CDL Air Brakes TestDual Air Brake SystemsMedium
A vehicle equipped with a dual air brake system has its primary system responsible for the rear brakes and the secondary system for the front brakes. If the primary system fails, how would the driver experience braking?
- ABraking only on the front wheels, with full power.
- BReduced braking power, primarily affecting the rear wheels.
- CComplete loss of all braking ability.
- DThe parking brake would automatically engage.
Show answer & explanationAnswer & explanation
Correct answer: B. Reduced braking power, primarily affecting the rear wheels.
In a dual air brake system, if the primary system (often for rear brakes) fails, the secondary system (often for front brakes) will still function. This results in reduced overall braking power, specifically impacting the rear wheels, but not a complete loss of braking.
Why the other options are wrong
- A. While the front brakes would work, the overall braking power would be reduced, not 'full power' compared to both systems working.
- C. The dual system design prevents complete loss of braking if one system fails.
- D. The parking brake typically engages when air pressure drops to a critical level, but it's not an automatic engagement specific to only one service brake system failure unless pressure drops significantly.
Dual Air System Partial Failure
If one of the two independent air brake systems fails, the other system will continue to function, providing partial braking capability, though with reduced effectiveness.
- Prevents total brake loss.
- Vehicle will still have some braking.
- Stopping distances will increase.
- Steering control may be affected.
Memory trick: One system down, still some stop, but not top.