Principles of Lifting Loads
Load Moment and Forward Stability
A forklift acts much like a seesaw, with the front wheels serving as the forward tipping axis. The weight of the forklift behind the front wheels creates a stabilizing forklift moment, while the load carried in front of the wheels creates an opposing load moment.
Load Moment and Stability
A moment is the turning effect created by a weight acting at a distance from a pivot point. Increasing either the weight of the load or its distance from the forward tipping axis increases the load moment.
OSHA 1910.178 Appendix A explains that, for forward stability, the forklift moment must be equal to or greater than the load moment. If the load moment slightly exceeds the forklift moment, the rear wheels may lose contact with the floor, resulting in loss of steering control. If the load moment greatly exceeds the forklift moment, the forklift can tip forward.
The physical relationship can be expressed as:
Forklift moment = forklift weight × distance from forklift CG to forward tipping axis
Load moment = load weight × distance from forward tipping axis to load CG
These formulas help explain why load weight and load position affect forklift stability. Operators, however, do not normally calculate these physical moments before handling each load.
Knowledge Check Choose the best answer for the question.
1-4. A forklift carries the same load but moves it farther forward. What happens to the load moment?
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