CDL General Knowledge TestAir Brakes (if applicable)Hard
A driver is inspecting the air brake system. They notice that the air compressor's automatic cut-out pressure is 135 psi, which is higher than the typical 125 psi. What is the potential consequence of this condition?
- AImproved braking performance due to higher available pressure.
- BFaster air pressure build-up during operation.
- CDamage to air system components due to over-pressurization.
- DReduced wear on the air compressor.
Show answer & explanationAnswer & explanation
Correct answer: C. Damage to air system components due to over-pressurization.
Operating an air brake system at pressures significantly above its designed maximum (e.g., 125 psi) can lead to over-pressurization, which can damage air tanks, air lines, and other components not rated for the higher pressure, potentially leading to catastrophic failure.
Why the other options are wrong
- A. While higher pressure might seem beneficial, exceeding the design limits of the system components is dangerous and could lead to failure, not improved performance.
- B. While higher pressure might eventually be reached, the primary concern is the safety of components, not just speed of build-up.
- D. Higher operating pressure and continuous running (if the governor is faulty) would increase, not reduce, wear on the compressor.
Air Governor Cut-Out Pressure
The air pressure at which the air governor signals the compressor to stop pumping air into the system.
- Typically 120-125 psi.
- Ensures system doesn't over-pressurize.
- Higher pressure indicates a faulty governor or safety valve.
Memory trick: Too Much Air? BOOM! Careful, My Dear!