Bendix Commercial Vehicle Systems WS-24 User Manual
®
Bendix® WS-24™ AntiLock Wheel Speed Sensor
SD-13-4860
PREVIOUS MODEL WHEEL SPEED SENSORS
90° WS-24
SENSOR
™
STRAIGHT WS-24
SENSOR
CONNECTORS
PACKARD GT
150 SERIES
FIGURE 1 - WHEEL SPEED SENSORS AND CONNECTORS
PACKARD
METRIPACK
150.2 SERIES
DEUTSCH
DTM06 SERIES
PACKARD
METRIPACK 280
(FEMALE)
DESCRIPTION
The WS-24™ wheel speed sensor is an electromagnetic
device used to obtain vehicle speed information for an
antilock controller. When the wheel rot ates, the sensor and
an exciter ring (sometimes called a “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.
™
SERIES
The WS-24™ sensor fit and function is
compatible with all previous Bendix models.
PACKARD
METRIPACK 280
SERIES (MALE)
DEUTSCH DT04
SERIES
EXCITER RING
STANDARD
ROUND TWO
PIN
MOUNTING
BLOCK
WHEEL
SPEED
SENSOR
Specifically, the speed 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-24
sensor is available in both straight and right
angle versions, to accommodate axle/wheel space
limitations. (See Figure 1.)
FIGURE 2 - WHEEL END ABS COMPONENTS
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.
1
P/N 5006849
P/N 5012878
PEAK TO PEAK
PREVIOUS
CLAMPING
SLEEVES HAVE
“BW” IN A
DIAMOND
FIGURE 3 - CLAMPING SLEEVES
CORRECT
CLAMPING
SLEEVES
HAVE “BX” IN
A SWOOSH
SYMBOL
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 the
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.) See Figure 4.
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.
™
Typically , the WS-24
sensor is installed in mounting blocks
that are welded to the axle housing. (See Figure 2.)
™
WS-24
wheel speed sensors are protected by a stainless
steel sheath. They are designed to be used with berylliumcopper clamping sleeves (sometimes referred to as a
“retainer bushing”, “friction sleeve” or “clip”) (See Figure 3).
The clamping sleeve provides a friction fit between the
™
mounting block bore and the WS-24
™
Please note that WS-24
wheel speed sensors must use
sensor.
clamping sleeve p/n 5012878 instead of p/n 5006849 (used
for previous wheel speed sensors). Always use correct
clamping sleeves to avoid problems associated with reduced
retention force, such as sensor movement and resulting
ABS trouble codes.
™
The friction fit allows the WS-24
sensor to "slide" back
and forth under force but to retain its position when the
force is removed.
™
When the WS-24
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.
LOW SPEED
PEAK TO PEAK
HIGH SPEED
FIGURE 4 - SPEED SENSOR VOLTAGE CYCLE OUTPUT
ANTILOCK CONTROLLER
& RELAY
WS-24™ SPEED SENSORS
EXCITER
FRONT WHEEL
FIGURE 5 - TYPICAL ANTILOCK SYSTEM
WHEELS
REAR WHEELS
TECHNICAL INFORMA TION
Electrical connector 2 Pin.
Sensor resistance 1500-2500 ohms
Output voltage A t a minimum of 100Hz
(approximately 7 mph) the sensor
output across the leads should be
0.400 VAC.
Sensor gap 0 to 0.015 inch.
Sensor body Outer diameter is 0.627 inch.
Normal resistance 1500-2000 Ohms.
range across pins (Note: Previous model WS-20
at room temperature sensor was rated at 2000-2500
Ohms.)
™
2
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