BENDIX SD-03-3619 User Manual

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Bendix® PP-DC® Park Control Valve

SD-03-3619

BUTTON

SUPPLY

FIGURE 1 - BENDIX® PP-DC® PARK CONTROL VALVE

EXHAUST

DELIVERY

SUPPLY

DESCRIPTION

The Bendix® PP-DC® park control valve is a push-pull, manually operable on/off valve. It is dash board-mounted and provides in-cab control of truck or bus parking brakes.

The valve is pressure sensitive—it automatically moves from the applied to the exhaust position when total system pressure drops below 20 to 40 psi. (Note that this is a Bendix mandated requirement. Refer to Bendix Technical Bulletin TCH-003-051). Also, manually pulling the button will apply the parking brakes.

The PP-DC valve body is made of non-metallic, noncorrosive material, and the cover is available in several variations (see Figure 1). The valve is designed to accept pipe thread ﬁ ttings or push-to-connect ﬁ ttings that use SAE J844 non-metallic air brake tubing.

Ports:

Port Embossed I.D. Primary Reservoir Supply SUP 11 Secondary Reservoir Supply SUP 12 Delivery DEL 21 Exhaust EXH 3

product specification and not a

BUTTON

COVER

EXHAUST

SUPPLY

EXHAUST

OPERATION

GENERAL

The PP-DC valve receives its supply of air from the primary service reservoir or the secondary service reservoir, whichever is at the higher pressure. When the button is pushed in, the valve delivers air to the spring brake chambers (usually through a spring brake valve such as the Bendix valve). The air releases the spring brakes for normal vehicle

operation.

To apply the parking brakes, the button is pulled out, which exhausts the PP-DC valve delivery and releases air from the spring brake chambers.

When total system pressure drops below 20 to 40 psi, the valve will automatically “pop out,” which removes the hold-off air in the chambers and applies the spring brakes.

PARKING BRAKES RELEASED

To release the parking brakes, the push-pull button is pushed in. The PP-DC valve plunger moves, closing the exhaust port with the exhaust seal and allowing the plunger o-ring to move past the guide spool. Supply air then travels out the delivery port to release the brakes.

SR-7® valve and a relay, or quick release,

Bendix®

ADB-22X

Disc Brake

Antilock

Modulator

(4 places)

Quick Release

Valve

™

Brake Valve

To Accessories

Air Dryer

Bendix

PP-DC®

Park Control

Valve

Bendix

PR-3™/ PR-4™

Valve

Bendix

EC-60

Controller

Front

Axle Reservoir

™

Electronic

Disc Brake

Service

Relay Valve

ADB-22X

™

Bendix

SR-7

Spring Brake

Modulating

Valve

Supply

Reservoir

Air Compressor

Air disc & drum brake actuation combined on a single axle are shown for pictorial purposes only.

FIGURE 2 - TYPICAL 4 X 2 TRUCK SCHEMATIC WITH BENDIX

Note that Figure 3 shows the primary service reservoir supplying the Bendix

PP-DC® valve. The double check valve diaphragm has sealed the secondary reservoir supply port and allows air to pass from the primary reservoir into the PP-DC valve.

If primary service reservoir pressure drops below secondary service reservoir pressure, the double check valve reacts as shown in Figure 4. It seals the primary service reservoir supply port and supplies the Bendix PP-DC park control valve with air from the secondary service reservoir. The push-pull button remains in and the spring brakes remain released.

PARKING BRAKES APPLIED

Figure 5 shows the PP-DC valve in the parking-brakesapplied position. This will occur when the driver manually pulls out the push-pull button, or when the total system pressure drops to below 20 to 40 psi.

As shown in Figure 6, when the button “pops” out, the exhaust seal moves to open the exhaust port to the atmosphere, allowing delivery line pressure to exhaust. The plunger o-ring moves to seal off supply pressure. Spring brake hold-off air is exhausted through the spring brake relay valve.

Rear

Axle Reservoir

PP-DC® PARK CONTROL VALVE

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-DC valve should be inspected every six (6) months or 1500 operating hours, whichever comes ﬁ rst, for proper operation. Should the PP-DC valve not meet the elements of the Operational Tests noted in this document, further investigation and service of the valve may be required.

SERVICE CHECKS

1. Remove any accumulated contaminants. Visually inspect the valve’s exterior for excessive wear or physical damage. Repair/replace as nec essary.

2. Inspect all air lines connected to the valve for signs of wear or physical damage. Repair/replace as necessary.

3. Test air line ﬁ ttings for excessive leakage. Repair or replace as necessary.

PRIMARY

SUPPLY

SECONDARY

SUPPLY

EXHAUST DELIVERY

PRIMARY

SUPPLY

SECONDARY

SUPPLY

EXHAUST DELIVERY

FIGURE 3 - PARK BRAKE RELEASED (Primary Reservoir Supply)

FIGURE 5 - PARK BRAKE APPLIED

PRIMARY

SUPPLY

FIGURE 4 - PARK BRAKE RELEASED (Secondary Reservoir Supply)

SECONDARY

SUPPLY

EXHAUST

DELIVERY

PRIMARY

SUPPLY

FIGURE 6 - PARK BRAKE EXHAUST

SECONDARY

SUPPLY

EXHAUST DELIVERY

LEAKAGE AND OPERATIONAL TESTS

To perform the tests that follow, connect two separate 120 psi air sources to the Bendix® PP-DC® valve supply ports. Tee an accurate test gauge into the supply lines, and provide for a means to control supply line pressure.

Connect a small volume with a gauge to the delivery port.

LEAKAGE TEST

1. Supply the valve with 120 psi from the primary reservoir supply port. With the button out, coat the exhaust port and the plunger stem with a soap solution. Leakage should not exceed a 1” bubble in ﬁ ve (5) seconds. There should be no leakage from the secondary reservoir supply port.

2. With the button out, supply the valve with 120 psi from the secondary reservoir supply port. There should be no leakage from the primary reservoir supply port.

3. With the button in, coat the exhaust port and the plunger stem with a soap solution. Leakage at both areas should not exceed a 1” bubble in three (3) seconds.

OPERATIONAL TEST

1. With the button out, supply either supply port with 120 psi of air. Then push the button in. Air pres sure should rise in the delivery volume equivalent to supply pressure.

2. Pull the button out. Delivery pressure should exhaust to 0 psi.

3. Build each supply source to 120 psi. Decrease supply pressure at the secondary service reservoir supply port at a rate of 10 psi per second. Primary supply pressure and delivery pressure should not drop below 100 psi. Repeat the test for decreasing primary service reservoir pressure.

4. Build each supply source to 120 psi. Then decrease both supply pressures to below 20–40 psi. The button should automatically “pop” out when pressure drops

within that range.

If the PP-DC park control valve fails to function as described, or if leakage is excessive, repair the valve or replace it at the nearest authorized Bendix

parts outlet.

REMOVAL

1. Identify and mark or label all air lines and their connections on the valve.

2. Remove the PP-DC valve from the vehicle and save the mounting hardware.

INSTALLATION

1. Install the Bendix PP-DC valve in its location on the dashboard. Using the mounting hardware saved in “REMOVAL,” secure the valve to the vehicle.

2. Reconnect all air lines to the valve using the identiﬁ cation made in “REMOVAL.”

3. Perform “LEAKAGE AND OPERATIONAL TESTS” before placing the vehicle back in service.

DISASSEMBLY

The disassembly and assembly procedures that follow are for reference only. Always have the appropriate maintenance kit on hand and use its instructions in lieu of those presented here. Refer to Figure 7 throughout the procedure.

1. Turn the button counterclockwise to remove it from the plunger stem.

2. Remove the four screws that secure the cover to the body, and remove the cover.

3. Pull the plunger stem to remove the plunger and the guide spool from the body.

4. Remove plunger spring(6) and discard.

5. If necessary, use a screwdriver to carefully remove the check valve seat from the body. Be sure not to damage the check valve seat or the body.

6. Remove and discard check valve seat o-rings(7) and (8).

7. Turn the body upside down and gently tap it on a ﬂ at surface to remove check valve(9). Discard the check valve.

8. Remove the guide spool from the plunger. Remove and discard o-ring(1) from the guide spool.

9. Remove and discard o-rings(2), (3) and (5) from the plunger. Also remove and discard exhaust seal(4).

CLEANING & INSPECTION

1. Wash all metal parts in mineral spirits and thoroughly dry.

2. Inspect all re-usable parts for excessive wear or damage. Inspect the body for gouges or deep scufﬁ ng. Replace key numbers 1-9 (and any parts not determined

usable) with genuine Bendix

replacements.

ASSEMBLY

Before assembly, lubricate all o-rings, o-ring grooves, rubbing surfaces and bores with Bendix silicone lubricant (Bendix piece number 291126) or equivalent.

1. Place check valve(9) into its seat in the body with its ﬂ at surface facing upward. If necessary, reach into the body to make sure the valve is seated evenly in the bore.

2. Install o-rings(7) and (8) on the check valve seat and install the check valve seat into the body. Make sure the seat is fully seated—its surface should be even with the body’s surface.

3. Install plunger spring(6) into the body. Make sure it stands upright and is seated properly in the body bore. (It should surround the protrusion or “lip” at the bottom of the body bore.)

4. Install o-rings(2), (3), (5) and exhaust seal(4) onto the plunger. Then install the plunger into the body. Line up the plunger’s index tabs with the spaces in the body bore for ease of installation.

BUTTON

COVER

GUIDE

SPOOL

SCREW

PLUNGER

STEM

CHECK VALVE SEAT

PLUNGER

INDEX TABS

BODY

FIGURE 7 - EXPLODED VIEW

5. Install o-ring(1) onto the guide spool. Then install the guide spool over the plunger and into the body. Press the guide spool into place ﬁ rmly.

6. Place the cover onto the body and secure with its four screws. Torque to 35 in. lbs.

7. Thread the button clockwise onto the plunger stem. It should take approximately three (3) full button revolutions to install it on the plunger. The protrusions on the side of the plunger should line up with the button grooves. Push on the button a number of times to make sure the plunger moves freely throughout its range of motion.

NOTE: BEFORE PLACING THE VEHICLE BACK INTO SERVICE, PERFORM THE “LEAKAGE AND OPERATIONAL TESTS” IN THIS DOCUMENT.

BENDIX SD-03-3619 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual