What is the primary function of a pushrod in an engine?

The primary function of a pushrod in an engine is to actuate the valve train. In overhead valve (OHV) engines, pushrods play a crucial role in operating the engine's valves. The pushrod transmits the movement from the camshaft to the rocker arms, which in turn open and close the engine valves. This process is essential for managing the intake of air and fuel as well as the expulsion of exhaust gases, contributing to the engine's overall efficiency.

The other options, while related to engine function, do not pertain to the specific role of the pushrod. Connecting the alternator involves electrical systems, transferring combustion energy pertains more to the dynamics of movement and power generation, and generating engine speed relates to the control of engine RPM rather than directly to the pushrod's function. Therefore, the significance of the pushrod lies squarely in its ability to operate the valve train and facilitate optimal engine performance.