If the tensile force is bigger than the yield stress of the material, the lock pin would easy to draw away

　　During the normal production period, the liebherr excavator lock pins can produce out two different kinds of the tensile stress, but writer need to attention that if the sum of these two tensile stress is bigger than the yield stress of the material in the high temperature condition, then the liebherr excavator lock pins would easy to draw away on its weakness position and formed into some heating cracks, for example, we also can called these heating cracks as the shrink cracks.

　　The deformation working principle of the liebherr excavator lock pins is under the effect of the pressure, the metal liquid would flow into the cavity of the liebherr excavator lock pins from th3e pressure room, so we also can regard this flowing pressure as the intensity stress of the metal liquid, and the resistance is the sum of he inside viscous force of the metal liquid and the friction force between the metal liquid and the liebherr excavator lock pins cavity.