Physics of the Forklift

Understanding the basic physics of load limits is an important part of safe forklift operation. Every lift truck of any type has a load rating chart, which indicates where on the fork you can lift how much weight. The key is that the centre of gravity of the forklift has to stay inside the wheelbase for it to be stable. The closer the load is to the front tires, the less likely you are to tip. Proper forklift operation always places the load as close to the wheels as possible, which means close to the carriage and low to the ground. Therefore, the driver has to take note to also avoid making sharp turns with a load held high in the air, as it can cause tipping over sideways. The higher the centre of gravity, the less stable the forklift is.

The design of a forklift truck is based on critical elements of physics. Stability is created through a cantilever system similar to a teeter-totter — two sides balanced on a pivot point, the fulcrum. On a forklift the forward wheels are the fulcrum. The load on the forks must be counterbalanced by weight on the other side of the fulcrum, or in other words, the truck itself and the counterweight that is built into it. Each forklift has a capacity rating that is listed on the data plate of the truck. Tilting the load forward or back or raising the load while tilted can completely change the expected stability. Driving on any sort of incline or rough surface (possibly a railroad track) can lead to disastrous results unless the driver plans ahead and compensates for the differences. Even simple things like starts, stops, or turns can shift the combined centre of gravity and cause trouble. Be sure to only lift to heights that are correctly defined for the truck.

Each forklift truck has a load centre. A common load centre is 24 inches. This information can be found on the data plate. The capacity of a truck is given in three factors on the data plate, namely the capacity in pounds, the load centre and the maximum height. The forklift’s overall capacity is determined by multiplying the pound capacity by the load centre. To determine if a load is appropriate for the forklift, multiply the weight of the load by its load centre. If the result is less than the maximum inch-pounds for that forklift, it is safe to lift the load.

Safety and stability are essential elements when using a forklift. It is clear that a degree of knowledge is necessary to safely operate one. Be certain that drivers have the required training to understand the complex physics of a forklift in order to prevent accidents that can damage goods or injure workers.