What is the maximum permissible air leakage rate for a straight truck or bus air brake system with the engine off and brakes released?

The correct answer is based on the regulatory standards for air brake systems in commercial vehicles, particularly those defined by the Department of Transportation and other safety regulations in the trucking industry. The maximum permissible air leakage rate for a straight truck or bus air brake system with the engine off and brakes released is set to ensure that the braking system remains effective and safe during operation.

A leakage rate of 1 PSI per minute is considered acceptable because it indicates that the air brake system is functioning properly and has minimal leakage. This standard is critical because excessive air loss can lead to brake failure, which compromises the safety of the vehicle and can endanger the driver and others on the road.

Higher leakage rates than this can signify issues within the braking system, such as worn or damaged components. These conditions must be addressed to maintain the vehicle's integrity and safety compliance. Therefore, keeping the leakage within the 1 PSI per minute threshold is crucial for the reliability of air brake systems in straight trucks and buses.