BENDIX EC-30 ABS-ATC CONTROLLER User Manual

7
ABS OPERATION
Bendix ABS uses wheel speed sensors, ABS modulators
and an ECU to control either four or six wheels. By monitoring
the wheel slip during braking, and adjusting the brake
pressure at each wheel, the EC-30
™
controller is able to
optimize slip between the tire and the road surface. When
excessive wheel slip is detected, the EC-30
™
controller will
activate ABS. The EC-30
™
controller controls the ABS
modulators to simulate a driver pumping the brakes.
However, the EC-30
™
controller is able to pump each brake
on the vehicle independently, and with greater speed and
accuracy than a driver.
Front Axle Control
Although both steering-axle wheels are controlled by
individual ABS modulators, the EC-30
™
controller does not
control them completely independently. The EC-30
™
controller uses a Modified Individual Regulation (MIR)
philosophy which blends the applied braking force between
the two steering axle brakes. MIR is used to minimize
steering wheel pull while ABS is active on an uneven road
surface (e.g. ice and asphalt).
Single Rear Axle Control
On vehicles with a single rear axle (4x2), the rear axle wheels
are controlled independently. Therefore, brake application
pressure at each wheel is adjusted according to the wheel
behavior on the road surface.
Dual Rear Axle Control
For vehicles with dual rear axles (6x2 or 6x4), one ABS
modulator controls both right wheels and the other modulator
controls both left wheels. Both wheels on each side receive
equal brake pressure during an ABS stop. In the case of
only four wheel speed sensors, the two rear sensors are
located on the lighter rear axle.
Normal Braking
During normal braking, brake pressure is delivered through
the ABS modulator and into the brake actuator. If the wheel
speed sensors do not detect an excessive slip, the EC-30
™
controller does not activate ABS control and the vehicle stops
with normal braking.
ATC OPERATION
Just as ABS improves vehicle stability during braking, ATC
improves vehicle stability and traction during vehicle
acceleration. By adding an ATC modulator and/or engine
communication, the EC-30
™
controller ATC function uses
the same wheel speed information and modulator control
as the ABS function. The EC-30
™
controller detects
excessive drive wheel speed, compares the speed of the
front, non-driven, wheels, and reacts to bring the wheel spin
under control. The EC-30
™
controller can be configured to
use engine torque limiting and/or differential braking to control
wheel spin. For optimal ATC performance, both methods
are recommended.
During ATC activation, the EC-30
™
controller will blink the
ATC active/warning lamp to advise the driver that drive-wheel
spin is occurring. When ATC is no longer active, the ATC
active/warning lamp turns off.
Engine Torque Limiting ATC
The engine torque limiting feature allows the EC-30
™
controller to reduce engine torque to a suitable level, in
relation to the amount of available traction. When the engine
torque is controlled, wheel slip can be optimized, producing
more traction between the wheel and road surface. Engine
torque limiting is especially beneficial in avoidance of a power
jackknife and when all drive wheels are on an equally slippery
surface. The EC-30
™
controller will verify that the driver is
pressing the accelerator (using J1939 or J1922) prior to
initiating an ATC event.
In order for the engine torque limiting ATC feature to be used,
the vehicle must be equipped with an electronically controlled
engine and throttle. When configured for engine torque
limiting ATC, the EC-30
™
controller must be connected to
an electronic engine via the SAE J1939 or J1922 serial
communications links.
Differential Braking ATC
Differential braking ATC allows the EC-30
™
controller to
gradually apply the brake on a spinning drive wheel. Since
the vehicle's differential tends to drive the wheel that presents
the least resistance (the wheel on the most slippery surface),
a slight brake application to this wheel forces the differential
to drive the wheel on the opposite side. The EC-30
™
controller
applies brake pressure to both rear-axle ABS modulators
by energizing the ATC modulator. The EC-30
™
controller
can then apply pressure only to the spinning wheel by
controlling the ABS modulators.
Differential braking ATC can be activated only when vehicle
speed is under 25 mph and one drive wheel is spinning faster
than the others.
In the event that differential braking, ATC is active for an
excessive time period, the EC-30
™
controller will disable
ATC to prevent overheating and fading of brakes. The EC-30
™
controller will re-enable ATC after a short period of time. The
ATC active/warning lamp will be on while the ATC is disabled.
In order for the differential braking control to be used, the
vehicle must be equipped with an antilock/traction relay
(ATR) valve (ATR-1 or ATR-2). The vehicle also must have
an electronically controlled engine throttle.
ATC Enable/Disable Switch
The ATC enable/disable switch allows the operator to enable
or disable the ATC feature as necessary. ATC can be
disabled while the vehicle is stationary or in motion. However,
ATC will not re-enable until the vehicle comes to a complete
stop, even with the switch in the enable position. The ATC
active/warning lamp will be on while the ATC is disabled.

BENDIX EC-30 ABS-ATC CONTROLLER Specifications

General

Brand	BENDIX
Model	EC-30 ABS-ATC CONTROLLER
Category	Controller
Language	English