron ore. In this stage, impurities such as sulfur, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium and vanadium are added to produce the exact steel required.
The materials used in modern steelmaking are:
The iron produced in a blast furnace, either as molten iron or as pig iron.
Scrap steel.
Alloying elements.
The electric arc furnace is used to remelt scrap steel so that it can be used again for producing steel products by forging or rolling. This is the difference with a blast furnace where new steel is produced from iron ore.
The original methods of producing steel were labour-intensive and highly skilled arts involving open crucibles, see finery forge, puddling, blister steel, crucible steel.
An important aspect of the industrial revolution was the development of large-scale methods of producing forgeable metal (bar iron or steel). The puddling furnace was initially a means of producing wrought iron, but was later applied to steel production. The Bessemer converter was the first successful mass steelmaking process, followed by the open hearth furnace.

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Radar gun

2008-12-09T06:52:00.000-08:00

How radar guns work
Radar guns are, in their most simple form, radio transmitters and receivers. They send out a radio signal, then receive the same signal back as it bounces off the objects. However, the radar frequency is different when it comes back, and from that difference the radar gun can calculate vehicle speed.
A radar beam is similar to the beam of a flashlight as it spreads out as the distance from the signal origin increases. The signal then bounces off objects in the path of the beam and are reflected back to the gun. The gun uses the doppler effect to calculate the speed of the object in the beam's path. Using a comparison of frequency shift between received images instead of the frequency shift between sent and received frequencies creates what is known as moving radar, the radar must be stationary to measure speed.
All bands of radar work the same way; they simply operate on different frequencies. X band guns are becoming less common due to the fact the beam is strong and easily detectable. Also, most automatic doors utilize radio waves on X band and can possibly affect the readings of police radar. As a result K band and Ka band are most commonly used by police agencies.
Traffic radar comes in many models. There are hand held, stationary and moving radar instruments. Hand held units are mostly battery powered, and for the most part are used as stationary speed enforcement tools. Stationary radar is mounted in police vehicles, and may have one or two antennas. These are employed when the vehicle is parked. Moving radar is employed, as the name implies, when the police vehicle is in motion. These devices are very sophisticated, able to track vehicles approaching and receding both in front of and behind the patrol vehicle. They can also track the fastest vehicle in the selected radar beam, front or rear.

Problems with radar guns
Although radar is an effective tool to acquire an object's speed, there are problems with it. Today's technology is relatively effective and error free so most inaccurate speed measurements are caused by the user.
For speed to be accurately calculated, the object whose speed is desired ideally should be the only moving object in the beam of the radar. If this is not the case, as in a police officer monitoring speed on a stretch of busy road, more articulation is needed in testifying to a particular vehicle's speed.
The National Highway Traffic Safety Administration (NHTSA), in cooperation with the International Association of Chiefs of Police (IACP) has developed a training program for the operation of police traffic radar. This curriculum provides radar instrument operators with the skills required to properly set up, test, and operate to identify targets. It also provides the operators with information regarding state and local laws and ordinances which apply to the user's jurisdiction. This training, while strongly recommended, is not mandatory in some states. Other states require the successful completion of this training and issue a certificate of completion.
Police officers are also trained in the practice of visual estimation of speed and distance, and the radar is thus used as a verification of the visual estimation. In addition, it is easy enough to testify that the vehicle in the offside lane was passing vehicles in the nearside lane, and is therefore the vehicle whose speed is showing on the readout as traveling above the posted limit.
The angle in which the object is in relation to the radar source can also affect the reading. This phenomenon includes angles on a horizontal and vertical plane and is known as the Cosine Effect. It is suggested that interference in the RADAR band by cellular phones, transmitters of other kinds, power wires, high tension wires, signs and even stationary walls can create erroneous readings. This is not taken into account when a photo RADAR is used and numerous discrepancies can creep in.

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Radar detector

2008-12-09T06:42:00.000-08:00

Description
One of the technologies that law enforcement agencies can use to measure the speed of a moving vehicle uses doppler radar to beam a radio wave at the vehicle, and then infer the vehicle's speed by measuring the Doppler effect-moderated change in the reflected wave's frequency. Radar guns can be hand-held, vehicle mounted or statically mounted.
Radar detectors use a superheterodyne receiver to detect these electromagnetic emissions from the radar gun, and raise an alarm to notify the motorist when a transmission is detected. False alarms can occur however due to the large number of devices, such as automatic door openers, that operate in the same part of the electromagnetic spectrum as radar guns.

Counter technology
Radar guns and detectors have evolved alternately over time to counter each other's technology in a form of civilian electronic "warfare". For example, as new frequencies have been introduced, radar detectors have initially been "blind" to them until their technology too has been updated. Similarly, the length of time and strength of the transmissions have been lowered to reduce the chance of detection, which in turn has resulted in more sensitive receivers and more sophisticated software counter technology. Lastly, radar detectors may combine other technologies, such as GPS-based technology with a point of interest database of known speed trapping locations, into a single device to improve their chances of success.

Radar Detector Detectors
Main article: Radar detector detector
The superheterodyne receiver in radar detectors have a local oscillator that radiates slightly, so it is possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz). The VG-2 Interceptor was the first device developed for this purpose, but has since been eclipsed by the Spectre III. This form of "electronic warfare" cuts both ways - since detector-detectors use a similar superheterodyne receiver, many early "stealth" radar detectors were equipped with a radar-detector-detector-detector circuit, which shuts down the main radar receiver when the detector-detector's signal is sensed, thus preventing detection by such equipment. This technique borrows from ELINT surveillance countermeasures. In the early 1990s, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor. This resulted in detector manufacturers responding by changing their local oscillator frequency. Today, practically every radar detector on the market is immune to the VG-2 Interceptor.

Radar Scrambling
Although some companies advertise that their radar detectors can passively 'scramble' or 'absorb' radar (such as Rocky Mountain Radar), many or all of their products do not affect radar and laser equipment due to the low power intake from the device versus the high power that bounces off a vehicle.
It is illegal in many countries to sell or possess any products that actively transmit radar signals intended to jam radar equipment.Actively transmitting on an FCC licensed frequency without a license is a violation of FCC regulations and a felony in the USA.

LIDAR Detection
Main article: LIDAR detector
Newer speed detection devices use pulsed laser light, commonly referred to as LIDAR, rather than radio waves. Radar detectors, which detect radio transmissions, are therefore unable to detect the infrared light emitted by LIDAR guns so a different type of device called a LIDAR detector is required. LIDAR detection, however, is not nearly as effective as radar detection because the output beam is very focused. While radar's radio waves can expand to 85 feet (26 m) across at 1,000 feet (300 m) from their source, LIDAR's light beam diffuses to only about 6 feet (1.8 m). Also, a police officer targeting a car will most likely aim for the center mass or headlight of the vehicle and, because radar detectors are mounted on the windshield away from the beam's aim, they may not alert at all. Lastly, with such a focused beam, an officer using a LIDAR gun can target a single car in close proximity to others at ranges of up to 3,000 feet (910 m).
Despite the advent of LIDAR speed detection, radar remains more prevalent because of its lower price relative to LIDAR equipment and the amount of radar equipment already in service.

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Pulse detonation engine

2008-12-09T06:40:00.000-08:00

Concept
All regular jet engines and most rocket engines operate on the deflagration of fuel, that is, the rapid but subsonic combustion of fuel. The pulse detonation engine is a concept currently in active development to create a jet engine that operates on the supersonic detonation of fuel.
The basic operation of the PDE is similar to that of the pulse jet engine; air is mixed with fuel to create a flammable mixture that is then ignited. The resulting combustion greatly increases the pressure of the mixture to approximately 100 atmospheres,which then expands through a nozzle for thrust. To ensure that the mixture exits to the rear, thereby pushing the aircraft forward, a series of shutters are used to close off the front of the engine. Careful tuning of the inlet ensures the shutters close at the right time to force the air to travel in one direction only through the engine.
The main difference between a PDE and a traditional pulsejet is that the mixture does not undergo subsonic combustion but instead, supersonic detonation. In the PDE, the oxygen and fuel combination process is supersonic, effectively an explosion instead of burning. The other difference is that the shutters are replaced by more sophisticated valves. In some PDE designs from General Electric, the shutters are eliminated through careful timing, using the pressure differences between the different areas of the engine to ensure the "shot" is ejected rearward.
The main side effect of the change in cycle is that the PDE is considerably more efficient. In the pulsejet the combustion pushes a considerable amount of the fuel/air mix (the charge) out the rear of the engine before it has had a chance to burn (thus the trail of flame seen on the V-1 flying bomb). Even while inside the engine the mixture's volume is continually changing, which is an inefficient way to burn fuel. In contrast the PDE deliberately uses a high-speed combustion process that burns all of the charge while it is still inside the engine at a constant volume. This increases the burn efficiency, i.e. the amount of heat produced per unit of fuel, above any other engines, although conversion of that energy into thrust remains inefficient.
Another side effect, not yet demonstrated in practical use, is the cycle time. A traditional pulsejet tops out at about 250 pulses per second due to the cycle time of the mechanical shutters, but the aim of the PDE is thousands of pulses per second, so fast that it is basically continual from an engineering perspective. This should help smooth out the otherwise highly vibrational pulsejet engine – many small pulses will create less volume than a smaller number of larger ones for the same net thrust. Unfortunately, detonations are many times louder than deflagrations.
The major difficulty with a pulse-detonation engine is starting the detonation. While it is possible to start a detonation directly with a large spark, the amount of energy input is very large and is not practical for an engine. The typical solution is to use a deflagration-to-detonation transition (DDT) - that is, start a high-energy deflagration, and have it accelerate down a tube to the point where it becomes fast enough to become a detonation. Alternatively the detonation can be sent around a circle and valves ensure that only the highest peak power can leak into exhaust.
This process is far more complicated than it sounds, due to the resistance the advancing wavefront encounters (similar to wave drag). DDTs occur far more readily if there are obstacles in the tube. The most widely used is the "Shchelkin spiral", which is designed to create the most useful eddies with the least resistance to the moving fuel/air/exhaust mixture. The eddies lead to the flame separating into multiple fronts, some of which go backwards and collide with other fronts, and then accelerate into fronts ahead of them.
The behavior is difficult to model and to predict, and research is ongoing. As with conventional pulsejets, there are two main types of designs: valved and valveless. Designs with valves encounter the same difficult-to-resolve wear issues encountered with their pulsejet equivalents. Valveless designs typically rely on abnormalities in the air flow to ensure a one-way flow, and are very hard to achieve a regular DDT in.
NASA maintains a research program on the PDE, which is aimed at high-speed, about Mach 5, civilian transport systems. However most PDE research is military in nature, as the engine could be used to develop a new generation of high-speed, long-range reconnaissance aircraft that would fly high enough to be out of range of any current anti-aircraft defenses, while offering range considerably greater than the SR-71, which required a massive tanker support fleet to use in operation.
While most research is on the high speed regime, newer designs with much higher pulse rates in the hundreds of thousands appear to work well even at subsonic speeds. Whereas traditional engine designs always include tradeoffs that limit them to a "best speed" range, the PDE appears to outperform them at all speeds. Both Pratt & Whitney and General Electric now have active PDE research programs in an attempt to commercialize the designs.
Key difficulties in pulse detonation engines are achieving DDT without requiring a tube long enough to make it impractical and drag-imposing on the aircraft; reducing the noise (often described as sounding like a jackhammer); and damping the severe vibration caused by the operation of the engine.

First PDE powered flight

In-flight picture of the heavily modified pulsed detonation aircraft on January 31, 2008.
The first flight of an aircraft powered by a pulse detonation engine took place at the Mojave Air & Space Port on January 31, 2008.The project was developed by the Air Force Research Laboratory and Innovative Scientific Solutions, Inc. The aircraft selected for the flight was a heavily modified Scaled Composites Long-EZ, named Borealis.The engine consisted of four tubes producing pulse detonations at a frequency of 80 Hz, creating up to 200 pounds of thrust. Many fuels were considered and tested by the engine developers in recent years, but a refined Octane was used for this flight. A small rocket system was used to facilitate the liftoff of the Long-EZ, but the PDE operated under its own power for 10 seconds at an altitude of approximately 100 feet. Obviously, this flight took place at a low speed whereas the appeal of the PDE engine concept lies more at high speeds, but the demonstration showed that a PDE can be integrated into an aircraft frame without experiencing structural problems from the 195-200 dB detonation waves. No more flights are planned for the modified Long-EZ, but the success is likely to fuel more funding for PDE research. The aircraft itself has been moved to the National Museum of the United States Air Force for display

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Turboprop

2008-12-09T06:37:00.000-08:00

Technological aspects

Polish turboprop, single engine, two seat trainer PZL-130 Orlik TC-I of Orlik Aerobatic Team
In a turboprop, much of the jet thrust is sacrificed in favor of shaft power, which is obtained by extracting additional power (to that necessary to drive the compressor) from the turbine expansion process. While the power turbine may be integral with the gas generator section, many turboprops today feature a free power turbine, on a separate coaxial shaft. This enables the propeller to rotate freely, independent of compressor speed. Owing to the additional expansion in the turbine system, the residual energy in the exhaust jet is low. Consequently, the exhaust jet produces (typically) less than 10% of the total thrust.
Because the propeller is much larger in diameter than the power turbine, the tip speed of the propeller can become supersonic. To prevent this, a speed reduction gearbox is inserted between the power turbine and propeller shafts. The gearbox is part of the engine, whereas in a turboshaft the (helicopter) rotor reduction gearbox is remote from the engine.
Residual thrust on a turboshaft is avoided by further expansion in the turbine system and/or truncating and turning the exhaust through 180 degrees, to produce two opposing jets. Apart from the above, there is very little difference between a turboprop and a turboshaft.
While most modern turbojet and turbofan engines use axial-flow compressors, turboprop engines usually contain at least one stage of centrifugal compression. Centrifugal compressors have the advantage of being simple and lightweight, at the expense of a streamlined shape.

Twin turboprop ATR 72 of Aerocaribbean airlines
Propellers lose efficiency as aircraft speed increases, so turboprops are normally not used on high-speed aircraft. However, propfan engines, which are very similar to turboprop engines, can cruise at flight speeds approaching Mach 0.75. To increase the efficiency of the propellers, a mechanism can be used to alter the pitch, thus adjusting the pitch to the airspeed. The variable pitch propeller, also called controllable pitch propeller, can also be used to generate negative thrust while decelerating on the runway. After an engine outage, the pitch can be adjusted to a vaning pitch (called feathering), thus minimizing the drag of the non-functioning propeller.
Some commercial aircraft with turboprop engines include the Bombardier Dash 8, ATR 42, ATR 72, BAe Jetstream 31, Embraer EMB 120 Brasilia, The Fairchild Swearingen Metroliner, and Saab 340 and 2000.

History

A Rolls-Royce RB.50 Trent on a test rig at Hucknall, in March 1945
The world's first turboprop was the Jendrassik Cs-1, designed by the Hungarian mechanical engineer György Jendrassik. It was produced and tested in the Ganz factory in Budapest between 1939 and 1942. It was planned to fit to the Varga RMI-1 X/H twin-engined reconnaissance bomber designed by László Varga in 1940, but the program was cancelled. Jendrassik had also designed a small-scale 75 kW turboprop in 1937.
The first British turboprop engine was the Rolls-Royce RB.50 Trent, a converted Derwent II fitted with reduction gear and a Rotol 7-ft, 11-in five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 — the sole "Trent-Meteor" — which thus became the world's first turboprop powered aircraft, albeit a test-bed not intended for production It first flew on 20th September 1945. From their experience with the Trent, Rolls-Royce developed the Dart, which became one of the most reliable turboprop engines ever built. Dart production continued for more than fifty years. The Dart-powered Vickers Viscount was the first turboprop aircraft of any kind to go into production and sold in large numbers It was also the first four-engined turboprop. Its first flight was on 16th July 1948. The world's first single engined turboprop aircraft was the Armstrong Siddeley Mamba-powered Boulton Paul Balliol, which first flew on 24th March 1948
While the Soviet Union had the technology to create a jet-powered strategic bomber comparable to Boeing's B-52 Stratofortress, they instead produced the Tu-95 "Bear", powered with four Kuznetsov NK-12 turboprops, mated to eight contra-rotating propellers (two per nacelle) with supersonic tip speeds to achieve maximum cruise speeds in excess of 575 mph, faster than many of the first jet aircraft and comparable to jet cruising speeds for most missions. The Bear would serve as their most successful long-range combat and surveillance aircraft and symbol of Soviet power projection throughout the end of the 20th century. The USA would incorporate contra-rotating turboprop engines, such as the ill-fated Allison T40, into a series of experimental aircraft during the 1950s, but none would be adopted into service.
The first American turboprop engine was the General Electric T31, first used in the sole experimental Convair YP-81 It first flew in December 1945, the first aircraft to use a combination of turboprop and turbojet power. America skipped over turboprop airliners in favor of the Boeing 707, but the technology of the unsuccessful Lockheed Electra was used in both the long-lived P-3 Orion as well as the classic C-130 Hercules, one of the most successful military aircraft ever in terms of length of production. One of the most popular turboprop engines is the Pratt & Whitney Canada PT6 engine.
The first turbine powered, shaft driven helicopter was the Bell XH-13F, a version of the Bell 47 powered by Continental XT-51-T-3 (Turbomeca Artouste) engine

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Reciprocating engine

2008-12-09T06:35:00.000-08:00

History
The earliest known examples of rotary to reciprocating motion were the crankshaft-driven saqiya chain pump, and the waterwheel-powered preciprocating piston pump which were both engineered by the Arab inventor, Al-Jazari, in 1206. In one of his piston-pump engines, the rotary motion of the waterwheel was converted into a reciprocating action to drive a pair of piston pumps that provided fountains for the kings of the Turkish Artuqid dynasty.
The reciprocating engine developed in Europe during the 18th century, first as the atmospheric engine then later as the steam engine. These were followed by the Stirling engine and internal combustion engine in the 19th century. Today the most common form of reciprocating engine is the internal combustion engine running on the combustion of petrol, diesel or natural gas and used to power motor vehicles.
One of the most advanced reciprocating engines ever made was the 28-cylinder, 3,500 hp (2610 kW) Pratt & Whitney R-4360 "Wasp Major" radial engine which powered the last generation of large piston-engined planes before the jet engine and turboprop took over from 1944 onward. It had a total engine capacity of 71.5 litres (2.52 cu ft).
The largest reciprocating engine ever built is the Wärtsilä-Sulzer RTA96-C turbocharged two-stroke diesel engine of 2006 built by Japan’s Diesel United, Ltd. It is used to power the largest modern container ships such as the Emma Mærsk. It is five stories high (13.5 m/44 ft), 27 metres (89 ft) long, and weighs over 2,300 metric tons (2,500 short tons) in its largest 14 cylinders version producing more than 84.42MW (114,800 bhp). Each cylinder has a capacity of 1,820 litres (64 cu ft), making a total capacity of 25,480 litres (900 cu ft) for the largest versions.

[edit] Common features in all types
There may be one or more pistons. Each piston is inside a cylinder, into which a gas is introduced, either already hot and under pressure (steam engine), or heated inside the cylinder either by ignition of a fuel air mixture (internal combustion engine) or by contact with a hot heat exchanger in the cylinder (stirling engine). The hot gases expand, pushing the piston to the bottom of the cylinder. The piston is returned to the cylinder top (Top Dead Centre) either by a flywheel or the power from other pistons connected to the same shaft. In most types the expanded or "exhausted" gases are removed from the cylinder by this stroke. The exception is the Stirling engine, which repeatedly heats and cools the same sealed quantity of gas.
In some designs the piston may be powered in both directions in the cylinder in which case it is said to be double acting.

Steam piston engineA labeled schematic diagram of a typical single cylinder, simple expansion, double-acting high pressure steam engine. Power takeoff from the engine is by way of a belt.1 - Piston2 - Piston rod3 - Crosshead bearing4 - Connecting rod5 - Crank6 - Eccentric valve motion7 - Flywheel8 - Sliding valve9 - Centrifugal governor.
In all types the linear movement of the piston is converted to a rotating movement via a connecting rod and a crankshaft or by a swashplate. A flywheel is often used to ensure smooth rotation. The more cylinders a reciprocating engine has, generally, the more vibration-free (smoothly) it can operate. The power of a reciprocating engine is proportional to the volume of the combined pistons' displacement.
A seal needs to be made between the sliding piston and the walls of the cylinder so that the high pressure gas above the piston does not leak past it and reduce the efficiency of the engine. This seal is provided by one or more piston rings. These are rings made of a hard metal which are sprung into a circular grove in the piston head. The rings fit tightly in the groove and press against the cyinder wall to form a seal.
It is common for such engines to be classified by the number and alignment of cylinders and the total volume of displacement of gas by the pistons moving in the cylinders usually measured in cubic centimetres (cm³ or cc) or litres (l) or (L) (US:liter). For example for internal combustion engines, single and two-cylinder designs are common in smaller vehicles such as motorcycles, while automobiles typically have between four and eight, and locomotives, and ships may have a dozen cylinders or more. Cylinder capacities may range from 10 cm³ or less in model engines up to several thousand cubic centimetres in ships' engines.
The compression ratio is a measure of the performance in an internal-combustion engine or a Stirling Engine. It is the ratio between the volume of the cylinder, when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke.
Cylinders may be aligned in line, in a V configuration, horizontally opposite each other , or radially around the crankshaft. Opposed piston engines put 2 pistons working at opposite ends of the same cylinder and this has been extended into triangular arrangements such as the Napier Deltic. Some designs have set the cylinders in motion around the shaft, see the Rotary engine.

Stirling piston engineRhombic Drive Beta Stirling Engine Design showing the second displacer piston (green) within the cylinder which shunts the working gas between the hot and cold ends , but produces no power itself.Pink - Hot cylinder wall,Dark grey - Cold cylinder wall,Green - Displacer piston,Dark blue - Power piston,Light blue - Flywheels
In steam engines and internal combustion engines valves are required to allow the entry and exit of gasses at the correct time in the piston's cycle. These are worked by cams or cranks driven by the shaft of the engine. Early designs used the D slide valve but this has been largely superseded by Piston valve or Poppet valve designs.
Internal combustion engines operate through a sequence of strokes which admit and remove gases to and from the cylinder. These operations are repeated cyclically and an engine is said to be 2-stroke, 4-stroke or 6-stroke depending on the number of strokes it takes to complete a cycle.
In some steam engines the cylinders may be of varying size with the smallest bore cylinder working the highest pressure steam. This is then fed through one or more, increasingly larger bore cylinders successively, to extract power from the steam at increasingly lower pressures. These engines are called Compound engines.

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Jet engine

2008-12-09T06:32:00.000-08:00

History
See also: Timeline of jet power
Jet engines can be dated back to the first century AD, when Hero of Alexandria (a Phoenician) invented the aeolipile. This used steam power directed through two jet nozzles so as to cause a sphere to spin rapidly on its axis. So far as is known, it was little used for supplying mechanical power, and the potential practical applications of Hero's invention of the jet engine were not recognized. It was simply considered a curiosity.
Jet propulsion only literally and figuratively took off with the invention of the rocket by the Chinese in the 13th century. Rocket exhaust was initially used in a modest way for fireworks but gradually progressed to propel formidable weaponry; and there the technology stalled for hundreds of years.
In Ottoman Turkey in 1633 Lagari Hasan Çelebi took off with what was described to be a cone shaped rocket and then glided with wings into a successful landing winning a position in the Ottoman army. However, this was essentially a stunt.
The problem was that rockets are simply too inefficient at low speeds to be useful for general aviation. In 1913 René Lorin came up with a form of jet engine, the subsonic ramjet, which would have been somewhat more efficient, but he had no way to achieve high enough speeds for it to operate, and the concept remained theoretical for quite some time.
However, engineers were beginning to realize that the piston engine was self-limiting in terms of the maximum performance which could be attained; the limit was essentially one of propeller efficiency This seemed to peak as blade tips approached the speed of sound. If engine, and thus aircraft, performance were ever to increase beyond such a barrier, a way would have to be found to radically improve the design of the piston engine, or a wholly new type of powerplant would have to be developed. This was the motivation behind the development of the gas turbine engine, commonly called a "jet" engine, which would become almost as revolutionary to aviation as the Wright brothers' first flight.
The earliest attempts at jet engines were hybrid designs in which an external power source first compressed air, which was then mixed with fuel and burned for jet thrust. In one such system, called a thermojet by Secondo Campini but more commonly, motorjet, the air was compressed by a fan driven by a conventional piston engine. Examples of this type of design were Henri Coandă's Coandă-1910 aircraft, and the much later Campini Caproni CC.2, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II. None were entirely successful and the CC.2 ended up being slower than the same design with a traditional engine and propeller combination.
The key to a practical jet engine was the gas turbine, used to extract energy from the engine itself to drive the compressor. The gas turbine was not an idea developed in the 1930s: the patent for a stationary turbine was granted to John Barber in England in 1791. The first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture. The main problems were safety, reliability, weight and, especially, sustained operation.
In Hungary, Albert Fonó In 1915 devised a solution for increasing the range of artillery, comprising a gun-launched projectile which was to be united with a ramjet propulsion unit. This was to make it possible to obtain a long range with low initial muzzle velocities, allowing heavy shells to be fired from relatively lightweight guns. Fonó submitted his invention to the Austro-Hungarian Army but the proposal was rejected. In 1928 he applied for a German patent on aircraft powered by supersonic ramjets, and this was awarded in 1932
The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume. His engine was an axial-flow turbojet.
In 1923, Edgar Buckingham of the US National Bureau of Standard published a report expressing scepticism that jet engines would be economically competitive with prop driven aircraft at the low altitudes and airspeeds of the period: "there does not appear to be, at present, any prospect whatever that jet propulsion of the sort here considered will ever be of practical value, even for military purposes."
Instead, by the 1930s, the piston engine in its many different forms (rotary and static radial, aircooled and liquid-cooled inline) was the only type of powerplant available to aircraft designers. This was acceptable as long as only low performance aircraft were required, and indeed all that were available.

The Whittle W.2/700 engine flew in the Gloster E.28/39, the first British aircraft to fly with a turbojet engine, and the Gloster Meteor
In 1928, RAF College Cranwell cadet Frank Whittle formally submitted his ideas for a turbo-jet to his superiors. In October 1929 he developed his ideas further.. On 16 January 1930 in England, Whittle submitted his first patent (granted in 1932).The patent showed a two-stage axial compressor feeding a single-sided centrifugal compressor. Practical axial compressors were made possible by ideas from A.A.Griffith in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Whittle would later concentrate on the simpler centrifugal compressor only, for a variety of practical reasons. Whittle had his first engine running in April 1937. It was liquid-fuelled, and included a self-contained fuel pump. Whittle's team experienced near-panic when the engine would not stop, accelerating even after the fuel was switched off. It turned out that fuel had leaked into the engine and accumulated in pools. So the engine would not stop until all the leaked fuel had burned off. Whittle was unable to interest the government in his invention, and development continued at a slow pace.

Heinkel He 178, the world's first aircraft to fly purely on turbojet power
In 1935 Hans von Ohain started work on a similar design in Germany, apparently unaware of Whittle's work.His first engine was strictly experimental and could only run under external power, but he was able to demonstrate the basic concept. Ohain was then introduced to Ernst Heinkel, one of the larger aircraft industrialists of the day, who immediately saw the promise of the design. Heinkel had recently purchased the Hirth engine company, and Ohain and his master machinist Max Hahn were set up there as a new division of the Hirth company. They had their first HeS 1 centrifugal engine running by September 1937. Unlike Whittle's design, Ohain used hydrogen as fuel, supplied under external pressure. Their subsequent designs culminated in the gasoline-fuelled HeS 3 of 1,100 lbf (5 kN), which was fitted to Heinkel's simple and compact He 178 airframe and flown by Erich Warsitz in the early morning of August 27, 1939, from Rostock-Marienehe aerodrome, an impressively short time for development. The He 178 was the world's first jet plane.
The world's first turboprop was the Jendrassik Cs-1 designed by the Hungarian mechanical engineer György Jendrassik. It was produced and tested in the Ganz factory in Budapest between 1939 and 1942. It was planned to fit to the Varga RMI-1 X/H twin-engined reconnaissance bomber designed by László Varga in 1940, but the program was cancelled. Jendrassik had also designed a small-scale 75 kW turboprop in 1937. Whittle's engine was starting to look useful, and his Power Jets Ltd. started receiving Air Ministry money. In 1941 a flyable version of the engine called the W.1, capable of 1000 lbf (4 kN) of thrust, was fitted to the Gloster E28/39 airframe specially built for it, and first flew on May 15, 1941 at RAF Cranwell.

A picture of an early centrifugal engine (DH Goblin II) sectioned to show its internal components
A Scottish aircraft engine designer, Frank Halford, working from Whittle's ideas developed a "straight through" version of the centrifugal jet; his design became the de Havilland Goblin.
One problem with both of these early designs, which are called centrifugal-flow engines, was that the compressor worked by "throwing" (accelerating) air outward from the central intake to the outer periphery of the engine, where the air was then compressed by a divergent duct setup, converting its velocity into pressure. An advantage of this design was that it was already well understood, having been implemented in centrifugal superchargers, then in widespread use on piston engines. However, given the early technological limitations on the shaft speed of the engine, the compressor needed to have a very large diameter to produce the power required. This meant that the engines had a large frontal area, which made it less useful as an aircraft powerplant due to drag. A further disadvantage was that the air flow had to be "bent" to flow rearwards through the combustion section and to the turbine and tailpipe, adding complexity and lowering efficiency. Nevertheless, these types of engines had the major advantages of light weight, simplicity and reliability, and development rapidly progressed to practical airworthy designs.

A cutaway of the Junkers Jumo 004 engine.
Austrian Anselm Franz of Junkers' engine division (Junkers Motoren or Jumo) addressed these problems with the introduction of the axial-flow compressor. Essentially, this is a turbine in reverse. Air coming in the front of the engine is blown towards the rear of the engine by a fan stage (convergent ducts), where it is crushed against a set of non-rotating blades called stators (divergent ducts). The process is nowhere near as powerful as the centrifugal compressor, so a number of these pairs of fans and stators are placed in series to get the needed compression. Even with all the added complexity, the resulting engine is much smaller in diameter and thus, more aerodynamic. Jumo was assigned the next engine number in the RLM numbering sequence, 4, and the result was the Jumo 004 engine. After many lesser technical difficulties were solved, mass production of this engine started in 1944 as a powerplant for the world's first jet-fighter aircraft, the Messerschmitt Me 262 (and later the world's first jet-bomber aircraft, the Arado Ar 234). A variety of reasons conspired to delay the engine's availability, this delay caused the fighter to arrive too late to decisively impact Germany's position in World War II. Nonetheless, it will be remembered as the first use of jet engines in service.
In the UK, their first axial-flow engine, the Metrovick F.2, ran in 1941 and was first flown in 1943. Although more powerful than the centrifugal designs at the time, the Ministry considered its complexity and unreliability a drawback in wartime. The work at Metrovick led to the Armstrong Siddeley Sapphire engine which would be built in the US as the J65.
Following the end of the war the German jet aircraft and jet engines were extensively studied by the victorious allies and contributed to work on early Soviet and US jet fighters. The legacy of the axial-flow engine is seen in the fact that practically all jet engines on fixed wing aircraft have had some inspiration from this design.
Centrifugal-flow engines have improved since their introduction. With improvements in bearing technology the shaft speed of the engine was increased, greatly reducing the diameter of the centrifugal compressor. The short engine length remains an advantage of this design, particularly for use in helicopters where overall size is more important than frontal area. Also as their engine components are more robust they are less liable to foreign object damage than axial-flow compressor engines.
Although German designs were more advanced aerodynamically, the combination of simplicity and advanced British metallurgy meant that Whittle-derived designs were far more reliable than their German counterparts. British engines also were licensed widely in the US (see Tizard Mission),and were sold to the USSR who reverse engineered them with the Nene going on to power the famous MiG-15. American and Soviet designs, independent axial-flow types for the most part, would not come fully into their own until the 1960s, although the General Electric J47 provided excellent service in the F-86 Sabre in the 1950s.
By the 1950s the jet engine was almost universal in combat aircraft, with the exception of cargo, liaison and other specialty types. By this point some of the British designs were already cleared for civilian use, and had appeared on early models like the de Havilland Comet and Avro Canada Jetliner. By the 1960s all large civilian aircraft were also jet powered, leaving the piston engine in niche roles here as well.
Relentless improvements in the turboprop pushed the piston engine out of the mainstream entirely, leaving it serving only the smallest general aviation designs, and some use in drone aircraft. The ascension of the jet engine to almost universal use in aircraft took well under twenty years.
However, the story was not quite at an end, for the efficiency of turbojet engines was still rather worse than piston engines, but by the 1970s with the advent of high bypass jet engines, an innovation not foreseen by the early commentators like Edgar Buckingham, at high speeds and high altitudes that seemed absurd to them, only then did the fuel efficiency finally exceed that of the best piston and propeller engines, and the dream of fast, safe, economical travel around the world finally arrived, and their dour, if well founded for the time, predictions that jet engines would never amount to much, were killed forever.

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Gas turbine

2008-12-09T06:29:00.000-08:00

Theory of operation
Gas turbines are described thermodynamically by the Brayton cycle, in which air is compressed isentropically, combustion occurs at constant pressure, and expansion over the turbine occurs isentropically back to the starting pressure.
In practice, friction, and turbulence cause:
non-isentropic compression: for a given overall pressure ratio, the compressor delivery temperature is higher than ideal.
non-isentropic expansion: although the turbine temperature drop necessary to drive the compressor is unaffected, the associated pressure ratio is greater, which decreases the expansion available to provide useful work.
pressure losses in the air intake, combustor and exhaust: reduces the expansion available to provide useful work.

Brayton cycle
As with all cyclic heat engines, higher combustion temperature means greater efficiency. The limiting factor is the ability of the steel, nickel, ceramic, or other materials that make up the engine to withstand heat and pressure. Considerable engineering goes into keeping the turbine parts cool. Most turbines also try to recover exhaust heat, which otherwise is wasted energy. Recuperators are heat exchangers that pass exhaust heat to the compressed air, prior to combustion. Combined cycle designs pass waste heat to steam turbine systems. And combined heat and power (co-generation) uses waste heat for hot water production.
Mechanically, gas turbines can be considerably less complex than internal combustion piston engines. Simple turbines might have one moving part: the shaft/compressor/turbine/alternative-rotor assembly (see image above), not counting the fuel system.
More sophisticated turbines (such as those found in modern jet engines) may have multiple shafts (spools), hundreds of turbine blades, movable stator blades, and a vast system of complex piping, combustors and heat exchangers.
As a general rule, the smaller the engine the higher the rotation rate of the shaft(s) needs to be to maintain top speed. Turbine blade top speed determines the maximum pressure that can be gained,this produces the maximum power possible independent of the size of the engine. Jet engines operate around 10,000 rpm and micro turbines around 100,000 rpm.
Thrust bearings and journal bearings are a critical part of design. Traditionally, they have been hydrodynamic oil bearings, or oil-cooled ball bearings. These bearings are being surpassed by foil bearings, which have been successfully used in micro turbines and auxiliary power units.

Types of gas turbines

Aeroderivatives and jet engines

Diagram of a gas turbine jet engine
Airbreathing jet engines are gas turbines optimized to produce thrust from the exhaust gases, or from ducted fans connected to the gas turbines. Jet engines that produce thrust primarily from the direct impulse of exhaust gases are often called turbojets, whereas those that generate most of their thrust from the action of a ducted fan are often called turbofans or (rarely) fan-jets.
Gas turbines are also used in many liquid propellant rockets, the gas turbines are used to power a turbopump to permit the use of lightweight, low pressure tanks, which saves considerable dry mass.
Aeroderivatives are also used in electical power generation due to their ability to startup, shut down, and handle load changes more quickly than industrial machines. They are also used in the marine industry to reduce weight. The GE LM2500 and LM6000 are two common models of this type of machine.
Amateur gas turbines A popular hobby is to construct a gas turbine from an automotive turbocharger. A combustion chamber is fabricated and plumbed between the compressor and turbine. Like many technology based hobbies, they tend to give rise to manufacturing businesses over time. Several small companies manufacture small turbines and parts for the amateur. See external links for resources.

Auxiliary power units
Auxiliary power units (APUs) are small gas turbines designed for auxiliary power of larger machines, such as those inside an aircraft. They supply compressed air for aircraft ventilation (with an appropriate compressor design), start-up power for larger jet engines, and electrical and hydraulic power.

Industrial gas turbines for electrical generation

GE H series power generation gas turbine. This 480-megawatt unit has a rated thermal efficiency of 60% in combined cycle configurations.
Industrial gas turbines differ from aeroderivatave in that the frames, bearings, and blading is of heavier construction. Industrial gas turbines range in size from truck-mounted mobile plants to enormous, complex systems. They can be particularly efficient——up to 60%——when waste heat from the gas turbine is recovered by a heat recovery steam generator to power a conventional steam turbine in a combined cycle configuration. They can also be run in a cogeneration configuration: the exhaust is used for space or water heating, or drives an absorption chiller for cooling or refrigeration. A cogeneration configuration can be over 90% efficient. The power turbines in the largest industrial gas turbines operate at 3,000 or 3,600 rpm to match the AC power grid frequency and to avoid the need for a reduction gearbox. Such engines require a dedicated enclosure, both to protect the engine from the elements and the operators from the noise.
Simple cycle gas turbines in the power industry require smaller capital investment than either coal or nuclear power plants and can be scaled to generate small or large amounts of power. Also, the actual construction process can take as little as several weeks to a few months, compared to years for base load power plants. Their other main advantage is the ability to be turned on and off within minutes, supplying power during peak demand. Because they are less efficient than combined cycle plants, they are usually used as peaking power plants, which operate anywhere from several hours per day to a couple dozen hours per year, depending on the electricity demand and the generating capacity of the region. In areas with a shortage of base load and load following power plant capacity, a gas turbine power plant may regularly operate during most hours of the day and even into the evening. A typical large simple cycle gas turbine may produce 100 to 300 megawatts of power and have 35–40% thermal efficiency. The most efficient turbines have reached 46% efficiency.

Compressed air energy storage
Main article: Compressed air energy storage
One modern development seeks to improve efficiency in another way, by separating the compressor and the turbine with a compressed air store. In a conventional turbine, up to half the generated power is used driving the compressor. In a compressed air energy storage configuration, power, perhaps from a wind farm or bought on the open market at a time of low demand and low price, is used to drive the compressor, and the compressed air released to operate the turbine when required.

Turboshaft engines
Turboshaft engines are often used to drive compression trains (for example in gas pumping stations or natural gas liquefaction plants) and are used to power almost all modern helicopters. The first shaft bears the compressor and the high speed turbine (often referred to as "Gas Generator" or "N1"), while the second shaft bears the low speed turbine (or "Power Turbine" or "N2"). This arrangement is used to increase speed and power output flexibility.

Radial gas turbines
Main article: Radial turbine
1963, Norway, Jan Mowill initiated the development at Kongsberg Våpenfabrikk. Various successors have made good progress in the refinement of this mechanism. Owing to a configuration that keeps heat away from certain bearings the durability of the machine is improved while the radial turbine is well matched in speed requirement

Scale jet engines

Scale jet engines are scaled down versions of this early full scale engine
Also known as miniature gas turbines or micro-jets.
Many model engineers relish the challenge of re-creating the grand engineering feats of today as tiny working models. Naturally, the idea of re-creating a powerful engine such as the jet, fascinated hobbyists since the very first full size engines were powered up by Hans von Ohain and Frank Whittle back in the 1930s.
Recreating machines such as engines to a different scale is not easy. Because of the square-cube law, the behaviour of many machines does not always scale up or down at the same rate as the machine's size (and often not even in a linear way), usually at best causing a dramatic loss of power or efficiency, and at worst causing them not to work at all. An automobile engine, for example, will not work if reproduced in the same shape at the size of a human hand.
With this in mind the pioneer of modern Micro-Jets, Kurt Schreckling, produced one of the world's first Micro-Turbines, the FD3/67 This engine can produce up to 22 newtons of thrust, and can be built by most mechanically minded people with basic engineering tools, such as a metal lathe. Its radial compressor, which is cold, is small and the hot axial turbine is large experiencing more centrifugal forces, meaning that this design is limited by Mach number. Guiding vanes are used to hold the starter, after the compressor impeller and before the turbine. No bypass within the engine is used.

Microturbines

A micro turbine designed for DARPA by M-Dot
Also known as:
Turbo alternators
MicroTurbine (registered trademark of Capstone Turbine Corporation)
Turbogenerator (registered tradename of Honeywell Power Systems, Inc.)
Microturbines are becoming widespread for distributed power and combined heat and power applications. They are one of the most promising technologies for powering hybrid electric vehicles. They range from hand held units producing less than a kilowatt, to commercial sized systems that produce tens or hundreds of kilowatts.
Part of their success is due to advances in electronics, which allows unattended operation and interfacing with the commercial power grid. Electronic power switching technology eliminates the need for the generator to be synchronized with the power grid. This allows the generator to be integrated with the turbine shaft, and to double as the starter motor.
Microturbine systems have many advantages over reciprocating engine generators, such as higher power density (with respect to footprint and weight), extremely low emissions and few, or just one, moving part. Those designed with foil bearings and air-cooling operate without oil, coolants or other hazardous materials. Microturbines also have the advantage of having the majority of their waste heat contained in their relatively high temperature exhaust, whereas the waste heat of recriprocating engines is split between its exhaust and cooling system.However, reciprocating engine generators are quicker to respond to changes in output power requirement and are usually slightly more efficient, although the efficiency of microturbines is increasing. Microturbines also lose more efficiency at low power levels than reciprocating engines.
They accept most commercial fuels, such as gasoline, natural gas, propane, diesel, and kerosene as well as renewable fuels such as E85, biodiesel and biogas.
Microturbine designs usually consist of a single stage radial compressor, a single stage radial turbine and a recuperator. Recuperators are difficult to design and manufacture because they operate under high pressure and temperature differentials. Exhaust heat can be used for water heating, space heating, drying processes or absorption chillers, which create cold for air conditioning from heat energy instead of electric energy.
Typical microturbine efficiencies are 25 to 35%. When in a combined heat and power cogeneration system, efficiencies of greater than 80% are commonly achieved.
MIT started its millimeter size turbine engine project in the middle of the 1990s when Professor of Aeronautics and Astronautics Alan H. Epstein considered the possibility of creating a personal turbine which will be able to meet all the demands of a modern person's electrical needs, just like a large turbine can meet the electricity demands of a small city. According to Professor Epstein current commercial Li-ion rechargeable batteries deliver about 120-150 Wh/kg. MIT's millimeter size turbine will deliver 500-700 Wh/kg in the near term, rising to 1200-1500 Wh/kg in the longer term

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Engine

2008-12-09T06:26:00.000-08:00

Modern

Animation showing the four stages of the 4-stroke combustion engine cycle:1. Induction (Fuel enters)2. Compression3. Ignition (Fuel is burnt)4. Emission (Exhaust out)
English inventor Sir Samuel Morland allegedly used gunpowder to drive water pumps in the 17th century. For more conventional, reciprocating internal combustion engines, the fundamental theory for two-stroke engines was established by Sadi Carnot, France, 1824, whilst the American Samuel Morey received a patent on April 1, 1826. Sir Dugald Clark (1854 – 1932) designed the first two-stroke engine in 1878 and patented it in England in 1881. Automotive production has used a range of energy-conversion systems. These include electric, steam, solar, turbine, rotary, and piston-type internal combustion engines. The petrol internal combustion engine, operating on a four-stroke Otto cycle, has been the most successful for automobiles, while diesel engines are used for trucks and buses. Karl Benz was one of the leaders in the development of new engines. In 1878 he began to work on new designs. He concentrated his efforts on creating a reliable gas two-stroke engine that was more powerful, based on Nikolaus Otto's design of the four-stroke engine. Karl Benz showed his real genius, however, through his successive inventions registered while designing what would become the production standard for his two-stroke engine. Benz was granted a patent for it in 1879.
In 1896, Karl Benz was granted a patent for his design of the first engine with horizontally-opposed pistons. Many BMW motorcycles use this engine type. His design created an engine in which the corresponding pistons move in horizontal cylinders and reach top dead center simultaneously, thus automatically balancing each other with respect to their individual momentums. Engines of this design are often referred to as flat engines because of their shape and lower profile. They must have an even number of cylinders and six, four or two cylinder flat engines have all been common. The most well-known engine of this type is probably the Volkswagen beetle engine. Engines of this type continue to be a common design principle for high performance aero engines (for propellor driven aircraft) and, engines used by automobile producers such as Porsche and Subaru.
Continuance of the use of the internal combustion engine for automobiles is partly due to the improvement of engine control systems (onboard computers providing engine management processes, and electronically controlled fuel injection). Forced air induction by turbocharging and supercharging have increased power outputs and efficiencies available. Similar changes have been applied to smaller diesel engines giving them almost the same power characteristics as petrol engines. This is especially evident with the popularity of smaller diesel engine propelled cars in Europe. Larger diesel engines are still often used in trucks and heavy machinery. They do not burn as clean as gasoline engines, however they have far more torque. The internal combustion engine was originally selected for the automobile due to its flexibility over a wide range of speeds. Also, the power developed for a given weight engine was reasonable; it could be produced by economical mass-production methods; and it used a readily available, moderately priced fuel - petrol.

Mercedes V6 engine in 1996

School model of engine

School model of an engine
There has been a growing emphasis on the pollution producing features of automotive power systems. This has created new interest in alternate power sources and internal-combustion engine refinements. Although a few limited-production battery-powered electric vehicles have appeared, they have not proved to be competitive owing to costs and operating characteristics. In the twenty-first century the diesel engine has been increasing in popularity with automobile owners. However, the gasoline engine, with its new emission-control devices to improve emission performance, has not yet been significantly challenged.
The first half of the twentieth century saw a trend to increasing engine power, particularly in the American models. Design changes incorporated all known methods of raising engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the speed at which power is generated. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements. In passenger cars, V-8 layouts were adopted for all piston displacements greater than 250 cubic inches (4 litres).
The design principles favoured in Europe, because of economic and other restraints such as smaller and twistier roads, leant toward smaller cars and corresponding design principles that concentrated on increasing the combustion efficiency of smaller engines. This produced more economical engines with earlier four-cylinder designs rated at 40 horsepower (30 kW) and six-cylinder designs rated as low as 80 horsepower (60 kW), compared with the large volume V-8 American engines with power ratings in the range from 250 to 350 hp (190 to 260 kW).
Earlier automobile engine development produced a much larger range of engines than is in common use today. Engines have ranged from 1 to 16 cylinder designs with corresponding differences in overall size, weight, piston displacement, and cylinder bores. Four cylinders and power ratings from 19 to 120 hp (14 to 90 kW) were followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead camshafts were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and '80s saw an increased interest in improved fuel economy which brought in a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency. The Bugatti Veyron 16.4 operates with a W16 engine meaning that two V8 cylinder layouts are positioned next to each other to create the W shape.
The largest internal combustion engine ever built is the Wärtsilä-Sulzer RTA96-C, a 14-cylinder, 2-stroke turbocharged diesel engine that was designed to power the Emma Maersk, the largest container ship in the world. This engine weighs 2300 tonnes, and when running at 102 RPM produces 109,000 bhp (80,080 kW) consuming some 13.7 tonnes of fuel each hour.

auto meter speedometer

Utility Trailer Axles

automobile dvd player

Used Diesel Generator

mini utility truck

jeep oem part

gasoline pressure washer

motorcycle scissor lift

motorcycle handle bars

motorcycle tank cover

R C Motorcycle

Car Sticker Decal

automotive car lift

digital car compasses

Lego Mindstorms

2008-11-30T06:43:00.000-08:00

Robotics Invention System

RCX

First-generation RCX programmable brick.
The first generation of Lego Mindstorms was built around a brick known as the RCX. It contains a 8-Bit collision detector Renesas H8/300 microcontroller as its internal CPU.It also contains 32K of RAM that stores the Firmware and User Programs. The brick is programmed by downloading a program (written in one of several available programming languages) from a PC or Mac to the brick's RAM via a special infrared (IR) interface. After the user starts a program, an RCX-enabled Mindstorms creation may function totally on its own, acting on internal and external stimuli according to the programmed instructions. Also, two or several more RCX bricks can communicate with each other through the IR interface, enabling inter-brick cooperation or competition. In addition to the IR port, there are three sensor input ports and three motor output ports (also usable for lamps, etc). There is also an LCD that can display the battery level, the status of the input/output ports, which program is selected or running, and other information.
Version 1.0 RCX bricks feature a power adapter jack to allow continuous operation instead of the limited operation time when using batteries. In version 2.0 (as well as later 1.0s included in the RIS 1.5), the power adapter jack was removed. Power adapter-equipped RCX bricks are popular for stationary robotics projects (such as robot arms) or for controlling Lego model trains. In the latter context, the RCX needs to be programmed with Digital Command Control (DCC) software required for automated model train operation..
The IR interface on the RCX is able to communicate with Spybots, Scout Bricks, Lego Train, and the NXT (using a third-party infrared link sensor.) The RCX IR frequency is 38.5KHz which is generated by one of the RCX's internal timers.
All versions of the RCX have a unique number printed on it. Little is known about the reasoning behind this number, except for the use of technical support and as a ID number of the RCX for your Lego Mindstorms account on the now-defunct Lego Mindstorms RCX website.

Programming languages
Lego-supplied languages:
RCX Code (included in the Mindstorms consumer version sold at toystores)
ROBOLAB (based on LabVIEW and developed at Tufts University)
Popular third-party languages:
http://roboteq.sourceforge.net/ open source programming with graphical interface
C and C++ under BrickOS (formerly LegOS)
Java under leJOS or TinyVM
NQC ("Not Quite C")
pbFORTH (extensions to the Forth programming language)
pbLua (An NXT API for the Lua programming language)
Visual Basic (Through the COM+ interface supplied on the CD)
RobotC (New Language and NXT Compatible)
Interactive C (Language similar to C used in robotics competitions.)
XSLisp an implementation of Lisp for the RCX (1 + 2) and NXT

Lego camera
The Lego camera on its own is technically not a robotic toy; rather, it is a normal webcam (a Logitech Quickcam Web) packaged into a Lego shell. Being a normal webcam, the Lego Camera is, unlike most Mindstorms products, not programmable and is only usable connected to a PC or some other device that supports USB webcams.
The Lego camera is meant to be used with the included Vision Command software which can also interface with an RCX and thus enables creating robots with "vision". The software is capable of detecting different lightings, motion, and colors. It can also be used with any other software that uses a webcam. The webcam is capable of recording up to 30 frames per second. It also contains a microphone to record sound for videos.

Cybermaster

Lego Cybermaster
Cybermaster was mainly sold in Europe and Australia/New Zealand, but was available for a short time in America via the Lego Club magazines. It was aimed at a younger audience as an early attempt of merging computer gaming with robotics and Lego. The Pbrick shares many, especially software, features with the RCX but differs in appearance and technical specifications: 1 output (plus 2 built-in) and 3 sensors.
It uses RF (27 MHz R/C band) instead of IR for communication.
It has two built-in motors with integrated tachometers and speedometers.
It is limited to passive sensors (a simple A/D with internal pull-up resistors).
The sensors shipped with it are color coded and have internal resistors in their open state (allowing the Pbrick to sense which sensor is attached to which port).
It has a fixed firmware (so it cannot be upgraded or replaced).
It has limited RAM for programs and only one program slot.
Despite its obvious limitation it has a number of advantages over its 'big brother', the RCX.
The RF link has greater range and is omnidirectional.
The built-in tachometer and speedometer sensors on the internal motors provides the same function as the external rotation sensor to the RCX, but without using up sensor ports.
This makes it very useful for various mobile platforms and performing basic motion/positioning tasks.
It talks the same protocol as the RCX but cannot communicate directly to it (due to IR vs RF) but with a repeater (a computer with 2 serial ports and a simple program) they can be integrated.

Codepilot
Sold as part of the Barcode Truck kit. This unit was the first programmable brick (or Pbrick). It features a single motor, a single touch sensor and a light sensor. It is programmed by setting it to 'learn' and using the light sensor to feed barcoded commands. The command set is very limited. Since barcode is just a series of variances in light, this form of command entry was dubbed VLL (Visual Light Link) and has been used in several later Lego models.

Scout
Lego also released a blue computer called the Scout, which has 2 sensor ports, 2 motor ports, and a built in light sensor, but no PC interface. It comes with the Robotics Discovery Set. The Scout can be programmed from a collection of built-in program combinations. In order to program the Scout, a user must enable "power mode" on it. The Scout can store one program.
There was a plan for Lego to create a booster set that allows you to program the Scout from a computer with a software such as RCX code. However, due to the complexity of this project, it was abandoned.
The RCX can control the Scout brick using the "Send IR Message" program block. The RCX does all of the controlling, and therefore can be programmed with the PC, while the Scout accepts commands. The Scout brick must have all of its options set to "off".
The Scout is also capable of using VLL to control a Micro Scout.

Micro Scout
The Micro Scout was added as an entry level to Lego robotics. It is a very limited Pbrick with a single built-in light sensor and a single built-in motor. It has seven built-in programs and can be controlled by a Scout, Spybotics or RCX unit using VLL.
The unit was sold as part of the Droid Developer Kit (featuring R2D2) and later the Darkside Developer Kit (featuring an AT-AT Imperial Walker).

Spybotics
Main article: Lego Spybotics
Spybotics was more of an attempt to expand on the Cybermaster line. The kits were sold together with a computer game where part was played on the computer and part was played by controlling the Spybot to solve a number of fixed missions. The Pbrick itself shares many features with the Cybermaster, but it has no tachometers or speedometers and a single integrated touch sensor.
It also features a light sensor which doubles as computer interface. This interface can also be used to connect to the Scout, Micro Scout and possibly the Codepilot using VLL. It has an expanded IR functionality allowing it to communicate with other Spybots or RCX units. The IR unit also has limited direction and range function, allowing it to track and locate other Spybots, IR Remote Controls/beacons or RCX units.

Lego Mindstorms NXT
Main article: Lego Mindstorms NXT
Lego Mindstorms NXT is a programmable robotics kit released by Lego in July 2006, replacing the first-generation LEGO Mindstorms kit. The kit consists of 519 Technic pieces, 3 servo motors, 4 sensors (ultrasonic, sound, touch, and light), 7 wires, a USB cable, and the NXT brick. It also includes NXT-G, a graphical programming environment that enables the creation and downloading of programs to the NXT.
The NXT is the "brain" of a Mindstorms robot. This computer-controlled Lego brick lets the robot autonomously perform different operations.

fsa bicycle parts

PTZ Dome Camera

14 ibook battery

bronze marine hardware

countdown clock timer

aluminum oxide abrasive

tongkat ali extract

Glue Chip Glass

textile machinery spares

SNAP Lock Punch

Cardboard Counter Display

zoom stereo microscope

abb circuit breaker

Reverse Parking Sensor

digital thermometer waterproof

medical ozone generator

foil stamp machine

Car Wheel Balancer

Camcorder Uses

2008-11-30T06:40:00.000-08:00

Media

Operating a camcorder
Camcorders have found use in nearly all corners of electronic media, from electronic news organizations to TV/current-affairs productions. In locations away from a distribution infrastructure, camcorders are invaluable for initial video acquisition. Subsequently, the video is transmitted electronically to a studio/production center for broadcast. Scheduled events such as official press conferences, where a video infrastructure is readily available or can be feasibly deployed in advance, are still covered by studio-type video cameras (tethered to "production trucks.")

Home video
For casual use, camcorders often cover weddings, birthdays, graduation ceremonies, and other personal events. The rise of the consumer camcorder in the mid to late '80s led to the creation of shows such as the long-running America's Funniest Home Videos, where people could showcase homemade video footage.

Politics
Political protestors who have capitalized on the value of media coverage use camcorders to film things they believe to be unjust. Animal rights protesters who break into factory farms and animal testing labs use camcorders to film the conditions the animals are living in. Anti-hunting protesters film fox hunts. Tax protesters provide live coverage of anti-tax demonstrations and protests. Anti-globalization protesters film the police to deter police brutality. If the police do use violence there will be evidence on video. Activist videos often appear on Indymedia.
The police use camcorders to film riots, protests and the crowds at sporting events. The film can be used to spot and pick out troublemakers, who can then be prosecuted in court.

Entertainment and movies
Camcorders are often used in the production of low-budget TV shows where the production crew does not have access to more expensive equipment. There are even examples of movies shot entirely on consumer camcorder equipment (see Blair Witch Project and 28 Days Later). In addition, many academic filmmaking programs have switched from 16mm film to digital video, due to the vastly reduced expense and ease of editing of the digital medium as well as the increasing scarcity of film stock and equipment. Some camcorder manufacturers cater to this market, particularly Canon and Panasonic, who both support "24p" (24 frame/s, progressive scan; same frame rate as standard cinema film) video in some of their high-end models for easy film conversion.
Even high-budget cinema is done using camcorders in some cases; George Lucas used Sony CineAlta camcorders in two of his three Star Wars prequel movies. This process is referred to as digital cinematography.

Formats
The following list covers consumer equipment only. (For other formats see Videotape)

Analog

8 mm Camcorder
Lo-Band: Approximately 3 megahertz bandwidth (250 lines EIA resolution or ~333x480 edge-to-edge)
BCE (1954): First tape storage for video, manufactured by Bing Crosby Entertainment from Ampex equipment.
BCE Coloer (1955): First color tape storage for video, manufactured by Bing Crosby Entertainment from Ampex equipment.
Simplex (1955): Developed commercially by RCA and used to record several live broadcasts by NBC.
Quadruplex (1955): Developed formally by Ampex, and this became the recording standard for the next 20 years.
Vera (1955): An experimental recording standard developed by the BBC, but was never used or sold commerically.
Umatic (1971): The initial tape used by Sony to record video.
Umatics (1974): A small sized version of Umatic used for portable recorders.
Betamax (1975): Only used on very old Sony and Sanyo camcorders and portables; obsolete by the mid/late-80s in the consumer market.
Type B (1976): Co-developed by Sony and Ampex and this became the broadcast standard in europe for most of the 1980s.
Type C (1976): Co-developed by Sony and Ampex.
VHS (1976): Compatible with VHS standard VCRs, though VHS camcorders are no longer made. Obsolete.
VHS-C (1982): Originally designed for portable VCRs, this standard was later adapted for use in compact consumer camcorders; identical in quality to VHS; plays in standard home VCRs. Still available in the low-end consumer market (JVC model GR-AXM18 is VHS-C; see page 19 of the owner's manual}. Relatively short running time compared to other formats.
Betacam (1982): Introduced by Sony as a 1\2 inch tape for professional video recorders.
MUSE (1983): Commercial system for analogue 1080i broadcasts developed
Video8 (1985): Small-format tape developed by Sony to combat VHS-C's compact palm-sized design; equivalent to VHS or Betamax in picture quality, but not compatible. High quality audio as standard. Obsolete.
Hi-Vision (1985): MUSE renamed Hi-Vision and players started appearing on the market that could playback 1080i analogue video.
Hi-Band: Approximately 5 megahertz bandwidth (420 lines EIA resolution or ~550x480 edge-to-edge)
Laserdisk (1978): Marketed originally as LaserVision.
Umatic BVU (1982): Largely used in high-end consumer and professional equipment. The introduction of Umatic BVU spelled the end of 16mm film recordings.
Umatic BVU-SP (1985): Largely used in high-end consumer and professional equipment. The introduction of Umatic BVU spelled the end of 16mm film recordings.
Betacam-SP (1986): An minor upgrade to the Betacam format, but because of the upgrade, it became a broadcast standard.
MII (1986): Panasonic's answers to Betacam-SP
S-VHS (1987): Largely used in medium-end consumer and prosumer equipment; rare among mainstream consumer equipment, and rendered obsolete by digital gear like DigiBetacam and DV.
S-VHS-C (1987): An upgrade to provide near-laserdisc quality. Now limited to the low-end consumer market (example: JVC SXM38). As per VHS-C, relatively short running time compared to other formats.
Hi8 (1988): Enhanced-quality Video8; roughly equivalent to Super VHS in picture quality, but not compatible. High quality audio as standard. Now limited to low-end consumer market (example: Sony TRV138)
W-VHS (1994): Short lived 1080i tape format that had the ability to record.

fsa bicycle parts

PTZ Dome Camera

14 ibook battery

bronze marine hardware

countdown clock timer

aluminum oxide abrasive

tongkat ali extract

Glue Chip Glass

textile machinery spares

SNAP Lock Punch

Cardboard Counter Display

zoom stereo microscope

abb circuit breaker

Reverse Parking Sensor

digital thermometer waterproof

medical ozone generator

foil stamp machine

Car Wheel Balancer

Camcorder

2008-11-30T06:36:00.000-08:00

History

Before the camcorder. This separate portable Betamax recorder and camera arrangement slightly predates the first camcorders
Video cameras were originally designed for broadcasting television images — see television camera. Cameras found in television broadcast centres were extremely large, mounted on special trolleys, and wired to remote recorders located in separate rooms. As technology advanced, miniaturization eventually enabled the construction of portable video-cameras and portable video-recorders.
Prior to the introduction of the camcorder, portable video-recording required two separate devices: a video-camera and a VCR. Specialized models were introduced by both JVC (VHS) and Sony (Umatic & Betamax) to be used for mobile work. The portable VCR consisted of the cassette player/recorder unit, and a television tuner unit. The cassette unit could be detached and carried with the user for video recording. While the camera itself could be quite compact, the fact that a separate VCR had to be carried generally made on-location shooting a two-man job, however the advent of these portable VCRs helped to eliminate the phrase "film at eleven". Rather than wait for the lengthy process of film developing, portable VCRs and video cameras allowed video to be shown during the 6 o'clock news.
In 1982, two events happened that eventually led to the home camcorder boom: JVC introduced the VHS-C format, and Sony released the first professional camcorder named Betacam. VHS-C was essentially VHS with a reduced-size cassette that had been designed for portable VCRs. Sony's Betacam was a standard developed for professional camcorders, which used component video to provide a superior picture. At first, cameramen did not welcome Betacam, because before it, carrying and operating the VCR unit was the work of a video engineer; after Betacam they came to be required to operate both video camera and VCR. However the cable between cameramen and video engineers was eliminated, the freedom of cameramen improved dramatically and Betacam quickly became the standard for both news-gathering and in-studio video editing.
In 1983, Sony released the Betamax-based Betamovie BMC-100P, the first consumer camcorder. A novel technique in the BMC-100P was used to reduce the size of the spinning video head drum, which was then used for many subsequent camcorders. Nevertheless, the unit could not be held with one hand and was typically resting on a shoulder. Some later camcorders were even larger, because the Betamovie models had only optical viewfinders and no playback or rewind capability. Most camcorders were and still are designed for right-handed operation, though a few possessed ambidextrous ergonomics. That same year JVC released its own camcorder using its pre-existing VHS-C format. The VHS-C cassette held enough tape to record 40 or 120 minutes of VHS video, while a mechanical adapter enabled playback of VHS-C videocassettes in home VCRs.
In the meantime, Sony was busy redesigning its Betamax system to create the new Video8 standard, released in 1985. Video8 eliminated the problem of short running time, by using an all-new metal composition video cassette whose 8mm tape width is 33% less than VHS/Betamax tape (~12.7 mm), allowing even further miniaturization in the recorder's tape-transport assembly and cassette media.
Both VHS-C and 8mm video represented a trade-off for the consumer. Although the Video8 and Hi8 camcorders produced quality equal to VHS-C and Super VHS-C camcorders (250/420 lines horizontal), the standard 8 mm cassette had the advantage with up to two hours length (four hours in slow mode). On the down side, since the 8 mm format was incompatible with VHS, 8 mm recordings could not be played in consumers' VHS VCRs. Equally important entry-level VHS-C camcorders were priced less than 8 mm units, and thus neither "won" the war. It became a stalemate. (Side note - In 1986 companies like Panasonic began releasing full-sized VHS/S-VHS camcorders, which offered up to 3 or 9 hours record time, and thus found a niche with videophiles, industrial videographers, and college TV studios.)
In the mid-1990s, the camcorder reached the digital era with the introduction of DV and miniDV. Its cassette media was even smaller than 8 mm media, allowing another size reduction of the tape transport assembly. The digital nature of miniDV also improved audio and video quality over the best of the analog consumer camcorders (SVHS-C, Hi8), although some users still prefer the analog nature of Hi8 and Super VHS-C, since neither of these produce the "background blur" or "mosquito noise" of Digital compression. Variations on the DV camcorder include the Digital8 camcorder and the MPEG2-based DVD camcorder.
The evolution of the camcorder has seen the growth of the camcorder market as price reductions and size reductions make the technology more accessible to a wider audience. When camcorders were first introduced, they were bulky shoulder-operated luggables that cost over $1,500 US dollars As of 2008, an entry-level camcorder fits in the palm of a person's hand and is sold at a retail price of approximately 100 US dollars
Overview
Camcorders contain 3 major components: lens, imager, and recorder. The lens gathers and focuses light on the imager. The imager (usually a CCD or CMOS sensor on modern camcorders; earlier examples often used vidicon tubes) converts incident light into an electrical signal. Finally, the recorder converts the electric signal into digital video and encodes it into a storable form. More commonly, the optics and imager are referred to as the camera section.

Lens
The lens is the first component in the light path. The camcorder's optics generally have one or more of the following adjustments:
aperture or iris to regulate the exposure and to control depth of field;
zoom to control the focal length and angle of view;
shutter speed to regulate the exposure and to maintain desired motion portrayal;
gain to amplify signal strength in low-light conditions;
neutral density filter to regulate the exposure.
In consumer units, the above adjustments are often automatically controlled by the camcorder's electronics, but can be adjusted manually if desired. Professional units offer direct user control of all major optical functions.

Imager
The imager converts light into electric signal. The camera lens projects an image onto the imager surface, exposing the photosensitive array to light. The light exposure is converted into electrical charge. At the end of the timed exposure, the imager converts the accumulated charge into a continuous analog voltage at the imager's output terminals. After scan-out is complete, the photosites are reset to start the exposure-process for the next video frame.
With the first (digital) camcorders, an analog-to-digital (ADC) converter digitized the imager (analog) waveform output into a discrete digital-video signal. The images in these cameras was a CCD which was analogue by nature. Modern cameras will generally have a CMOS chip in place of a CCD as a CMOS is completely digital in nature and there is no analogue voltage signal to digitize because the light is sampled directly by each pixel and converted to a binary digital signal per each pixel.
CCD chips will generally see better in low light conditions because of the CCD's nature of capturing more light in the infrared range, but will severely lack in the human visibility spectrum, thus sacrificing color, on the other hand CMOS imagers do not have great low light capability but will capture the visible spectrum better and thus displaying color properly.

Recorder
The third section, the recorder, is responsible for writing the video-signal onto a recording medium (such as magnetic videotape.) The record function involves many signal-processing steps, and historically, the recording-process introduced some distortion and noise into the stored video, such that playback of the stored-signal may not retain the same characteristics/detail as the live video feed.
All but the most primitive camcorders imaginable also need to have a recorder-controlling section which allows the user to control the camcorder, switch the recorder into playback mode for reviewing the recorded footage and an image control section which controls exposure, focus and white-balance.
The image recorded need not be limited to what appeared in the viewfinder. For documentation of events, such as used by police, the field of view overlays such things as the time and date of the recording along the top and bottom of the image. Such things as the police car or constable to which the recorder has been allotted may also appear; also the speed of the car at the time of recording. Compass direction at time of recording and geographical coordinates may also be possible. These are not kept to world-standard fields; "month/day/year" may be seen, as well as "day/month/year", besides the ISO standard "year-month-day". And the Danish police have the speed of the police car in the units "km/t" sic (time being Danish for "hour").

Consumer camcorders

Analog vs. digital
Camcorders are often classified by their storage device: VHS, Betamax, Video8 are examples of older, videotape-based camcorders which record video in analog form. Newer camcorders include Digital8, miniDV, DVD, Hard drive and solid-state (flash) semiconductor memory, which all record video in digital form. (Please see the digital video page for details.) In older digital camcorders, the imager-chip, the CCD was considered an analog component, so the digital namesake is in reference to the camcorder's processing and recording of the video. Many next generation camcorders use a CMOS imager, which register photons as binary data as soon as the photons hit the imager and thus tightly marrying part 2 and 3.
It should be noted that the take up of digital video storage in camcorders was an enormous milestone. MiniDV storage allows full resolution video (720x576 for PAL,720x480 for NTSC), unlike previous analogue video standards. Digital video doesn't experience colour bleeding, jitter, or fade, although some users still prefer the analog nature of Hi8 and Super VHS-C, since neither of these produce the "background blur" or "mosquito noise" of Digital compression. In many cases, a high-quality analog recording shows more detail (such as rough textures on a wall) than a compressed digital recording (which would show the same wall as flat and featureless). Although, the low resolution of analogue camcorders may negate any such benefits.
The highest-quality digital formats, such as MiniDV and Digital Betacam, have the advantage over analog of suffering little generation loss in recording, dubbing, and editing (MPEG-2 and MPEG-4 do suffer from generation loss in the editing process only). Whereas noise and bandwidth issues relating to cables, amplifiers, and mixers can greatly affect analog recordings, such problems are minimal in digital formats using digital connections (generally IEEE 1394, SDI/SDTI, or HDMI).
Although both analog and digital can suffer from archival problems, digital is more prone to complete loss. Theoretically digital information can be stored indefinitely with zero deterioration on a digital storage device (such as a hard drive), however since some digital formats (like miniDV) often squeeze tracks only ~10 micrometers apart (versus ~500 μm for VHS), a digital recording is more vulnerable to wrinkles or stretches in the tape that could permanently erase several scenes worth of digital data, but the additions tracking and error correction code on the tape will generally compensate for most defects. On analog media similar damage barely registers as "noise" in the video, still leaving a deteriorated but watchable video. The only limitation is that this video has to be played on a completely analogue viewing system, otherwise the tape will not display any video due to the damage and sync problems. Even digital recordings on DVD are known to suffer from DVD rot that permanently erase huge chunks of data. Thus the one advantage analog seems to have in this respect is that an analog recording may be "usable" even after the media it is stored on has suffered severe deterioration whereas it has been noticed that even slight media degradation in digital recordings may cause them to suffer from an "all or nothing" failure, i.e. the digital recording will end up being totally un-playable without very expensive restoration work.

Modern recording media
For more information, see tapeless camcorder.
Some recent camcorders record video on flash memory devices, Microdrives, small hard disks, and size-reduced DVD-RAM or DVD-Rs using MPEG-1, MPEG-2 or MPEG-4 formats. However because these codecs use inter-frame compression, frame-specific-editing requires frame regeneration, which incurs additional processing and can cause loss of picture information. (In professional usage, it is common to use a codec that will store every frame inidividually. This provides easier and faster frame-specific editing of scenes.)
Most other digital consumer camcorders record in DV or HDV format on tape and transfer content over FireWire (some also use USB 2.0) to a computer, where the huge files (for DV, 1GB for 4 to 4.6 minutes in PAL/NTSC resolutions) can be edited, converted, and (with many camcorders) also recorded back to tape. The transfer is done in real time, so the complete transfer of a 60 minute tape needs one hour to transfer and about 13GB disk space for the raw footage only - excluding any space needed for render files, and other media. Time spent in post-production (editing) to select and cut the best shots varies from instantaneous "magic" movies to hours of tedious selection, arrangement and rendering.

Consumer market
As the mainstream consumer market favors ease of use, portability, and price, consumer camcorders emphasize these features more than raw technical performance. For example, good low-light capabilities require large capturing chips, which affects price and size. Thus, consumer camcorders are often unable to shoot useful footage in dim light (though some units, particularly single-chip units by Sony, offer night vision capability) which utilizes the infrared sensitivity of the CCD imager, though this sacrifices color in well lit recording. Manual controls need space, either in menus or as buttons and make the use more complicated, which goes against the requirement of ease of use. Consumer units offer a plethora of I/O options (IEEE 1394/Firewire, USB 2.0, Composite and S-Video), but lack many manual settings, often excluding video exposure, gain control, or sound level management. For the beginner, entry-level camcorders offer basic recording and playback capability.
For the sophisticated hobbyist, high-end units offer improved optical and video performance through multi-CCD or multi-CMOS components and name-brand optics, manual control of camera exposure, removable optics, and more, but even consumer camcorders which are sold for $1000 such as the Panasonic GS250 are not well-suited for recording in dim light. When dimly-lit areas are brightened in-camera or in post-production, considerable noise distracts the viewer. Commercial special noise reduction algorithms are available to fix this as those available from Neat Image\Neat Video.

JVC GZ-MG555 hybrid camcorder (MPEG-2 SD-Video)
Before the 21st century, consumer video editing was a difficult task requiring a minimum of two recorders. Now, however, a contemporary Personal Computer of even modest power can perform digital video editing with editing software. Many consumer camcorders bundle a light (feature-limited) version of such software, as do some computers, and more advanced software is widely available at a variety of price points.
As of 2007, analog camcorders are still available but not widely marketed anymore; those that are still available are often less than US$250, but require special capture hardware for non-linear editing which may run into the thousands of dollars due to the plethora of sync and signal problems that may not be resolved with cheap capture equipement. In terms of sales, miniDV camcorders (and to a much lesser extent, Digital8) dominate most first world markets. Camcorders which record directly on DVD media are also on the rise, primarily among users with no plans to edit their footage. Nonetheless, software for editing video files created by DVD camcorders is available, including Womble DVD and VideoRedo. A user may also choose to recode the transport files of a dvd to that of an MPEG2 file which is supported by many other editing suites.
Hard disk based camcorders are appearing as well; JVC and Sony are the primary manufacturers of these units. Increased storage capacity over other types of media is the main advantage with these models; however, with this follows a slightly reduced image quality and loss of flexibility when compared to other formats such as MiniDV, making the ease of transferring the footage to a PC for quick editing the main attraction of Hard disk camcorders. Another downside Hard Drive based camcorders is the recording device itself which can be damaged irreparably by power failure or physical shock to the unit.

Other devices with video-capture capability
Video-capture capability is now available in selected models of cellphones, digicams, and other portable consumer electronic devices such as media players. Typically only digital cameras offer videos that are of useful quality for anything other than a novelty. The marketing approach is to claim 320 X 240 video is "VHS quality," and 640 X 480 video is "DVD quality." A few cameras can offer 800 X 600 resolution, and a recent development is High Definition (720p) in cameras such as the Sanyo Xacti HD1.
All are limited somewhat by having to serve as both cameras and camcorders. Compared to a dedicated camcorder they have poor low light performance, limited options, and many do not offer zoom during filming. (This is because the noise from the zooming motor is heard on the clip, only a few digicams have a manual zoom). Many either have fixed focus lenses, or autofocus lenses that are sluggish and noisy compared to a camcorder.
The quality varies widely depending on the compression format used and the type of device. Frame rates can range from 30 frame/s down to 10 frame/s, or can be variable, slowing down in dark settings. The length of clips can also vary from "unlimited" (up to the capacity of the storage media) down to as little as 30 seconds.
Low end MPEG-4 camcorders can often record unlimited length video clips at 320 X 240, but the quality is far below even a VHS-C camcorder. In addition, MPEG-4 is currently not widely supported in many video editing programs.
The use of digicams for recording video clips is limited mainly to circumstances where quality is not an issue. This is gradually being offset by the greater sophistication of the cameras, the increasing storage capacity of flash cards and microdrives, and the desire of consumers to carry only a single device.

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Secure Digital card

2008-11-30T06:34:00.001-08:00

History
In August 1999, Panasonic, SanDisk, and Toshiba first agreed to develop and market the SD (Secure Digital) Memory Card, which was a development of the MMC. With a physical profile of 24 mm × 32 mm × 2.1 mm, the new card provided both DRM up to the SDMI standard, and a high memory density for the time.
The new format was designed to compete with Sony's Memory Stick format that was released the previous year, which featured MagicGate DRM, and was physically larger. It was thought that DRM features would be widely used due to pressure from music and other media suppliers to prevent piracy. The features are largely unused.
At the 2000 CES trade show Matsushita, SanDisk and Toshiba Corporation announced the creation of the SD Card Association, to promote SD cards. It is headquartered in California and its executive membership includes some 30 world-leading high-tech companies and major content companies. Early samples of the SD Card were available in the first quarter of 2000, with production quantities of 32 and 64 megabytes available 3 months later.
In April 2006, the SDA released a detailed specification for the non-security related portions of the SD Memory Card standard. In addition, they released specifications for the SDIO (Secure Digital Input Output) cards and the standard SD host controller. During the same year, specifications were finalised for the small form-factor microSD (formerly known as TransFlash) and SDHC, with capacities in excess of 2 GB and a minimum sustained read/write speed of 2.2 MB/s.

Design and implementation

An SD card, mini SD card, and micro SD card from top to bottom.
SD cards are based on the older MultiMediaCard (MMC) format, but have a number of differences:
The SD card is asymmetrically shaped in order not to be inserted upside down, while an MMC would go in most of the way but not make contact if inverted.
Most SD cards are physically thicker than MMCs. SD cards generally measure 32 mm × 24 mm × 2.1 mm, but can be as thin as 1.4 mm, just like MMCs (see below).
The contacts are recessed beneath the surface of the card, protecting the contacts from contact with the fingers.
SD cards typically have transfer rates in the range of 10-20 MBytes/s, but this is always changing, particularly in light of recent improvements to the MMC standard.
Devices with SD slots can use the thinner MMCs, but the standard SD cards will not fit into the thinner MMC slots. miniSD and microSD cards can be used directly in SD slots with a simple passive adapter, since they differ in size and shape but not electrical interface. With an active electronic adapter, SD cards can be used in CompactFlash or PC card slots. Some SD cards include a USB connector for compatibility with desktop and laptop computers, and card readers allow SD cards to be accessed via connectivity ports such as USB, FireWire, and the parallel printer port. SD cards can also be accessed via a floppy disk drive with a FlashPath adapter.

Optional write-protect tab
When looking at the card from the top (see pictures) there is one required notch on the right side (the side with the diagonal notched corner).
On the left side may be a write-protection notch. If this is present, the card cannot be written to. If the notch is covered by a slide-able write protection tab, or absent, then the card is writeable.
Not all devices support write protection, which is an optional feature of the SD standard.
Some SD cards have no write-protection notch, and it is absent completely in the MicroSD and MiniSD formats.
Some music and film media companies (e.g. Disney) have released limited catalogs of records and/or videos on SD. These usually contain DRM-encoded Windows Media files, making use of the SD format's DRM capabilities. Such media is usually permanently marked read-only, by adding the notch with no tab.

File system
Like other flash card technologies, most SD cards ship preformatted with the FAT or FAT 32 file system. The ubiquity of this file system allows the card to be accessed on virtually any host device with an SD reader. Also, standard FAT maintenance utilities (e.g. ScanDisk) can be used to repair or retrieve corrupted data. However, because the card appears as a removable hard drive to the host system, the card can be reformatted to any file system supported by the operating system.
Defragmentation tools are used on hard disks to optimise the file system access speed. On an SD card, this is pointless, as any block can be accessed as fast as any other. Doing this will wear the card out slightly, as only so many writes can be made before failure.
However, note that any file recovery tool will struggle to recover files from highly fragmented data if the File Allocation Table becomes highly corrupted.

Speeds
There are different speed grades available which are measured with the same system as CD-ROMs, in multiples of 150 kB/s (1x = 150 kB/s). Basic cards transfer data up to six times (6x) the data rate of the standard CD-ROM speed (900 kB/s vs. 150 kB/s). High-speed cards are made with higher data transfer rates like 66x (10 MB/s), and high-end cards have speeds of 200x or higher. Note that maximum read speed and maximum write speed may be different, with maximum write speed typically lower than maximum read speed. Some digital cameras require high-speed cards (write speed) to record video smoothly or capture multiple still photographs in rapid succession. The SD card specification 1.01 allows for a maximum speed of 66x. Higher speeds of up to 200x are defined by specification 2.0.

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Magnetic-coded lock

2008-11-30T06:31:00.000-08:00

History
The magnetic-coded lock was invented by an engineer in Nanchang, China. There have been several Chinese patents taken out on this technology. The improved version of this technology is currently on patent pending status granted by US Patent and Trademark Office.

Tumbler bible and key operation, showing placement of magnetic cylinders

Design
Magnetic-coded technology utilizes multiple pairs of magnetic pins with opposing poles that are embedded inside keys and plugs. When a correctly matched key is inserted into the lock, not only are all the mechanical pins pushed into the correct positions, the magnetic pins are also driven to the appropriate level by the magnetic force inside the key.
The magnetic pins are made with permanent magnets which means the magnets stay magnetized. The intensity of the magnet will not decay over time or be affected by other magnetic fields.

Operation
In order to open a magnetic-coded lock, three criteria must be met: correct teething of the key, magnetic pin locations and poles of the magnetic pins. If any of these three criteria are not satisfied, the lock stays inoperable and cannot be turned.

Equations
N - Magnetic-coded lock key combinations
C - Conventional pin-tumbler lock combinations
m - Pairs of embedded magnets. (multiple pairs can be embedded)

Features

Advantages
Anti-picking:
The embedded magnetic pins are not exposed to the key way, therefore, no lifting force can be applied to move the magnetic pins. Most standard forms of lock picking are therefore preventable.
Anti-bumping :
Lock bumping transmits kinetic energy from the key to the drive pins, to split the bottom and top pins. The embedded magnetic technology has no physical contact points between key and magnetic pins, therefore no kinetic energy is transmitted.
Key control:
Due to the magnetic cylinder elements embedded in the keys, there is a high degree of key control. Unlawful key duplications are minimized by limited access to key blanks (locksmiths) and unique magnetic coding in the key that cannot easily be determined by inspecting the target lock.
Cost Effectiveness :
Because the manufacturing process is based on the pin and tumbler platform, the cost of manufacturing is significantly reduced when compared to high security locks with comparable security features. These high security locks often utilize new locking mechanisms which increase the cost of manufacturing.

Disadvantages
Manufacturing Complexities:
A special tool set and procedures have to be developed to accomplish the task of embedding the magnets inside both the keys and the locks.

Installation
The same as conventional lock installation. Drilling with hole saw may be required in doors lacking a hole for assembly

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Tubular pin tumbler lock

2008-11-30T06:30:00.000-08:00

A tubular pin tumbler lock, also known as Ace lock or "axial pin tumbler lock" or "radial lock", is a variety of pin tumbler lock in which 6-8 pins are arranged in a circular pattern, and the corresponding key is tubular or cylindrical in shape.
Joseph Bramah is credited with the invention of the forefather of the tubular pin tumbler lock except his used iron wafers not cylinders (red and blue in diagrams). He received a patent for his new lock in 1784. J.A. Blake is credited with patenting the first tubular lock in 1833. Walter R. Schlage continued the development of the tubular lock. He was awarded 11 patents.
Tubular locks are commonly seen on bicycle locks, computer locks, elevators, and a variety of coin-operated devices such as vending machines and coin-operated washing machines.

Security
Tubular pin tumbler locks are generally considered to be safer and more resistant to picking than standard locks, though there are several ways to open them without a key. Even though the pins are exposed, making them superficially easier to pick, they are designed such that after all pins are manipulated to their shear line, once the plug is rotated 1/6 to 1/8 around, the pins will fall into the next pin's hole, requiring re-picking to continue. As such, picking the lock without using a device to hold its pins in place once they reach their shear line requires one complete pick per pin.
Such locks can be picked by a special tubular lock pick with a minimum of effort in very little time; it is also possible to defeat them by drilling with a special “hole saw” drill bit. Standard tubular lock drill bit sizes are .375" (9.53 mm) diameter and .394" (10 mm) diameter.To prevent drilling, many tubular locks have a middle pin made of hardened steel, or contain a ball bearing in the middle pin.
In 2004, videos circulating on the Internet demonstrated that some tubular pin tumbler locks could be easily opened with the shaft of an inexpensive ballpoint pen (e.g., BIC brand) of matching diameter. Trade website BikeBiz.com revealed that the weaknesses of the tubular pin tumbler mechanism had first been described in 1992 by UK journalist John Stuart Clark (see Kryptonite lock).

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Lock picking

2008-11-30T06:28:00.000-08:00

Method

This article or section contains instructions, advice, or how-to content.The purpose of Wikipedia is to present facts, not to teach subject matter. Please help improve this article either by rewriting the how-to content or by moving it to Wikiversity.
One uses the file to polish the top of the key; that is, the part of the key that the pins come into contact with. (Before starting the impressioning, it is good to count the number of pins in the lock with a hook pick, thus helping choose the correct sized blank.) The key is put into the keyhole and gently turned, binding the key, which is then jiggled up and down. This serves to leave perpendicular scrapes of the pins on the key.
After filing a few thousandths of brass off of the key with the pippen or rat tail file, the process is repeated. Care must be taken to only file if a little dimple is seen in the key grooves. When enough material has been filed from the blank, the blank will approximate the cut of the key and the lock should open when the key is turned.
This method makes high-security drivers (if they are grooved or mushroomed) irrelevant. This method works well on car doors and other wafer locks.

Tool sets
The tools for lock picking are usually different for each type of lock and can sometimes be improvised from common items.
Lock pick kits can be purchased openly via the Internet. Many different selections are present. Nine-piece sets and a 32-piece set equipped with a Pick Gun for example differ in value and price greatly. However, many lock pickers state that for most locking devices, a basic set of five picks is enough; therefore it is unnecessary to carry around a wide variety of professional lock picks.

Torque wrench

A traditional set of lockpicks. The two tools on the left are torque(said 'tork') wrenches
A torque wrench is a tool used in picking locks. Typically shaped like a letter "L" (although the vertical part of the letter is much elongated in comparison to the horizontal part), it is used to apply torsion to the inner cylinder of a lock, in order to hold any picked pins in place, while the other pins are shifted. The torsion wrench is then used to turn the inner cylinder and open the lock.
Despite its popular name, the tool provides torsion, not tension. A tension wrench would be, by definition, a tool that stretches something. A torsion wrench would be a tool that twists.
Some torsion wrenches (called "Feather Touch" wrenches, among other names) are coiled into a spring at the bend in the "L", which helps the user apply constant torque. Some users, however, maintain that such wrenches reduce torque control and the feedback available to the user.

Hook pick
The hook pick is self explanatory, it is similar to the half diamond pick, but has a hook shaped tip rather than a half diamond shape. The hook pick is sometimes referred to as a 'feeler' and is generally used to lift the pins individually, rather than 'rake' them simultaneously.

Warded pick
A warded pick is a device for opening warded locks. It is generally made to conform to a generalized key shape relatively simpler than the actual key used to open the lock; this simpler shape allows for internal manipulations.

Legal status

United States
In the United States, laws concerning possession of lock picks vary from state to state. Generally, possession and use of lock picks is considered equivalent to the possession of a crowbar or any other tool that may or may not be used in a burglary. Illegal possession of lock picks is generally prosecuted as a felony under the category of possession of burglary tools or similar statutes. In many states, simple possession is completely legal as their statutes require proof of intent. In some states, however, possession without appropriate licensure is considered prima facie evidence of intent to commit a crime, rendering simple possession a crime.
In California, locksmiths must be licensed by the state.However possession by layman is considered legal in most states, as illegal possession must be coupled with felonious or malicious intent.This is also the case in Utah , Massachusetts, Maine, New Hampshire, Washington, DC, and New York.

European Union
Most countries of the European Union don't regulate the possession of lock picks. All responsibility concerning criminal or legal acts using the picks is taken by the user of the lock picks, when the owner of the lock picks may be involved in the jurisdiction or legal process as an accomplice or witness.

Netherlands
In the Netherlands, owning lock picks is legal, but using them on someone else's locks without permission is not. There is a lock picking championship, the Dutch Open (organised by TOOOL), which was reported on in the newspapers.

Poland
In Poland according to the delinquency Codeep Act article 129 § 1:1) possessing, producing or obtaining a lockpick by a person whose profession and occupation doesn't require it;2) delivering a lockpick to a person whose profession and occupation doesn't require it;3) […]is punishable with arrest, freedom limitation or fine. § 3 says that a lockpick is forfeited even if it wasn't a property of the principal.

United Kingdom
In the United Kingdom, a person who carries a lock pick set (even a home made one) can be charged with the offence of "going equipped", unless they have a good reason for carrying them The penalty for this can be upward of 5 years' imprisonment. The arresting officer must have "reasonable cause".

New Zealand
In New Zealand lock picking tools are not illegal, but possession with the intent to use them for burglary carries a potential penalty of three years in prison.

Media
When lockpicking is shown in movies and television shows, the torsion wrench is almost always omitted. Picking a pin and tumbler lock without torsion is impossible unless there is a major defect in the lock.
In some modern dramas (such as FOX's 24) in which realistic depiction of events is favored, the pick-and-wrench technique is fully shown (albeit often executed in a second or two, which doesn't accurately reflect the luck involved with raking an unfamiliar lock).
Although there do exist raking tools in which a single element may be used to open a lock (such as automobile "tryout" keys), these are rarely used in media depictions, and almost as rarely used in real life. The broad width of these picks allows for the necessary application of torque, just as an external source of torque is not required when using a standard key.

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Disc tumbler lock

2008-11-30T06:26:00.000-08:00

The Abloy Disklock or Disc tumbler lock is a lock composed of slotted rotating detainer discs. A specially cut key rotates these discs like the tumblers of a safe to align the slots, allowing the sidebar to drop into the slots, thus opening the lock. Unlike a wafer tumbler lock or a pin tumbler lock, this mechanism does not use springs. From a security standpoint, the disc tumbler lock cannot be bumped. The lock was invented by Emil Henriksson in 1907 and manufactured by Abloy. Another popular brand in Malaysia is Solex.
The lock is difficult to pick and is sold as a "high security" lock. Picking the lock requires a lot of time, a dedicated, professionally made tool and special expertise, but has been done. The locking mechanism can be also disabled destructively by drilling into the lock to destroy the sidebar. Anti-drilling plates can be installed to prevent this.
In areas of the world where this type of lock has historically been rare or unknown, the term disc tumbler lock is sometimes used to refer to wafer tumbler locks.

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Padlock

2008-11-30T06:25:00.000-08:00

History

Medieval padlock in Kathmandu

Viking Age padlock found at Birka.
The earliest padlocks used in America, sometimes called “smokehouse” locks, were formed from wrought iron sheet and employed simple lever and ward mechanisms. The design was brought over from England. These locks afforded little protection against forced and surreptitious entry. Contemporary with the smokehouse padlocks and originating in the Slavic areas of Europe, “screw key” padlocks opened with a helical key that was threaded into the keyhole. The key pulled the locking bolt open against a strong spring. Padlocks that offered more key variance were the demise of the screw lock. Improved manufacturing methods allowed the manufacture of better padlocks that put an end to the Smokehouse around 1910.
Around the middle of the 19th century, “Scandinavian” style locks were introduced in America and became a more secure alternative to the prevailing smokehouse and screw locks. These locks had a cast iron body that was loaded with a stack of rotating disks. Each disk had a central cutout to allow the key to pass through them and two notches cut out on the edge of the disc. When locked, the discs passed through cut-outs on the shackle. The key rotated each disk until the notches, placed along the edge of each tumbler in different places, lined up with the shackle, allowing the shackle to slide out of the body. The McWilliams company received a patent for these locks in 1871. The “Scandinavian” design was so successful that JHW Climax & Co. of Newark, New Jersey continued to make these padlocks until the 1950’s. Today, other countries are still manufacturing this style of padlock.
Contemporary with the Scandinavian padlock ("Polhem locks") were the “cast heart” locks, so called because of their shape. A significantly stronger lock than the smokehouse and much more resistant to corrosion than the Scandinavian, the hearts had a lock body sand cast from brass or bronze and a more secure lever mechanism. Heart locks had two prominent characteristics: one was a spring-loaded cover that pivoted over the keyhole to keep dirt and insects out of the lock that was called a “drop”. The other was a point formed at the bottom of the lock so a chain could be attached to the lock body to prevent the lock from getting lost or stolen. Cast heart locks were very popular with railroads for locking switches and cars because of their economical cost and excellent ability to open reliably in dirty, moist, and frozen environments.
Around the 1870s, lock makers realized they could successfully package the same locking mechanism found in cast heart locks into a more economical steel or brass shell instead of having to cast a thick metal body. These lock shells were stamped out of flat metal stock, filled with lever tumblers, and then riveted together. Although more fragile than the cast hearts, these locks were attractive because they cost less. In 1908, Adams & Westlake patented a stamped & riveted switch lock that was so economical that many railroads stopped using the popular cast hearts and went with this new stamped shell lock body design. Many lock manufacturers made this very popular style of lock.

Early padlock style, on the front gates of St. Peter's Basilica
In 1877 Yale & Towne was granted a patent for a padlock that housed a stack of levers and had a shackle that swung away when unlocked. It was a notable design because the levers were sub-assembled into a “cartridge” that could be slid into a cast brass body shell. The assembly would remain together by means of two taper pins passed through the shell and cartridge. This design gave the commercial padlock market a serviceable, rekeyable padlock. About twenty years later Yale made another “cartridge” style padlock that employed their famous pin tumbler mechanism and a shackle that slid out of the body instead of swinging away.
Although machining metal was a method that was available to lock makers since the early 1800s, it was not economically feasible to do so until the very early 1900s when electrical generation and distribution became widespread. Some of the earliest padlocks (c. 1905) that were made from a machined block of cast or extruded metal resemble today’s modern padlock. Corbin and Eagle were one of the first lock makers to machine a solid block of metal and insert a relatively new pin tumbler mechanism and a sliding shackle into the holes machined into the body. This style of padlock was both strong and easy to manufacture. Many machined body padlocks were designed to be disassembled so that locksmiths could easily fit the locks to a certain key. The machined body padlocks are still very popular today. The process of machining allows many modern padlocks to have a “shroud” covering the shackle, which is an extension of the body around the shackle to protect the shackle from getting sheared or cut.
In the early 1920s, Harry Soref started Master Lock off with the first laminated padlock. Plates that were punched from sheet metal were stacked and assembled. Holes that were formed in the middle of the plates made room to accommodate the locking mechanism. The entire stack of plates, loaded with the lock parts in it, was riveted together. This padlock was popular for its low cost and an impact-resistant laminated plate design. Today, many lock makers copy this very efficient and successful design.
Die-casting became popular in the early 1930s among lock makers. Not only was it a very inexpensive way to make padlocks, but it allowed designers to design padlocks with a broad range of geometrical features and ornate designs that sand casting and machining wouldn’t allow. Some lock makers, like Junkunc Brothers, augmented their machined solid body padlock products with the less expensive and more attractive die-cast bodied padlocks. The Wise Lock Company embraced this new medium in making a novel padlock that, with the key inserted, would split lengthwise along the body in order to create an opening in the shackle. Chicago lock pioneered their new “double bitted wafer” and “ACE” products by installing them into a die cast body. With the advent of inexpensive machining done overseas and the overall poor perception of the security of die cast locks, they no longer dominate today’s padlock market.

Rating

A high security padlock.
Forced entry involves the use of tools such as hammers, bolt cutters, chisels, and drills; consequently, forced entry attacks exhibit obvious signs of entry. Surreptitious attacks involve picks, bump keys, shims, unauthorized key duplication, and other bypass techniques that, when employed, do not show obvious signs of compromise.
A quantitative measure of a padlock’s resistance to forced and surreptitious entry can be determined with tests developed by organizations such as ASTM, Sold Secure (United Kingdom), CEN (Europe), and TNO (The Netherlands).

Components
A padlock is composed of a body, shackle, and a locking mechanism. The typical shackle is a “U” shaped loop of metal (round or square in cross-section) that encompasses what is being secured by the padlock (i.e., chain link or hasp). Generally, most padlock shackles either swing away (typical of older padlocks) or slide out of the padlock body when in the unlocked position. Unusually designed padlocks may include a straight, circular, or flexible (cable) shackles. Some shackles split apart and come together to lock and unlock.
There are two basic types of padlock locking mechanisms: integrated & modular. Integrated locking mechanisms directly engage the padlock’s shackle with the tumblers. Examples of integrated locking mechanisms are rotating disks (found in "Scandinavian" style padlocks where a disk rotated by the key enters a notch cut into the shackle to block it from moving) or lever tumblers (where a portion of the bolt that secures the shackle enters the tumblers when the correct key is turned in the lock). Padlocks with integrated locking mechanisms are characterized by a design that does not allow disassembly of the padlock. They are usually older than padlocks with modular mechanisms and often require the use of a key to lock.
The more modern modular locking mechanisms, however, do not directly employ the tumblers to lock the shackle. Instead, they have a plug within the “cylinder” that, with the correct key, turns and allows a mechanism, referred to as a “locking dog” (such as the ball bearings found in American Lock Company padlocks) to retract from notches cut into the shackle. Padlocks with modular locking mechanisms can often be taken apart to change the tumblers or to service the lock. Modular locking mechanism cylinders frequently employ pin, wafer, and disk tumblers. Padlocks with modular mechanisms are usually automatic, or self-locking (that is, the key is not required to lock the padlock).

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Lock bumping

2008-11-30T06:23:00.000-08:00

History
In the 1970s, locksmiths in Denmark shared a technique for knocking on a lock cylinder while applying slight pressure to the back of the lock plug. When the pins would jump inside of the cylinder, the plug would be able to slide out freely, thus enabling the locksmith to disassemble the lock quickly The use of a bump key was not introduced until some time later and was first recognized as a potential security issue around 2002–2003 by Klaus Noch who brought it to the attention of the German media After further examination of the procedure, a white paper was drafted in 2005 by Barry Wels & Rop Gonggrijp of The Open Organization Of Lockpickers (TOOOL) detailing the method and its applicability.A patent exists for a lock device following the same principle as the bump key from 1926–1928.
The technique then attracted more popular attention in 2005 when a Dutch television show, Nova, broadcast a story about the method After the method received further publicity from TOOOL presentations at security conference talks, members of TOOOL and a Dutch consumer group, Dutch Consumentenbond, analyzed the capability of the method on 70 different lock models and with trained and untrained users in a 2006 study
At the same time, Marc Tobias, an American security expert, began to talk publicly in the United States about the technique and its potential security threats. In 2006, he released two further white papers regarding the technique and its potential legal ramifications.

Mechanics

When the correct key is inserted, the gaps between the key pins (red) and driver pins (blue) align with the edge of the plug, called the shear line(yellow).
A pin tumbler lock is composed of a series of spring-loaded stacks called pin stacks. Each pin stack is composed of two pins that are stacked on top of each other: the key pin, which touches the key when it is inserted, and the driver pin, which is spring driven. When the proper key is inserted into the lock, all of the key pins and driver pins align along the "shear line," allowing the cylinder to turn. That is, when the bottom of the driver pins and, therefore, the top of the key pins form a straight line, the cylinder can be turned, thus rotating the key pins away from the driver pins. When no key or the wrong key is in the lock, pin misalignment prevents the cylinder from turning.
When bumping a lock, the key is initially inserted into the keyway one notch (pin) short of full insertion. Bumping the key inward forces it deeper into the keyway. The specially designed teeth of the bump key jiggle all of the pins in the lock. The key pins transmit this force to the driver pins. Because the pin movements are highly elastic, the driver pins separate from the key pins for a split second and are then pushed back by the spring. Even though this separation only lasts a split second, if a light force is applied to the key, the cylinder can be turned and the lock can be opened while the driver pins are elevated above the keyway.

Countermeasures

Lock designs
High-quality locks may be more vulnerable to bumping unless they employ specific countermeasures. More precise manufacturing tolerances within the cylinder make bumping easier because the pins move more freely and smoothly. Locks made of hardened steel are more vulnerable because they are less prone to damage during the bumping process that might cause a cheaper lock to jam.
Locks having security pins (spool or mushroom pins, etc.)—even when combined with a regular tumbler mechanism—generally make bumping somewhat more difficult but not impossible. Electronic locks, magnetic locks, and locks using rotating disks are not vulnerable to this attack.
Because a bump key must have the same blank profile as the lock it is made to open, restricted or registered key profiles are much safer from bumping, since the correct key blanks cannot be obtained legally without permission or registration with relevant locksmith associations. While this would make it harder to obtain key blanks, regular keys can be filed down to act as bumpkeys.
Locks that have trap pins that engage when a pin does not support them will jam a lock's cylinder. Another countermeasure is shallow drilling, in which one or more of the pin stacks is drilled slightly shallower than the others. If an attempt were made on a lock that has shallow drilled pin stacks, the bump key will be unable to bump the shallow drilled pins because they are too high for the bump key to engage.

Lock brands
Locks made by ABLOY, KABA, EVVA, Medeco, Schlage, Kwikset and other manufacturers such as BiLock are advertised to be bump proof. ABLOY uses disc tumbler locking mechanism that cannot be bumped. Kwikset offers a new technology called SmartKey that eliminates the shear line in traditional pin tumbler locks and provides advanced protection. KABA experT cylinders consist of 4 rows of pins using a total of 22 pin possibilities, therefore the bumping method cannot be used to gain entry. KABA pExtra is an inline system that is available with a magnetic pin to prevent the bumping method being used. However, key copiers are freely available for Kaba ExperT keys
Medeco and Schlage Primus locks are advertised as unbumpable due to sidebars that must be aligned to a specific depth to enable pin movement and pins chiseled at angles to further thwart bumping.However there are also recent studies about how easy it is to bypass this sidebars feature. Master Lock also makes a line of bump resistant locks, using so-called bump stop security.
ABLOY Protec employs a mechanism totally different than pin tumbler cylinders which renders it secure against bumping.Authorized key copiers for these locks exist only on behalf of Abloy.

Other countermeasures
Pickbuster is an aftermarket lock bumping countermeasure in the form of a liquid gel which fills the cylinder serving to dampen the kinetic energy of the bump attack and prevent the key pin separating from the driver pin. This solution has recently been tested by ERA with positive results, and is undergoing extended testing by the Institute of Certified Locksmiths. However, this solution is thought by many to attract dust and grit, resulting in a jammed lock.

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Cylinder lock

2008-11-30T06:22:00.000-08:00

A cylinder lock is a lock in constructed with a cylinder that a locksmith can easily unscrew to facilitate rekeying. The cylinder may contain any of a variety of locking mechanisms, including the pin tumbler lock, the wafer tumbler lock and the disc tumbler lock.
The first main advantage to a cylinder lock is that the cylinder may be changed without altering the boltwork. Removing the cylinder typically requires only loosening a set screw, then unscrewing the cylinder from the boltwork. The second is that it is usually possible to obtain, from a lock manufacturer, cylinders in different formats that can all be used with the same type of key. This allows the user to have keyed-alike, and master-keyed systems that incorporate a wide variety of different types of lock, such as nightlatches, deadbolts and roller door locks. Typically, padlocks can also be included, although these rarely have removable cylinders.
Standardised types of cylinder include key-in-knobset cylinders, rim (also known as nightlatch) cylinders, Ingersoll format cylinders, American, and Scandinavian round mortise cylinders, and Scandinavian oval cylinders. There are also standardised cross-sectional profiles for lock cylinders that may vary in length - for example to suit different door thicknesses. These profiles include the europrofile (or DIN standard), the British oval profile and the Swiss profile.
Cruciform pin-tumbler locks may also use interchangeable cylinders, as do a few sophisticated lever locks.
Individually Keyed System (KD)With an individually keyed system, each cylinder can be opened by its individual key.
Keyed Alike (KA)This system allows for a number of cylinders to be operated by the same key. It is ideally suited to residential applications such as front and back doors.
Master Keyed (MK)A master-keyed system involves each lock having its own individual key which will not operate any other lock in the system, but where all locks can be operated by a single master-key.
Grand Master Keyed (GMK)This is an extension of the master-keyed system where each lock has its own individual key and the locks are divided into 2 or more groups. Each lock group is operated by a master-key and the entire system is operated by one grand master-key.
Common Entrance Suite / Maison Keying (CES)This system is widely used in apartments, office blocks and hotels. Each apartment (for example) has its own individual key which will not open the doors to any other apartments, but will open common entrance doors and communal service areas.

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Pin tumbler lock

2008-11-30T06:17:00.000-08:00

History
The basic principles of the pin tumbler lock may date as far back as 2000 BC in Egypt; the lock consisted of a wooden post affixed to the door, and a horizontal bolt that slid into the post. The bolt had vertical openings into which fitted a set of pins. These could be lifted, using a key, to a sufficient height to allow the bolt to move and unlock the door.
Inventor Linus Yale, Sr. patented a cylindrical pin tumbler lock in 1848, a design which was further improved and patented by his son, Linus Yale, Jr., in 1861. Yale, Jr.'s design is very similar to pin tumbler locks manufactured today.

Design
The pin tumbler is commonly used in cylinder locks. In this type of lock, an outer casing has a cylindrical hole in which the plug is housed. To open the lock, the plug must rotate.
The plug has a straight-shaped slot known as the keyway at one end to allow the key to enter the plug; the other end may have a cam or lever which activates a mechanism to retract a locking bolt. The keyway often has protruding ledges which serve to prevent the key pins from falling into the plug, and to make the lock more resistant to picking. A series of holes, typically five or six of them, are drilled vertically into the plug. These holes contain key pins of various lengths, which are rounded to permit the key to slide over them easily.
Above each key pin is a corresponding set of driver pins, which are spring-loaded. Simpler locks typically have only one driver pin for each key pin, but locks requiring multi-keyed entry, such as a group of locks having a master key, may have extra driver pins known as spacer pins. The outer casing has several vertical shafts, which hold the spring-loaded pins.
When the plug and outer casing are assembled, the pins are pushed down into the plug by the springs. The point where the plug and cylinder meet is called the shear point. With a key properly cut and inserted into the groove on the end of the plug, the pins will rise causing them to align exactly at the shear point. This allows the plug to rotate, thus opening the lock. When the key is not in the lock, the pins straddle the shear point, preventing the plug from rotating. Sets of locks with a master key will have one set of shear points that are identical to the others in the set and one set that is unique to that

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Circular saw

2008-11-30T06:14:00.000-08:00

Sawmill blades
Saw mills use very large circular saws, up to nine feet (2.97 meters) in diameter. They are either left or right-handed, depending on which side of the blade the plank falls away from. Benching determines which hand the saw is. Saws of this size typically have a shear pin hole, off axis, that breaks if the saw is overloaded and allows the saw to spin free. The most common version is the ITCO (insert tooth cut-off) which has replaceable teeth. Sawmill blades are also used as an alternative to a radial arm saw.

Cordwood saws
Cordwood saws, also called buzz saws in some locales, use blade of a similar size to sawmills. Where a sawmill rips (cuts with the grain) a cordwood saw crosscuts (cuts across the grain). Cordwood saws can have a blade from 20 to more than 36 inches diameter depending on the power source and intended purpose. Buzz saws are used to cut long logs (cordwood) and slabs (sawmill waste) into pieces suitable for home heating (firewood).
Most cordwood saws consist of a frame, blade, mandrel, cradle, and power source. The cradle is a tilting or sliding guide that holds logs during the cutting process. Some cordwood saws are run from a belt from a farm tractor power takeoff pulley. Others are equipped with small gasoline engines or even large electric motors as power sources. The mandrel is a shaft and set of bearings that support and transfer power to the blade. The frame is a structure that supports the cradle and blade at a convenient working height.
Cordwood saws were once very popular in rural America. They were used to cut smaller wood into firewood in an era when hand powered saws were the only other option. Logs too large for a cordwood saw were still cut by hand. Chainsaws have largely replaced cordwood saws for firewood preparation today. Still, some commercial firewood processors and others use cordwood saws to save wear and tear on their chainsaws. Most people consider cordwood saws unsafe and outdated technology.

Hand-held circular saws
The term circular saw is most commonly used to refer to a hand-held electric circular saw designed for cutting wood, which may be used less optimally for cutting other materials with the exchange of specific blades. Circular saws can be either left or right handed, depending on which side of the blade the motor sits.
Blades for timber are almost universally tungsten carbide tipped (TCT). High speed steel (HSS) blades are also available. The saw base can be adjusted for depth of cut. Adjusting the depth of cut helps minimize kickback. The saw base can also be adjusted to tilt up to 50 degrees in relation to the blade.
The saw can be designed for the blade to mount directly to the motor's driveshaft (known colloquially as a sidewinder), or be driven indirectly by a perpendicularly-mounted motor via worm gears, garnering considerably higher torque (Worm-drive saws).
The worm-drive portable circular saw was invented in 1924 by the Michel Electric Handsaw Company which renamed itself Skilsaw Inc., today a subsidiary of Robert Bosch GmbH. Portable circular saws are often still called Skilsaws or Skil saws. Its successor is still sold by Skil as the model 77. To get around the Skil patents, Art Emmons of Porter-Cable invented the direct-drive sidewinder saw in 1928. Recently smaller cordless circular saws with rechargeable batteries have become popular.

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Alaskan mill

2008-11-30T06:13:00.000-08:00

An Alaskan mill is a type of sawmill that is used by one or two operators to mill logs into planks for use in furniture, building and other types of timber construction.

The mill attachment consists of a pair of rails which are attached to bar of the chainsaw. The rails ride on the face of the log and guide the chainsaw blade through the log at a consistent depth so that planks of a predetermined thickness can be cut. The distance between the rails and the bar determines this thickness and it can be adjusted by moving the rails along a post at each end of the mill attachment. The rails are then locked in place using lock screws.

Small mills use a single chainsaw and can be handled by a single operator. Larger mills use two chainsaws, one on either side of the attachment and these require two operators. This larger style of mill requires a special bar which allows the two chainsaw heads to be attached at either end. The width of the plank that can be cut is determined by the length of the bar, so for logs having a large diameter, the longer bar is necessary.

For the first cut, a pair of rails are usually attached to the log to give the mill attachment a reference surface to guide it. Subsequent cuts are made using the surface of the previous cut as the guide.

Alasakan mills are relatively cheap to purchase compared to other types of mill and are also straightforward to make. They are therefore popular with hobbyist woodworkers who have access to felled timber.

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Chainsaw

2008-11-30T06:11:00.000-08:00

Construction

Chainsaw chain

A chainsaw clutch
A chainsaw consists of a several parts.
Engine (typically a two-stroke gasoline (petrol) internal combustion engine or electric motor,)
Drive mechanism - typically a clutch and sprocket.
Guide bar (essentially a long metal frame of a very hard wearing alloy)
Cutting chain. Usually each segment in this chain (which is constructed from riveted metal sections similar to a bicycle chain, but without rollers) features a small sharp blade, called a "tooth." "Skip tooth" chain has a tooth only on every second link, and is used for reduced risk of the chain clogging when cutting very soft wood. In modern chainsaws the teeth are not straight blades; they have a forward section that first chips a piece of wood from the bottom of the cut, then another section, at a right angle to the first, which chips a piece from the wall of the cut. There are left and right-handed teeth, depending on which wall of the cut they will chip. Left and right teeth are alternated in the chain. Chains come in varying pitch and gauge; the pitch of a chain is defined as half of the length spanned by any three consecutive rivets (e.g., 0.325 inch), while the gauge is the thickness of drive link where it fits into the guide bar (e.g., 0.05 inch).
The underside of each link features a small metal finger that keeps the tooth centered between the rails of the bar, helps to carry lubricating oil around the bar, and engages with the engine's drive sprocket inside the body of the saw. The engine drives the chain around the track by a centrifugal clutch, engaging the chain at high speed but running free at lower speed. The chain on the lower side of the cutter bar is normally used for cutting, working towards the operator.
As chainsaws become more popular among home owners, chainsaw manufacturers are introducing features to make them easier to use.
As chainsaw carving has become more popular, chainsaw manufacturers are making special short, narrow-tipped bars for carving. These are called "quarter tipped," "nickel tipped" or "dime tipped" bars, based on the size of the round tip. Echo sponsors a carving series,as well as carvers such as former Runaways singer Cherie Currie.RedMax specifically built the G3200 CV chainsaw for carving applications.

Maintenance

Logging near Apiary, Oregon
Most chainsaws require two sources of lubrication. Like most two-stroke engines, the engine is lubricated by its fuel, which contains about 2–5% (depending on model) oil dissolved in the fuel. Separate chain oil or bar oil is used for the external lubrication of the bar and chain. The chain oil is depleted quickly because it tends to be thrown off the chain by centrifugal force, and it is soaked up by sawdust. The chain oil reservoir is usually topped up at the same time as refuelling, and the reservoir is large enough so that the saw runs out of fuel and stops before the chain oil runs dry. Failing to keep the chain oil topped up, or using an oil of incorrect viscosity, is a common source of damage to saws, and tends to lead to rapid wear of the bar, or the chain jamming or coming off the bar.
In addition to being quite thick, chain oil is particularly sticky (due to "tackifier" additives) to reduce the amount thrown off the chain. Although motor oil is a common emergency substitute, it is lost even faster and so leaves the chain underlubricated.
Chains must be kept very sharp to perform well, and become blunt very rapidly if they touch soil, metal or stones. When blunt, they tend to produce powdery sawdust, rather than the longer, clean shavings characteristic of a sharp chain; a sharp saw also needs very little force from the operator to push it into the cut. Special hardened chains (made with tungsten carbide) are used for applications where soil is likely to contaminate the cut, such as for cutting through roots.
The air intake filter tends to clog up with sawdust. This must be cleaned from time to time, but is not a problem during normal operation.

Safety

A chainsaw operator wearing full safety gear using a gasoline-driven chain saw
Main articles: Chainsaw safety features and chainsaw safety clothing
Despite safety features and protective clothing, injuries can still arise from chainsaw use, from the large forces involved in the work, from the fast-moving, sharp chain, or from the vibration and noise of the machinery.
The most common accident arises from kickback, when a chain tooth at the tip of the guide bar catches on wood without cutting through it. This throws the bar (with its moving chain) in an upward arc toward the operator, often causing serious injury or even death.
Another dangerous situation occurs when heavy timber begins to fall or shift before a cut is complete – the chainsaw operator may be trapped or crushed. Similarly, timber falling in an unplanned direction may harm the operator or other workers, or an operator working at a height may fall or be injured by falling timber.
Like other hand-held machinery, the operation of chainsaws can cause vibration white finger, tinnitus or industrial deafness.
The risks associated with chainsaw use mean that protective clothing and hearing protectors are normally worn while operating them, and many jurisdictions require that operators be certified or licensed to work with chainsaws. Injury can also result if the chain breaks during operation due to poor maintenance or attempting to cut inappropriate materials.

History

Electric chainsaw
The origin is debated, but the first chainsaw was probably made around 1830 by the German orthopaedist Bernard Heine. This instrument, the osteotome, had links of a chain carrying small cutting teeth with the edges set at an angle; the chain was moved around a guiding blade by turning the handle of a sprocket wheel. As the name implies, this was used to cut bone.
Two important contributors to the modern chainsaw are Joseph Buford Cox and Andreas Stihl; the latter patented and developed a chainsaw in 1926 and a gasoline-powered chainsaw in 1929, and founded a company to mass-produce them. In 1927, Emil Lerp, the founder of Dolmar, developed the world's first gasoline-powered chainsaw and mass-produced them. McCulloch and Industrial Equipment Corp in North America started to produce chainsaws. The early models were heavy, two-person devices with long bars. Often chainsaws were so heavy that they had wheels like dragsaws. Other outfits used driven lines from a wheeled power unit to drive the cutting bar.
After World War II, improvements in aluminum and engine design lightened chainsaws to the point where one person could carry them. In some areas the skidder / chainsaw crews have been largely replaced by the feller buncher and harvester.
Chainsaws have almost entirely replaced simple man-powered saws in forestry. They come in many sizes, from small electric saws intended for home and garden use, to large "lumberjack" saws. Members of military engineer units are trained to use chainsaws.

Chainsaws for stone, concrete and brick

A chainsaw cutting concrete
Special chainsaws are used to cut concrete, brick and natural stone. These use similar chains to ordinary chainsaws, but with cutting edges made using diamond. They may be gasoline or hydraulically driven, and the chain is lubricated with water, because of high friction and to remove stone-dust. The machine is used in construction, for example in cutting deep square holes in walls or floors, in stone sculpture for removing large chunks of stone during pre-carving, by fire-departments for gaining access to buildings and in restoration of buildings and monuments, for removing parts with minimal damage to the surrounding structure.

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Portable sawmill

2008-11-30T06:10:00.000-08:00

History
Prior to the advent of the portable 'mill, small-scale sawmills were generally cobbled-together affairs constructed and operated by (almost always) two men with a penchant for tinkering. This was, and remains, a traditional occupation for Amish men; unlike most mechanical systems, small sawmills typically do not use electricity.
The portable 'mills represented the first effort at careful engineering and design. Unlike traditional mills, they used a resaw blade of the type used on a band saw rather than a circular blade, which reduced weight and cost, and reduced the size and weight of the bearings and support blocks. It also allowed for a different design where the head, consisting of the blade and a power source, moves back and forth while the log being cut remains stationary. This is in contrast to traditional mills where the log moves on a trolley while the blade remains fixed.
Larger mills have recently come on the market which are portable only in sections. These are faster and can handle larger logs.

Advantages
Portable mills can be trailered and set up on site, next to the trees being cut. There is a good degree of shimming and alignment to get the rails set up straight, and this takes time. Some business transport their mill to harvest urban timber where moving the logs would be impractical.

Uses
The portable mills can cut lumber with speed and accuracy, though the subsequent steps of planing and drying must still be performed to produce finished lumber. Commodity lumber in standard sizes can be made this way. Occasionally, this is done.
The more common use, however, is in the production of specialty timber products not readily available through lumber yards. Portable mills are particularly effective for truing up logs for use in log construction, replacing the traditional use of a drawknife, which is inordinately time-consuming. They are also used for low-volume production of specialty hardwoods used in furniture, and can be used to produce the large timbers used in post-and-beam framing techniques.

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Band saw

2008-11-30T06:09:00.000-08:00

Metal-cutting band saws

19th century wood bandsaw
When cutting metals or timber, a constant flow of liquid over the blade facilitates cutting by lubricating to keep the blade cool as well as preventing encrustation or smearing on the blade, prolonging blade life and making for greater cutting accuracy. Brushes or brushwheels are sometimes used to remove chips and encrustation from the blade as it exits the material. Band saws are available in vertical and horizontal designs. These units range from manually operated machines to fully automatic machines. Band speeds range from 40 feet per minute to 5000 feet per minute.
Machine shop bandsaws may also be horizontal or vertical. Small bandsaws may employ a gravity-fed blade or the rate of descent may be controlled by a hydraulic cylinder bleeding through an adjustable valve. When the saw is set up for a cut, the operator raises the saw by hand and the material is clamped in place and the saw is turned on, the blade slowly descending into the material, cutting it as the band blade moves. When the cut is complete, a switch is tripped and the saw automatically turns off.

Feed mechanisms
Gravity feed saws fall under their own weight against a hydraulic cylinder which has a control valve. Common in small saws.
Hydraulic feed saws use a positive pressure hydraulic piston to advance the saw through the work. Common in production saws.
Screw feed employ a leadscrew to move the saw.

Fall mechanisms
Pivot saws hinge in an arc as they advance through the work.
Single Column saws have a large diameter column that the entire saw rides up and down on, very similar to a radial drill.
Dual column saws have a pair of large columns, one on either side of the work, for very high rigidity and precision. The dual column setup is unable to make use of a miter base due to inherent design. Dual column saws are the largest variety of machine bandsaws encountered, to the point where some make use of a rotary table and X axis to perform complex cutting.

Automated saws
Automatic bandsaws feature preset feed rate, return, fall, part feeding, and part clamping. These are used in production environments where having a machine operator per saw is not practical. One operator can feed and unload many automatic saws.
Some automatic saws rely on NC/CNC control to not only cut faster, but to be more precise and perform more complex miter cuts.

Large band saws
Timber mills use very large band saws for ripping lumber; they are preferred over circular saws for ripping because they can accommodate large-diameter timber and because of their smaller kerf (cut size), resulting in less waste.
The blades range in size from about (4" wide x 19' long x 22 ga thickness) to (16" wide x 62' long x 11 ga thickness). The blades are mounted on wheels with a diameter large enough not to cause metal fatigue due to flexing when the blade repeatedly changes from a circular to a straight profile. It is stretched very tight (with fatigue strength of the saw metal being the limiting factor). Band saws of this size need to have a deformation worked into them that counteracts the forces and heating of operation. This is called benching. They also need to be removed and serviced at regular intervals. Sawfilers or sawdoctors are the craftsmen responsible for this work.
The shape of the tooth gullet is highly optimized and designed by the sawyer and sawfiler. It varies according to the mill, as well as the type and condition of the wood. Frozen logs often require a frost notch ground into the gullet to break the chips. The shape of the tooth gullet is created when the blade is manufactured and its shape is automatically maintained with each sharpening. The sawfiler will need to maintain the grinding wheel's profile with periodic dressing of the wheel.

Head saws
Head saws are large band saws that make the initial cuts in a log. They generally have a two to three inch tooth space on the cutting edge and sliver teeth on the back. Sliver teeth are non-cutting teeth designed to wipe slivers out of the way when the blade needs to back out of a cut.

Resaws
A resaw is a large bandsaw optimized for cutting timber along the grain to reduce larger sections into smaller sections or veneers. Resawing veneers requires a wide blade - commonly 2" to 3" (52 - 78 mm) - with a small kerf to minimize waste. Resaw blades of up to 1" (26 mm) may be fitted to a standard bandsaw.

Double cut saws
Double cut saws have cutting teeth on both sides. They are generally very large, similar in size to a head saw.

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Blade

2008-11-30T06:07:00.000-08:00

Patterns of knife blades

Blade styles with typical edges highlighted.
There are a variety of knife blade shapes; some of the most common are listed below.
(1) A normal blade has a curving edge, and flat back. A dull back lets the wielder use fingers to concentrate force; it also makes the knife heavy and strong for its size. The curve concentrates force on a small point, making cutting easier. This knife can chop as well as pick and slice.
(2) A curved, trailing-point knife has a back edge that curves upward. This lets a lightweight knife have a larger curve on its edge. Such a knife is optimized for slicing or slashing. Trailing point blades provide a larger cutting area, or belly, and are common on skinning knives.

Clip-point blade
(3) A clip-point blade is like a normal blade with the back "clipped" or concavely formed to make the tip thinner and sharper. The back edge of the clip may have a false edge that could be sharpened to make a second edge. The sharp tip is useful as a pick, or for cutting in tight places. If the false edge is sharpened it increases the knife's effectiveness in piercing. The Bowie knife has a clipped blade and clip-points are quite common on pocket knives and other folding knives.

Drop-point blade
(4) A drop point blade has a convex curve of the back towards the point. It handles much like the clip-point through with a stronger point less suitable for piercing. Swiss army pocket knives often have drop-points on their larger blades.

Spear-point blade
(5) A spear-point blade is a symmetrical blade with a spine that runs along the middle of the blade. The point is in line with the spine. Spear-points may be single-edged (with a false edge) or double-edged or may have only a portion of the second edge sharpened. Pen-knives are often single-edged, non-spined spear-points, usually quite small, named for their past use in sharpening quills for writing. Pen-knife may also nowadays refer to somewhat larger pocket knives which are often drop-points. Some throwing knives may have spear-points but without the spine, being only flat pieces of metal.
(6) A needle-point blade is a symmetrical, highly tapered, twin-edged blade often seen in fighting blades, such as the Fairbairn-Sykes commando knife. Its long, narrow point offers good penetration but is liable to breakage if abused. Although often referred to as a knife, this design may also be referred to as a stiletto or (slender variety of) dagger due to its use as a stabbing weapon albeit one very capable of slashing as well.
(7) A spay-point (once used for spaying animals）has a single, mostly straight edge that curves strongly upwards at the end to meet a short, dull, straight clip from the dull back. With the curved end of the blade being closer to perpendicular to the blade's axis than other knives and lacking a point, making penetration unlikely, spay points can be suitable for skinning.
(8) A Westernized tanto style knife has a somewhat chisel-like point that is thick towards the point (being close to the spine) and is thus quite strong. It is superficially similar to the points on most Japanese long and short swords (katana and wakizashi). The traditional Japanese tantō knife uses the blade geometry of (1). The Westernized tanto is often straight but may also be gently curved. The point is actually a second edge on the end of the blade, with a total edge angle of 60 – 80 degrees. Some varieties may have the back edge angled to the point slightly and sharpened for a short distance from the point.
(9) A sheepsfoot knife has a straight edge and a straight dull back that curves towards the edge at the end. It gives the most control, because the dull back edge is made to be held by fingers. Sheepsfoot look like a sheep's hoof. They were used mostly by sailors in old times, as the shape of the tip prevented accidental penetration of the work or a person when the ship rolled suddenly.
(10) A Wharncliffe blade is similar in profile to a sheep's foot but the curve of the back edge starts closer to the handle and is more gradual. Its blade is much thicker than a knife of comparable size.
(11 and 12) An ulu (Inuit woman's knife) knife is a sharpened segment of a circle. This blade type has no point, and has a handle in the middle. It is good for scraping, and sometimes chopping. It is the strongest knife shape. The semi-circular version appears elsewhere in the world and is called a head knife. It is used in leatherworking both to scrape down leather (reducing thickness), and to make precise, rolling cuts for shapes other than straight lines.
Not pictured is the undulating style found on items like the kris or flame-bladed sword. These blades have a distinct wavy design and are sharpened on both sides, typically tapering to (or close to) a symmetrical point.

Patterns of sword blades
Swords may have either a straight blade or a curved one. A straight sword was thought to primarily intended for hacking and stabbing, yet recent studies have shown this to be untrue, as many slicing techniques were used. The difference between a hacking cut and a slashing one is essentially the same as the difference between using a butcher's knife and a chef's knife; one forces an edge straight into a material while the other is pulled along the material to get more of a slicing action. Hacking cuts were usually followed by a slicing action, where the sword is drawn backwards to maximize the cut. For more information see Western Martial Arts or kenjutsu.
Some variations included
the flame blade (undulated blade, for both psychological effect and some tactical advantage of using a non-standard blade: vibrations and easier parry)
the colichemarde, essentially found in smallsword

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Axe

2008-11-30T06:05:00.000-08:00

History

Roman axe in an ancient Roman relief in Brescia, Italy

A bronze axe from the Chinese Shang Dynasty, 12th to 11th centuries BC
Initially axes were probably not hafted. The first true hafted axes are known from the Mesolithic period (ca. 6000 BC). Axes made from ground stone are known since the Neolithic. Few wooden hafts have been found from this period, but it seems that the axe was normally hafted by wedging. Birch-tar and raw-hide lashings were used to fix the blade.
Sometimes a short section of deer antler (an "antler sleeve") was used, which prevented the splitting of the haft and softened the impact on the stone blade itself, helping absorb the impact of each axe blow and lessening the chances of breaking the handle. The antler was hollowed out at one end to create a socket for the axehead. The antler sheath was then either perforated and a handle inserted into it or set in a hole made in the handle instead.
The distribution of stone axes is an important indication of prehistoric trade. thin sectioning is used to determine the provenance of the stone blades. In Europe, Neolithic 'axe factories', where thousands of ground stone axes were roughed out are known from many places, such as:
Great Langdale, Great Britain (tuff)
Rathlin Island, Ireland (porcellanite)
Krzemionki, Poland (flint)
Plancher-les-Mines, France (pelite)
Val de'Aoste, Italy (omphacite).
Stone axes are still produced and in use today in parts of Irian Jaya, New Guinea. The Mount Hagen area was an important production centre.
From the late Neolithic/Chalcolithic onwards, axes were made of copper or copper mixed with arsenic. These axes were flat and hafted much like their stone predecessors. Axes continued to be made in this manner with the introduction of Bronze metallurgy. Eventually the hafting method changed and the flat axe developed into the ‘flanged axe,’ then palstaves, and later winged and socketed axes.
The Proto-Indo-European word for "axe" may have been pelek'u- (Greek pelekus πέλεκυς, Sanskrit parashu, see also Parashurama), but the word was probably a loan, or a Neolithic wanderwort, ultimately related to Sumerian balag, Akkadian pilaku- Symbolism, ritual, and folklore

Minoan symbolic labrys of gold, 2nd millennium BC: many Arkalochori Axes have been found in the Arkalochori cave
At least since the late Neolithic, elaborate axes (battle-axes, T-axes, etc.) had a religious significance and probably indicated the exalted status of their owner. Certain types almost never show traces of wear; deposits of unshafted axe blades from the middle Neolithic (such as at the Somerset Levels in Britain) may have been gifts to the deities.
In Minoan Crete, the double axe (labrys) had a special significance, used by women priests in religious ceremonies. In 1998 a labrys, complete with an elaborately embellished haft, was found at Cham-Eslen, Canton of Zug, Switzerland. The haft was 120 cm long and wrapped in ornamented birch-bark. The axe blade is 17,4 cm long and made of antigorite, mined in the Gotthard-area. The haft goes through a biconical drilled hole and is fastened by wedges of antler and by birch-tar. It belongs to the early Cortaillod culture.
In the Roman fasces, the axe symbolized the authority to execute and were often used as symbols for Fascist Italy under Mussolini.
In folklore, stone axes were sometimes believed to be thunderbolts and were used to guard buildings against lightning, as it was believed (mythically) that lightning never struck the same place twice. This has caused some skewing of axe distributions.
Steel axes were important in superstition as well. A thrown axe could keep off a hailstorm, sometimes an axe was placed in the crops, with the cutting edge to the skies to protect the harvest against bad weather. An upright axe buried under the sill of a house would keep off witches, while an axe under the bed would assure male offspring.

A collection of old Australian axes
Basques, Australians and New Zealanders have developed variants of rural sports that perpetuate the traditions of log cutting with axe. The Basque variants, splitting horizontally or vertically disposed logs, are generically called aizkolaritza (from aizkora: axe).
In Yorùbá mythology, the oshe (double-headed axe) symbolizes Shango, Orisha (god) of thunder and lightning. It is said to represent swift and balanced justice. Shango altars often contain a carved figure of a woman holding a gift to the god with a double-bladed axe sticking up from her head.

Parts of the axe

A diagram showing the main points on an axe.
The axe is comprised of two primary components, the axe head, and the haft.
The axe head is typically bounded by the bit (or blade) at one end, and the poll (or butt) at the other, though some designs feature two bits opposite each other. The top corner of the bit where the cutting edge begins is called the toe, and the bottom corner is known as the heel. Either side of the head is called the cheek, which is sometimes supplemented by lugs where the head meets the haft, and the hole where the haft is mounted is called the eye. The part of the bit that descends below the rest of the axe-head is called the beard, and a bearded axe is an antiquated axe head with an exaggerated beard that can sometimes extend the cutting edge twice the height of the rest of the head.
The axe haft is sometimes called the handle. Traditionally, it was made of a resilient hardwood like hickory or ash, but modern axes often have hafts made of durable synthetic materials. Antique axes and their modern reproductions, like the tomahawk, often had a simple, straight haft with a circular cross-section that wedged onto the axe-head without the aid of wedges or pins. Modern hafts are curved for better grip and to aid in the swinging motion, and are mounted securely to the head. The shoulder is where the head mounts onto the haft, and this is either a long oval or rectangular cross-section of the haft that's secured to the axe head with small metal or wooden wedges. The belly of the haft is the longest part, where it bows in gently, and the throat

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Cutting

2008-11-30T06:03:00.000-08:00

Cutting is the separation of a physical object, or a portion of a physical object, into two portions, through the application of an acutely directed force. An implement commonly used for cutting is the knife or in medical cases the scalpel. However, any sufficiently sharp object is capable of cutting if it has a hardness sufficiently larger than the object being cut, and if it is applied with sufficient force. Cutting also describes the action of a saw which removes material in the process of cutting.
Cutting is a compressive and shearing phenomenon, and occurs only when the total stress generated by the cutting implement exceeds the ultimate strength of the material of the object being cut. The simplest applicable equation is stress = force/area: The stress generated by a cutting implement is directly proportional to the force with which it is applied, and inversely proportional to the area of contact. Hence, the smaller the area (i.e., the sharper the cutting implement), the less force is needed to cut something.
When referring to propagating plants, cutting is one of the methods that can be used. It involves cutting a part of the plant typically a healthy shoot, with sharp and sterile scissors or any other cutting device, and then placing the removed part in water. Some cuttings do not require water. Certain shoots when cut are able to grow when placed in vermiculite or potting soil. However, the former is the easiest to do as most shoots when cut from the main plant need time to grow roots, and then they are able to be transferred to potting soil.

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Tractor

2008-11-30T06:01:00.000-08:00

National variations
In Britain, Ireland, Australia, India, Spain, and Germany the word "tractor" usually means "farm tractor", and the use of the word "tractor" to mean other types of vehicles is familiar to the vehicle trade but unfamiliar to much of the general public. In Canada and the US the word is also used to refer to a road tractor.

History
The first powered farm implements in the early 1800s were portable engines – steam engines on wheels that could be used to drive mechanical farm machinery by way of a flexible belt. Around 1850, the first traction engines were developed from these, and were widely adopted for agricultural use. Where soil conditions permitted, like the US, steam tractors were used to direct-haul ploughs, but in the UK and elsewhere, ploughing engines were used for cable-hauled ploughing instead. Steam-powered agricultural engines remained in use well into the 20th century, until reliable internal combustion engines had been developed.[4]
In 1892, John Froelich built the first practical gasoline-powered tractor in Clayton County, Iowa. Only two were sold, and it was not until 1911, when the Twin City Traction Engine Company developed the design, that it became successful.
In Britain, the first recorded tractor sale was the oil-burning Hornsby-Ackroyd Patent Safety Oil Traction engine, in 1897. However, the first commercially successful design was Dan Albone's three-wheel Ivel tractor of 1902. In 1908, the Saunderson Tractor and Implement Co. of Bedford introduced a four-wheel design, and went on to become the largest tractor manufacturer outside the USA at that time.

A 1920 International Harvester tractor, showing features inherited from earlier steam tractor designs.
While unpopular at first, these gasoline-powered machines began to catch on in the 1910s when they became smaller and more affordable. Henry Ford introduced the Fordson, the first mass-produced tractor in 1917. They were built in the U.S., Ireland, England and Russia and by 1923, Fordson had 77% of the U.S. market. The Fordson dispensed with a frame, using the strength of the engine block to hold the machine together. By the 1920s, tractors with a gasoline-powered internal combustion engine had become the norm.
The classic farm tractor is a simple open vehicle, with two very large driving wheels on an axle below and slightly behind a single seat (the seat and steering wheel consequently are in the center), and the engine in front of the driver, with two steerable wheels below the engine compartment. This basic design has remained unchanged for a number of years, but enclosed cabs are fitted on almost all modern models, for reasons of operator safety and comfort.
Originally, plows and other equipment were connected via a drawbar, or a proprietary connecting system; prior to Harry Ferguson patenting the three-point hitch. Recently, Bobcat's patent on its front loader connection has expired; and compact tractors are now being outfitted with quick-connect attachments for their front-end loaders.
Larger types of modern farm tractors include articulated four wheel or eight wheel drive units with one or two power units which are hinged in the middle and steered by hydraulic clutches or pumps. In the early 21st century, articulated or non-articulated, steerable multi-track "tractors" have largely supplanted the two-track clutch-steered "Caterpiller" type for farm use. These tractors bear little resemblance to the classic farm tractor design.

A modern steerable all-tracked power unit planting wheat in North Dakota
A variety of specialty farm tractors have been developed for particular uses. These include "row crop" tractors with adjustable tread width to allow the tractor to pass down rows of corn, tomatos or other crops without crushing the plants, "wheatland" or "standard" tractors with non-adjustable fixed wheels and a lower center of gravity for plowing and other heavy field work for broadcast crops, and "high crop" tractors with adjustable tread and increased ground clearance, often used in the cultivation of cotton and other high-growing row crop plant operations, and "utility tractors", typically smaller tractors with a low center of gravity and short turning radius, used for general purposes around the farmstead. Many utility tractors are used for non-farm grading, landscape maintenance and excavation purposes, particularly with loaders, backhoes, pallet forks and similar devices. Small garden or lawn tractors designed for suburban and semi-rural gardening and landscape maintenance also exist in a variety of configurations.

Operation

A lawn tractor towing a cargo cart
Modern farm tractors usually have five foot-pedals for the operator on the floor of the tractor. The pedal on the left is the clutch. The operator presses on this pedal to disengage the transmission for either shifting gears or stopping the tractor. Two of the pedals on the right are the brakes. The left brake pedal stops the left rear wheel and the right brake pedal does the same with the right side. This independent left and right wheel braking augments the steering of the tractor when only the two rear wheels are driven. This is usually done when it is necessary to make a tight turn. The split brake pedal is also used in mud or soft dirt to control a tire that spins due to loss of traction. The operator presses both pedals together to stop the tractor. For tractors with additional front-wheel drive, this operation often engages the 4-wheel locking differential to help stop the tractor when travelling at road speeds.
A fifth pedal just in front of the seat operates the rear differential lock (diff lock) which prevents wheelslip. The differential allows the outside wheel to travel faster than the inside one during a turn. However, in traction conditions on a soft surface the same mechanism could allow one wheel to slip, thus preventing traction to the other wheel. The diff lock overrides this, causing both wheels to supply equal traction. Care must be taken to unlock the differential, usually by hitting the pedal a second time, before turning, since the tractor cannot perform a turn with the diff lock engaged.
The pedal furthest to the right is the foot throttle. Unlike in automobiles, it can also be controlled from a hand-operated lever ("hand throttle"). This helps provide a constant speed in field work. It also helps provide continuous power for stationary tractors that are operating an implement by shaft or belt. The foot throttle gives the operator more automobile-like control over the speed of the tractor for road work. This is a feature of more recent tractors; older tractors often did not have this feature. In the UK it is mandatory to use the foot pedal to control engine speed while travelling on the road. Some tractors, especially those designed for row-crop work, have a 'de-accelerator' pedal, which operates in the reverse fashion to an automobile throttle, in that the pedal is pushed down to slow the engine. This is to allow fine control over the speed of the tractor when manoeuvring at the end of crop rows in fields- the operating speed of the engine is set using the hand throttle, and if the operator wishes to slow the tractor to turn, he simply has to press the pedal, turn and release it once the turn is completed, rather than having to alter the setting of the hand throttle twice during the maneuver.

Power and transmission

A 1958 Series II Field Marshall
Modern farm tractors employ large diesel engines, which range in power output from 18 to 575 horsepower (15 to 480 kW). Tractors can be generally classified as two-wheel drive, two-wheel drive with front wheel assist, four-wheel drive (often with articulated steering), or track tractors (with either two or four powered rubber tracks). Variations of the classic style include the diminutive lawn tractors and their more capable and ruggedly constructed cousins, garden tractors, that range from about 10 to 25 horsepower (7.5-18.6 kW) and are used for smaller farm tasks and mowing grass and landscaping. Their size—especially with modern tractors—and the slower speeds are reasons motorists are urged to use caution when encountering a tractor on the roads.

A PTO shaft connected to a tractor.
Most tractors have a means to transfer power to another machine such as a baler, slasher or mower. Early tractors used belts wrapped around a flywheel to power stationary equipment. Modern tractors use a power take-off (PTO) shaft to provide rotary power to machinery that may be stationary or pulled. Almost all modern tractors can also provide external hydraulic fluid and electrical power.
Most farm tractors use a manual transmission. They have several sets of gear ratios divided into speeds. In order to change the ratio, it is usually necessary to stop the tractor. Between them they provide a range of speeds from less than one mile per hour suitable for working the land, up to about 25 miles per hour (40 km/h) for road use. Furthermore it is usually not necessary to change gear in order to reverse, one simply selects a lever. Older tractors usually require that the operator depress the clutch in order to shift between gears (a limitation of straight-cut gears in the gearbox), but many modern tractors have eliminated this requirement with the introduction of technologies such as power shifting in the 1960s and more modern continuously variable transmissions. This allows the operator more and easier control over working speed than the throttle alone could provide.
Slow, controllable speeds are necessary for most operations that are performed with a tractor. They help give the farmer a larger degree of control in certain situations, such as field work. However, when travelling on public roads, the slow operating speeds can cause problems, such as long queues or tailbacks, which can delay or aggravate other road users. To alleviate conditions, some countries (for example the Netherlands) employ a road sign on some roads that means "no farm tractors". Some modern tractors, such as the JCB Fastrac, are now capable of much more tolerable road speeds of around 50 mph (80 km/h).

Backhoe loader
Main article: Backhoe loader

A common backhoe-loader. The backhoe is on the left, the bucket/blade on the right.
The most common variation of the classic farm tractor is the hoe, also called a hoe-loader. As the name implies, it has a loader assembly on the front and a backhoe on the back. Backhoes attach to a 3 point hitch on farm or industrial tractors. Industrial tractors are often heavier in construction particularly with regards to the use of steel grill for protection from rocks and the use of construction tires. When the backhoe is permanently attached, the machine usually has a seat that can swivel to the rear to face the hoe controls. Removable backhoe attachments almost always have a separate seat on the attachment.
Backhoe-loaders are very common and can be used for a wide variety of tasks: construction, small demolitions, light transportation of building materials, powering building equipment, digging holes,loading trucks, breaking asphalt and paving roads. Some buckets have a retractable bottom, enabling them to empty their load more quickly and efficiently. Buckets with retractable bottoms are also often used for grading and scratching off sand. The front assembly may be a removable attachment or permanently mounted. Often the bucket can be replaced with other devices or tools.
Their relatively small frame and precise control make backhoe-loaders very useful and common in urban engineering projects such as construction and repairs in areas too small for larger equipment. Their versatility and compact size makes them one of the most popular urban construction vehicles.
In the UK, the word "JCB" is sometimes used colloquially as a genericized trademark for any such type of engineering vehicle. The term JCB now appears in the Oxford English Dictionary, although it is still legally a trademark of J. C. Bamford Ltd.

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Agricultural machinery

2008-11-30T05:59:00.000-08:00

History

Hand tools
The first person to turn from the hunting and gathering lifestyle to farming probably did so by using his bare hands, and perhaps some sticks or stones. Tools such as knives, scythes, and wooden plows were eventually developed, and dominated agriculture for thousands of years. During this time, almost everyone worked in agriculture, because each family could barely raise enough food for themselves with the limited technology of the day.

The Industrial Revolution
With the coming of the Industrial Revolution and the development of more complicated machines, farming methods took a great leap forward. Instead of harvesting grain by hand with a sharp blade, wheeled machines cut a continuous swath. Instead of threshing the grain by beating it with sticks, threshing machines separated the seeds from the heads and stalks.

Steam power
These machines required a lot of power, which was originally supplied by horses or other domesticated animals. With the invention of steam power came the portable engine and later the traction engine, a multipurpose, mobile energy source that was the ground-crawling cousin to the steam locomotive. Agricultural steam engines took over the heavy pulling work of horses, and were also equipped with a pulley that could power stationary machines via the use of a long belt. The steam-powered behemoths were low-powered by today's standards but, because of their size and their low gear ratios, they could provide a large drawbar pull. Their slow speed led farmers to comment that tractors had two speeds: "slow, and darn slow."

The internal combustion engine
Gasoline, and later diesel engines became the main source of power for the next generation of tractors. These engines also contributed to the development of the self-propelled, combined harvester and thresher, or combine for short. Instead of cutting the grain stalks and transporting them to a stationary threshing machine, these combines cut, threshed, and separated the grain while moving continuously through the field.

Types
Combines might have taken the harvesting job away from tractors, but tractors still do the majority of work on a modern farm. They are used to pull implements—machines that till the ground, plant seed, or perform a number of other tasks.
Tillage implements prepare the soil for planting by loosening the soil and killing weeds or competing plants. The best-known is the plow, the ancient implement that was upgraded in 1838 by a man named John Deere. Plows are actually used less frequently in the U.S. today, with offset disks used instead to turn over the soil and chisels used to gain the depth needed to retain moisture.
The most common type of seeder is called a planter and spaces seeds out equally in long rows, which are usually 2 to 3 feet apart. Some crops are planted by drills, which put out much more seed in rows less than a foot apart, blanketing the field with crops. Transplanters fully or partially automate the task of transplanting seedlings to the field. With the widespread use of plastic mulch, plastic mulch layers, transplanters, and seeders lay down long rows of plastic, and plant through them automatically.
After planting, other implements can be used to cultivate weeds from between rows, or to spread fertilizer and pesticides. Hay balers can be used to tightly package grass or alfalfa into a storable form for the winter months.
Modern irrigation also relies on a great deal of machinery. A variety of engines, pumps and other specialized gear are used to provide water quickly and in high volumes to large areas of land. Similar types of equipment can be used to deliver fertilizers and pesticides.
And, besides the tractor, a variety of vehicles have been adapted for use in various aspects of farming, including trucks, airplanes, and helicopters, for everything from transporting crops and making equipment mobile, to aerial spraying and livestock herd management.

New technology and the future
The basic technology of agricultural machines has changed little in the last century. Though modern harvesters and planters may do a better job or be slightly tweaked from their predecessors, the US$250,000 combine of today still cuts, threshes, and separates grain in essentially the same way it has always been done. However, technology is changing the way that humans operate the machines, as computer monitoring systems, GPS locators, and self-steer programs allow the most advanced tractors and implements to be more precise and less wasteful in the use of fuel, seed, or fertilizer. In the foreseeable future, some agricultural machines will be capable of driving themselves, using GPS maps and electronic sensors. Even more esoteric are the new areas of nanotechnology and genetic engineering, where submicroscopic devices and biological processes, respectively, are being used as machines to perform agricultural tasks in unusual new ways.
Agriculture may be one of the oldest professions, but the development and use of machinery has made the job title of farmer a rarity. Instead of every person having to work to provide food for themselves, less than 2% of the U.S. population today works in agriculture, yet that 2% provides considerably more food than the other 98% can eat. It is estimated that at the turn of the 20th century, one farmer in the U.S. could feed 25 people, where today, that ratio is 1:130 (in a modern grain farm, a single farmer can produce cereal to feed over a thousand people). With continuing advances in agricultural machinery, the role of the farmer will become increasingly specialized and rare.

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Stone tool

2008-11-30T05:56:00.000-08:00

Paleolithic tools

Flint (tool)
Prehistoric stone-working techniques of the Palaeolithic are divided into four 'Modes' The Mode 1 industries (Oldowan, Clactonian) created rough flake tools by hitting a suitable stone with a hammerstone. The resulting flake would have a natural sharp edge for cutting and could afterwards be sharpened further by striking another smaller flake from the edge if necessary (known as retouch). These early toolmakers may also have worked the stone they took the flake from (known as a core) to create chopper cores although there is some debate over whether these items were tools or just discarded cores The Mode 2 (eg Acheulean or Biface) toolmakers also used the Mode 1 flake tool method but supplemented it by also using wood or bone implements to pressure flake fragments away from stone cores to create the first true hand-axes. The use of a soft hammer made from wood or bone also resulted in more control over the shape of the finished tool. Unlike the earlier Mode 1 industries, the core was prized over the flakes that came from it. Another advance was that the Mode 2 tools were worked symmetrically and on both sides (hence the name Biface) indicating greater care in the production of the final tool.
Mode 3 technology emerged towards the end of Acheulean dominance and involved the Levallois technique. It is commonly associated with Neanderthal Mousterian industry. The long blades (rather than flakes) of the Upper Palaeolithic Mode 4 industries appeared during the Upper Palaeolithic[2]. The Aurignacian culture is a good example of mode 4 tool production. Mode 5 stone tools involve the production of Microliths. Examples include the Magdalenian culture.

Polished stone tools

An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools.

Five types of tools found in Ecuador
Ground stone tools became important during the Neolithic period. These ground or polished implements are manufactured from larger-grained materials such as basalt, greenstone and some forms of rhyolite which are not suitable for flaking. The greenstone industry was important in the English Lake District, and is known as the Langdale axe industry. Ground stone implements included adzes, celts, and axes, which were manufactured using a labour-intensive, time-consuming method of repeated grinding against an abrasive stone, often using water as a lubricant. Because of their coarse surfaces, some ground stone tools were used for grinding plant foods and were polished not just by intentional shaping, but also by use. Manos are hand stones used in conjunction with metates for grinding corn or grain. Polishing increased the intrinsic mechanical strength of the axe. Polished stone axes were important for the widespread clearance of woods and forest during the Neolithic period, when crop and livestock farming developed on a large scale.

References
^ Barton, RNE, Stone Age Britain English Heritage/BT Batsford:London 1997 qtd in Butler, 2005. See also Wymer, JJ, The Lower Palaeolithic Occupation of Britain, Wessex Archaeology and English Heritage, 1999.
^ Lewin, R., Foley, R. A. 2004. Principles of Human Evolution (2nd Ed.) Blackwell Science, UK. ISBN: 0-632-04704-6

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Sickle

2008-11-30T05:53:00.001-08:00

sickle is a hand-held agricultural tool with a curved blade typically used for harvesting grain crop or cutting grass for hay. The inside of the curve is sharp, so that the user can draw or swing the blade against the base of the crop, catching it in the curve and slicing it at the same time. The material to be cut may be held in a bunch in the other hand (for example when reaping), held in place by a wooden stick, or left free. When held in a bunch, the sickle action is towards the user (left to right for a right-handed user), but when used free the sickle is usually swung the opposite way. Different types may be referred to as a grasshook, swap hook, rip-hook, slash-hook, reaping hook, brishing hook or bagging hook.

Using a sickle
The blade of a sickle is often cranked to one side, to make it easier to keep the blade closer to the ground; this makes it right- or (more rarely) left-handed. Sickles used for reaping are usually serrated.
The sickle was largely superseded by the scythe, which is more comfortable and efficient to use for many purposes, but it continues in use in many parts of the world, and for certain uses where a scythe is not convenient. The most noticeable difference between a sickle and a scythe is the length of the handle – a sickle is a one-handed tool with a short handle, used while bending down to the ground, while a scythe is a two-handed tool, used standing up, with a long, often curved haft, and a much longer blade.
A blade which is used regularly to cut the silica-rich stems of cereal crops acquires a characteristic sickle-gloss, or wear pattern. When this pattern appears on ancient stone tools, it can indicate early use or development of agricultural use.
In Greek myths, the sickle was used as a weapon by Cronus and Perseus.

Additional uses
The sickle is used as part of the well known symbol of the hammer and sickle, which is the symbol of Communism or Revolutionary Socialism. The sickle represents the agricultural working class or peasantry in this symbol.
Sickle is a fictional unit of money in the Harry Potter series.
SS-25 Sickle is the NATO reporting name for the RT-2PM Topol intercontinental ballistic missile.
Tacitus reports that golden sickles were used in Druidic rituals.

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Scythe

2008-11-30T05:51:00.000-08:00

Use

Using a scythe
Using a scythe is called mowing (or often scything, to distinguish it from mowing with more complex machinery). Mowing is done by holding the top handle in the left hand and the central one in the right, with the arms straight, the blade parallel to the ground and very close to it, and the body twisted to the right. The body is then twisted steadily to the left, moving the scythe blade along its length in a long arc from right to left, ending in front of the mower, thus depositing the cut grass to the left. Mowing proceeds with a steady rhythm, stopping at frequent intervals to sharpen the blade. The correct technique has a slicing action on the grass, cutting a narrow strip with each stroke – a common beginner's error is to chop or hack at the grass, with the blade length at right angles to it, thus trying to cut too wide a strip of grass at once. This is much harder work, and is ineffective. Cutting too close to the ground can contaminate the blade with soil, rapidly blunting it. Much of the skill is in keeping the blade close to the ground and the cuts even.
Mowing is normally done cutting out of the uncut grass, the mower moving along the mowing-edge with the uncut grass to their right. The cut grass is laid in a neat row to the left, on the previously mown land. Each strip of ground mown by a scythe is called a swathe (pronounced : rhymes with "bathe") or swath （ rhymes with "Goth"). Mowing may be done by a team of mowers, usually starting at the edges of a meadow then proceeding clockwise and finishing in the middle. Mowing grass is easier when it is damp, and so hay-making traditionally began at dawn and often stopped early, the heat of the day being spent raking and carting the hay cut on previous days.
Mowing with a scythe is a skilled task, performed with relative ease by experienced mowers, but often poorly and with very great effort by beginners. Long-bladed traditional scythes with double-curved wooden snaiths are harder to use at first, but once mastered are more effective and comfortable for longer periods. Shorter-bladed or hack-scythes are easier for beginners. A skilled mower using a traditional long-bladed scythe can even cut very short grass, and this is how lawns were maintained until the invention of the lawnmower.
In addition to mowing grass and reaping crops, a scythe can also be used for mowing reed or sedge, remaining effective even with the blade under water.

History

A modern scythe of a pattern common in parts of Europe
According to the Dictionary of Greek and Roman Antiquities of Sir William Smith, the scythe, known in Latin as the falx foenaria (as opposed to the sickle, the falx messoria), was used by the ancient Romans; for illustration, Smith shows an image of Saturn holding a scythe, from an ancient Italian cameo.
According to Jack Herer and "Flesh of The Gods" (Emboden, W.A., Jr., Praeger Press, NY, 1974.); the ancient Scythians grew hemp and harvested it with a hand reaper that we still call a scythe. Cannabis inhalation by the Scythians in funeral rituals was recorded by the Greek Historian Herodotus (circa 450 B.C.E.) in the early 5th Century B.C.E. The nomadic Scythians introduced the custom to other races such as the Thracians.
The scythe appeared in Europe during the 12th and 13th centuries. Initially used mostly for mowing grass, it replaced the sickle as the tool for reaping crops by the 16th century, the scythe allowing the reaper to stand rather than stoop. In about 1800 the addition of light wooden fingers above a scythe blade produced a form of scythe called the cradle which soon replaced the simple scythe for reaping grain and mowing other tall vegetation such as reeds. In the developed world, all of these have now largely been replaced by motorized lawnmowers and combine harvesters.
The Abbeydale Industrial Hamlet in Sheffield, England is a museum of a scythe-making works that was in operation from the end of the 18th century until the 1930s. This was part of the former scythe-making district of north Derbyshire, which extended into Eckington.Other English scythe-making districts include that around Belbroughton.
Mowing with a scythe remained common for many years even after most mowing became mechanized, because a side-mounted finger-bar mower (whether horse or tractor drawn) cannot mow in front of itself. Scythes would therefore be used to open up a meadow – to mow the first swathes, thus letting the mechanical mower in to complete the mowing.

Mechanical "scythes"
The Allen Scythe is a gasoline-powered finger-bar mower. Despite its name, it does not resemble a hand scythe (except in purpose). The motor drives a toothed blade sliding back and forth horizontally across stationary teeth to produce a scissor action, and also drives two large wheels. There are handles to allow the machine to be controlled by an operator walking behind it. It was manufactured between 1935 and 1973 in Oxford, England. Similar machines are still made (usually just called "mowers"), sometimes as an attachment to other pedestrian-controlled machinery such as rotary tillers.

Scythes in national cultures

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The curved blade of the scythe is clearly shown. Note: this image shows the blade with its edge uppermost – normally used the other way up, with the blade pointing to the left of the mower.
The scythe is still an indispensable tool for farmers in developing countries and in mountainous terrain.
In Romania, for example, in the highland landscape of the Apuseni mountains, scything is a very important annual activity, taking about 2-3 weeks to complete for a regular house. As scything is a tiring physical activity and is relatively difficult to learn, farmers help each other by forming teams. After each day's harvest, the farmers often celebrate by having a small feast where they dance, drink and eat, while being careful to keep in shape for the next day's hard work.
Among Basques scythe-mowing competitions are still a popular traditional sport, called segalaritza (from sega: scythe). The contenders compete to cut a defined section of grown grass before his rival does the same.
The Norwegian municipality of Hornindal has three scythe blades of in its coat-of-arms.

Mythology
The scythe also plays an important traditional role, often appearing as weapons in the hands of mythical beings such as Cronus, the Four Horsemen of the Apocalypse and the Grim Reaper (Death). This stems mainly from the Christian mythological interpretation of death as a "harvester of souls." Kali, the Hindu Goddess of Death, also used a scythe.

Military uses
A war scythe has had its blade transformed so that it extends upright from the staff, and is used much like a halberd. It was widely used by Polish peasants (kosynierzy) in the 18th and 19th centuries.
Scythes also were used for scythed chariots.