Abstract
Mechanical conditions when a truck crane is overturned are formulated against the two cases where the ground is very stiff and the ground is possible to fail. In the latter case, the bearing properties of the ground can be expressed based on an empilical equation and the degree of danger against ground failure defined by the equation can be almost simultaneously estimated by use of personal computer. The effect of some conditions, including yield stress of ground, boom angle etc, on the overturning conditions of an actual truck crane is finally evaluated.
