Bendix Commercial Vehicle Systems EC-60 ESP Controllers (Advanced Models) - Manual (Page 9)

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Bendix ® Smart ATC ™ Traction Control
The EC-60 ™ controller has an additional feature known as
Smart ATC ™ traction control. Smart ATC ™ traction control
monitors the accelerator pedal position (using J1939) to
help provide optimum traction and vehicle stability. By
determining the driver’s throttle input and adapting the
target slip of the drive wheels to the driving situation, the
Smart ATC ™ traction control allows higher wheel slip when
the accelerator pedal is applied above a preset level.
The wheel slip allowed by Smart ATC
™ is decreased when
driving through a curve for improved stability.
Disabling ATC Engine Control and Smart ATC ™
Traction Control
ATC Engine Control and Smart ATC ™ traction control will
be disabled under the following conditions:
1. In response to a serial communications request from
an off-board tool.
2. At power-up until the ECU detects a service brake
application.
3. If the ECU receives a J1939 message indicating that
the vehicle is parked.
4. If the dynamometer test mode is active. This may be
accomplished via an off-board tool or the diagnostic
blink code switch.
FIGURE 11 - RSP EXAMPLE
A Real World Example
Of How The RSP
System Operates:
Excessive speed for road
conditions creates forces
that exceed the threshold
at which a vehicle is likely
to rollover on a higher-
friction surface.
The system automatically reduces
engine torque and applies the
service brakes (based on the
projected rollover risk) to reduce
the vehicle speed, thereby
reducing the tendency to roll
over.
5. When certain diagnostic trouble code conditions are
detected.
Optional ATC Mud/Snow (Off-Road) Mode
In some road conditions, the vehicle operator may desire
additional drive wheel slip when ATC is active. The
Advanced EC-60 ™ controller has an optional control mode
to permit this desired performance.
The vehicle operator can activate the Mud/Snow function
with a switch on the dash panel. Alternately, a J1939
message may be used to place the vehicle in this mode.
The ATC/ESP Indicator Lamp will flash steadily at a rate of
once every 2.5 seconds to confirm that the ATC mud/snow
mode is engaged.
To exit the ATC Mud/Snow mode, depress and release the
ATC Mud/Snow switch.
Drag Torque Control Functional Overview
Advanced EC-60 ™ controllers have a feature referred to as
drag torque control which reduces wheel slip on a driven
axle due to driveline inertia. This condition is addressed by
increasing the engine torque to overcome the inertia.
Drag torque control increases vehicle stability on low-
traction road surfaces during down-shifting or retarder
braking.
ADVANCED ABS WITH STABILITY
CONTROL
Overview
ESP stability system reduces the risk of rollovers, jackknifing
and other loss of control. ESP features include Roll Stability
Program (RSP) and Yaw Control. During operation, the
ECU of the Bendix Advanced ABS system constantly
compares performance models to the vehicle’s actual
movement, using the wheel speed sensors of the ABS
system, as well as lateral, yaw, and steering angle sensors.
If the vehicle shows a tendency to leave an appropriate
travel path, or if critical threshold values are approached,
the system will intervene to assist the driver.
Roll Stability Program
Bendix RSP, an element of the overall ESP system,
addresses rollover conditions. In the case of a potential
roll event, the ECU will override the throttle and quickly
apply brake pressure at all wheel ends to slow the vehicle
combination. The level of braking application during an
RSP event will be proportional to roll risk.
See Figure 11.
Yaw Stability
Yaw stability counteracts the tendency of a vehicle to spin
about its vertical axis. During operation, if the friction
between the road surface and the tires is not sufficient
to oppose lateral (side) forces, one or more of the tires
can slide, causing the truck/tractor to spin. These events