For combination vehicles, what is the maximum leakage rate acceptable?

• A. Less than 2 psi in one minute
• B. Less than 3 psi in one minute
• C. Less than 4 psi in one minute
• D. Less than 5 psi in one minute

Answer: (C)

The maximum acceptable leakage rate for combination vehicles is less than 4 psi in one minute. This standard ensures that the air brake system remains effective and reliable, which is crucial for the safety of the vehicle and its operation. A leakage rate greater than this can indicate potential issues within the brake system, such as worn components or leaks, which could compromise stopping power and overall braking efficiency.

Maintaining a lower leakage rate is essential for safe operation, as it helps ensure that the air pressure needed for the brakes to function properly is retained. A leakage rate of less than 4 psi allows for adequate time to detect and rectify any issues before they become a safety hazard. This standard is part of regular pre-trip inspections to ensure that the vehicle is fit for operation and meets safety requirements.