What is the function of connecting rods?

• A. To convert rotary motion to linear motion.
• B. To attach pistons to the crankshaft.
• C. To seal the combustion chamber.
• D. To regulate fuel flow to the cylinders.

Answer: (B)

The connecting rod is the link that attaches the piston to the crankshaft, transmitting the piston’s up-and-down force into the crankshaft’s rotation. The small end connects to the piston via the wrist pin, and the big end mounts to the crankpin. As the piston is pushed by combustion, the rod carries that force to the crank, producing rotational motion and smoothing the conversion between linear piston movement and crank rotation. It also must withstand alternating tension and compression during each cycle. This is different from sealing the combustion chamber (that’s done by piston rings) or regulating fuel flow (handled by the fuel system).