CDL Air Brakes TestInspecting Air Brake SystemsHard
A driver is performing a governor cut-in/cut-out test. The air compressor should cut in when the air pressure drops to approximately what PSI, and cut out when it reaches approximately what PSI?
- ACut-in at 100 psi, Cut-out at 125 psi
- BCut-in at 90 psi, Cut-out at 115 psi
- CCut-in at 110 psi, Cut-out at 135 psi
- DCut-in at 85 psi, Cut-out at 100 psi
Show answer & explanationAnswer & explanation
Correct answer: A. Cut-in at 100 psi, Cut-out at 125 psi
The air compressor governor typically cuts in (starts pumping air) when the system pressure drops to around 100 psi and cuts out (stops pumping air) when the pressure reaches approximately 125 psi. This range ensures adequate air supply for safe braking operations.
Why the other options are wrong
- B. This range is slightly lower than the generally accepted standard, particularly the cut-out pressure.
- C. This range is typically too high; while some systems may operate slightly higher, 100/125 is the general standard.
- D. This range is generally too low for safe and efficient operation of modern air brake systems.
Governor Cut-in/Cut-out
The pressure points at which the air compressor is activated (cut-in) and deactivated (cut-out) by the governor to maintain system air pressure.
- Cut-in: compressor starts, typically 100 psi.
- Cut-out: compressor stops, typically 125 psi.
- Ensures adequate air pressure for braking.
Memory trick: Hundred in, twenty-five out, that's what the air brakes are all about!