Air Brake Manual
Air Brake Manual
Air Brake Manual
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30<br />
14<br />
31<br />
16<br />
39<br />
14<br />
Application air directed from either the foot or hand<br />
valve causes control pressure to move through the<br />
control (service) line and act on the relay emergency<br />
valve (39). This control pressure will cause the relay<br />
emergency valve to direct air from the trailer reservoir<br />
(16) to the trailer brake chambers (14). The pressure<br />
directed by the relay emergency valve to the trailer<br />
brake chambers will be the same as the pressure<br />
directed to the tractor brake chambers. In such a<br />
system, brake lag time has been minimized with the<br />
addition of the trailer reservoir and relay emergency<br />
valve.<br />
Release of the foot or hand valve stops the flow of<br />
application air. The relay portion of the valve returns to<br />
its original position, stopping the flow of air pressure.<br />
The exhausting ports of the valve exhaust the air<br />
pressure from the brake chambers, releasing the<br />
brakes. In this system, the brakes of both the tractor<br />
and trailer can be released quickly.<br />
Caution: Trailer brakes must not be used to hold a parked<br />
vehicle that is left unattended. Loss of pressure will<br />
result in loss of brakes. Always set the parking brake.<br />
Emergency Application<br />
22 21<br />
14<br />
16<br />
39<br />
14<br />
48