What does the air compressor governor control?

The air compressor governor plays a crucial role in the air brake system of a truck by controlling when air is pumped into the air brakes. It monitors the air pressure in the system and activates the compressor when the pressure drops below a certain threshold. Once the system reaches a predetermined pressure level, the governor shuts off the compressor to prevent over-pressurization. This regulation ensures that the air brake system operates efficiently and reliably, maintaining the necessary pressure for safe braking.

Options discussing temperature or speed pertain to aspects of the compressor's functioning but do not address the direct control over the braking system's air supply. Similarly, while air pressure applied to the brakes is vital to braking performance, the governor specifically manages the workflow and replenishment of that air, not the pressure applied at the brake itself. Therefore, the correct emphasis is on the governor's function in determining when air is pumped into the braking system.