1
Bendix
®
R-12DC
™
Relay Valve with Biased Double Check
DESCRIPTION
The relay valve in an air brake system functions as a relay
station to speed up the application and release of the
brakes. The valve is normally mounted at the rear of the
vehicle in proximity to the chambers it serves. The valve
operates as a remote controlled brake valve that delivers
FIGURE 1 - EXTERIOR VIEWS
EXTERIOR R-12DC
™
VALVE
(MODEL WITH 2 HORIZONTAL PORTS)
PRIMARY
SERVICE
DELIVERY
SUPPLY (2)
SD-03-1068
SECONDARY
SERVICE
EXTERIOR
R-12DC
™
VALVE
(MODEL WITH
4 VERTICAL
DELIVERY PORTS)
EXTERIOR
R-12DC
™
VALVE
(MODEL WITH 2
HORIZONTAL AND 2
VERTICAL DELIVERY
PORTS)
PRIMARY
SERVICE
PORT
FIGURE 2 - R-12DC
™
RELAY VALVE WITH BIASED DOUBLE CHECK SECTIONAL VIEW
RELAY
PISTON
VALVE
RETAINER
EXHAUST
SEAT
RETAINING
RING
EXHAUST
PORT
SECONDARY
SERVICE PORT
DOUBLE CHECK
DIAPHRAGM
GUIDE
SPRING
CAP SCREW
SEALING
RING
COVER
RELAY
PISTON
O-RING
SPRING
O-RINGS
INLET
EXHAUST
VALVE
or releases air to the chambers in response to the control
air delivered to it from the foot brake valve.
The R-12DC
™
relay valves are designed for either reservoir
or frame mounting. (See Figure 1). For ease of servicing,
the inlet/exhaust valve can be replaced without the need for
line removal.
