Relay Valve
The Relay Valve functions as a remote-controlled brake valve to speed up both the application and release of the service brakes on tractors and trailers. The valve relays a small volume of modulated signal pressure from the control valve into a large volume of modulated delivery air from the service reservoir of similar pressure to the rear service brake chambers.
With a control port, supply port, delivery port and an exhaust port, when the control valve is operated, the relay delivers air from the service reservoir to the service chamber at the same pressure as the control signal, causing the brakes to apply. As long as the control pressure is maintained, the relay will hold a like pressure in the air chambers and automatically replace any air lost because of minor leaks between it and the air chambers.
Releasing the control valve signals the relay to exhaust the air from the chambers through the relay exhaust port. If control pressure is partially released, then the service brake pressure will be released proportionately.
Some relay valves also incorporate an anti-compounding feature. Anti-compounding is a safety feature which prevents both the service and spring brake chambers from being applied at the same time, which could create high enough pressures to damage the braking mechanism.
Relay Valve Catalog Page
Unique Design
- Available with built-in anti-compounding two-way check valve for spring brake control
- NPT, metric and PTC (push-to-connect) ports for ease in plumbing
- Aids in meeting latest FMVSS-121 requirements
- Cover may be rotated for installation without affecting performance or warranty