The role of the connecting rod is to transmit the force borne by the piston to the crankshaft and convert the reciprocating motion of the piston into the rotary motion of the crankshaft.

Connecting rod is composed of connecting rod body, connecting rod cap, connecting rod bolt, connecting rod bearing bush and other parts. Connecting rod body and connecting rod cap are divided into connecting rod small end, connecting rod body and connecting rod big end.

The small end of the connecting rod is used to install the piston pin to connect the piston. The rod body is usually made into "I" or "H" section to reduce the mass on the premise of meeting the strength and stiffness requirements.

The connecting rod big end is connected with the connecting rod journal of the crankshaft. Generally, it is made into a separate type. The half cut with the rod body is called the connecting rod cap, and the two are connected together by connecting rod bolts.

The connecting rod bearing bush is installed in the large end hole seat of the connecting rod and is installed with the connecting rod journal on the crankshaft. It is one of the most important mating pairs in the engine. The commonly used antifriction alloys mainly include white alloy, copper lead alloy and aluminum base alloy.