Arizona Air Brakes CDL Practice Test

When an air compressor develops a leak, the one-way check valve is the component that helps maintain air pressure in the tanks. This valve allows air to flow from the compressor into the storage tanks but prevents air from escaping back through the compressor. Its primary function is to maintain the integrity of the air system by ensuring that once the air is stored in the tanks, it does not leak out through the compressor, which can be especially critical in maintaining adequate pressure for brake systems and other air-operated components.

While other components like the tractor protection valve and emergency relay valve serve important roles in the air brake system—such as preventing air loss in the case of a malfunction or protecting the trailer during a brake application—they do not specifically serve the function of retaining air within the storage tanks when a leak occurs in the compressor. The air compressor itself, while crucial for generating and supplying air to the system, cannot retain air when there is a failure or leak in its operation. Thus, the one-way check valve is vital in maintaining system pressure and functionality when issues arise with the compressor.