A quick release air brake valve, also known as a dump valve or emergency valve, is a device used in a vehicle's air brake system to quickly release air from the air brake lines. This can be useful in an emergency situation where the driver needs to stop the vehicle quickly, such as if the vehicle's regular brakes fail.

The quick release valve is usually located on the dashboard or near the brake pedal and is activated by pressing a button or pulling a lever. When the valve is activated, it opens a passage between the air brake lines and the atmosphere, allowing the air to escape and the brakes to be applied more quickly. The valve is usually spring-loaded, so when the button or lever is released, the valve closes again, preventing further air loss.

Some quick release valves may also have a safety feature that prevents them from being activated unless the vehicle's regular brakes are applied first. This is to prevent the driver from accidentally releasing all the air from the brake lines and rendering the brakes inoperable.