CDL Air Brakes TestAir Brake System PartsEasy
A technician is inspecting a commercial vehicle's air brake system. They observe that the air compressor governor consistently cuts out at 125 psi and cuts in at 100 psi. What is the primary function of the air compressor governor in this scenario?
- ATo filter moisture and oil from the compressed air before it enters the air tanks.
- BTo prevent excessive air pressure from building up in the air storage tanks, acting as a safety relief.
- CTo regulate the amount of air pressure applied to the brake chambers during braking.
- DTo control when the air compressor starts and stops, maintaining system pressure within a set range.
Show answer & explanationAnswer & explanation
Correct answer: D. To control when the air compressor starts and stops, maintaining system pressure within a set range.
The air compressor governor's main role is to regulate the air pressure within the system by controlling the compressor's operation. It ensures the pressure stays between the cut-in and cut-out limits.
Why the other options are wrong
- A. This describes the function of the air dryer, not the governor.
- B. This describes the function of the safety valve, not the governor.
- C. This describes the function of the brake pedal valve and service brake system, not the governor.
Air Compressor Governor
A device that controls the air compressor's operation to maintain air pressure within a specific range (cut-in and cut-out pressures) in the air brake system.
- Starts compressor when pressure drops to cut-in value (e.g., 100 psi).
- Stops compressor when pressure reaches cut-out value (e.g., 125 psi).
- Essential for preventing over-pressurization and under-pressurization.
Memory trick: The Governor Governs the Compressor's Cycles.