background image

9

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.

Summary of Contents for M-21

Page 1: ...f individual wheel control applications the modulator is always the last control valve through which air passes on its way to the service brake actuator and a solenoid assembly which contains one norm...

Page 2: ...21 OR M 22 MODULATOR TO ANTILOCK CONTROLLER TO ANTILOCK CONTROLLER TO ANTILOCK CONTROLLER TO ANTILOCK CONTROLLER They are as follows Identification Air Line Connection 1 Supply incoming air from foot...

Page 3: ...SUPPLY DIAPHRAGM SUPPLY SOLENOID SPRING EXHAUST DIAPHRAGM EXHAUST SOLENOID BRAKE CHAMBER EXHAUST PORT FIGURE 4 M 21 M 22 MODULATOR NON ANTILOCK APPLICATION HELD POSITION BRAKE VALVE SPRING SUPPLY DIA...

Page 4: ...lifts the exhaust diaphragm from its seat Returning air flows past the open exhaust and out the modulator exhaust port Air will also flow past the open supply diaphragm and back to the application de...

Page 5: ...creased The modulator can enter the antilock hold or re apply mode from the antilock exhaust mode ANTILOCK HOLD The antilock controller will place the modulator in the hold position when it senses tha...

Page 6: ...ten or replace as necessary 4 Perform the ROUTINE OPERATION AND LEAKAGE TESTING described in this manual OPERATION LEAKAGE TESTS LEAKAGE TESTING 1 Park the vehicle on a level surface and block or choc...

Page 7: ...OURCE Read 3 5 to 5 OHMS B EXHAUST to SOURCE Read 3 5 to 5 OHMS C EXHAUST to HOLD Read 7 to 10 OHMS D Individually test the resistance of each pin to vehicle ground and note there is NO CONTINUITY If...

Page 8: ...ITION BRAKE VALVE SPRING SUPPLY DIAPHRAGM FIGURE 9 M 21 M 22 MODULATOR CONNECTOR VIEW M 21 MODULATOR M 22 MODULATOR CONNECTOR HOLD EXHAUST SOURCE EXHAUST HOLD SOURCE CONNECTOR SUPPLY SOLENOID SPRING E...

Page 9: ...rized 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 mod...

Page 10: ...10...

Page 11: ...11...

Page 12: ...12 BW1664 2004 Bendix Commercial Vehicle Systems LLC All rights reserved 6 2004 Printed in U S A...

Reviews: