Forklift


A forklift is a powered industrial truck used to lift and move materials over short distances.
The forklift was developed in the early 20th century by various companies, including Clark, which made transmissions, and Yale & Towne Manufacturing, which made hoists.
Since World War II, the development and use of the forklift truck has greatly expanded worldwide. Forklifts have become an indispensable piece of equipment in manufacturing and warehousing. In 2013, the top 20 manufacturers worldwide posted sales of $30.4 billion, with 944,405 machines sold.

History

The forerunners of the modern forklift were manually powered hoists to lift loads. In 1906, the Pennsylvania Railroad introduced battery-powered platform trucks for moving luggage at their Altoona, Pennsylvania, station.
World War I saw the development of different types of material-handling equipment in the United Kingdom by Ransomes, Sims & Jefferies 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 and lift tractors in its factories. In 1919, the Towmotor Company and, in 1920, Yale & Towne Manufacturing, entered the lift truck market in the United States. Continuing development and expanded use of the forklift continued through the 1920s and 1930s. The introduction of hydraulic power and the development of the first electrically powered forklifts, along with the use of standardized pallets in the late 1930s, helped to increase the popularity of forklift trucks.
file:Shipprovisioning.jpg|thumb|A forklift loading a cruise liner
The start of World War II, like World War I before it, spurred the use of forklift trucks in the war effort. Following the war, more efficient methods for storing products in warehouses were implemented, and warehouses needed more maneuverable forklift trucks that could reach greater heights. For example, in 1954, a British company named Lansing Bagnall, now part of KION Group, developed what was claimed to be the first narrow-aisle electric-reach truck. That development changed the design of warehouses leading to narrower aisles and higher load-stacking, which increased storage capability.
During the 1950s and 1960s, operator safety became a concern due to increasing lifting heights and capacities. Safety features such as load backrests and operator cages called overhead guards, began to be added to forklifts. In the late 1980s, ergonomic design began to be incorporated in new forklift models to improve operator comfort, reduce injuries, and increase productivity. During the 1990s, undesirable exhaust emissions from forklift operations began to be tackled, which led to emission standards being implemented for forklift manufacturers in various countries. The introduction of AC power forklifts, along with fuel cell technology, were refinements in continuing forklift development.

Design

Components

A typical counterbalanced forklift contains the following components:
  • Truck framethe 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.
  • Counterweighta 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 battery may serve as part of the counterweight.
  • Cabthe 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. When enclosed, the cab may also be equipped with a cab heater for cold climate countries along with a fan or air conditioning for hot weather.
  • Overhead guarda 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 an integrated part of the frame assembly.
  • Power sourcemay consist of an internal combustion engine that can be powered by LP gas, CNG, gasoline or diesel fuel. Electric forklifts are powered by either a battery or fuel cell that provides power to the electric motors; some fuel cell forklifts may be powered by multiple fuel cells at once. For warehouses and other indoor applications, electric forklifts have the advantage of not producing carbon monoxide.
  • Tilt cylindershydraulic cylinders that are mounted to the truck frame and the mast. The tilt cylinders pivot the mast backwards or forwards to assist in engaging a load.
  • Mastthe 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 driven hydraulically, and operated by one or more hydraulic cylinders directly or using chains from the cylinder or cylinders. It may be mounted to the front axle or the frame of the forklift. A 'container mast' variation allows the forks to raise a few meters without increasing the total height of the forklift. This is useful when double-loading pallets into a container or under a mezzanine floor.
  • Carriagethe 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.
  • Load backresta 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.
  • Attachmentsmay consist of a mechanism that is attached to the carriage, either permanently or temporarily, to help in the proper engagement of the load. A variety of material-handling attachments are available. Some attachments include sideshifters, slipsheet attachments, carton clamps, multipurpose clamps, rotators, fork positioners, carpet poles, pole handlers, container handlers and roll clamps.
  • Tireseither solid for indoor use, or pneumatic for outside use.

    Attachments

Common forklift attachments include:
  • Dimensioning devicesfork truck-mounted dimensioning systems provide dimensions for the cargo to facilitate truck-trailer space utilization and to support warehouse automation systems. The systems normally communicate the dimensions via 802.11 radios. NTEP-certified dimensioning devices are available to support commercial activities that bill based on volume.
  • Sideshiftera hydraulic attachment that allows the operator to move the tines and backrest laterally. This allows easier placement of a load without having to reposition the truck.
  • Rotatorto aid the handling of skids that may have become excessively tilted, and for 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 positionera hydraulic attachment that moves the tines together or apart. This removes the need for the operator to manually adjust the tines for different-sized loads.
  • Roll and barrel clamp attachmenta mechanical or hydraulic attachment used to squeeze the item to be moved. It is used for handling barrels, kegs, or paper rolls. This type of attachment may also have a rotate function. The rotate function would help an operator to insert a vertically stored paper into the horizontal intake of a printing press for example.
  • Pole attachmentsin 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 attachmentshydraulic 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 of attachment. With these attachments in use, the forklift truck is sometimes referred to as a clamp truck.
  • Slip sheet attachment a hydraulic attachment that reaches forward, clamps onto a slip sheet and draws the slip sheet onto wide and thin metal forks for transport. The attachment will push the slip sheet and load off the forks for placement.
  • Drum handler attachmenta mechanical attachment that slides onto the tines. 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 basketa lift platform that slides onto the tines and is meant for hoisting workers. The man basket has railings to keep the person from falling and brackets for attaching a safety harness. Also, a strap or chain is used to attach the man basket to the carriage of the forklift.
  • Telescopic forkshydraulic attachments that allow the forklift to operate in warehouses designed for "double-deep stacking", which means that two pallet shelves are placed behind each other without any aisle between them.
  • Scalesfork truck-mounted scales enable operators to efficiently weigh the pallets they handle without interrupting their workflow by travelling to a platform scale. Scales are available that provide legal-for-trade weights for operations that involve billing by weight. They are easily retrofitted to the truck by hanging on the carriage in the same manner as forks hang on the truck.
  • Single-double forksforks that in the closed position allow movement of a single pallet or platform but when separated, turn into a set of double forks that allow carrying two pallets side by side. The fork control may have to replace the side-shifter on some lift trucks.
  • Snow plougha mechanical attachment that allows the forklift operator to easily and quickly move snow. The snow plough can often also be utilised at other times of the year as an attachment to clean up workplaces.
  • Skipsa mechanical attachment that is fitted to the forklift to allow safe and speedy removal of waste to the appropriate skip or waste compactor. There are two types of skips: the roll-forward type and the bottom-emptying type.