Air Brake Practice Test 2025 – All-in-One Resource to Master Your Certification!

The device that stores compressed air in an air brake system is the air reservoir tank. This component plays a crucial role in maintaining the pressure needed for the air brakes to operate effectively. The air reservoir tank collects and stores the compressed air generated by the compressor, ensuring that there is a ready supply of air available when the brakes are applied.

By supplying a steady flow of compressed air, the reservoir allows the braking system to function efficiently and ensures that there is sufficient pressure to engage the brakes when needed. This storage capability is particularly important during periods of high demand, such as when multiple braking actions occur in quick succession. In contrast, the other options do not serve the purpose of storing compressed air: brake shoes are part of the friction system that slows down the vehicle, the master cylinder operates the hydraulic system in hydraulic brakes, and the pressure gauge measures the air pressure in the system rather than storing it.