ASE School Bus Technician Brakes Certification (S4) Practice

The maximum allowable leakage at the exhaust port of the limiting quick release valve is specified to be 1 inch soap bubble every three seconds. This standard is in place to ensure that the braking system operates effectively without excessive air loss. The quick release valve is critical for the braking system's performance, as it helps reduce lag in the release of the brakes by promptly venting air from the brake chambers.

If leakage exceeds this limit, it could indicate a malfunction or wear in the valve, which might lead to compromised braking performance. Keeping the leakage to this allowable limit helps maintain system integrity and responsiveness, ensuring the safety of the vehicle and its passengers.