BENDIX SD-03-1068 User Manual

Bendix® R-12DC™ Relay Valve with Biased Double Check
PRIMARY
SERVICE
SUPPLY (2)
EXTERIOR R-12DC
(MODEL WITH 2 HORIZONTAL PORTS)
FIGURE 1 - EXTERIOR VIEWS
VALVE
SECONDARY
SERVICE
DELIVERY
EXTERIOR
R-12DC™ VALVE
(MODEL WITH
4 VERTICAL
DELIVERY PORTS)
EXTERIOR R-12DC™ VALVE (MODEL WITH 2
HORIZONTAL AND 2
VERTICAL DELIVERY
PORTS)
SD-03-1068
DESCRIPTION
The relay valve in an air brake system functions as a relay station to speed up the application and release of the brakes. The valve is normally mounted at the rear of the vehicle in proximity to the chambers it serves. The valve operates as a remote controlled brake valve that delivers
PRIMARY SERVICE
CAP SCREW
SEALING
RING
RELAY PISTON O-RING
EXHAUST
SEAT
SPRING
O-RINGS
RETAINING
RING
FIGURE 2 - R-12DC™ RELAY VALVE WITH BIASED DOUBLE CHECK SECTIONAL VIEW
PORT
COVER
RELAY
PISTON
VALVE
RETAINER
EXHAUST
EXHAUST
PORT
or releases air to the chambers in response to the control air delivered to it from the foot brake valve.
The R-12DC™ relay valves are designed for either reservoir or frame mounting. (See Figure 1). For ease of servicing, the inlet/exhaust valve can be replaced without the need for line removal.
SECONDARY
SERVICE PORT
INLET
VALVE
SPRING
DOUBLE CHECK
DIAPHRAGM
GUIDE
1
OPERATION
APPLICA TION
Under normal conditions, the internal biased double check valve assures that the primary service signal controls the valve. Air pressure delivered to the primary service port enters the small cavity above the piston and moves the piston down. The exhaust seat moves down with the piston and seats on the inner or exhaust portion of the inlet/exhaust valve, sealing off the exhaust passage. At the same time, the outer or inlet portion of the inlet/exhaust valve moves off its seat, permitting supply air to flow from the reservoir, past the open inlet valve and into the service brake chambers. In the event of a loss of the primary service line, (see Figure 4) the double check valve mechanism in the cover of the R-12DC™ valve will move, shutting off the primary service line, and instead allow the secondary service line to apply the air pressure needed to operate the valve.
Note: Secondary service line may leak out of the primary service at control pressures up to 20 psi when the primary signal is not present.
BALANCE
The air pressure being delivered by the open inlet valve also is effective on the bottom area of the relay piston.
R-12DC
VALVE
RELAY PISTON
INLET
EXHAUST
VALVE
RESERVOIR
ANTILOCK SENSOR
TONE RING
FIGURE 3 - R-12DC SYSTEM COMPONENTS
SECTIONAL VIEW WITH TYPICAL
BRAKE VALVE
(DELIVERY LINES ARE
SHOWN)
ANTILOCK
MODULATOR
EXHAUST
PORT
BRAKE
CHAMBERS
BRAKES
APPLIED
BRAKE PEDAL
APPLIED
BRAKE PEDAL
APPLIED
NORMAL: BIASED
DOUBLE-CHECK VALVE
ALLOWS PRIMARY
CONTROL LINE SUPPLIES
RELAY PISTON
CONTROL LINE
FAILURE
BRAKE PEDAL
APPLIED
SECONDARY
CONTROL LINE
SUPPLIES RELAY
PISTON
FIGURE 4 - R-12DC
2
APPLIED POSITION (SHOWING BIASED DOUBLE CHECK OPERATIONAL VIEWS)
BRAKE PEDAL
POSITION
HELD
BRAKE
CHAMBERS
MAINTAIN
APPLICATION
AIR PRESSURE
FROM BRAKE
CHAMBERS IS
EXHAUSTED
HERE
BRAKE PEDAL
RELEASED
AIR PRESSURE
ABOVE RELAY
VALVE IS
EXHAUSTED
HERE
BRAKE CHAMBERS RELEASED
FIGURE 5 - R-12DC
BALANCE POSITION
When air pressure beneath the piston equals the service air pressure above, the piston lifts slightly and the inlet spring returns the inlet valve to its seat. The exhaust remains closed as the service line pressure balances the delivery pressure. As delivered air pressure is changed, the valve reacts instantly to the change, holding the brake application at that level.
EXHAUST OR RELEASE
When air pressure is released from the service port and air pressure in the cavity above the relay piston is exhausted through the brake valve. At the same time, air pressure beneath the 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 brake 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
FIGURE 6 - R-12DC
EXHAUST POSITION
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.
REMOVAL AND INSTALLATION
REMOVAL
1. Block and hold vehicle by means other than air brakes.
2. Drain air brake system reservoirs.
3. If entire valve is to be removed, identify air lines to facilitate installation. Prior to disassembly, remove as much contamination as possible from the exterior of the device taking care to keep all contamination from entering the open ports.
4. Disconnect air lines from valve*.
5. Remove valve from reservoir or if remotely mounted, remove mounting bolts and 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 snap ring, exhaust cover assembly and then inlet/exhaust valve.
3
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)
18
DIFFERENTIAL SPRING
(CONTROLS CRACK PRESSURE*)
(NOT REQUIRED FOR MOST
MODELS.
SEE BELOW.)
HORIZONTAL
DELIVERY
PORTS
CAP SCREW
PRIMARY CONTROL
2
PORT 1/4 NPT 3
5
4
1
6
7
8
CONTROL PORT
SECONDARY
1/4 NPT
CAP
SCREW
9
10
SUPPLY
PORT
DIFFERENTIAL SPRINGS
*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.)
VERTICAL DELIVERY
PORTS
FIGURE 7 - R-12DC™ EXPLODED VIEW
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 .
4
11
12
13
14
15
16
17
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.
5. Remove piston (9) from the body (10) and retain for reuse.
6. Remove and discard o-ring (8) from piston (9).
7. Depress and hold the exhaust cover assembly (16) and remove and discard retaining ring (17) from the valve body (10).
8. Slowly release the holding force on the exhaust cover assembly (16) to relax the spring.
9. Remove and discard the following parts: a. Exhaust cover assembly (16) b. O-rings (14 & 15) c. Spring (13) d. Inlet exhaust valve (1 1) e. Retainer (12)
CLEANING AND INSPECTION
1. Wash all metal parts in mineral spirits and dry them thoroughly.
(Note: When servicing the R-12DC™ valve, all springs and all rubber parts should be replaced.)
2. Inspect all metal parts for deterioration and wear, as evidenced by scratches, scoring and corrosion.
3. Inspect the exhaust valve seat on the relay piston for nicks and scratches which could cause excessive leakage.
4. Inspect the inlet valve seat in the body for scratches and nicks, which could cause excessive leakage.
5. Inspect the check valve seat in the R-12DC™ valve cover and make sure all internal air passages in this area are open and clean and free of nicks and scratches.
6. Replace all parts not considered serviceable during these inspections and all springs and rubber parts. Use only genuine Bendix replacement parts, available from any authorized Bendix parts outlet.
ASSEMBLY
Note: All torque specified in this manual are assembly torque and can be expected to fall off slightly after assembly. Do not re-torque after initial assembly torque fall. For assembly ,
hand wrenches are recommended. Prior to assembly, lubricate all o-rings, o-ring bores and any
sliding surface with a silicone lubricant equivalent to Dow Corning #10.
Wash all remaining parts in mineral spirit s and dry thoroughly. Using the lubricant provided in this kit, lightly lubricate all o-rings, o-ring grooves, body bores any sliding surfaces.
1. Install o-rings (14 & 15) in the exhaust cover assembly (16).
2. Install o-ring (8) on piston (9).
3. Install sealing ring (7) on cover (1).
4. Install retainer (12) on inlet exhaust valve (1 1) and insert both in the body (10).
5. Install spring (13) in the body (10).
6. Install exhaust cover assembly (16) in the body (10). Depress and hold the exhaust cover assembly in the body .
7. Install retaining ring (17) in the body (10). Make certain the retaining ring is completely seated in the groove in the body.
8. Install piston (9) in body (10).
9. Install o-ring (5) on double check cover (6), install spring (2), guide (3) and double check diaphragm (4) in cover (1). Install cover (1) and torque torx head screws to 80-100 in. lbs.
10.Referring to the marks made during disassembly , install cover (1).
11. Install the mounting bracket (not shown) on the cover (1).
12.Install the four cap screws in the cover (1) and torque to 80-100 inch pounds.
13. Test the valve as outlined in the Operational and Leakage Test section before returning the valve to service.
INSTALLATION
1. Clean air lines.
2. Inspect all lines and/or hoses for damage and replace as necessary.
3. Install valve and tighten mounting bolts.
4. Connect air lines to valve (plug any unused ports).
5. T est valve as outlined in Operational and Leakage T ests.
OPERA TIONAL AND LEAKAGE TEST
1. Chock the wheels, fully charge air brake system and adjust the brakes.
2. Make several brake applications and check for prompt application and release at each wheel.
3. Check for inlet valve and o-ring leakage. Make this check with the service brakes released. Coat the exhaust port and the area around the retaining ring with a soap solution; a 1” bubble in 3 seconds leakage is permitted.
4. Check for exhaust valve leakage. Make this check with the service brakes fully applied. Coat the outside of the valve where the cover joins the body to check for seal ring leakage; no leakage is permitted.
If the valves do not function as described above, or if leakage is excessive, it is recommended that the valves be replaced with new or remanufactured units or repaired with genuine Bendix parts, available at any authorized Bendix parts outlet.
GENERAL SAFETY GUIDELINES
5
SPRING
BRAKES
TONE RING
LINE
MODULATOR
ANTI-COMPOUND
RELAY VALVE
SPRING BRAKE
ANTI-COMPOUNDING
RELAY
VALVE
R-12DC
SPRING
BRAKES
SENSOR
WHEEL SPEED
SPRING
BRAKE VALVE
SR-1
VALVE
PARKING
WARNING
INDICATORS
ABS/TRACTION
ABS
ECU
SERVICE
VALVE
BRAKE
ENGINE ECU
DC-4
MODULATOR
CHECK
DOUBLE
BRAKE
CHAMBER
VALVE
AIR DRYER
GAUGE
SERVICE
RESERVOIR
FRONT AXLE
SINGLE
SUPPLY
RESERVOIR
REAR AXLE
VALVE
CHECK
SERVICE
RESERVOIR
WARNING
INDICATOR
LOW PRESSURE
DIAGNOSTIC
CONNECTION
QUICK
MODULATOR
VALVE
RELEASE
MODULATOR
COMPRESSOR
TONE RING
SENSOR
WHEEL SPEED
SENSOR
WHEEL SPEED
TONE RING
FIGURE 8 - TYPICAL PIPING SCHEMATIC
6
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 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 ANY work on the 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.
11. For vehicles with Antilock Traction Control (ATC), the ATC function must be disabled (ATC indicator lamp should be ON) prior to performing any vehicle maintenance where one or more wheels on a drive axle are lifted off the ground and moving.
7
8
BW1933 © 2007 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2007 Printed in U.S.A.
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