What is the function of a piston pin?

[CaliLynn]

The function of a piston pin is to connect the piston and the small end of the connecting rod, transmitting the forces between them. Piston pins are typically made of low-carbon steel or low-carbon alloy steel. For engines below 150 horsepower, materials such as 15, 20, 15Cr, 20Cr, and 20Mn2 steel are used. For engines above 150 horsepower, materials like CrNi3A, 18CrMnTi2, and 20SiMnVB are employed. There are three common methods for fixing piston pins: 1. Floating pin design, where the pin can rotate freely in both the piston pin boss and the small end of the connecting rod; 2. Fixed to the piston pin boss, allowing rotation only in the small end of the connecting rod; 3. Fixed to the small end of the connecting rod, permitting rotation only in the piston pin boss.