CDL Air Brakes TestAir Brake System PartsMedium
A driver is inspecting the air brake system and notices that the check valve between the primary and secondary air tanks is leaking. What is the primary risk associated with a leaking check valve in a dual air brake system?
- ABoth air tanks will lose pressure if one system fails.
- BThe low air pressure warning will not activate.
- CThe parking brake will not release.
- DThe air compressor will run continuously.
Show answer & explanationAnswer & explanation
Correct answer: A. Both air tanks will lose pressure if one system fails.
The purpose of check valves in a dual air brake system is to prevent air from flowing from one tank to the other. If a check valve leaks, a failure (e.g., a major leak) in one air system (primary or secondary) could cause the other, normally isolated system to also lose air pressure, compromising the entire braking system.
Why the other options are wrong
- B. The low air pressure warning system monitors tank pressure; if a leak causes pressure to drop, the warning would still activate, possibly for both tanks.
- C. The parking brake typically relies on spring brakes, which are released by air pressure; a general loss of air pressure from a leaking check valve could affect it, but the direct risk is loss of isolation.
- D. While a leak might cause the compressor to run more, the primary risk of a check valve leak is system integrity, not just compressor cycling.
Dual Air System Check Valve
A one-way valve in a dual air brake system that isolates the primary and secondary air tanks, preventing air loss from one system if the other fails.
- Ensures independent operation of primary and secondary braking systems.
- Crucial for maintaining partial braking capability during a single system failure.
- A leak compromises system redundancy.
Memory trick: Check Valve Leaks, Tanks Link, Then Sink.