Home › CDL Practice Tests › Air Brakes Questions › Question 54
Before air pressure falls below what value must the low air pressure warning activate?
- A.Before pressure falls below 60 psi
- B.Before pressure falls below 100 psi
- C.Only after pressure reaches 20 psi
- D.Only after the engine is shut off
Correct answer
A. Before pressure falls below 60 psi
Why
The warning light and buzzer (or wig wag on older vehicles) must come on before the gauge drops below 60 psi. That timing gives the driver a working reserve to stop before spring brakes begin to apply at much lower pressure.
Manual topic: Air Brakes - Safety Valve and Low Pressure Warning · From the Air Brakes practice bank (AB-054).