The load weight, weight distribution, size, shape, and position are key factors affecting the capacity and the stability of the forklift. Determining a forklift’s safe load capacity The load size, position, and weight distribution critically affect the forklift’s capacity and the stability of the truck. Loads come in all shapes and sizes, not just symmetrical boxes. If the load is not centered at the specified position, the forklift’s capacity will be reduced.

The stated capacity of a forklift only applies to the load center indicated on the data plate. OSHA addresses load stability in Appendix A of the Powered Industrial Trucks Standard. The distance is always measured perpendicular to the line of action.

With forklifts, the distance is measured from the point at which the truck will tip over to the object’s line of action.

Moment – The product of the object’s weight times the distance from a fixed point (usually the fulcrum).

Longitudinal stability – The truck’s resistance to overturning forward or rearward.

Load center – The horizontal distance from the load’s edge to the line of action through the load’s center of gravity.

Line of Action – An imaginary vertical line through an object’s center of gravity.

Lateral stability – A truck’s resistance to overturning sideways.

Fulcrum – The forklift’s axis of rotation when it tips over.

For symmetrical loads, the center of gravity is at the middle of the load.

Center of gravity – The point on an object at which all the object’s weight is concentrated.

Forklift Load Stability Terms and Definitions Too often operators are not provided sufficient training regarding loads and the dangers presented with operating a forklift beyond its load capacity. Operators also need to understand the importance of load stability. Operating a forklift requires not only an understanding of the controls to drive the forklift and the possible hazards of the workplace surroundings.

Forklift capacity chart