The air brake leakage rate for a combination vehicle (engine and brakes off) should be less than what psi per minute?

For a combination vehicle, the air brake leakage rate is critical because it indicates the integrity of the air brake system. When the vehicle is not running (engine and brakes off), the acceptable leakage rate is defined to ensure safety and reliability.

The correct answer, which is a leakage rate of less than 3 psi per minute, is aligned with safety regulations regarding air brake systems. A leakage rate at or below this threshold demonstrates that the air brakes are functioning properly, minimizing the risk of brake failure due to unwanted air loss. Keeping the leakage rate under 3 psi means that the system retains sufficient air pressure, ensuring that the brakes will engage reliably when needed.

Higher leakage rates pose a risk, as they could mean that the braking system could fail to maintain adequate pressure in a critical situation, leading to longer stopping distances and decreased vehicle control. Proper maintenance and regular testing of the air brake system’s leakage rate are essential for fleet safety and compliance with state regulations.