SD-13-4860 Bendix WS-24 Antilock Wheel Speed Sensor

SD-13-4860Bendix WS-24 Antilock Wheel Speed SensorVarious Bendix WS-24 Wheel Speed SensorsWS-24 Speed Sensors with Trade Dress90 AngleBendix WS-24 SensorStraightWS-24 Sensor90 AngleWS-24 SensorStraightWS-24 SensorThe appearance of the WS-24 wheel speed sensorsmay vary depending upon the date and location ofmanufacture, but they are interchangeable providedthey are the same type, e.g., straight or 90 .ConnectorsPackard GT 150SeriesPackardMetripack150.2 SeriesDeutsch DTM06SeriesPackardMetripack 280Series (female)PackardMetripack 280Series (male)DeutschDT04 SeriesStandardRound2-PinFigure 1 – Wheel Speed Sensors and ConnectorsDESCRIPTIONThe Bendix WS -24 wheel speed sensor is anelectromagnetic device used to obtain vehicle speedinformation for an antilock controller. When the wheelrotates, the sensor and an exciter ring (sometimes called a“rotor” or “tone” wheel) generate a simple AC signal. Thissignal is sent to the controller, which analyzes the data andcommands the antilock system accordingly.Specifically, the speed sensor consists of a coil, pole piece,and a magnet. The exciter is a steel ring or gear-like deviceExciter RingMounting BlockWheelSpeedSensorFigure 2 – Wheel End ABS Components1

GENERAL SAFETY GUIDELINESWARNING! PLEASE READ ANDFOLLOW THESE INSTRUCTIONSTO AVOID PERSONAL INJURY OR DEATH:When working on or around a vehicle, the followingguidelines should be observed AT ALL TIMES: Park the vehicle on a level surface, apply the parkingbrakes and always block the wheels. Always wear personalprotection equipment. Stop the engine and remove the ignition key when workingunder or around the vehicle. When working in the enginecompartment, the engine should be shut off and the ignitionkey should be removed. Where circumstances require thatthe engine be in operation, EXTREME CAUTION should beused to prevent personal injury resulting from contact withmoving, rotating, leaking, heated or electrically-chargedcomponents. Do not attempt to install, remove, disassemble orassemble a component until you have read, and thoroughlyunderstand, the recommended procedures. Use only theproper tools and observe all precautions pertaining to useof those tools. If the work is being performed on the vehicle’s air brakesystem, or any auxiliary pressurized air systems, makecertain to drain the air pressure from all reservoirs beforebeginning ANY work on the vehicle. If the vehicle isequipped with a Bendix AD-IS air dryer system, a Bendix DRM dryer reservoir module, or a Bendix AD-9si airdryer, be sure to drain the purge reservoir. Following the vehicle manufacturer’s recommendedprocedures, deactivate the electrical system in a mannerthat safely removes all electrical power from the vehicle. Never exceed manufacturer’s recommended pressures. Never connect or disconnect a hose or line containingpressure; it may whip and/or cause hazardous airbornedust and dirt particles. Wear eye protection. Slowly openconnections with care, and verify that no pressure ispresent. Never remove a component or plug unless you arecertain all system pressure has been depleted. Use only genuine Bendix brand replacement parts,components and kits. Replacement hardware, tubing, hose,fittings, wiring, etc. must be of equivalent size, type andstrength as original equipment and be designed specificallyfor such applications and systems. Components with stripped threads or damaged parts shouldbe replaced rather than repaired. Do not attempt repairsrequiring machining or welding unless specifically statedand approved by the vehicle and component manufacturer. Prior to returning the vehicle to service, make certain allcomponents and systems are restored to their properoperating condition. For vehicles with Automatic Traction Control (ATC), the ATCfunction must be disabled (ATC indicator lamp should beON) prior to performing any vehicle maintenance whereone or more wheels on a drive axle are lifted off the groundand moving. The power MUST be temporarily disconnected from theradar sensor whenever any tests USING A DYNAMOMETERare conducted on a vehicle equipped with a Bendix Wingman system. You should consult the vehicle manufacturer's operatingand service manuals, and any related literature, inconjunction with the Guidelines above.2WARNING: Not all wheels and valve stems arecompatible with Bendix Air Disc Brakes. Use onlywheels and valve stems approved by the vehiclemanufacturer to avoid the risk of valve stem shearand other compatibility issues.WARNING: AVOID CREATINGDUST. POSSIBLE CANCER AND LUNGDISEASE HAZARD.While Bendix Spicer Foundation Brake LLC doesnot offer asbestos brake linings, the long-termaffects of some non-asbestos fibers have not beendetermined. Current Occupational Safety and HealthAdministration (OSHA) Regulations cover exposurelevels to some components of non-asbestos linings,but not all. The following precautions must be usedwhen handling these materials.Avoid creating dust. Compressed air or dry brushingmust never be used for cleaning brake assembliesor the work area. Bendix recommends that workers doing brakework must take steps to minimize exposureto airborne brake lining particles. Properprocedures to reduce exposure include workingin a well-ventilated area, segregation of areaswhere brake work is done, use of local filteredventilation systems or use of enclosed cells withfiltered vacuums. Respirators approved by theMine Safety and Health Administration (MSHA)or National Institute for Occupational Safetyand Health (NIOSH) should be worn at all timesduring brake servicing. Workers must wash before eating, drinking, orsmoking; shower after working, and should notwear work clothes home. Work clothes shouldbe vacuumed and laundered separately withoutshaking. OSHA & EPA Regulations regarding testing,disposal of waste, and methods of reducingexposure for asbestos are set forth in 29 &40 Code of Federal Regulations §1910.1001 &61.150, respectively. These Regulations providevaluable information which can be utilized toreduce exposure to airborne particles. Safety Data Sheets on this product, as requiredby OSHA, are available from Bendix. Call1-800-247-2725 and speak to the Tech Team ore-mail techteam@bendix.com.that has regularly spaced high and low spots called “teeth.”The sensor is mounted in a fixed position, while the exciteris installed on a rotating member so that its “teeth” move,in close proximity, past the tip of the sensor.The Bendix WS-24 sensor is available in both straight and90 versions, to accommodate axle/wheel space limitations.(See Figure 1.)

OPERATIONTECHNICAL INFORMATIONThe sensor’s magnet and pole piece form a magnetic field.As the exciter ring passes by the sensor, the magnetic fieldis altered, which generates AC voltage in the sensor coil.Each time an exciter tooth and its adjacent space move pastthe tip of the sensor, an AC voltage “cycle” is generated.Electrical connector - 2 PinThe number of AC cycles per revolution of the vehicle’swheel depends on the number of teeth in the exciter ring,which is programmed into the antilock controller. Usingthe programmed data, the controller can calculate “vehiclespeed” by analyzing the frequency of AC cycles sent bythe speed sensor. (The frequency of AC cycles is directlyproportional to wheel speed.) See Figure 4.Sensor body outer diameter - 0.627 inchAC voltage is also proportional to speed, but voltage is notused to determine speed. It is only an indication of AC signalstrength. The amount of AC voltage generated by a specificspeed sensor depends on the distance, or “gap” betweenthe tip of the sensor and the surface of the exciter. Voltageincreases as the sensor gap decreases.Typically, the Bendix WS-24 wheel speed sensor isinstalled in mounting blocks that are welded to the axlehousing. (See Figure 2.) The WS-24 wheel speed sensorsare protected by a stainless steel sheath. The sensors aredesigned to be used with beryllium copper or stainless steelclamping sleeves (sometimes referred to as a “retainerbushing”, “friction sleeve” or “clip”) (See Figure 3). Theclamping sleeve provides a friction fit between the mountingblock bore and the WS-24 wheel speed sensor.Sensor resistance (-40 C - 220 C) 1100 - 3400 ohmsOutput voltage - At a minimum of 100 Hz (approximately7 mph) at a gap of .028 inches should produce a sensorvoltage of 0.350 VACSensor resistance (20 C) 1575 - 2100 ohmsNote: Previous model Bendix WS-20 sensor’s normalresistance range across pins at room temperature wasrated at 2000 - 5000 ohms.The friction fit allows the WS-24 sensor to “slide” back andforth under force but to retain its position when the force isremoved.When the WS-24 sensor is inserted all the way into themounting block and the wheel is installed on the axle, thehub exciter contacts the sensor, which pushes the sensorback. Also, normal bearing play will “bump” the sensor awayfrom the exciter. The combination of these two actions willestablish a running clearance or air gap between the sensorand the exciter.Peak to PeakLow SpeedNote that Bendix sleeve part number 5006849 can not beused with the WS-24 wheel speed sensors. Always usethe correct clamping sleeves to avoid problems associatedwith reduced retention force, such as unwanted sensormovement and resulting ABS trouble codes.Peak to PeakHigh SpeedFigure 4 – Speed Sensor Voltage Cycle OutputBeryllium Copper Clamping SleevesPart No. 5006849(Do not use withBendix WS-24 Sensors)“BW” in adiamondStainless Steel Clamping SleevePart No.5012878“BX” in aswooshsymbolPart No.K152407Knorr-BremseLogoSwooshSymbolFigure 3 – Clamping Sleeves3