Air Pressure Regulation & Control Flashcards
6 cards from real Air Brake Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Air Pressure Regulation & Control flashcards as text
What is the typical 'cut-out' pressure for an air brake compressor governor?
Answer: 125 psi
The governor cuts out (stops the compressor from pumping) at approximately 125 psi, which is the normal maximum operating pressure for air brake systems.
What happens when air pressure drops below the governor 'cut-in' pressure?
Answer: The compressor begins pumping air back into the system
When pressure falls to the cut-in level (approximately 100 psi), the governor signals the compressor to start pumping air to rebuild system pressure.
What is the purpose of the safety relief valve in an air brake system?
Answer: To release excess air if the governor fails and pressure becomes dangerously high
The safety relief valve is a backup protection device that opens to vent air if the governor malfunctions and pressure exceeds a safe limit (usually set at 150 psi).
Which component in the air brake system separates oil and moisture from the compressed air before it enters the tanks?
Answer: The air dryer
The air dryer removes moisture and oil from the compressed air before it reaches the air tanks, preventing corrosion, freezing, and contamination of the brake system.
What does it indicate if the air pressure does not rise from 50 to 90 psi within 3 minutes at engine idle?
Answer: There is a problem with the air compressor or a significant air leak in the system
FMCSA requires pressure to build from 50 to 90 psi within 3 minutes at idle, indicating the compressor is working properly; failure to do so signals a compressor or major leak problem.
What is the function of the one-way check valve located between the wet and dry tanks?
Answer: It prevents air from flowing back from the dry tank to the wet tank if pressure drops
The one-way check valve ensures that air flows only from the wet tank to the dry/supply tanks and not backward, maintaining pressure in the system even if the wet tank develops a leak.