Why is it important to check the pressure relief valve on air brake systems?

Checking the pressure relief valve on air brake systems is crucial primarily to prevent over-pressurization. The pressure relief valve functions as a safety mechanism that releases excess air pressure from the system to avoid potential damage and failure. Without proper functioning of this valve, excessive air pressure can lead to catastrophic failures, such as burst air lines or damage to components within the air brake system. This could endanger the safety of the vehicle and its operation.

Maintaining the correct pressure in the air brake system is vital for ensuring overall performance, but that is a secondary benefit to the primary role of safety provided by the pressure relief valve. While aspects like improving braking performance and reducing wear on brake pads are important for vehicle operation, they do not capture the essential safety function that the pressure relief valve serves in preventing over-pressurization.