Powered Industrial Lift Truck
Reference Guide (OSHA)
What are typical characteristics of lift trucks and what are some differences between a lift truck and an automobile?
Unlike automobiles, lift trucks are steered with their rear wheels.
Because lift trucks are steered with their rear wheels, they have a tighter turning radius (Truck #2) than if they were similar to automobiles and were steered with their front wheels (Truck #1).
The Center of Gravity (CG) of an unloaded lift truck is between the front and rear axles. The triangle defined by the support points A, B and C is called the Stability Triangle. The CG of the lift truck will shift as the load is applied. The CG of the loaded lift truck will also shift as the CG of the load moves forward, upward or to the side. If the CG of the load moves and causes the combined CG of the lift truck and load to move outside of the stability triangle, the lift truck will become unstable and tilt over.
The front wheels of a lift truck serve as the fulcrum point between the weight of the lift truck and the weight of the load being carried. If the CG of the load moves forward and causes the combined CG of the lift truck and load to move forward of the front wheels, the lift truck will become unstable and tilt forward.
The load capacity of the lift truck is found on the data plate attached to the lift truck body. This data plate lists the maximum amount of load that can be safely carried by the lift truck. This data plate also lists the load center or the distance the load’s CG can be forward of the face of the forks.
By titling the load backward, the load CG will move toward the front wheels. By moving the load CG toward the front wheels, the combined CG of the lift truck and load will be shifted toward the lift truck CG and cause the loaded lift truck to become more stable. Tilting the load forward causes the load CG to move away from the front wheels and thus causes the loaded lift truck to become less stable.
When operating a loaded lift truck on an incline, travel forward up the incline and backward down the incline. This will ensure that the CG of the load will remain above the front drive axle.
Never drive across an inclined roadway or ramp. Never make turns while traveling on an inclined roadway or ramp. These maneuvers can cause the combined CG of the lift truck and the load to move outside of the stability triangle and cause the lift truck to tilt over.
When traveling over rough surfaces, slow down and avoid obstacles. Cross railroad tracks at an angle.
How can the capacity of a lift truck be calculated?
Maximum capacity is calculated using the following equation:
Maximum capacity (in inch-pounds) = (D+A) x Cap., where:
D = the distance (in inches) from the center of the front axle to the face of the forks.
A = the rated load center (in inches) as shown on the data plate.
Cap. = the lift truck’s rated capacity (in pounds) at the rated load center as shown on the data plate.
If the actual load center is different than the rated load center, the following method can be used to calculate an actual capacity based on the actual load center.
Calculate the maximum capacity of the lift truck in inch-pounds using the equation (D+A) x Cap. and the data plate values of A and rated capacity.
Divide the calculated maximum capacity by the sum of D and the actual load center.
Actual capacity = maximum capacity / (D + actual load center)
What are some of the considerations that must be taken into account when loading trucks or rail cars, especially from a loading dock?
Inspect the floor of the truck or rail car to ensure that it will support the lift truck and the load.
Chock the trailer wheels to prevent movement.
Place and secure all dock plates, boards and ramps.
What must an operator do when parking a lift truck or leaving it unattended?
Park the lift truck in a safe location out of the traffic flow.
Fully lower the load engaging means.
Put the equipment controls in neutral.
Set the emergency brake.
Turn off the power.
Block both drive wheels if the lift truck is parked on an incline.
What should be included in the pre-operation inspection of a lift truck?
Tires and wheels – tires should be free from damage and excessive wear. Wheels should be free from damage and missing lug nuts. Check the air pressure in pneumatic tires, using a long tire gauge and facing the tread, not the side of the tire.
Safety equipment – horn, lights, seat belt, warning lights and/or back-up alarm should be operational.
Steering mechanism – the freeplay in the steering should not be more than one or two inches in either direction as the steering wheel is turned.
Brakes – the brake pedal should depress smoothly, not require excessive force to operate and not sink under continued pressure. The brakes should not grab or cause the truck to swerve when applied.
Battery – electrolyte levels should be maintained. Check to ensure tight and corrosion-free connections.
Cooling system – fluid levels should be maintained. Check for leaks.
Fuel and hydraulic systems – fuel and hydraulic hoses and connections should be in good condition. Check for leaks around fittings and connecting points. The hydraulic system control levers should move smoothly and return to neutral when released. Feel for roughness in the action when the forks are raised or tilted. Fuel and fluid levels should be maintained.
Lift system – chains, hydraulic cylinders, mast and upright components and forks should not be broken, chipped, misaligned, warped or worn.
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