Wheel Speed Sensors; Br9235 ™ Abs Modulator Valve; Br935 Abs Modulator Relay Valves - BENDIX TABS-6 TRAILER ABS MODULE Manual

BENDIX wS-4

wHEEL SPEED SENSORS

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Wheel speed data is provided to the TABS-6 module from
the WS-24 wheel speed sensors (see Figure 6). Vehicles
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have an exciter ring (or "tone ring") as part of the wheel
assembly, and as the wheel turns, the teeth of the exciter
ring pass the wheel speed sensor, generating an AC signal.
The TABS-6 module receives the AC signal, which varies in
voltage and frequency as the wheel speed changes. (The
default setting expects a 100-tooth tone ring to be used.)
Vehicle axle and ABS control configurations determine if
two or four wheel speed sensors are required. See page
17 for electrical system schematics showing wheel speed
sensor connector pin locations.
A proper sensor installation is critical to correct ABS
operation.
Typically, the WS-24 sensor is installed in mounting blocks
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that are welded to the axle housing. WS-24
sensors are protected by a stainless steel sheath. They
are designed to be used with beryllium copper clamping
sleeves (sometimes referred to as a "retainer bushing",
"friction sleeve" or "clip") (See Figure 6). The clamping
sleeve provides a friction fit between the mounting block
bore and the WS-24 sensor.
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90° Speed
Sensors
Straight Speed
Sensors
FIGURE 6 - BEndIx WS-24
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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.
2. Install the new clamping sleeve fully into the block,
with the retaining tabs toward the inside of the vehicle.
Please note that WS-24
use the correct clamping sleeve to avoid problems
associated with reduced retention force, such as sensor
movement and resulting ABS trouble codes.
3. 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 lead wire to the knuckle/
axle housing 3-6 inches from the sensor.
4. Apply a moderate amount of dielectric non-conductive
grease to both the sensor connector and harness
connector.
wheel speed
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Sensor
Clamping
Sleeve
Logo Stamped
into Sleeve
WHEEL SPEEd SEnSORS
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wheel speed sensors must
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5. Engage the connectors, and push together until the
lock tab snaps into place.
NOTE: It is important for the wheel bearings to be
adjusted per the manufacturer's recommendations.
The friction fit allows the WS-24
forth under force but to retain its position when the force
is removed. When the WS-24
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.
Excessive wheel end play can result in diagnostic trouble
codes in cases where the sensor is pushed too far away
from the tone ring.
BENDIX BR935
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RELAY VALVES
Bendix BR9235 modulator relay valves (MRV) are
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required when additional modulator relay valves are
needed for multichannel brake systems (e.g. 2S/2M, 4S/3M
ABS configurations).
The MRV is an electro-pneumatic control valve and is the
last valve that air passes through on the way to the brake
chambers. The normally-open hold solenoid and normally-
closed exhaust solenoid are activated to precisely modify
the brake pressure on command. During normal braking,
the BR9235 MRV functions as a standard relay valve. As
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brakes are applied or released by the driver, the control
signal from the tractor foot valve causes the BR9235
MRV to apply proportional pressure to the trailer brake
chambers.
The BR9235 MRV is available in both tank and bracket
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mounting styles.
FIGURE 7 - BEndIx BR9235
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VALVE
sensor to slide back and
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sensor is inserted all the
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ABS MODULATOR
3-Pin Modulator
Solenoid
Connector
3/8" NPT Supply
Port with Integral
Filter
Four 3/8" NPT Delivery Ports
(to Brake Chambers)
mOdULATOR RELAY
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