SD-03-3611
Bendix® PP-1®, PP-2™, PP-5™, PP-8™, & RD-3™ Push-Pull Type Control Valves

Bendix®
PP-1® Valve

Bendix®
PP-5™ Valve
Bendix®
PP-2™ Valve

Bendix®
RD-3™ Valve
Bendix®
PP-8™ Valve

Figure 1 – Push-Pull Type Control Valves

DESCRIPTION
The PP valves are push‑pull manually operable on‑off air
control valves with an exhaust function. Most are pressure
sensitive, so that they will automatically move from the
applied to the exhaust position as supply pressure is
reduced to a certain minimum, depending on the
spring installed. The exception to this is the Bendix®
PP‑8 ™ valve and some Bendix ® PP‑1 ® valves which
do not contain a spring. The PP‑8 valve also has a
larger diameter shaft for button mounting so that when
installed on the same panel with other PP valves the
buttons cannot be inadvertently mixed. The PP-8 valve is
normally used to operate tractor spring brakes independently
from the trailer.
The Bendix® PP‑5™ valve is unique in having an auxiliary
piston in the lower cover which, upon receiving a pneumatic
signal of 18 psi or more, will cause the valve to move
from the applied to the exhaust position from a 100 psi
application.

The Bendix® PP‑2™ valve has an auxiliary port which
may be plumbed into a service brake line to release the
spring brakes if a service application is made, preventing
compounding of forces on the foundation brakes.

PURPOSE OF THIS MANUAL
This document is intended to act as a source of maintenance
information to those involved in servicing Bendix® push-pull
type control valves.

ADDITIONAL SUPPORT
For additional service information, contact the Bendix
Tech Team online at [email protected], or by calling
1-800-AIR-BRAKE (1-800-247-2725), option 2. Tech
Team members are available Monday through Thursday,
8:00 a.m. to 6:00 p.m. and Friday, 8:00 a.m. to 5:00 p.m. ET.

The Bendix® RD‑3™ valve differs slightly in that it normally
remains in the exhaust position and requires a constant
manual force to hold it in the applied position.
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GENERAL SAFETY GUIDELINES

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

When working on or around a vehicle, the following guidelines should be observed AT ALL TIMES:
▲ Park the vehicle on a level surface, apply the ▲ Never connect or disconnect a hose or line
parking brakes, and always block the wheels.
containing pressure; it may whip and/or cause
Always wear personal protection equipment.
hazardous airborne dust and dirt particles. Wear
eye protection. Slowly open connections with
▲ Stop the engine and remove the ignition key
care, and verify that no pressure is present. Never
when working under or around the vehicle.
remove a component or plug unless you are
When working in the engine compartment,
certain all system pressure has been depleted.
the engine should be shut off and the ignition
key should be removed. Where circumstances ▲ Use only genuine Bendix ® brand replacement
require that the engine be in operation, EXTREME
parts, components, and kits. Replacement
CAUTION should be used to prevent personal
hardware, tubing, hose, fittings, wiring, etc.
injury resulting from contact with moving,
must be of equivalent size, type, and strength as
rotating, leaking, heated, or electrically charged
original equipment and be designed specifically
components.
for such applications and systems.
▲ Do not attempt to install, remove, disassemble, ▲ Components with stripped threads or damaged
or assemble a component until you have read,
parts should be replaced rather than repaired.
and thoroughly understand, the recommended
Do not attempt repairs requiring machining or
procedures. Use only the proper tools and
welding unless specifically stated and approved
observe all precautions pertaining to use of those
by the vehicle and component manufacturer.
tools.
▲ Prior to returning the vehicle to service, make
certain all components and systems are restored
▲ If the work is being performed on the vehicle’s
to their proper operating condition.
air brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure ▲ For vehicles with Automatic Traction Control
from all reservoirs before beginning ANY work
(ATC), the ATC function must be disabled (ATC
on the vehicle. If the vehicle is equipped with
indicator lamp should be ON) prior to performing
a Bendix ® AD-IS® air dryer system, a Bendix ®
any vehicle maintenance where one or more
DRM™ dryer reservoir module, a Bendix® AD-9si®,
wheels on a drive axle are lifted off the ground
AD-HF®, or AD-HFi® air dryer, be sure to drain the
and moving.
purge reservoir.
▲ The power MUST be temporarily disconnected
▲ F o l l o w i n g t h e v e h i c l e m a n u f a c t u r e r ’s
from the radar sensor whenever any tests USING
recommended procedures, deactivate the
A DYNAMOMETER are conducted on a vehicle
electrical system in a manner that safely removes
equipped with a Bendix® Wingman® system.
all electrical power from the vehicle.
▲ Never exceed manufacturer’s recommended
pressures.
▲ You should consult the vehicle manufacturer's operating and service manuals, and any related literature,
in conjunction with the Guidelines above.

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

REMOVAL

BENDIX® PP-1® VALVE

9
7

8
Supply

Delivery

6

4
5

Figure 2

Block and/or hold the vehicle by a means other than air
brakes and drain all reservoirs.
1. Drive the button roll-pin out with a punch and remove
the button.

Button Roll Pin

Panel Mounting
Nut

3
Exhaust

BENDIX® PP-8™ VALVE
Panel Mounting
Nut

9

2. Mark each air supply line and its port for easy
reinstallation, then disconnect them. Remove the valve
from the panel by removing the panel mounting nut.

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INSTALLATION
1. Install the valve in panel, securing with the panel
mounting nut.

Supply

2. Reconnect the air lines using marks made during
removal as a guide.

Delivery
4

6

3. Install the operating button. Secure the operating button
by installing the button roll pin.

DISASSEMBLY: BENDIX® PP-1®, PP-8™, &
RD-3™ VALVES
1. Remove the two cap screws (3) which retain the lower
cover and remove the cover. Remove the sealing
ring (4).
2. Insert a small punch through the roll pin hole in the stem
and remove the locknut (5).

3

5

Figure 3

Exhaust

BENDIX® RD-3™ VALVE
Button Roll Pin

Panel Mounting
Nut

9

3. Remove the inlet-exhaust valve (6) and plunger (7) and
spring (8), if any.

7
8

4. Remove the o-ring (9) from the plunger.
Supply

Delivery
4

6

3

5

Figure 4

Exhaust
3

DISASSEMBLY: BENDIX® PP-2™ VALVE

DISASSEMBLY: BENDIX® PP-5™ VALVE

1. Insert a small punch through the roll pin hole in the
plunger and remove the locknut (1) from the plunger.

1. Perform the same operations as for the PP-1® valve.

2. Withdraw the plunger and remove the spring (9) and
the o-ring (8).
3. Remove the two machine screws (2) and remove the
lower cover (3).

2. Remove the inlet seal (10), shown in Figure 6, from the
lower cover. Remove the ring diaphragm (4) from the
inlet seat.
3. Remove the piston (11) and the o-ring (2).

BENDIX® PP-5™ VALVE

4. Remove the inlet-exhaust valve (4) and the piston (5).
5. Remove the o-rings (6 & 7) from the piston.

BENDIX® PP-2™ VALVE
9
Panel
Mounting
Nut

Button Roll
Pin

7

8

Supply
6

Supply

2

Brake
Valve
Port

4

5

3
5

4

10

Delivery

4

Figure 5

Delivery

8

9

1

6

11

7

Figure 6

3
Pilot Air
Inlet

2

OPERATING AND LEAKAGE TESTS

BENDIX® PP-5™ VALVE
1. Proceed as for Bendix® PP-1® valve through Step 4.

Do not install fittings or tubing into the exhaust port
if used for parking brake control. If a worn PP-1 or
PP-8 valve is used for parking brake control and the
exhaust plumbing is kinked, bent, or restricted, the
vehicle might not park, and a roll away may result,
potentially resulting in injury or death.
Bendix®
Valve

Automatic
Exhaust
(psi)

Momentary
Apply

Pilot Trip
Feature
(psi)

Non-Automatic

PP-1®

20, 30, 40
or 60

–

–

–

PP-2™

40

–

–

–

PP-5™

40, 50
or 60

–

18 or 24

–

™

–

Must
be held
manually

–

–

PP-8™

–

–

–

Will remain in
either position

RD-3

Table 1 - Push-Pull Type Control Valves Operation

BENDIX® PP-1®, PP-8™, & RD-3™ VALVES
1. Run the vehicle until the air system reaches full
reservoir pressure (120-135 psi). Turn off the vehicle.
2. Move the control valve button & plunger from side to
side and up and down. Do not push the button in. If
there is any play, or if audible leakage is detected, the
valve must be replaced.

2. Connect a modulated source of air pressure to the pilot
air inlet. With the button pushed in (applied position)
with 125 psi supply pressure and a gradually increasing
pressure applied at the pilot air port, the valve should
move to the release position with a pilot pressure of
not more than 18 psi. Leakage in this mode should not
exceed a 1-in. bubble in three (3) seconds at the
exhaust port and a 1-in. bubble in five (5) seconds at
the plunger stem.

BENDIX® PP-2™ VALVE
1. Proceed as for the PP-1 valve through Step 1.
2. With the button pulled out (exhaust position), leakage
at the brake valve port or at the plunger stem should
not exceed a 1-in. bubble in five (5) seconds.
3. Push the button in. Supply pressure should be present
in the delivery volume. Leakage at the exhaust port
or around the plunger stem should not exceed a 1-in.
bubble in five (5) seconds.
4. Pull the button out and apply supply pressure at the
brake valve port. Supply pressure should be present
in the delivery volume and leakage at the exhaust port
should not exceed a 1-in. bubble in five (5) seconds.
NOTE: If any of the above push-pull valves do not
function as described or if leakage is excessive,
it is recommended they be returned to our
nearest authorized distributor for a service new or
remanufactured replacement.

3. Identify the dash valve exhaust hose location – if there
is a hose still connected to the Park Control Valve
Exhaust Port, it is advised to disconnect it and remove
any fitting.
4. With the button pulled out (exhaust position), rotate the
button and plunger in a clockwise direction – stopping
every 90º to check for leakage.
5. Using a soap solution, check for leaks. The allowable
leakage should not exceed a 1” bubble in 5 seconds
at any location on the valve.
6. Push the button in (applied position) and check for
leaks. (The Bendix® RD-3™ valve will have to be
manually held in this position.) The leakage should
not exceed a 1” bubble in 3 seconds at any location
on the valve.
7. Reduce the supply pressure. At a pressure from 60
to 20 psi, depending on the part number specific
automatic release pressure, the button should pop out
automatically, exhausting the delivery volume. (This
does not apply to the RD-3, PP-8 or some PP-1 valves
without an automatic release pressure).

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SD-03-3611 Rev 008 ©2024 Bendix Commercial Vehicle Systems LLC, a member of Knorr-Bremse • 3/24 • All Rights Reserved

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