What is one of the main functions of a hydraulic governor system?

The main function of a hydraulic governor system is to limit speed rise during load changes. This system is critical in maintaining the stability and safety of machinery, particularly in steam engines and turbines. When there is a sudden change in load, such as when additional machinery is activated or deactivated, the hydraulic governor responds by adjusting the fuel or steam supply to ensure that the engine's speed remains within safe operational limits. This regulation helps prevent damage that could occur from excessive speeds, ensuring both the longevity of the equipment and the safety of operations. By controlling the speed, the governor maintains efficiency and prevents the complications associated with rapid speed fluctuations.

In contrast, the other choices deal with different aspects of boiler or engine operation that do not directly relate to the primary function of managing speed in response to load changes.