BENDIX BW2872 User's Manual
Contents
1. Typical School Bus Air System Schematic with a Bendix AD 9 Air Dryer Wheel Speed Sensor Park Control and Tone Ring Valve Air Disc Brake Dual Brake Valve r w BVA 85 Brake Valve Actuator Antilock Electronic Controller Quick Release Valve Stop Light Switch ET Pressure Bendix BVA 85 Door Interlock Kit T fy aaa Gann Antilock HO Modulator T 4 places Traction Solenoid Relay pe cl a Valve D ontrol Valve o To Accessories Protection Valve Pressure Bendix Indicator AD 9 l Automatic Slack Air Dryer E Adjuster 5 ae Rear Axle ac uster J a Spring Brake Dium Chamber Air Pressure Brake T l Supply Front Axle Gauge 7 Reservoir Reservoir Wheel ee S 2 Speed Sensor Compressor Single Check Manual Drain and Tone Ring Valve Valve Visit www bendix com or www foundationbrakes com for Service Data Sheets and other literature such as the following BW902 BW1114 BW1231 BW1555 BW2780 BW2786 BW5057 BW2197 SD 13 4815 SD 13 4863 Air Brake Handbook EC 30 ABS Controller EC 60 ABS Controller GENERAL SAFETY GUIDELINES WARNING PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH When working on or2. Typical School Bus Air System Schematic with a Bendix AD IS Air Dryer Wheel T Speed Sensor m and Tone Ring Park Control Valve gt Air Disc Brake Dual Brake Valve w BVA 85 Brake Valve Actuator Quick Stop Light Release Switch s Ben 3 valve s 2 Bendix Antilock Electronic Controller AD IS Air Dryer Governor Automatic Slack Adjuster Compressor Brake rm Bendix BVA 85 Door Interlock Kit Traction Solenoid Relay Valve c GOO Chamber To Accessories Front Axle Reservoir TEST 1 Governor cut out Low pressure warning Pressure build up VEHICLE PARKED WHEELS CHOCKED Drain all the reservoirs to 0 psi Start the engine and run at fast idle The low pressure warning should be on Note on vehicles equipped with ABS the warning lamp will also come on momentarily when the ignition is turned on On some systems such as the Bendix AD IS dryer system illustrated reservoirs may not fill simultaneously and one reservoir may fill to 110 psi before the other starts to fill Low pressure warning dash warning lamp should go off above 60 psi Build up time pressure should build from 85 100 psi within 40 seconds Governor c
3. 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 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 beainnina ANY work on the Specify genuine Bendix brand replacement parts every time you service your air brake system All genuine Bendix brand replacement parts are manufactured to meet original OE specifications to guarantee quality reliability and proper operating performance Rely on genuine Bendix brand replacement parts to keep your Air Brake System operating efficiently With thousands of authorized Bendix Pa
4. ck Indicator Modulator IO 4 places Rear Axle Automatic Slack Reservoir Adjuster pe Air Pressure Gauge Wheel Valve Speed Sensor and Tone Ring TEST 3 Pressure Modulator Valve and Traction Control Valve Chuff M a FULL PRESSURE ENGINE STOPPED PARKING BRAKES RELEASED K Not Make and hold a brake application When ignition power is applied each pressure modulator valve PMV solenoid is briefly energized If the air system is fully charged and the service brake pedal is depressed during ignition the modulator creates a single sharp audible chuff of air pressure The modulators are energized in a certain pattern as follows right front left front right rear left rear This test is performed only when the vehicle is stationary if the vehicle moves the chuff test will not be performed NOTE The Bendix EC 60 electronic controller will perform a pressure modulator valve PMV chuff test on all installed modulators in the following order 1 Steer Axle Right PMV 2 Steer Axle Left PMV 3 Drive Axle Right PMV 4 Drive Axle Left PMV 5 Additional Axle Right PMV 6 Additional Axle Left PMV 7 Drive Axle Traction Control Valve TCV The pattern will then repeat itself See appropriate Service Data Sheet for repairs MAKE ALL NECESSARY REPAIRS BEFORE PROCEEDING TO TEST 4 TEST 4 Leakage service air delivery M uM FULL PRESSURE ENGINE STOPPED PARKING BRAKES RELEASED OF Not Make an
5. d hold an 80 90 psi brake application This can be accomplished by using the Bendix BVA 85 brake valve actuator If the vehicle is not equipped with a BVA 85 brake valve actuator an assistant should be used to maintain a constant brake application during these tests Allow pressure to stabilize for 1 minute then begin timing for 2 minutes while watching the dash gauges for a pressure drop A 4 psi drop within 2 minutes is allowable for either service reservoir Check brake chamber push rod travel refer to chart for allowable tolerances With the parking brakes released and service brakes applied with 80 to 90 psi of air pressure to the service chambers Brake Maximum Allowable Max Allowable Chamber Size Stroke Stroke Long Stroke 12 1 3 8 1 3 4 16 1 3 4 20 1 3 4 2 24 1 3 4 2 24 Max Stroke 2 1 2 30 2 2 1 2 Check the angle formed between the brake chamber push rod and slack adjuster arm It should be approximately 90 in the applied position 80 90 psi and the same across the axle MAKE ALL NECESSARY REPAIRS BEFORE PROCEEDING TO TEST 5 SEE CHECKLIST 4 FOR COMMON CORRECTIONS Spring Brake Control Valve School Bus Air Brake System Troubleshooting Charging Spring Brake Chamber Notes Drum Brake Coach and School Bus Primary Secondary Parking Accessories Control The color c
6. ge can be heard remove the unloaders and repair or replace as necessary RETEST TO VERIFY PROPER OPERATION OF ALL ITEMS REPAIRED OR REPLACED TEST 2 Leakage reservoir air supply For additional information refer to the video Assessing Air Brake System Air Leakage Bendix part number BW2327 CD FULL PRESSURE ENGINE STOPPED PARKING BRAKES APPLIED 1 Allow the air pressure to stabilize for at least 1 minute 2 Observe the dash gauge pressures for 2 minutes and note any pressure drop A 4 psi drop within 2 minutes is allowable for either service O O reservoir MAKE ALL NECESSARY REPAIRS BEFORE PROCEEDING TO TEST 3 SEE CHECKLIST 2 FOR COMMON CORRECTIONS CHECKLIST 2 If there is excessive leakage in the supply side of the pneumatic system one or more of the following devices could be causing the problem NOTE A leak detector or soap solution will aid in locating the faulty component Supply lines and fittings Low pressure indicator s Service brake relay valve s Spring brake relay valve where applicable Dual brake valve Park control valve System safety valve s in the supply reservoir and or air dryer Governor may be mounted on the air dryer as illustrated on the compressor or remotely Compressor discharge line RETEST TO VERIFY PROPER OPERATION OF ALL ITEMS REPAIRED OR REPLACED OoOonN DON FS W PP Manual Drain Low Pressure PAA Antilo
7. he front axle reservoir should retain most O 1 of its pressure With no air pressure in the rear axle reservoir make and release a brake application A Front axle brakes should apply and release Oy B If the vehicle is equipped with a spring brake modulating valve the rear axle brakes should also apply and release by exhausting spring O O brake air MAKE ALL NECESSARY REPAIRS BEFORE PROCEEDING SEE CHECKLIST 6 FOR COMMON CORRECTIONS CHECKLIST 6 If the vehicle fails to pass the tests outlined then check the following components for NoN SW PP leakage and proper operation Fittings Kinked hose or tubing Pressure protection valves Double check valves Parking control valve Relay valves antilock modulators Inverting relay spring brake control valve optional RETEST TO VERIFY PROPER OPERATION OF ALL ITEMS REPAIRED OR REPLACED Note The optional Bendix BVA 85 actuator for Bendix E 6 E 8P and E 10 based brake valve configurations plus the door interlock kit Pc No K036675 is intended to provide an approximately 40 psi service brake application to all wheels when the following conditions are met e Passenger door is open RED crossing flashers are ON e Vehicle speed is below 3 mph Indication is provided to the operator in the event that the control pressure to the BVA 85 actuator drops below the minimum pressure required to hold the bus
8. 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 Automatic 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 Bendix brand wheel end solutions are brought to you by IX Bendix Spicer Foundation Brake LLC www bendix com www foundationbrakes com Printed on recycled paper
9. oding of the brake system schematic follows TMC Recommended Practice 423 Air disc amp drum brake actuation combined on a single axle are shown for pictorial purposes only CHECKLIST 4 If there is excessive leakage in the service side of the pneumatic system one or more of the following devices could be causing the problem NOTE A leak detector or soap solution will aid in locating the faulty component 1 Loose service lines and fittings Park control valve Stoplight switch Spring brake chamber service chamber and or brake chamber diaphragms Service brake relay valves Dual brake valve Inverting relay spring brake control valve where applicable usually found on the spring brake relay valve straight trucks and buses 8 Double check valve If the automatic slack adjuster is not adjusting repair or replace to obtain the desired setting CAUTION If the brake chamber push rod travel exceeds the allowable stroke identify and correct the root cause of the excess stroke Do not make manual adjustments of an automatic slack adjuster once it can no longer automatically adjust the brakes Manual adjustment DOES NOT fix the underlying wheel end adjustment As soon as possible have the vehicle inspected by a qualified technician or consult the manufacturer s troubleshooting guidelines to find and fix the problem ND OO SP W PDP RETEST TO VERIFY PROPER OPERATION OF ALL ITEMS REPAIRED OR REPLACED TEST 5 Manual Parking Brake O
10. peration FULL PRESSURE ENGINE IDLING 600 900 RPM Manually operate the park control yellow button valve and note that parking brakes apply and release promptly as the control valve button is pulled out and pushed in MAKE ALL NECESSARY REPAIRS BEFORE PROCEEDING TO TEST 6 SEE CHECKLIST 5 FOR COMMON CORRECTIONS CHECKLIST 5 If sluggish performance is noted check for the following 1 Dented or kinked lines 2 Improperly installed hose fitting 3 A faulty quick release valve or spring brake control valve 4 Damaged or improperly installed spring brake chamber and or service chambers 5 Foundation brake component binding improper installation and or lack of lubrication RETEST TO VERIFY PROPER OPERATION OF ALL ITEMS REPAIRED OR REPLACED TEST 6 Dual circuit system integrity check emergency braking and or automatic application of the parking brake FULL PRESSURE ENGINE STOPPED PARKING BRAKES RELEASED Drain the front axle or secondary reservoir to 0 psi The rear axle or primary reservoir should retain most of its pressure With no air pressure in the front axle reservoir make a brake application A The rear axle brakes should apply and release when the application is released B The stop lamps should light and go off when the application is released Pop Pressure Vehicle Test Procedure Note Bendix is not aware of any federal legislation that specifies the pressure at which the YELLOW parking brake control valve mus
11. rts Outlets across North America you re never far from quality genuine Bendix brand replacement parts BW2872 2010 Bendix Commercial Vehicle Systems LLC a member of the Knorr Bremse Group 6 2010 All Rights Reserved School Bus Air Brake Systems Small version of BW2872 Bendix Quick Reference Catalog Air Brake System Troubleshooting Wallchart Brake Balance Procedure Troubleshooting Bendix ESP Stability System Wallchart Troubleshooting Bendix ESP Stability System BVA 85 Brake Valve Actuator vehicle If the vehicle is equipped with a Bendix 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 Use only genuine Bendix brand 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 Components with stripped threads or damaged parts should be replaced rather than repaired Do not attempt repairs requiring
12. t automatically trip to apply the vehicle parking brakes This includes the Federal Motor Carrier Safety Regulations FMCSR for in use vehicles the CVSA out of service criteria and the Federal Motor Vehicle Safety Standards FMVSS for newly manufactured vehicles Although the trip pressure for the parking brake control valve is not stipulated for in use or newly manufactured vehicles a parking brake control valve trip pressure of 20 40 psi is currently 02 2009 specified as part of the Commercial Driver License in the CDL Manual The CDL Manual is not consistent with the regulations cited above See Bulletin TCH 003 051 continued TEST 6 Continued OK Not OK Pop Pressure Vehicle Test Procedure Continued Install an accurate shop standard pressure gauge in the secondary service reservoir Build pressure in the service reservoirs until the compressor cut out is reached shut the engine off Fully open the manual drain valve on the primary service reservoir allowing the reservoir to drain completely Open the secondary reservoirs manual drain valve creating a bleed rate of approximately 20 50 psi min Monitor the pressure gauge noting the pressure at which the parking control automatically pops This is not a Federal requirement See Note in previous column Close the drain cocks recharge the system and drain the rear axle primary reservoir to 0 psi T
13. ut out cuts out at the correct pressure 135 psi maximum Governor cut in reduce the service air pressure to governor cut in The difference between cut in and cut out pressure must not exceed 30 psi MAKE ALL THE NECESSARY REPAIRS BEFORE PROCEEDING TO TEST 2 SEE CHECKLIST 1 FOR COMMON CORRECTIONS CHECKLIST 1 If the low pressure warning lamp or buzzer doesn t come on 1 Check the warning lamp wiring 2 Check the warning lamp bulb 3 Repair or replace the buzzer bulb or low pressure warning switch es If the governor cut out is higher or lower than specified by the vehicle manual 1 Repair replace or adjust the governor as necessary after ensuring the compressor unloader mechanism is operating correctly If the low pressure warning occurs below 60 psi 1 Check the dash gauge with test gauge known to be accurate 2 Repair or replace the faulty low pressure indicator switch If the compressor build up time exceeds 40 seconds or is considerably greater than the permanent record figure 1 Examine the compressor air inlet filter and inlet line checking for restrictions damage or wear Clean or replace the filter or inlet line as necessary 2 Check the compressor discharge port and line for excessive carbon Clean or replace the discharge line as necessary If carbon is present find the cause of the excessive heat 3 With the system fully charged and governor in the unloaded mode listen at the compressor inlet for leakage If leaka
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