Forklifts or forklifts are part of the industrial trucks and are used for in-house handling and transport of goods . In contrast to simple lift trucks , for example , they have their own drive and a lifting frame in order to create stacks or to operate storage racks .
The most common lifting loads are between one and eight tons. Lifting heights of up to six meters are common. However, much larger vehicles are also available; The load capacity of forklifts can be over 70 tons, depending on their size and weight. In principle, the employers' liability insurance associations in Germany only permit stacking and storage processes up to a height of ten meters in which people are directly involved through industrial trucks; Exceptions are possible.
- (This is why high-bay warehouses with correspondingly high ceiling heights - often already computer-controlled - are used Usually store them faster and more precisely, especially if they are automated. You take the goods to be stored from the industrial trucks and store them.)
Forklift trucks are especially designed for the transport of pallets . An essential element of the forklift is its lifting unit, which consists of a lifting mast and fork carriage. The fork carriage carries (as a rule) two steel tines with adjustable spacing, which can usually be moved up and down with a hydraulic cylinder via a pulley system with a link chain . Some forks can also be moved transversely as a slide or the distance between the forklift forks can be changed hydraulically. The prongs are called forks and give the forklift its name.
The first forklift truck was developed by employees of the entrepreneur Eugene Clark in 1924. From this invention, the Clark Material Handling Company emerged , which still exists today. Today, the majority of forklift trucks are manufactured in Asia , whereby existing quality standards are achieved through the use of European and Japanese components ( Nissan or Cummins engines, Okamura transmissions, Iskra hydraulics, Hoesch profiles, ZF transmissions, Metalrota rollers, controls from Curtis Instruments ).
Delimitation and distinction
Other vehicles - in particular wheel loaders and tractors - can also perform similar tasks by using appropriate attachments (in particular forks). These vehicles are - as a limitation of the broader view of warehouse logistics theory - not counted as industrial trucks by the German statutory accident insurance .
Forklift trucks can be differentiated according to the following criteria:
- Drive type (diesel, gas, electric)
- Number of wheels (three or four wheels)
- Accessibility (wheel-supported, self-supporting, reach mast)
- Operator, sitting position or control station (tiller guidance, standing or sitting stacker as a cross, side or front seat)
- Lifting height (single to four mast)
- Tires (air, super elastic, solid rubber)
- Safety aspects (explosion-proof forklifts)
Forklift trucks are usually controlled by an operator on board and driven by an internal combustion or electric motor. The combustion engines work with a propane / butane mixture ( liquid gas ), diesel fuel or natural gas . Petrol-powered forklifts are practically non- existent in the EU .
Electric or gas powered forklifts are also allowed to work indoors. In Switzerland, forklifts with internal combustion engines may only be used indoors after thorough investigation.
Drives with electric motors avoid pollutant emissions. You need a traction battery , the mass of which in this case contributes to the balance of the center of gravity. Lead-acid batteries are therefore often used in steel troughs, usually with a nominal voltage of 80 volts. There are DC and AC motors used with inverters. The motor also serves as a regenerative brake.
Forklift trucks have rear steering with a very large steering angle to achieve a small turning circle . As a rule, the turning circle is only about as large as the length of the vehicle. Forklift trucks with three or four wheels are built. With three-wheeled construction, the single wheel is at the rear, with four-wheeled models, the rear wheels are usually connected by a pendulum rigid axle that is fixed to the forklift at one point. This means that the forklift can also drive on uneven surfaces, but the triangle is retained, which means that there is a higher risk of tipping over with an unloaded forklift than with a vehicle with a square because the center of gravity is closer to the lateral tipping edges that meet at the point of support of the pendulum axle.
To improve stability, most forklift trucks do not have axle suspension. On four-wheel forklifts, however, vibration dampers can be mounted on the rear swing axle to prevent swaying. The suspension is provided by special forklift tires and a sprung driver's seat that can be adjusted to the driver's weight.
Forklift trucks are operated using pedals and hand levers. Since almost all of them have synchronized automatic transmissions , there are essentially two operating systems. The first has a right drive and a left brake pedal and the direction of travel is selected using a hand lever, which is usually located on the steering wheel . (This direction of travel transmitter can, for example, also be located on the first lever, the control unit for the mast, so that the driver can keep his hand on the switch levers.)
Second, a system in which a separate pedal is used for driving forwards and backwards; this applies in particular to forklifts manufactured by Linde . With this system there is no direction switch.
In the first-mentioned variant, there is often an additional so-called inching pedal , which ensures that the forklift can use its full hydraulic power for the stacking processes when it is stationary. Characteristically, this pedal comes close to a clutch pedal , but is perceived by the driver as an additional brake that is often used during the stacking process, as it can generally be operated with less effort than the actual brake and less laboriously than the parking brake.
The control levers for the mast and / or other devices for lifting loads are usually located to the right of the driver. The first two levers extend and tilt the mast. Other levers control any dynamic attachments that are connected to the hydraulic system and give the truck additional functions and options.
In particular, it is customary to operate a sideshift via the third lever - often ex works - with which the fork back (with the fork prongs attached) can be moved to the left and right. For forklifts - similar to wheel loaders and similar vehicles - there is a large number of attachments that can usually be controlled using this third or fourth lever.
In some forklifts, instead of these control levers - which are pulled forwards and backwards - a control stick similar to a joystick is used, in which one at a time can perform the function of two classic control levers. This should save the driver the need to change hands.
Most common front forklift trucks have a steering wheel (usually with a steering knob ) or alternatively a joystick . In the case of side-thrust trucks in particular, the “Mini” and “Midi” steering wheel designs are used as steering wheels due to the lack of space. On mini steering wheels, the left palm rests on the crank knob, while the corresponding arm rests on an armrest that can be adjusted to the driver's movements. With Midi steering wheels, the entire steering unit can be ergonomically adjusted.
The steering is usually also hydraulically assisted with steering wheels and steers the rear wheel (or the rear wheels) far more strongly than is possible with a passenger car, for example. This results in the great maneuverability of a forklift.
A conventional forklift usually only needs its own vehicle length to turn and turns more or less around the inside front tire when the steering is fully turned. With four-way forklifts, all wheels can be steered, which means that the forklift does not have to turn around. Because of these driving characteristics, forklifts pose a danger to pedestrians and the drivers of other vehicles, as they can be surprised by the swinging rear end, sudden changes in direction and other driving maneuvers that are not possible for other vehicles, among other things when trying to get close to a forklift truck.
The driver's seat is not always mounted in the forward direction; In the case of side-thrust trucks in particular, the seat is turned by 90 degrees and the driver has to look to the right when driving forwards and to the left when driving backwards. Some forklift seats can be rotated to a limited extent to the left and right (with pedals and levers); advanced forklifts can even turn the entire driver's cab 360 degrees.
Forklift seats are usually sprung, as this is the only way to dampen shocks - especially on the drivers' intervertebral discs - that are transmitted through the chassis. In order to safely pick up the load, forklift trucks do not have sprung axles and usually run with treadless solid rubber or tread-bearing super-elastic tires instead of pneumatic tires . The suspension of the seat can be adapted to the weight of the driver in order to compensate for this health hazard due to the lack of other cushioning.
Modern forklifts query the seat setting via a sensor; if the set load on the seat is not achieved, the forklift refuses to drive.
Modern forklifts have a touch-sensitive screen that allows further settings and displays instead of an instrument panel with switches and indicator lights. Fault messages from the hydraulic and brake systems, oil levels, tank and charge levels, but also operating hours and maintenance intervals can be displayed in plain text, as graphics or numbers.
The switching behavior of the synchronous transmission is set in five speed levels using the so-called hare-turtle setting; where the maximum speed can be reached at level five, while at lower gear the synchromesh gear does not select the higher gears.
The entire lighting, existing indicators, ventilation, etc. is also controlled via such a panel or buttons and switches. The variety and differences - even with forklifts from the same manufacturer - mean that instruction (already required by law) for a new driver and a study of the manual appear to be indispensable.
A particularly impressive variant of the counterbalance forklift is the all-terrain forklift , also known as the large tire forklift. The focus here is on off-road mobility due to high ground clearance, low-pressure tires, high traction, extremely robust construction of the chassis, mast and steering axle, powerful engines, usually diesel engines , with top models hydrostatic transmission and high stability with good climbing ability. Some of these forklifts have all-wheel drive. All-terrain forklifts are also used outside of the company in difficult terrain, for example in forestry, wood industry, mines, recycling industry, heavy industry, in plant construction, in concrete works and brickworks.
Another special variant is the reach truck . Reach trucks are self-supporting and wheel-supported at the same time. To take up the load, the mast is pushed forward so that the fork lies freely in front of the vehicle and can be lowered to the ground. To transport the load, however, the mast is retracted between the wheel arms, which improves driving stability and reduces the need for a counterweight. When the mast is arranged on the side, the load is picked up by the extendable mast arranged on the side and placed on the table for transport. Since you sit sideways on this forklift, it is also called a sideways-seated stacker. Reach trucks are intended for the internal transport of long loads in particular. Reach trucks have always been only available with electric drive.
Narrow aisle truck
Narrow-aisle warehouses are set up in order to use the space as much as possible. The corridors between the shelves are so narrow that the forklift has no more space to maneuver between the shelves. The narrow-aisle truck therefore has a fork that is rotated 90 degrees to the direction of travel and can be extended and retracted to the side. Since these warehouses can reach heights of ten meters and more and you no longer have a good overview of the goods to be removed or stored from the ground, the driver's cab is lifted with a fork on some narrow-aisle forklifts. In the narrow aisles, the forklifts are usually kept on track with guide rails or electronic systems, as there is only a few centimeters of space between the forklift and the rack.
Four and multi-way forklifts
In order to increase maneuverability, especially in narrow warehouse aisles, cross-forklifts, better known as multi-directional sideloaders, are equipped with swiveling wheels and can then drive into warehouse aisles without laborious maneuvering across the loading direction. If the wheels can be swiveled by 90 degrees, one speaks of four-way forklifts , with wheels that can be swiveled as required, of multi-way forklifts .
Multi-way sideloaders are used for the in-house transport of long goods from 4 meters. The wood industry, metal industry, steel processing and steel trading sectors in particular use these sideloaders.
At the side loader or cross forklift truck , the pair of forks arranged transversely to the direction of travel. The load is picked up at right angles to the direction of travel. The goods are transported lengthways, so lengths of up to 34 meters can be lifted and transported. Therefore useful side loader for transporting long loads, the transport would otherwise be set with front lift trucks, for example, by the width of gears or Halletoren limits. Forklifts of this type are often used in the timber trade, in carpentry and in the steel industry.
For special applications, a forklift can be equipped with special attachments. These have been compatible around the world according to the DIN standard for older devices or according to the FEM standard since around 1980. In addition to elongated, hollow plug-on tines (fork shoes), common attachments also include shovels, telescopic forks, rotating devices, sideshifters, tine adjusters, and paper roll and barrel clamps. When using the attachments, some of which are quite heavy and protruding, the residual load capacity is reduced. The reduction results from the increase in the load center distance and the dead weight of the attachments.
The reduction in load capacity can be calculated in four steps using the following formula:
- Forklift torque M St = Q (X + C)
- Attachment torque M E = G E (ESP + X)
- Residual torque M R = M St - M E
- Residual load capacity GL = M R ÷ (X + V + L / 2)
the abbreviations stand for:
- M St .. Self-torque forklift
- Q .. Truck rated capacity
- X .. Measure center front axle, fork carriage back
- C .. center of gravity (of the forklift)
- M E .. Moment of attachment
- M R .. residual torque
- G E .. Dead weight attachment
- ESP .. special focus on attachment
- GL .. maximum permissible weight of the load
- V .. Front dimensions of the attachment
- L / 2 .. center of gravity of the load
There are also easy-to-use calculation programs on the websites of some implement manufacturers.
The maximum load to be lifted can be read off as a function of the lifting height using a residual capacity diagram to be attached to the forklift. If the attachment has already been installed at the factory and forms a unit with the original device that is difficult to separate (especially with the sideshift), the original load diagram is often omitted and replaced by the remaining capacity diagram.
The residual capacity diagram usually contains the device number on the nameplate, which must always be attached to every attachment.
- In Germany, an annual inspection according to the accident prevention regulations (UVV) of the employers' liability insurance association is required; the inspection carried out is indicated with a sticker.
- An annual LPG system test (positive or negative pressure method) is required for LPG forklifts.
- A six-monthly emissions test is mandatory for LPG forklifts. The CO content in partial and full load operation must be reduced to a minimum.
- An annual emissions test is mandatory for forklifts with diesel combustion engines. The basis for this is TRGS 554 (the blackening number for full load and partial load operation is decisive).
- Proof of qualification (driver's license or floor conveyor license) for the in-house driving of floor conveyor vehicles is a basic requirement in Germany for the proper use of all forklifts (electric or internal combustion engine) according to the guidelines of the employers' liability insurance association.
The proportion of accidents involving forklift trucks is 1.3 percent of all reportable accidents at work. The number of fatal accidents is falling sharply. At 58 percent, the so-called start-up accidents come first. These are accidents in which those involved are hit, grazed or crushed by the forklift. Accidents while getting on and off the vehicle account for 18 percent. Tipping accidents due to excessive speed, especially when cornering or driving improperly with a raised load, only account for 4 percent. The remaining 20 percent of accidents are caused by damage caused by falling loads, unauthorized passengers or assembly and repair. Most accidents are caused by driving errors. However, inadequate regulation of internal traffic and maintenance deficiencies also have their share.
In Germany, the driving license for internal driving is regulated according to the professional association regulations (BGV) of the DGUV . Proof of competence is provided by means of a floor conveyor license , generally called a (fork) forklift license, which can be acquired through training, the scope of which, according to DGUV Principle 308-001 (formerly BGG 925), is at least ten hours of 45 minutes in theoretical training got to; the duration of the practice with driving test has not been determined. In addition, the company must issue a written order and instruct its trained drivers before they start their work. Further instruction is required once a year. The drivers must be of suitable health. The compulsion on companies to use a G25 occupational medical check-up as proof before starting work with certified doctors has been eased. However, it is still used by many companies to avoid gaps in the evidence.
The floor conveyor license is not a driving license in the sense of the driving license regulation . The forklift falls (in Germany) in the driving license class L, which is included in the driving license class B, among other things. If the design-related maximum speed of 25 km / h is not exceeded, the weight restrictions of class B to 3.5 tons do not apply. For driving orders with higher speeds and weight classes - provided the forklift is technically capable and approved - a higher suitable driving license (C1 or C) must otherwise be available, depending on the permissible total weight.
The forklift must be equipped in accordance with its approval for road traffic . From a speed of 25 km / h pneumatic tires are mandatory. Exceptions are possible locally, but in these rare cases, indicators and mirrors are usually required today.
If the driver of a forklift truck loses his driver's license , for example because he drove his car too fast on the road, then he is obliged according to DGUV to report this loss to his employer, as he does not have any motorized industrial trucks that the Driving license regulation would be subject to driving outside of a company premises or special area. The withdrawal of the driving license can be an indication for the employer to check the health and character of the driver out of turn and, if necessary, to withdraw the written driving license . A new G25 examination ( DGUV Information 205-427 ) required by the employer , which comes to the corresponding findings, also leads to the driver being blocked from further driving under operational conditions. In some companies, the operating license to drive the forklift is linked to the possession of a valid driver's license; in these cases, with the loss of the driving license in road traffic, the authorization to drive in these establishments automatically expires.
Floor conveyor tickets are currently only valid nationally. In Switzerland, for example, the Accident Insurance Act (UVG), the Labor Act (ArG) and the Ordinance for the Prevention of Accidents and Occupational Diseases (VUV) are decisive. You can only drive there with a Suva -recognized ID. Training by the military and training by the (internal) Suva-certified driving school are recognized.
- Walter Rödig, Gerhard Vogel: Dr. Rödig's encyclopedia of industrial trucks. 6th edition AGT Verlag Thum 2001, ISBN 978-3-87009-007-4 .
- logisticshalloffame.net: EUGENE BRADLEY CLARK
- Clark Material Handling Company: History
- Silvia Rumetshofer: Video of a multi- way sideloader . In: Youtube. Bulmor industries, March 10, 2016, accessed June 17, 2020 .
- Lars Range: Driving forklifts safely - Textbook Güterkraft . Verlag Heinrich Vogel, Munich 2007, page 11
- Austria: Training content for the forklift license