Bendix Commercial Vehicle Systems eTrac Automated Air Pressure Transfer System - Manual (Page 5)

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4.2 Automatic Mode: Bendix ® eTrac ™ System Active Mode.
Figure 4 shows the Bendix eTrac system in its Active Mode where the “dump” valve controls the delivery of air to the
rear axle suspension air bags. This diagram is for both automatic and semi-automatic applications.
DEL SUP EX H
Drive axle Tag axle
• An Automatic Traction Control (ATC)
event is detected by the ABS ECU.
Bendix ® Smart ATC ™ works to aid
traction.
• If the vehicle speed is below
25 MPH, the solenoid valve will be
energized by the Bendix ® ABS ECU
and the valve moves to the CLOSED
position.
• The relay valve moves to the
unapplied position, permitting the
air pressure from the tag axle to be
released (“dumped”).
• The delivery from the leveling valve
maintains the drive axle suspension
air bag pressure.
• The Bendix eTrac system intervention
automatically ends five (5) seconds
after the traction event ends.
The air is vented from the tag
axle suspension air bags
Air supply
Double check valve
Pressure protection valve
Solenoid valve
(CLOSED)
Backfeed
valve
Limiting
valve
Delivery to the
drive axle air bag
suspension
Air from the tag axle
air bag suspension
is vented through the
“dump” valve exhaust
“Dump” valve
LEVELING
VALVE
Bendix ®
brand ABS
controller*
FIGURE 4 - BENDIX ® eTrac ™ SYSTEM ACTIVE MODE
SUP
• *For vehicles with Bendix ® EC-80 ™ ATC/ESP ECUs:
When the eTrac system is in the semi-automatic mode, if the parking brake is set,
the ability to vent air pressure from the tag axle with the eTrac feature is disabled.