Bendix Commercial Vehicle Systems TABS-6 ADVANCED SINGLE CHANNEL - Manual (Page 3)

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3. ANTILOCK BRAKE SYSTEM
(ABS) OPERATION
The Bendix ® TABS‑6 ™ Adv module uses wheel speed
sensors, modulator relay valve (MRV); and an ECU to
optimize the contact between the tires and the road surface
during a braking event where excessive wheel slip — or
wheel lock‑up — is detected.
When a situation is detected where the system needs to
intervene, the ECU will activate the MRV to apply controlled
brake pressure at the wheel ends.
The TABS-6 Adv module ECU is able to modulate the brake
pressure with greater speed and accuracy than a driver.
Normal Braking
During normal braking the TABS-6 Adv module functions
as a standard relay valve. If the ECU does not detect
excessive wheel slip, it will not activate the ABS system,
and the vehicle will stop with normal braking.
Axle Control
Axle control uses the modulator relay valve to control the
wheels at both ends of a given axle (or multiple axles in
cases where the MRV is controlling several axles).
In the case of braking surfaces with poor overall traction
(e.g. roads that are worn, slippery, or are made of loose
gravel) — or braking surfaces with areas of poor traction
(e.g. asphalt roads with patches of ice) — axle control ABS
interventions will maintain the wheel that is not slipping at
just under the speed that will lock the wheel. The system
permits the other wheel (that is experiencing slippage)
temporary periods of wheel‑lock during the intervention.
Axle control should not be used on 5th wheel dollies or
steerable axles.
When intervening on regular traction road surfaces, a
system configured for axle control performs similar to a
side control, two‑modulator system.
ABS Fail‑Safe
The Bendix ® TABS‑6 ™ Adv module is designed to react
in a fail-safe manner in the event of a system Diagnostic
Trouble Code (DTC). For example, if the ECU detects that
a sensor is not responding, an ABS system DTC will be
set and the TABS‑6 Adv module will illuminate the trailer
ABS indicator lamp and revert to a fail‑safe mode where
some, or all, Advanced ABS functions (including TRSP)
may not function. Even in cases where the ABS system
is completely disabled, the standard pneumatic brake
function of the vehicle will still be available, but without the
benefits of ABS. The TRSP feature is also disabled with an
active ABS system diagnostic code. If the indicator lamp
is illuminated, always have the ABS system serviced at the
earliest opportunity.
3/4" NPT Supply
Port 1
Four 3/8" NPT Delivery
Ports 21
(To Brake Chambers)
3/8" NPT Control Port
with Integral Filter
3/8” NPT Load Port 42
for Air Suspension
(Plugged for Non-Air Suspension or Spring
Suspension Sensor Vehicles)
FIGURE 2 ‑ porTS uSed