What safety feature prevents air from escaping too quickly from the system?

The check valve is an essential safety feature in the air brake system that ensures air does not escape too quickly. It is designed to allow air to flow in one direction while preventing reverse flow. This is particularly important because if air were to escape rapidly, it could result in loss of brake pressure and ultimately lead to brake failure. By maintaining a steady pressure within the system, the check valve helps to ensure that the brakes remain effective when needed, contributing to the overall safety and reliability of the vehicle.

The other components, while they play important roles in the air brake system, do not serve the same function as the check valve. The quick release valve is designed for rapid release of air, which can speed up the brake release process, but does not prevent air from escaping. The air dryer removes moisture from the air system to prevent freezing and corrosion but does not control air flow directly. The modulating control valve is used in some applications to help control brake pressure more gradually but does not prevent air from escaping in the manner that the check valve does.