Braking systems and vehicle control
What the exam tests
The exam checks your understanding of service, parking and auxiliary braking, air-brake behaviour, ABS/EBS and how load and gradient affect stopping distance.
Core rules
- The service brake is the foot brake; the parking brake holds the vehicle when stationary; the auxiliary brake includes engine braking and retarders.
- In an air-brake system, pressure must build to the normal range before driving. A low-pressure warning means stop safely and investigate.
- ABS prevents wheel lock but does not shorten every stop, especially on loose or icy surfaces. Keep steering control and brake firmly as designed.
- On a long descent, select a lower gear before the slope and use the engine brake or retarder. Do not ride the service brake continuously.
- Load increases stopping distance. Leave more space and brake earlier.
Worked example
A loaded truck descends a mountain road. The driver feels the brakes fading after repeated use. The correct response is to stop safely, let the brakes cool, and continue in a lower gear with auxiliary braking, not to press harder.
Traps that cost marks
Coasting downhill in neutral; pumping ABS brakes; ignoring an air-pressure warning; using the retarder aggressively on ice without considering drive-wheel grip.
Key points
- Air pressure normal before driving.
- Low-pressure warning: stop and check.
- ABS helps steering, not every stopping distance.
- Downhill: low gear and auxiliary brake.
- Load and speed increase stopping distance.