Home › CDL Practice Tests › Air Brakes Questions › Question 119
What should the driver do if the yellow parking knob pops out on its own while driving?
- A.Push it back in repeatedly and continue driving
- B.Assume the knob is loose and ignore it
- C.Speed up to rebuild pressure faster
- D.Treat it as an automatic spring brake application from low air pressure, and stop safely immediately
Correct answer
D. Treat it as an automatic spring brake application from low air pressure, and stop safely immediately
Why
A knob that pops uncommanded is the system announcing it has reached the spring application range. Fighting it by pushing it back in without restoring pressure wastes the last of the air and delays the inevitable stop.
Manual topic: Air Brakes - Spring Brakes and Parking Brakes · From the Air Brakes practice bank (AB-119).