Home › CDL Practice Tests › Air Brakes Questions › Question 181
What is the primary role of engine braking (including an engine retarder) on a downgrade?
- A.To replace the service brakes completely in an emergency stop
- B.To build air pressure in the tanks
- C.To keep the brake drums warm in cold weather
- D.To hold the vehicle's speed down so the service brakes are used less and stay cool for when they are needed
Correct answer
D. To hold the vehicle's speed down so the service brakes are used less and stay cool for when they are needed
Why
Engine braking absorbs energy through the drivetrain instead of turning it into heat at the wheels. Saving the foundation brakes keeps their full stopping power available for traffic, curves, and the bottom of the grade.
Manual topic: Air Brakes - Downgrade Braking · From the Air Brakes practice bank (AB-181).