What is the primary function of a governor on an engine?

The primary function of a governor on an engine is to limit the RPM (revolutions per minute) of the engine. A governor is a crucial component, especially in heavy machinery and equipment, as it ensures that the engine operates within safe and optimal speed limits. By monitoring the engine’s RPM, the governor can automatically adjust the fuel supply or throttle position, preventing the engine from exceeding its maximum allowable speed. This prevents potential damage due to over-revving, enhances safety, and maintains performance efficiency during operation.

In the context of this question, while increasing fuel efficiency, regulating coolant temperature, and controlling transmission shifting are important engine functions, they are not the primary responsibilities of a governor. The governor's specific role in regulating engine speed is critical to safe operation and overall engine health.