Fixation Method Of Piston Pin

The piston pin is a cylindrical pin installed on the piston skirt, with its middle part passing through the connecting rod small end hole, used to connect the piston and connecting rod. Its main function is to transfer the gas force borne by the piston to the connecting rod, or to make the small end of the connecting rod drive the piston to move together.
In order to reduce weight, piston pins are generally made of high-quality alloy steel and made into hollow sections. The piston pin bears significant periodic impact loads under high temperature conditions, and due to the small swing angle of the piston pin in the pin hole, it is difficult to form a lubricating oil film, resulting in poor lubrication conditions. Therefore, the piston pin must have sufficient stiffness, strength, and wear resistance, and the mass should be as small as possible. The pin and pin hole should have appropriate clearance and good surface quality.
A piston pin usually consists of three parts: a pin body, a pin eye, and a pin groove. The pin body is subjected to piston pressure and friction, and needs to have extremely high wear resistance and toughness; The pin eye is directly connected to the small end of the connecting rod and needs to have good tensile and shear resistance; The pin groove is used to place the pin card.
There are three ways to fix piston pins: floating pins, semi floating pins, and fixed pins. Floating pins can rotate in both the piston pin seat and the connecting rod small end. Due to their relatively small sliding speed on the working surface, the heat generated by friction is correspondingly reduced, and the wear is small and uniform. Therefore, floating pins are widely used.
If there is abnormal noise in the piston pin, it may damage the piston pin bushing, wear the connecting rod bearing and crankshaft connecting rod journal, and even pull off the piston pin or connecting rod top, damaging the cylinder block. Therefore, maintenance and upkeep of the piston pin are very important.