What is the maximum permissible air leakage rate for a combination vehicle when the engine and brakes are off?

The maximum permissible air leakage rate for a combination vehicle when the engine and brakes are off is no more than 2 psi per minute. This standard is set to ensure that the air brake system is adequately sealed and functioning properly. If the leakage rate exceeds this threshold, it may indicate that there are issues such as worn seals, damaged airlines, or other defects in the braking system that could compromise safety. A leakage rate over 2 psi per minute could lead to insufficient air pressure being maintained in the system, which is critical for effective braking performance. Regular checks and maintenance help to identify and resolve such issues, ensuring that the vehicle remains safe to operate on the road.