Gudgeon pin

[1] In very early engine designs, including those driven by steam, and many very large stationary or marine engines, the gudgeon pin is located in a sliding crosshead that connects to the piston via a rod.

[2] The gudgeon pin is typically a forged short hollow rod made of a steel alloy of high strength and hardness that may be physically separated from both the connecting rod and piston or crosshead.

[1] The design of the gudgeon pin, especially in the case of small, high-revving automotive engines is challenging.

The gudgeon pin has to operate under some of the highest temperatures experienced in the engine, with difficulties in lubrication due to its location, while remaining small and light so as to fit into the piston diameter and not unduly add to the reciprocating mass.

[citation needed] Gudgeon pins use two broad design configurations: semi-floating and fully floating.