Forklift Types, Components and Stability Principles
This domain tests whether you understand what keeps a forklift upright and how machine type changes the risk. Questions often compare counterbalanced trucks with reach trucks, pallet trucks and rough-terrain trucks, then ask which component controls a given hazard.
Core rules
- Counterbalanced truck: the counterweight offsets the load. The stability triangle is formed by the two front wheel contact points and the pivot of the steer axle; the combined centre of gravity (CG) must stay inside it.
- Longitudinal stability: load moment is load weight × load centre. A heavier load or a load further from the fork face increases the tipping moment.
- Lateral stability: turning, off-centre loads and uneven ground shift the CG sideways; speed and steering angle increase centrifugal force.
- Load centre: horizontal distance from the vertical fork face to the load CG. Rated capacity applies at the stated load centre and lift height, not at every height.
- Components: mast, carriage, forks, backrest extension, overhead guard, counterweight, data plate, seat belt, horn, lights, brakes, steering and hydraulic system all have a safety function.
Worked example
A truck is rated 2,000 kg at a 600 mm load centre. The actual load CG is 900 mm from the fork face. Derated capacity ≈ (2,000 × 600) ÷ 900 = 1,333 kg. A 1,500 kg load therefore exceeds capacity even though it is below the nominal 2,000 kg figure. The load must be split, repositioned or handled by a larger truck.
Traps
- Treating the data plate’s largest number as capacity at all heights and centres.
- Assuming a heavier forklift is always safer; stability depends on geometry and load moment.
- Ignoring attachment weight and forward shift.
- Raising a load while turning or travelling fast.