Antilock Braking Systems (ABS)
4 free questions, part of the Air Brakes CDL practice test
ABS does not shorten your stopping distance or let you drive faster or follow closer. Its only job is to keep the wheels from locking up during hard braking so you keep steering control. ELDT.io's free practice bank has 4 questions on ABS, covering how it works and when it became required equipment.
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Start Class A CDL Theory ($15)Questions about Antilock Braking Systems (ABS)
What is the purpose of ABS brakes?
ABS keeps wheels from locking up during hard braking by automatically pulsing brake pressure at any wheel that's about to skid. That helps you keep steering control while stopping hard, but it doesn't reduce your overall stopping distance.
What's the difference between ABS and non-ABS brakes?
With non-ABS brakes, a driver has to use stab braking or controlled braking to avoid a skid during a hard stop. With ABS, you brake the same way you normally would, hard and steady, and the system manages wheel lockup for you.
When did ABS become mandatory on commercial vehicles with air brakes?
Federal rules required ABS on new truck tractors with air brakes built on or after March 1, 1997, and on other air-braked commercial vehicles, meaning trucks, buses, trailers, and converter dollies, built on or after March 1, 1998.
What does it mean if the ABS malfunction lamp stays on after startup?
A malfunction lamp that stays lit after the startup bulb check means the ABS system isn't working correctly. The vehicle's regular brakes still work, but you won't have ABS protection against wheel lockup until it's reported and fixed.