Science Fair Project Encyclopedia
A forklift is a powered industrial truck used to hoist and transport materials by means of steel forks inserted under the load. The forklift was invented in 1917 by a transmission manufacturing company in order to facilitate the movement of heavy automotive subassemblies. It has since become an indispensable piece of equipment in many manufacturing and warehousing operations.
A typical forklift may be generally described as follows:
- The truck proper, which is a motive machine with wheels powered through a transmission and drive train
- An LPG, gasoline or diesel fueled internal combustion engine, or a battery-powered electric motor
- The counterweight, which is a heavy iron mass attached to the rear of the machine, necessary to compensate for the load. In an electric forklift, the large lead-acid battery itself may serve as a counterweight
- The mast, which is the vertical assembly that does the work of raising, lowering, and tilting the load; the mast is hydraulically operated and consists of a cylinder and interlocking rails for lifting and lowering operations and for lateral stability
- The carriage, which comprises flat metal plate(s) and is moved along the mast by means of chains
- Forks, which are the L-shaped members that engage the load. The back vertical portion of the fork attaches to the carriage by means of a hook or latch; the front horizontal portion is inserted into or under the load, usually on a pallet. Alternatively, a variety of other equipment is available, including slipsheet clamps, carton clamps, carpet rams, pole handlers, and others.
- The load back rest, which is a rack-like extension attached to the carriage to prevent the load from shifting backward
- The driver's overhead guard, which is a metal roof, supported by posts, that helps protect the operator from any falling debris
- The cab, with a seat for the operator and pedals and switches for controlling the machine—the cab is typically open and bounded by the cage-like overhead guard assembly.
Control and capability
Forklift trucks are available in many variations and load capacities. In a typical warehouse setting most forklifts used have load capacities of around one to five tons.
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. Some machines also allow the operator to move the tines and backrest laterally, allowing easier placement of a load. In addition, a few machines offer a hydraulic control to move the tines together or apart, removing the need for the operator to get out of the cab to manually adjust for a differently sized load.
Grab attachments for handling barrels or even kegs also have a control to operate the tongs that grab the load.
In some locations(such as carpet warehouses) a long metal pole is used instead of forks to lift large rolls.
Forklifts are rated for loads at a specified maximum weight and a specified forward center of gravity. This information is located on a nameplate provided by the manufacturer, and loads must not exceed these specifications.
An important aspect of forklift operation is its rear-wheel steering. While this increases maneuverability in tight cornering situations, it differs from a driver’s traditional experience with other wheeled vehicles as there is no caster action; indeed it is necessary to apply steering force to maintain a straight ahead course. These effects are observable when driving a car or other vehicle in reverse.
Another critical characteristic of the forklift is its instability; the forklift and load must be considered a unit, with a continually varying center 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 tipover accident. A forklift must not be used as a personnel elevator without the fitting of specific safety equipment. In the U.S., additional safety considerations are detailed in the applicable OSHA rules, and lift truck operators must be trained and certified.
- HGM Forklift Parts - lift truck parts online catalog
- Supralift - The largest marketplace for used forklift and warehouse trucks
- 29 CFR § 1910.178 Powered industrial trucks
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details