Bendix Commercial Vehicle Systems RV-4 User Manual

®

Bendix® RV-4™ Pressure Reducing Valve

SD-03-3520

SUPPLY

PORT

FIGURE 1

CONTROL

PORT

(PLUGGED)

EXHAUST

MOUNTING

HOLE (2)

DELIVERY (2)

EXHAUST PASSAGE

VALVE

SPRING

BALANCE

PISTON

BALANCE

PISTON

SPRINGS

EXHAUST

CONTROL

PISTON

CONTROL

PORT

(PLUGGED)

SUPPLY

PORT

DELIVERY

PORT (2)

SPRING

SHIMS

GENERAL DESCRIPTION

The RV-4™ pressure reducing valve is a normally open
pressure control device. The function of the RV-4™ valve is
to reduce system air pressure and maintain a constant
specified pre-set pressure below that of system pressure.
V arious pressure settings can be obtained through the use
of springs and shims in combination.

The RV-4™ valve has one supply port and two delivery ports.
A single pipe plug is installed in the control port and should
remain in place.

OPERATION

The spring force exerted on the balance piston determines
the delivery pressure of the valve. With no air pressure
present at the supply port, the inlet valve is unseated and

open while the exhaust passage through the center of the
control piston is sealed by the exhaust valve. Compressed
air entering the supply port flows past the open inlet valve,
around the balance piston and out the two delivery ports.
When air pressure on the balance piston overcomes spring
force, the piston moves and the valve spring forces the inlet
valve on its seat, closing off the supply of air . The exhaust
remains closed. If air pressure in the delivery line drops,
spring force under the balance piston overcomes air
pressure. Subsequent piston movement will unseat the inlet
valve allowing additional air pressure into the delivery lines.
If pressure in the delivery lines exceeds the pressure setting
of the valve, the force exerted by the air pressure will be
greater than the spring force. The balance piston will move
away from the exhaust valve, permitting air to flow past the
exhaust valve, through the hollow piston stem and out the
exhaust port. The inlet valve will remain closed.

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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 RV -4
valve should be inspected every 6 months or 1500 operating
hours, whichever comes first, for proper operation. Should
the RV-4™ valve not meet the elements of the operational
tests noted in this document, further investigation and service
of the valve may be required.

OPERATING & LEAKAGE TESTS

OPERA TING

Connect an accurate test gauge in the supply and delivery
lines of the RV-4™ valve. Make certain that supply air
pressure is at the vehicle manufacturers recommended level.
Delivery pressure should be within plus or minus 5 p.s.i. of
the delivery pressure specified for the RV-4™ valve. If not,
the valve should be repaired or replaced. If the valve meets
this operating test, proceed to the leakage tests. Do not
remove the gauges at this time.

LEAKAGE

With supply pressure at the level recommended by the vehicle
manufacturer, apply a soap solution to the 1/4" N.P.T . plug
in the control port, around the supply port and to the exhaust.
Leakage should not exceed a 1" diameter bubble in 3
seconds (175 SCCM). If leakage is excessive, the valve
should be repaired or replaced and the operating and leakage
tests performed at the time of repair or replacement. Proceed
to the “Removal and Installation” instructions. This concludes
the operation and leakage tests and the test gauges should
be removed.

WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURY OR DEATH:

When working on or around a vehicle, the following
general precautions should be observed at all times.

1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.

2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.

3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and

thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.

4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure from
all reservoirs before beginning
vehicle. If the vehicle is equipped with an AD-IS

™

air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.

5. Following the vehicle manufacturer’s
recommended procedures, deactivate the
electrical system in a manner that safely removes
all electrical power from the vehicle.

6. Never exceed manufacturer’s recommended
pressures.

7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.

8. Use only genuine Bendix® replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.

9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.

10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.

ANY work on the

REMOVAL & INSTALLATION

REMOV AL

1. Hold the vehicle on a level surface by means other than

the air brakes.

2. Remove all air pressure from all reservoirs.

3. Identify , mark and then disconnect all air lines

attached to the valve.

4. Remove the valve.

INST ALLATION

1. Inspect and clean all air lines that connect to the valve.

2. Clean the vehicle valve mounting area and mount the

valve.

3. Reconnect the air lines according to the identification

marks made during removal.

DISASSEMBL Y (Refer to Figure 2)

1. Remove exhaust cover screw (1), exhaust cover (2), and

exhaust diaphragm (3).

2. Remove four cap screws (4) with lockwashers (5) and

cover (6).

3. Remove control piston (7).

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