What is the proper procedure for the leak rate test?

The proper procedure for the leak rate test is to fully depress the service brake for 1 minute and observe the pressure drop, which should not exceed 3 psi. This procedure is crucial for ensuring that the braking system is functioning correctly and is free of leaks. An acceptable drop of no more than 3 psi within 1 minute indicates that the system is in good condition and will perform reliably while driving.

This standard is set to maintain safety and efficiency in braking systems, ensuring that the vehicle can come to a stop when required without the risk of brake failure due to air loss. A drop greater than this threshold would signify potential leaks or issues within the air brake system, which would require immediate attention and repairs before the vehicle can be deemed safe for operation on the road.

Other answers suggest different PSI drop limits or different time frames, which would not meet the established safety standards for leak testing in air brake systems. Proper adherence to this 3 psi drop criterion during the specified one-minute duration reflects compliance with best practices in vehicle maintenance and safety inspections.