Safety Section Avoiding Lift Truck Tipover Stability and Center of Gravity Lift Truck Stability The stability of the lift truck is determined by the location of its CG; or, if the truck is loaded, the combined CG of the truck and load. The lift truck has moving parts and, therefore, has a CG that moves. The CG moves forward or backward as the mast is tilted forward or backward. The CG moves up or down as the mast moves up or down. The CG and, therefore, the stability of the loaded lift truck, are affected by a number of factors such as: Counterbalanced lift truck design is based on the balance of two weights on opposite sides of a fulcrum (the front axle).
The load on the forks must be balanced by the weight of the lift truck. The location of the center of gravity of both the truck and the load is also a factor. This basic principle is used for picking up a load. The ability of the lift truck to handle a load is discussed in terms of center of gravity and both forward and sideways stability.
Center of Gravity (CG) z the size, weight, shape and position of the load z the height to which the load is lifted z the amount of forward or backward tilt z tire pressure z dynamic forces created when the lift truck is accelerated, braked or turned z condition and grade of surfaces on which the lift truck is operated The point within an object, at which the whole weight of the object may be regarded as being concentrated, is called the center of gravity or CG. If the object is uniform, its geometric center will coincide with its CG. If it is not uniform, the CG could be at a point outside of the object. When the lift truck picks up a load, the truck and load have a new combined CG.
These same factors are also important for unloaded lift trucks. They tip over sideways easier than a loaded lift truck carrying its load in the lowered position. 21