Home › CDL Practice Tests › Air Brakes Questions › Question 196
What is the main job of an antilock braking system (ABS) on a truck?
- A.To make the brake pedal unnecessary in an emergency
- B.To guarantee the shortest possible stop on every surface
- C.To sense a wheel that is about to lock and modulate brake pressure so the wheel keeps rolling and the driver keeps steering control
- D.To increase air pressure above the governor setting
Correct answer
C. To sense a wheel that is about to lock and modulate brake pressure so the wheel keeps rolling and the driver keeps steering control
Why
Locked wheels slide instead of rolling, and a sliding front tire cannot steer while a sliding trailer or drive tire can swing. ABS cycles pressure at the threatened wheel to keep it near the point of maximum grip.
Manual topic: Air Brakes - ABS · From the Air Brakes practice bank (AB-196).