CDL Combination Vehicles TestCombination Vehicle Air BrakesHard
What is the function of a 'check valve' located between the primary and secondary air supply tanks in a dual air brake system?
- AIt purges moisture from the air tanks.
- BIt allows air to flow in both directions to balance pressure.
- CIt regulates the pressure going to the brake chambers.
- DIt prevents air from escaping one tank if the other system fails.
Show answer & explanationAnswer & explanation
Correct answer: D. It prevents air from escaping one tank if the other system fails.
In a dual air system, check valves are critical for safety. They allow air to flow from the compressor to each tank but prevent air from flowing back or from one tank to the other. This ensures that if one system (primary or secondary) develops a leak, the other system retains its air pressure, allowing for continued braking capability on at least one axle set.
Why the other options are wrong
- A. The air dryer purges moisture from the air, not check valves.
- B. Check valves are one-way valves; they do not allow air to flow in both directions.
- C. Brake valves and relay valves regulate pressure to brake chambers, not check valves.
Dual Air System Check Valve
A check valve in a dual air brake system is a one-way valve that isolates the primary and secondary air tanks, ensuring that a leak in one system does not deplete the air pressure from the other system.
- One-way air flow.
- Maintains system redundancy.
- Crucial for safety in case of air leak.
Memory trick: A check valve 'Checks' air flow, ensuring 'Safety' in a dual system.