Home › CDL Practice Tests › Air Brakes Questions › Question 100
How does the driver normally set the parking brakes on an air brake vehicle?
- A.By pressing the foot valve as hard as possible
- B.By shutting off the fuel supply
- C.By putting the transmission in reverse
- D.By pulling out the parking brake control knob(s), which exhaust air from the spring brake chambers
Correct answer
D. By pulling out the parking brake control knob(s), which exhaust air from the spring brake chambers
Why
Pulling the knob vents the air that was holding the springs compressed, so the springs apply and hold the vehicle. Pushing the knob in recharges the chambers and releases the brakes once pressure is high enough.
Manual topic: Air Brakes - Spring Brakes and Parking Brakes · From the Air Brakes practice bank (AB-100).