Air Brake Practice Test

A combination vehicle air brake system can not spill more than ____ psi per minute with the engine shut off and brakes released.

1. 2

2. 4

3. 3

4. 5

The correct answer is: 3

The correct answer reflects the industry standard for acceptable air loss in a combination vehicle air brake system when the engine is off and the brakes are released. Specifically, a combination vehicle should not lose more than 3 psi in a minute under these conditions. This standard is essential for ensuring safety in operation. If the air brake system were to lose pressure at a rate greater than 3 psi per minute, this could indicate a leak or malfunction within the system, which could compromise braking effectiveness and pose serious risks while driving. Regularly checking this pressure loss during pre-trip inspections is a crucial part of maintaining vehicle safety and compliance with regulations set forth for commercial vehicles.