BC Transit – Air Brake Course

Relay Valve Operation
Control line from foot valve
Air dead ends here!
To rear brake chambers
Application air from the
foot valve arrives at the top
of the relay valve, via the
control line (bright green.)
It contacts a diaphragm
inside the relay valve, and
dead ends there.
This opens the relay valve
internally, and air from the
reservoir is metered to the
brake chambers.
From Reservoir
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