Home › CDL Practice Tests › Air Brakes Questions › Question 98
In what pressure range do spring brakes become fully effective as air pressure falls?
- A.About 90 to 100 psi
- B.About 120 to 135 psi
- C.About 20 to 45 psi
- D.Only at exactly 150 psi
Correct answer
C. About 20 to 45 psi
Why
As pressure bleeds through that low range, the springs progressively overcome the remaining air and clamp the brakes on. By the bottom of the range the parking and emergency application is complete.
Manual topic: Air Brakes - Spring Brakes and Parking Brakes · From the Air Brakes practice bank (AB-098).