2
TYPICAL RELAY VALVE PIPING SINGLE CIRCUIT SYSTEM
COMPRESSOR GOVERNOR
SUPPLY
RESERVOIR
SERVICE
RESERVOIR
BRAKE
VALVE
RELAY
VALVE
BRAKE
CHAMBERS
RELEASING
When air pressure is released from the service port and air
pressure in the cavity above the relay piston is exhausted,
air pressure beneath piston lifts the relay piston and the
exhaust seat moves away from the exhaust valve, opening
the exhaust passage. With the exhaust passage open, the
air pressure in the chambers is then permitted to exhaust
through the exhaust port, releasing the brakes.
PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performing any intrusive maintenance procedures. A warranty
may be voided if intrusive maintenance is performed during
the warranty period.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuable guide in determining the best maintenance interval
for air brake system components. At a minimum, the valve
should be inspected every 6 months or 1500 operating hours,
whichever comes first, for proper operation. Should the valve
not meet the elements of the operational tests noted in this
document, further investigation and service of the valve may
be required.
OPERATING AND LEAKAGE TEST
1. Fully charge air brake system and adjust brakes.
2. Make several brake applications and check for prompt
application and release at all appropriate wheels.
3. With brake valve in released position, coat the exhaust
port with soap solution and check for inlet valve and valve
guide o-ring leakage; 1" bubble in 5 seconds leakage
permitted.
4. Make and hold a brake valve application; coat the exhaust
port with soap solution and check for leakage; 1" bubble
in 3 seconds leakage permitted.
If leakage is detected, replacing the inlet/exhaust valve may
correct the problem. If leakage still occurs, leakage may be
caused by relay piston o-ring or exhaust valve seat.
5. Make and hold a brake valve application; coat outside of
valve body in area where cover joins the body for cover
o-ring leakage No leakage permitted. If the valve does
not function as described above, or if leakage is
excessive, it is recommended that the valve be replaced
with a new or remanufactured unit, or repaired with
genuine Bendix parts available at Bendix outlets.
REMOVING AND INSTALLING
REMOVING
Block and hold vehicle by means other than air brakes.
Drain air brake system reservoirs.
If entire valve is to be removed, identify air lines to facilitate
installation.
Disconnect air lines from valve*.
Remove mounting bolts, then valve.
*It is generally not necessary to remove entire valve to service
the inlet/exhaust valve. The inlet/exhaust valve insert can be
removed by removing the two exhaust cover cap screws
and cover. Insert then may be pulled out.
CAUTION: DRAIN RESERVOIRS BEFORE REMOVING
INSERT. Use care so as not to damage inlet/exhaust valve
or guide o-ring.
