Understanding the forklift stability triangle is essential for workplace safety. When workers understand their vehicle’s capacity limits and the general principle of the stability triangle, they can operate safely on the job and reduce the risk of hazardous incidents. The guide breaks down the details of the forklift stability triangle and what you can do to ensure that your forklift is stable during material handling and won’t create a safety hazard for you and your crew.
What Is the Forklift Stability Triangle?
The forklift stability triangle is an invisible triangle formed by the pivot point on the rear axle and the two front wheels joined by the front axle. As long as the center of gravity of the load is within this stability triangle, the forklift truck will not tip over. If you compromise the stability triangle, such as when your forklift carries too much weight at the front, you can cause the forklift’s center of gravity to shift too far forward and eventually tip dangerously.
You should understand these helpful terms related to the stability triangle:
- Lateral stability: A lift truck’s resistance to overturning sideways
- Longitudinal stability: A lift truck’s resistance to overturning forward or rearward
- Dynamic stability: The idea that an unloaded or loaded forklift can shift due to sudden stops, starts, turns or tilts
- Line of action: An imaginary vertical line through an object’s center of gravity
- Load center: The horizontal distance from the forklift’s line of action through the load’s center of gravity
For more terms, refer to OSHA’s appendix.
What Determines the Stability of a Forklift?
Three main factors govern the stability of a forklift: the size of the load, the terrain on which it is operating, and what type of forklift you are using.
The Load Size
When it comes to loads, you should consider both the size and distribution of that heavy load. Each forklift will have a specifically defined load capacity you should adhere to that will describe both of these factors. For example, a forklift may be rated to carry 4,000 pounds at 24 inches load center, but just 2,666 pounds at 36 inches load center. Never exceed the capacity of the forklift described on its data plate or name plate or you risk tipping.
The terrain on which the forklift operates also impacts its stability, as slippery and uneven surfaces can risk tipping the vehicle even if it is not exceeding load limits. Forklift operators should avoid traveling on oil, water, or other spills due to the risk of skidding. They should also avoid steep inclines and declines, or generally uneven surfaces. Finally, forklift operators should be aware of obstructions, holes, and speed bumps that can also cause the vehicle’s wheels to elevate.
The Type of Forklift
You can use many different types of forklifts, and each has its own stability profile. If you’re in the market for a forklift, carefully examine the specs on forklifts to determine which is the right one for your job.
Although you can find several types of forklifts, each forklift is best suited for a particular job. For example, you wouldn’t want to use a forklift meant for smaller tasks to do heavy-duty warehouse lifting. Or, if you need long objects moved like pipes and timber, you’d want a forklift ideally suited for that job, such as a side loader.
Tips to Improve Forklift Stability
Proper safety training is key to forklift stability, and you can improve the stability of your forklift to minimize the risks of tipping. Keep in mind these are general tips: check your forklift safety manual for more safety instructions.
Keep the load low to the ground
The higher the load is, the more unstable it becomes, so keep the load as low to the ground as possible. Ideally, you want the load to be just 4 to 6 inches from the ground. OSHA recommends tilting the mast back and positioning the heaviest part of the load as close to the carriage as possible, keeping your center of gravity from shifting too far forward. Keep the mast tilted back when traveling for maximum stability.
Do not accelerate or brake suddenly
Sudden movements affect forklift stability, so do not accelerate or brake suddenly. Keep your movements slow, gradual, and deliberate. Maintain control of the forklift at all times, and adjust your speed as needed.
Also, don’t suddenly change direction, which can shift the combined center of gravity rapidly and cause the vehicle to tip. Never turn on a ramp or any kind of surface grade.
Do not exceed your lift’s maximum load capacity
As discussed above, the load capacity has a huge impact on forklift stability, so never exceed the load capacity of your vehicle as described on the data plate or nameplate. Exceeding load capacity can very quickly cause the operator to either tip over or lose control of the steering. Make sure all lift truck operators on your job site are familiar with the vehicle’s maximum lift capacity.
Looking to rent a forklift?
If you’re ready to rent a forklift, the experts at BigRentz can help you determine which vehicle is right for the job you need to complete. They understand what forklifts are best suited to what tasks, and how to choose the safest option for you and your crew. Also, before you rent or buy a forklift, consider getting forklift training so you can be certified, and get a better understanding of forklift safety.