What is the main function of the mechanical overspeed governor?

The mechanical overspeed governor's primary function is to prevent the engine from exceeding its maximum rotational speed, thereby ensuring safety and operational integrity. It uses centrifugal forces created by rotating masses or counterweights to achieve this. If the engine speed surpasses a predetermined threshold, the governor activates a mechanism that reduces fuel flow or triggers some form of pressure relief, effectively allowing the engine to slow down and avoid damaging overspeed conditions.

In this context, using counterweights to dump pressure directly relates to how the governor operates, as this mechanical action serves to maintain the engine’s speed within safe limits. The other options do not accurately represent the primary role of the governor, as they either imply an increase in speed, maintain a fixed speed without addressing overspeed concerns, or incorrectly suggest that fuel control is the primary function without mentioning the overspeed aspect.