Home › CDL Practice Tests › Air Brakes Questions › Question 11
What is brake lag in an air brake system?
- A.The time the engine takes to restart
- B.The time it takes for air to travel through the lines and for the brakes to actually begin working after the pedal is pressed
- C.A delay in the turn signals
- D.Wear measured on the brake drum surface
Correct answer
B. The time it takes for air to travel through the lines and for the brakes to actually begin working after the pedal is pressed
Why
Unlike hydraulic fluid, air must flow and build pressure in the chambers, which takes roughly half a second or more. At highway speed that lag adds many feet to total stopping distance.
Manual topic: Air Brakes - Air Brake System Components · From the Air Brakes practice bank (AB-011).