BENDIX BW1662 User's Manual
Contents
1. SPEED FIGURE 2 SPEED SENSOR VOLTAGE CYCLE OUTPUT sasan m EXCITERS FRONT WHEEL REAR WHEELS FIGURE 3 TYPICAL ANTILOCK SYSTEM TECHNICAL INFORMATION Electrical Connector 2 Pin Output Voltage With a 3 000 Ohm resistor across the two sensor leads output voltage measured on a VOM 800 VAC Minimum at 42 Hz or approximately 5 mph Sensor Gap 0 to 015 inch Sensor Body Formulated Epoxy 628 Diameter Normal Resistance Range at Room Temp 2000 2500 ohms PREVENTIVE MAINTENANCE 1 Every 3 months 25 000 miles 900 operating hours or during the vehicle chassis lubrication interval make the visual inspections noted in SERVICE CHECKS below 2 Every 12 months 100 000 miles or 3600 operating hours perform the OPERATIONAL TEST in this manual SERVICE CHECKS Check all wiring and connectors Make sure connections are free from visible damage Examine the sensor Make sure the sensor mounting bracket and foundation brake components are not damaged Repair replace as necessary 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 working2. eplacement 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 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 LOOTOOTH EXCITER MOUNTING BLOCK MAX GAP SENSOR TO EXCITER 015 INCHES REMOVAL 1 Unplug the cable assembly connector from its lead Lift the lock tab and pull on the connector until it disengages Gently pry the sensor and bushing from the mounting block INSPECTION Look for any visible damage to the sensor cable assembly connector mounting block and foundation brake Repair or replace any damaged components Make sure the block is securely attached to the axle housing SENSOR INSTALLATION 1 For increased corrosion protection we recommend that a high temperature rated silicon or lithium based grease be applied to the interior of the mounting block the sensor and to a new clamping sleeve Gently push DO NOT STRIKE the sensor into the mounting block hole until it bottoms out on the face of the tone ring Secure the cable
3. exciter ring as described in this manual For additional troubleshooting information see the troubleshooting procedure for the specific antilock system in use BW1662 2005 Bendix Commercial Vehicle Systems LLC All rights reserved 1 2005 Printed in U S A
4. he programmed data the controller can calculate vehicle speed by analyzing the frequency of AC cycles sent by the speed sensor The frequency of AC cycles is directly proportional to wheel speed AC voltage is also proportional to speed but voltage is not used to determine speed It is only an indication of AC signal strength The amount of AC voltage generated by a specific speed sensor depends on the distance or gap between the tip of the sensor and the surface of the exciter Voltage increases as the sensor gap decreases The WS 20 wheel speed sensor is installed in a mounting block that is affixed to the axle housing See Figure 2 A spring loaded retainer bushing provides a friction fit between the mounting block bore and the WS 20 sensor The friction fit allows the WS 20 sensor to slide back and forth under force but to retain its position when force is removed This feature allows the WS 20 sensor to self adjust after it has been installed in the mounting block and the wheel is installed When the WS 20 sensor is inserted all the way into the mounting block and the wheel is installed on the axle the hub exciter contacts the sensor which pushes the sensor back Also normal bearing play will bump the sensor away from the exciter The combination of these two actions will establish a running clearance or air gap between the sensor and exciter PEAK TO PEAK aN LOW SPEED PEAK TO PEAK HIGH
5. 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 Ifthe 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 FIGURE 4 WS 20 WHEEL SPEED SENSOR INSTALLATION 10 SPEED SENSOR 100 TOOTH SPEED SENSOR EXCITER RIN W5 20 SPEED SENSOR 90 DEG 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 Use only genuine Bendix r
6. lead wire to the knuckle axle housing 3 6 inches from the sensor 3 Reconnect the connector to the sensor lead by plugging it into the appropriate socket on the pigtail harness and pushing until the lock tab snaps into place NOTE It is important for the wheel bearings to be adjusted per the manufacturer s recommendations to ensure that the antilock function does not shut down as a result of excessive wheel end play OPERATIONAL TESTING To test sensor operation one of two tests can be done TEST 1 Drive the vehicle in a safe area to a minimum speed of 15 mph Be sure to apply the vehicle brakes several times Then stop the vehicle and check the LED display on the Bendix controller If the dash light is out and the sensor LED s are not illuminated the sensor is installed properly TEST 2 Disconnect the connector from the sensor s socket or from the attached lead Raise the vehicle wheel so it rotates easily Connect a volt Ohm meter set to read Volts AC to the pins on the sensor or lead and spin the wheel Output voltage should read greater than 800 AC If the wheel is spun at 1 revolution per second about 7mph the reading should be greater than 1 0 volts AC lf the sensor fails to operate as described check the wiring from the controller to the sensor Make sure all connectors are properly and tightly installed Check for frayed or damaged wires and check and or reset the sensor air gap distance from sensor tip to
7. mam Servic Bendix WS 20 AntiLock Wheel Speed Sensor FIGURE 1 WS 20 ANTILOCK WHEEL SPEED SENSORS DESCRIPTION The WS 20 wheel speed sensor is an electromagnetic device used to obtain vehicle speed information for an antilock controller When the wheel rotates the sensor and an exciter e g rotor or tone wheel generate a simple AC signal This signal is sent to the controller which analyzes the data and commands the antilock system accordingly Specifically the soeed sensor consists of a coil pole piece and magnet The exciter is a steel ring or gear like device that has regularly spaced high and low spots called teeth The sensor is mounted in a fixed position while the exciter is installed on a rotating member so that its teeth move in close proximity past the tip of the sensor The WS 20 wheel speed sensor is available in both straight and right angle versions to accommodate axle wheel space limitations See Figure 1 OPERATION The sensor s magnet and pole piece form a magnetic field As an exciter tooth passes by the sensor the magnetic field is altered which generates AC voltage in the sensor coil Each time an exciter tooth and its adjacent space move past the tip of the sensor an AC voltage cycle is generated The number of AC cycles per revolution of the vehicle s wheel depends on the number of teeth in the exciter which is programmed into the antilock controller Using t
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