Bendix Commercial Vehicle Systems R-12DC DBL CHECK RELAY VALVE 3/07 - Manual (Page 4)

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*Crack Pressure is the amount of control
pressure required by the valve to initiate
air delivery. For Crack pressures other
than 4 psi, a differential spring is used in
the assembly to produce the required
valve response.
(Models designed to have a 4 psi crack
pressure do not require a differential spring.)
Key No. DESCRIPTION
1 VALVE COVER
2 VALVE SPRING
3 CHECK VALVE GUIDE
4 CHECK VALVE
5 O-RING
6 DOUBLE CHECK COVER
7 O-RING
8 O-RING
9 RELAY PISTON
10 VALVE BODY
11 INLET & EXHAUST VALVE
12 VALVE RETAINER
13 SPRING
14 O-RING
15 O-RING
16 EXHAUST COVER
17 RETAINING RING
18 DIFFERENTIAL SPRING (IF USED)
PRIMARY CONTROL
PORT 1/4 NPT
SECONDARY
CONTROL PORT
1/4 NPT
16
CAP SCREW
2
1
10
11
CAP
SCREW
3
4
5
6
7
9
8
DIFFERENTIAL SPRING
(CONTROLS CRACK PRESSURE*)
(NOT REQUIRED FOR MOST
MODELS.
SEE BELOW.)
17
15
14
13
12
VERTICAL
DELIVERY
PORTS
SUPPLY
PORT
HORIZONTAL
DELIVERY
PORTS
DIFFERENTIAL SPRINGS
FIGURE 7 - R-12DC ™ EXPLODED VIEW
1. Remove the four cap screws securing the mounting
bracket and cover to the body. Retain the cap screws
for reuse.
2. Discard the mounting bracket.
3. Remove and discard sealing ring (7) from the cover (1).
a. Remove the 2 torx screws securing the double check
cover (6) to the cover (1).
b. Remove the double check cover (6) from cover (1)
and remove and discard spring (2), guide (3), double
check diaphragm (4), and o-ring (5).
4. Remove and discard sealing ring (7) from the cover (1),
and mounting bracket.
Caution: Drain all reservoirs before attempting to remove
the inlet exhaust valve.
DISASSEMBLY
Note: Prior to disassembly, mark the location of the
mounting bracket to the cover and the cover to the body.
CAUTION: The valve body may be lightly clamped in a bench
vise during disassembly, however, over-clamping will result
in damage to the valve and result in leakage and/or
malfunction. If a vise is to be used, position the valve so
that the jaws bear on the supply ports on opposing sides of
the valve’s body.
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