BENDIX BW1571 User's Manual
Contents
1. 13 Remove the two check valve springs 20 and rubber check valves 21 FIGURE 5 INSETS VIEWS OF LOCATION OF THE FOUR CHECK VALVE ASSEMBLIES 4 DISASSEMBLY TYPE 2 SR 4 VALVE REFER TO FIG 5 1 Remove and save the eight cap screws holding the two spring retainers in place Remove the spring retainers and remove the springs 1 amp 2 taking note of the differences and from which cavity it was removed One is color coded green the other white With a pair of pliers grasp the raised surface of the two piston assemblies 3 and remove them from the valve body housing Refer to Fig 5 With a 5 16 inch Allen Wrench remove the four 3 8 inch pipe plugs from the SR 4 valve Three are in the main body and one is in the end cap Trailers without anti compounding feature will not have a check valve in the end cover Remove the four check valve assemblies 4 one under each of the 3 8 inch pipe plugs Note and mark the position of the end cover to the body Remove the four cap screws that retain the end cover Remove the end cover from the body Remove the sealing ring 5 from the end cover Remove the large piston from its bore by grasping the web with a pair of pliers and pulling Remove the spring 6 from the base of the bore Remove the o rings 7 amp 8 from the piston Remove the check valve assembly from the main body by lightly clamping the body in a vise and turning the check valve assembly counter2. Bendix SR 4 Spring Brake Control Valve 2 RESERVOIR CHARGING PORT SERVICE PORT DELIVERY PORTS 4 TRAILER SUPPLY PORT FIGURE 1A TYPE 1 2 RESERVOIR CHARGING L RESERVOIR CHARGING SERVICE PORT PORTS 4 TRAILER SUPPLY PORT FIGURE 1B FIGURE 1 SR 4 SPRING BRAKE CONTROL VALVE TYPE 1 amp TYPE 2 DESCRIPTION The SR 4 valve is provided in two different configurations Type 1 Fig 1A incorporates a nipple mounted PR 3 valve Type 2 Fig 1B has the function of the additional PR 3 valve integrated into the main housing There is no difference in the operational performance of the two designs The SR 4 trailer spring brake control valve is similar to the SR 2 valve It differs in function by utilizing both reservoirs for normal service braking but reserving sufficient air pressure to provide the required spring brake release in the event of a service system failure As seen in Fig 1 the complete assembly includes an SR 4 valve sub assembly similar in appearance to an SR 2 valve The SR 4 valve subassembly is an SR 2 valve modified by the addition of a check valve in the spring brake reservoir fitting which permits air to pass from the reservoir to the spring brake inlet valve but not in the opposite direction AT NO TIME SHOULD AN SR 2 VALVE BE SUBSTITUTED FOR THE SR 4 VALVE SUBASSEMBLY The SR 4 valve may be identified by the metal tag affixed to the cover by o
3. 0 inch pounds ASSEMBLY CHECK VALVES A AND B 1 Twist the check valves 21 into the springs 20 and place in their respective bores and install the socket head pipe plugs Torque to 140 170 inch pounds ASSEMBLY EXHAUST CHECK VALVE 1 If so equipped position the diaphragm 19 washer 18 and screw 17 in the control piston exhaust port Torque the screw from 15 to 25 inch pounds ASSEMBLY TYPE 2 SR 4 VALVE REFER TO FIG 5 1 Install diaphragm 14 into the exhaust port of the SR 4 valve Retain with the diaphragm washer and Phillips head screw Tighten securely 2 Twist the conical spring 12 onto the spring seat and the opposite end onto the check valve 13 install this subassembly into the check valve housing depress the spring seat and install the snap ring making sure it is fully seated in its groove 3 Install the inlet exhaust valve 10 into the RES 1 port making sure the flat side of the valve is against the inlet seat Install spring 9 into the valve making sure it is installed over the rubber protrusion of the valve 10 4 Install the o ring 11 into the groove on the check valve assembly Thread the check valve assembly into the RES 1 port Lightly clamp the SR 4 valve body in a vise and using a 1 1 4 inch end wrench torque to 150 400 inch pounds 5 Place the spring 6 into the large bore of the SR 4 valve body making sure it is seated in the base of the bore Insta
4. ECK VALVE C AND INLET EXHAUST VALVE 1 Place reservoir fitting 13 in a vise pipe threads down 2 Insert the check valve 26 check valve spring 25 valve retainers 24 and retaining ring 23 3 Install the flat inlet exhaust valve into the valve body NOTE The flat side of the valve with the four ears protruding rests against the inlet and exhaust seat 4 Place the inlet exhaust valve spring 15 in positions on the inlet exhaust valve 5 Properly align the reservoir fitting assembly 13 and install in body Torque to 200 to 300 inch pounds ASSEMBLY CONTROL PISTON AND COVER 6 Install the three o rings 10 11 amp 12 on the control piston 9 7 Position the control piston return spring 8 in the body and install the control piston 8 Install the seal ring 7 in the groove on the control piston cover and assemble the cover to the body Tighten the cap screw to 40 60 inch pounds ASSEMBLY PRESSURE PROTECTION VALVE 9 Install the o ring 5 on the pressure protection piston 3 and the rubber inlet exhaust valve over the stem NOTE Light lubrication of the piston stem will facilitate the rubber valve installation 10 Install the pressure protection piston assembly in the valve body and position the pressure protection spring on the piston 11 Position the spring retainer on top of the pressure protection piston assembly and secure with the four round head machine screws Torque to 20 3
5. ce of its spring allowing air to flow through check valve G and into reservoir 1 PARK APPLICATION To apply the trailer spring brakes the trailer supply line is exhausted by means of one of the cab controls Air pressure is removed from the control piston and the internal pressure protection piston closing the pressure protection valve and the spring brake inlet valve SERVICE SYSTEM FAILURE If air pressure is reduced in the service system pressure in the trailer supply line and in the tractor will be reduced until the internal pressure protection valve closes maintaining 50 60 p s i in the trailer supply line and the tractor service reservoir This will maintain 50 60 p s i on the control piston which will keep the spring brakes released At the same time the reduction in pressure in the tractor system will sound the low pressure signal alerting the driver If the service failure is in the 2 reservoir the air which passes the pressure protection valve will escape through the 2 reservoir and will not be able to resupply the 1 reservoir The 1 reservoir will retain full pressure because of the pressure protection check valve and check valve B This 2 SERVICE UNE L ANTI COMPOUND LINE PRESSURE PROTECTION PISTON F CHECK VALVE A CHECK VALVE B we a sf i ne ae Ss TRAILER SUPPLY LINE Jie ANTI COMPOUNDING CHECK VALVE SUPPLY PORT CONTROL PISTON D reserve supp
6. clockwise with a 1 1 4 inch end wrench Remove the spring 9 and the inlet exhaust valve 10 from the housing Remove the o ring 11 from the O D of the check valve assembly With a pair of I D snap ring pliers remove the snap ring in the end of the check valve assembly Remove the spring seat the conical spring 12 and the check valve 13 Using a Phillips head screwdriver remove the Phillips head screw and the diaphragm washer from the exhaust port of the SR 4 valve body Remove the diaphragm 14 CLEANING AND INSPECTION 1 Using mineral spirits or an equivalent solvent clean and thoroughly dry all metal parts Inspect the interior and exterior or all metal parts that will be reused for severe corrosion pitting or cracks Superficial corrosion and or pitting on the exterior portion of the valve is acceptable Inspect the bores of the valve housing for deep scuffing or gouges ASSEMBLY Prior to reassembling the SR 4 valve lubricate all o rings o ring grooves piston bores and metal to metal moving surfaces with Bendix silicone lubricant BW 650 M piece number 291126 IMPORTANT NOTE When pipe thread sealant is used during assembly and reinstallation particular care should be taken to assure that this material does not get into the valve itself Pipe sealant should be applied beginning with the second thread back from the end ASSEMBLY TYPE 1 SR 4 VALVE REFER TO FIG 4 RESERVOIR FITTING CH
7. itis spring loaded 2 Remove the spring 2 and pressure protection piston assembly 3 3 Remove the inlet valve 4 from the piston stem and o rings 5 from the piston NOTE Do not attempt to remove the retaining ring and stem from the piston REMOVAL AND DISASSEMBLY OF THE CONTROL PISTON 4 Note and mark the position of the control piston cover 6 on the valve body Remove the four 1 4 inch 20 hex head cap screws and lock washers which retain the cover to the body 5 Remove the cover seal ring 7 control piston assembly and spring 8 from the valve body 6 From the control piston 9 remove the three o rings 10 11 amp 12 Wii 17 SCREW 18 WASHER IF EQUIPPED 19 wie af 7 Remove the reservoir port fitting 13 from the valve body 8 Remove the o ring 14 from the reservoir fitting REMOVAL OF CHECK VALVE C 9 Place the reservoir fitting 13 in a vise and remove retaining ring 23 valve retainer 24 spring 25 and check valve 26 10 Remove the inlet valve spring 15 and inlet and exhaust valve 16 11 If so equipped remove the screw 17 washer 18 and diaphragm 19 from the exhaust port REMOVAL OF THE TWO SINGLE CHECK VALVES A amp B NOTE Figures 2 and 4 show check valve A and check valve B out of position for illustration 12 Remove the two 3 8 inch socket head pipe plugs which retain the two single check valves in the body
8. ll the o ring 7 amp 8 onto the piston Place the piston into the housing with the small end inside of the spring 6 6 Install the sealing ring 5 into its groove on the end cover Install the end cover over the piston installed in Step 5 with the trailer supply port oriented towards the exhaust port Retain with the four 1 4 inch cap screws torque to 30 60 inch pounds 7 Refer to Fig 2 Install the four check valve assemblies 4 into the cavities of the SR 4 valve and retain with the 3 8 inch pipe plugs Removed in Step 3 of Disassembly Apply a thread sealant or Teflon tape to the threads of the pipe plugs and torque to 130 170 inch pounds 8 Install the two piston assemblies 3 into their cavities place the spring 1 amp 2 over the bosses of the piston assemblies CAUTION THE SPRING COLOR CODED WHITE MUST BE INSTALLED ON THE PISTON CLOSEST TO THE END COVER AND THE GREEN COLOR CODED SPRING ON THE PISTON AWAY FROM THE END COVER Place the spring retainers over the springs and retain with the eight 10 cap screws Torque to 20 30 inch pounds INSTALLATION ilk 2 Clean air lines connecting to valve Inspect all lines and or hoses for damage and replace as necessary Install valve and tighten 4 Connect air lines to valve plug any unused ports 5 Test valve in accordance with the Operating and Leakage Tests OPERATING AND LEAKAGE TESTS Check the tractor dash gauge against a test ga
9. ly charged The spring brakes should remain released on both the tractor and trailer Leakage at the open drain cock should not exceed a 1 bubble in 5 seconds As this test is completed close the drain cock on the trailer reservoir If the SR 4 spring brake valve does not function as described above or leakage is excessive it is recommended that it be repaired or replaced with a genuine Bendix service replacement valve 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 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 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 If the work is being performed on the vehicle s air brake system
10. ly of air will provide at least one spring brake release after a manual application Service applications may still be made until the air in the 1 reservoir is exhausted If the service failure is in the 1 reservoir the pressure protection valve will close and allow air to supply the 2 reservoir This air will be available to release the spring brake through check valve B although service applications may not be made EMERGENCY APPLICATION WITH SERVICE SYSTEM FAILURE To brake the trailer after a service system failure the remaining 55 p s i pressure in the trailer supply line may be exhausted either manually or automatically by the trailer supply valve or parking control valve The spring brakes are then exhausted through the control piston and thus applied Sufficient pressure will be maintained in the trailer system to release the spring brakes at least once ANTI COMPOUNDING OPTION Under certain conditions when the tractor protection valve goes into the emergency mode during a service application the trailer supply line will be exhausted but some air may be trapped in the service line creating a service application plus a full spring application This creates a false park situation and adds an extra load on the foundation brake components This may be prevented by adding the optional anti compounding piping as shown in Figs 2 amp 3 FIGURE 3 SR 4 VALVE ANTI COMPOUNDING PLUMBING PREVENTIVE MAINTENANCE Im
11. ne of four cap screws Porting is as follows e 1 2 inch NPT or 3 4 inch NPT spring brake supply port for reservoir mounting e 4 3 8 inch NPT delivery ports e 2 1 4 inch NPT reservoir charging ports e 1 1 4 inch NPT trailer supply port e 1 1 4 inch NPT service port optional OPERATION FIG 2 CHARGING Air from the trailer supply line enters at the trailer supply port and depresses the control piston D opening the spring brake inlet valve E It also is conducted to the cavity under the pressure protection piston F When air pressure builds to approximately 60 p s i beneath the pressure protection piston the piston moves against the force of the pressure protection spring and opens the pressure protection inlet valve The air pressure now flows past check valve A into the 2 reservoir and past check valve B through the open spring brake inlet valve and into the spring brake PRESSURE PROTECTION PISTON SPRINGS PRESSURE PROTECTION INLET VALVES PRESSURE PROTECTION PISTON F EK VALE G RELAY VALVE INLET VALVE E T f A SPRING BRAKE FIGURE 2 SR 4 VALVE CROSS SECTIONAL SCHEMATIC units Air is prevented from flowing from the SR 4 valve into reservoir 1 by check valve C Air simultaneously flows into the PR 3 pressure protection valve Type 1 SR 4 valve or the second pressure protection piston Type 2 SR 4 valve At approximately 70 psi piston F moves against the resistan
12. 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 Following the vehicle manufacturer s recommended procedures deactivate the electrical system in a manner that safely removes all electrical power from the vehicle Never exceed manufacturer s recommended pressures 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 10 11 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 Componenis 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 Prior to returning the vehicle to service make certain all components and systems are restored to their proper operating condition 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
13. or more wheels on a drive axle are lifted off the ground and moving REMOVAL OF VALVE FROM VEHICLE 1 Check the vehicle wheels and drain all air system reservoirs completely Disconnect all supply delivery and exhaust lines at the trailer spring brake valve NOTE Mark all air lines and their relation to the spring brake valve for reconnection Remove the spring brake valve from the trailer 1 reservoir PR 3 VALVE REMOVAL AND TEST TYPE 1 SR 4 VALVE 1 2 3 Remove the PR 3 valve from the SR 4 valve assembly Apply 50 p s i air pressure at the supply port and apply a soap solution to the delivery port Leakage of a 1 bubble in 3 seconds is permissible Apply 100 p s i air pressure at the delivery port Apply a soap solution to the supply port No leakage permissible If the PR 3 valve does not function as described above or leakage is excessive it is suggested it be exchanged or replaced at the nearest Bendix distributor The PR 3 valve is not considered as serviceable internally If the PR 3 valve is disassembled DO NOT MIX the PR 3 valve parts with similar looking parts in the main assembly FIGURE 4 SR 4 VALVE DISASSEMBLY TYPE 1 REFER TO FIG 4 REMOVAL AND DISASSEMBLY OF THE PRESSURE PROTECTION PISTON FIG 4 1 Remove the four round head machine screws which secure the spring retainer 1 to the valve body NOTE Take caution when removing the spring retainer as
14. ore the 1 reservoir begins to charge see Fig 3 When full system pressure has been reached and the spring brakes fully released it is acceptable to have a slightly lower pressure reading in the service reservoirs than is registered on the dash gauge Apply a soap solution to the exhaust port and the vent Leakage of a 1 bubble in 5 seconds is permissible 2 Place the trailer supply valve in the exhaust position the spring brakes should apply Disconnect the trailer supply line and soap the hose coupling to check for leaks A 1 bubble in not less than 5 seconds is permissible 3 Reconnect the trailer supply hose coupling and recharge the trailer system The spring brakes should release Shut off the engine leaving the ignition on and open the drain cock on the 1 reservoir The tractor air system should bleed down to approximately 55 p s i with low pressure indication occurring at or before 60 p s i The 2 reservoir on the trailer should also bleed down to approximately 55 p s i but the spring brakes on tractor and trailer should remain released After the system is stabilized leakage at the open drain cock in the trailer should not exceed a 1 bubble in 5 seconds 4 Close the drain cock on the trailer 1 reservoir recharge the system stop the engine and open the drain cock on the 2 reservoir Again the tractor air system should bleed down to approximately 45 p s i but the 1 reservoir on the trailer should remain ful
15. portant 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 SR 4 valve should be inspected every 6 months or 1500 operating hours whichever comes first for proper operation Should the SR 4 valve not meet the elements of the operational tests noted in this document further investigation and service of the valve may be required SERVICE AND LEAKAGE TESTS Check the tractor dash gauge against a test gauge known to be accurate prior to performing these tests Connect the tractor air lines to the trailer on which the SR 4 trailer spring brake valve is to be tested Block all wheels or hold both vehicles by a means other than air brakes 1 Install two separate test gauges or one dual test gauge with one line to the 1 reservoir and the other line to the 2 reservoir Build the tractor and trailer to full system pressure by placing the trailer supply valve in the charge position and the parking control valve in the brakes released position Note As system pressure reaches approximately 60 p s i the 2 reservoir and the spring brakes should build up to approximately 60 p s i bef
16. uge known to be accurate prior to performing these tests Connect the tractor air lines to the trailer on which the SR 4 trailer spring brake valve is to be tested Block all wheels or otherwise hold both vehicles by a means other than air brakes during these tests TESTING THE REBUILT SR 4 VALVE Test the rebuilt SR 4 valve as explained in Service and Leakage Tests BW1571 2007 Bendix Commercial Vehicle Systems LLC All rights reserved 7 2007 Printed in U S A
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