Forklifts can and often do tip over. Lifting the rear tires off the ground can happen easily when you are unsure of the load’s weight, and some have knocked forklifts onto their sides. (Seatbelts are important.) Understanding the basic physics of load limits is an important part of safe forklift operation. It’s very easy to maneuver yourself into an uncorrectable position and lose control. 3,000 lb capacity electric forklifts and 55,000 lb capacity diesel monsters — all have the potential to become unstable and tilt. Even a lowly pallet-jack can tilt over.
The center of gravity of the lift truck has to stay inside the wheelbase for it to be stable.
Every lift truck of any type has a load rating chart, which indicates where on the fork you can lift how much weight. The closer the load is to the front tires, the less likely you are to tip. This is just like sitting on a see-saw or balance — a weight farther from the fulcrum applies more tilting moment. A 10,000 lb forklift might be de-rated to 2,000 with the load on the fork tips, or 5,000 lb with the weight elevated 15 feet. 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.
The important thing to remember is that the lift hydraulics don’t care if you pick up the load with the tip of the forks or the base of the forks, because it applies the same upward force either way. But using the fork tip puts a much larger (~3x depending on the fork length) tipping moment on the forklift. This is why the vehicle has to be designed such that it can tip itself — de-rating the unit by a factor of 3x or shortening the forks by 2/3rd to keep it from tipping would severely limit the usefulness of the forklift. Industrial vehicles often rely on the operator’s skill and experience for safe operation, in order to improve capacity or performance.
Likewise, making sharp turns with a load held high in the air can cause tipping over sideways. The higher the center of gravity, the less stable the forklift is. Forklifts can turn on a dime (some even have zero or negative turning radius) and many can reach 25-35mph, so it’s not hard to roll one over if you drive like an idiot.
Finally, sometimes you just hit the wrong lever and the carriage booms sideways into an immovable object. You can push yourself overusing the hydraulics on forklifts that have adjustable forks or carriage position.
Given all this, forklift accidents are actually pretty common. Thankfully, they’re very sturdy and can usually just be picked back up by a bigger forklift!
This always best to be trained by a safey specialist. Here at Louisiana Lift and Equipment we have certified trained safety specialist. Remember safety training is required by OSHA.
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