What is the maximum allowable leakage at the air compressor cylinder heads when tested at 100 psi?

The maximum allowable leakage at the air compressor cylinder heads when tested at 100 psi is defined as one soap bubble every five seconds. This standard is crucial for ensuring the proper functioning of the braking system in school buses. Excessive leakage can lead to inadequate air pressure, which directly affects braking performance and overall vehicle safety.

A leakage rate of one soap bubble every five seconds indicates that the system is maintaining an acceptable level of air retention, ensuring that the air compressor can effectively maintain the necessary pressure for optimal brake operation. This standard helps identify issues that could lead to air loss and potential braking failures, making it an essential part of routine maintenance for school bus technicians.

Other options, while they represent varying rates of leakage, do not meet the defined safety standards for air compressor performance. Allowing more frequent soap bubble appearances would signal a significant issue that could compromise braking efficiency and safety. Therefore, adherence to the five-second standard is vital for maintaining the integrity of the brake system.