‘Why Don’t Forklifts Tip Over When Lifting Heavy Loads?’

(Courtesy: Donald Boger)

(Courtesy: Donald Boger)

Forklift operators assume that their vehicles will be able to pick up and transport pallets full of products and other heavy loads. But how does a forklift actually do it?

It isn’t magic. It’s physics.

Basic Physical Laws

Without getting too far into the science of forklifts, the vehicles work on a simple principle: Weight and counterweight.

At the back of every forklift is a counterweight. The size of this counterweight will depend on the capacity of the forklift. Some vehicles are designed to lift no more than 3,000 pounds while others can pick up 15,000 pounds or more.

The counterweight acts as a balance for the weight being lifted by the truck’s forks. As long as the center of gravity is inside the wheelbase for the vehicle, the forklift won’t tip over.

Load Ratings

Every forklift has a load rating. Usually, this is printed on a metal plate that is attached to the forklift somewhere near the entrance to the cab. It’s supposed to be a constant reminder of how much the forklift can lift so that the driver doesn’t try to lift too much.

If the forklift is used to lift a load that is heavier that its load rating, it can and will tip forward. The closer the load is to the forklift’s front tires, the more likely it is to tip.

To understand why imagine a seesaw. The farther you sit from the center of the seesaw — known as the fulcrum — the more tilting momentum the seesaw has. Now apply that to a forklift: A forklift with a load rating of 10,000 pounds might actually only be able to lift 2,000 pounds if the load is on the fork’s tips.

Or it may be able to lift only 5,000 pounds if the load is elevated to 15 feet.

Load rating is the maximum weight the forklift can lift if the load is positioned flush with the back of the forks with the mast in the lowest position with the forks closest to the ground.

Sharp Turns and Weight

Moving the forklift introduces another variable into the equation: Momentum.

If you turn the forklift with the load held high in the air, it can cause the vehicle to tip sideways. That’s because the center of gravity is higher so the forklift is less stable.

Given the wheel configuration of a standard forklift, most can turn on a dime. Plus, most can travel 25 mph or more. So it’s not easy to roll a forklift if you drive unsafely.

Seatbelts and Safety


All of which underlines the fact that operators must always wear their seatbelts whenever the vehicle is in use.

The physics of a forklift are constantly changing due to the many variables: The size, position and height of the load, the motion of the vehicle, and the sharpness of turns. Forklifts can and do tip over all the time.

You can increase your safety and reduce the risk of injury by always belting yourself securely in the operator’s cabin.


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