La description

The piston pin is used to connect the piston and the connecting rod, and to transmit the force borne by the piston to the connecting rod or vice versa.

The piston pin is subjected to a large cyclic shock load under high temperature conditions, and it is difficult to form a lubricating film because the piston pin does not swing at a large angle in the pin hole, so the lubrication conditions are poor. For this reason, the piston pin must have sufficient stiffness, strength and wear resistance. The mass is as small as possible, and the pin and the pin hole should have a proper fit clearance and good surface quality. In general, the stiffness of the piston pin is particularly important. If the piston pin is bent and deformed, the piston pin seat may be damaged.

In short, the piston pin works under conditions of high pressure ratio, inability to form oil film and uncoordinated deformation. Therefore its design requires a sufficiently high mechanical strength and wear resistance, as well as a high fatigue strength.