Air Brake Practice Test

There should be no more than ____ air loss in a single-vehicle than with the brakes on and the engine off.

1. 3 psi in one minute.

2. 2 psi in 45 seconds.

3. 1 psi in one minute.

4. 1 psi in 30 seconds.

The correct answer is: 3 psi in one minute.

The correct answer indicates that there should not be more than 3 psi of air loss in a single vehicle with the brakes applied and the engine turned off over the span of one minute. This standard is crucial for ensuring the reliability and safety of the air brake system in commercial vehicles. Excessive air loss can signal potential leaks or issues within the braking system, which could lead to brake failure or reduced braking efficiency. Specifying 3 psi in one minute provides a reasonable threshold, allowing for some minor fluctuations in pressure while still ensuring that the air brake system is functioning properly. It reflects industry standards that aim to ensure adequate performance of the brakes, particularly under conditions where the system is expected to maintain pressure while stationary. Options reflecting lesser time frames or lower psi thresholds are less conducive to safety. For instance, stating lower psi losses in shorter time frames might be unnecessarily stringent or impractical given that all systems have some tolerance for minor variations. Therefore, establishing the loss limit at 3 psi in one minute allows for both reliability and efficiency in the operation of air brake systems.