What is the function of a governor in a diesel engine?

The function of a governor in a diesel engine primarily revolves around regulating engine speed to maintain a consistent RPM. The governor achieves this by adjusting the amount of fuel injected into the engine based on the load and desired speed. When the load on the engine increases, the governor responds by providing more fuel, which allows the engine to maintain its set speed. Conversely, if the load decreases, the governor reduces the fuel supply, preventing the engine from overspeeding. This automatic adjustment is crucial for ensuring optimal engine performance and efficiency, particularly in varying operational conditions.

In the context of the other choices, adjusting the fuel-air mixture is generally managed by different components within the fuel system, while controlling the timing of fuel injection involves specific timing mechanisms separate from the governor. Filtering out exhaust emissions pertains to emissions control systems and is not a function related to the performance of the governor. Thus, the primary role of maintaining a stable RPM under varying loads solidifies its importance in diesel engine operation.