Bendix Commercial Vehicle Systems eTrac Automated Air Pressure Transfer System User Manual

Bendix® eTrac™ Automated Air Pressure Transfer System

Drive axle Tag axle

Steer axle

Wheel speed sensors

(All wheel-ends)

Air supply

Bendix®

brand ABS

controller

(Premium or

Advanced)

Drive axle

suspension

air bags

(2)

See below for labeled

component descriptions

SUP

EXH

DEL

Leveling

valve

SD-13-21021

Tag axle

suspension

air bags

(2)

When needed, the

system provides

the ability to add air

pressure to the drive

axle suspension air

bags, and remove

air pressure from the

tag axle suspension

air bags

Bendix® R-12®

relay valve

(Premium or Advanced EC-60 designation or later)

Bendix® brand ABS controller

Example of a

Bendix® DC-4®

double-check

valve

Bendix® FCS-9700™

solenoid valve

Two Bendix® RV-3™

valves

FIGURE 1 - BENDIX® eTrac™ SYSTEM WITH SYSTEM COMPONENTS AND A SIMPLE LEVELING SYSTEM SCHEMATIC

Simple 6x2

Air Suspension

Leveling

Control System

The air pressure is distributed equally to the

drive and tag axle suspension air bags

SUP

DEL

EXH

Leveling

valve

1. INTRODUCTION

The Bendix® eTrac™ automated air pressure transfer system is used on 6 x 2 semi-tractors that feature Bendix® premium and advanced Antilock Brake Systems (ABS). This system complements the Bendix® Smart ATC

(

Automatic Traction Control) feature of our ABS system to provide improved traction at low speeds (e.g. pulling away on an inclined ramp, or in slippery conditions such as mud or snow-covered surfaces, etc.)

When active, the Bendix eTrac system vents — or “dumps” — the air pressure of the tag axle suspension air bags, and increases the air pressure in the drive axle

™

suspension air bags to a pre-determined maximum. This action helps the drive axle to gain more traction.

GENERAL SAFETY GUIDELINES

WARNING! PLEASE READ AND

FOLLOW THESE INSTRUCTIONS

TO AVOID PERSONAL INJURY OR DEATH:

When working on or around a vehicle, the following guidelines should be observed AT ALL TIMES:

▲ Park the vehicle on a level surface, apply the parking

brakes and always block the wheels. Always wear personal protection equipment.

▲ Stop the engine and remove the ignition key when

working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed. Where circumstances require that the engine be in operation, EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving, rotating, leaking, heated or electrically-charged components.

▲ Do not attempt to install, remove, disassemble or

assemble a component until you have read, and thoroughly understand, the recommended procedures. Use only the proper tools and observe all precautions pertaining to use of those tools.

▲ If the work is being performed on the vehicle’s air brake

system, or any auxiliary pressurized air systems, make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle. If the vehicle is equipped with a Bendix Bendix AD-9si™ air dryer, be sure to drain the purge reservoir.

▲

Following the vehicle manufacturer’s recommended procedures, deactivate the electrical system in a manner

that safely removes all electrical power from the vehicle ▲ Never exceed manufacturer’s recommended pressures. ▲ Never connect or disconnect a hose or line containing

pressure; it may whip. Never remove a component or

plug unless you are certain all system pressure has

been depleted. ▲ Use only genuine Bendix

components and kits. Replacement hardware, tubing,

hose,  ttings, etc. must be of equivalent size, type

and strength as original equipment and be designed

speci cally for such applications and systems.

▲ Components with stripped threads or damaged par ts

should be replaced rather than repaired. Do not

attempt repairs requiring machining or welding unless

speci cally stated and approved by the vehicle and

component manufacturer. ▲ Prior to returning the vehicle to service, make certain all

components and systems are restored to their proper

operating condition. ▲ For vehicles with Automatic Traction Control (ATC),

the ATC function must be disabled (ATC indicator

lamp should be ON) prior to performing any vehicle

maintenance where one or more wheels on a drive axle

are lifted off the ground and moving. ▲ The power MUST be temporarily disconnected

from the radar sensor whenever any tests USING A

DYNAMOMETER are conducted on a Bendix

Advanced ▲ You should consult the vehicle manufacturer's

operating and service manuals, and any related

literature, in conjunction with the Guidelines above.

DRM™ dryer reservoir module, or a Bendix

™

-equipped vehicle.

AD-IS® air dryer system, a

brand replacement parts,

Wingman®

2. DESCRIPTION

The system features two states (with or without the Mud/ Snow switch engaged) and three modes (Normal/inactive; System Active, and Pressure-Limiting Modes):

Mud/Snow Dash Switch Not Engaged

When the Mud/Snow dash switch is not engaged, the three modes of operation are:

● Normal (“automatic”) Mode is ready whenever the

vehicle is moving at less than 25 MPH. In this mode the system behaves just like a typical air suspension leveling system that adjusts for different loads by a mechanical leveling (height control) valve that adjusts all four rear suspension air bags as needed.

See Figure 3.

● TheActive Mode occurs when the vehicle encounters

road conditions where automatic traction control (ATC) is activated. In addition to the actions of the Bendix® Smart ATC system, the Bendix® eTrac™ system automatically vents (“dumps”) air pressure from the tag axle air bags. See Figure 4.

With the drop in air pressure in the tag axle, the leveling

valve normal function adds air pressure to the drive axle suspension air bags. When the air pressure reaches

a pre-determined maximum, the system enters the Pressure Limiting Mode.

● ThePressure-Limiting Mode prevents system air

pressure delivery to the drive axle suspension air bags above a pre-determined maximum pressure. The system will then — using the backfeed valve — permit the leveling valve to add air back into the tag axle suspension air bags as needed. See Figure 5.

Automaticactivationsareterminatedve(5)secondsafter

the end of an ATC event, and are not able to be initiated at vehicle speeds above 25 MPH.

Mud/Snow Dash Switch Engaged

This mode is sometimes called “semi-automatic” since the driver engages the Bendix eTrac system, however the

systemautomaticallyterminatesve(5)secondsafterthe

vehicle reaches ten (10) MPH.

By activating the Mud/Snow dash switch, the driver can be proactive in anticipating slippery conditions. For example,

adriver—movingatve(5)MPHapproachingasectionof

road that is coated with mud — may anticipate this problem zone and press the Mud/Snow switch. The Bendix eTrac system will immediately enter the Active Mode described above. When the drive axle reaches the pre-determined maximum pressure, the Pressure-Limiting Mode (described above) will be entered.

[It is useful to note that other systems where the driver is responsible for remembering to disengage the air transfer

(typicallybyusingadashbutton)canlead to signicant

damage to the driveline if left active.]

3. COMPONENTS See Figure 1.

The Bendix® eTrac™ system installation uses the following components:

• Electronic Control Unit (ECU):  The specically-

conguredBendix® Premium, or Advanced, ABS ECU

monitors the speed sensor signals at each wheel-end and during automatic traction control events under 25 MPH signals the Bendix® FCS-9700™ Solenoid Valve to close.

CAUTION: When replacing a Bendix eTracenabled ECU, it is important to replace it ONLY with another Bendix eTrac-enabled ECU as indicated by the CAUTION label located on the ECU. Installation of a non-eTrac-enabled ECU on an eTrac-equipped vehicle can result in erroneous eTrac system interventions, potentially causing vehicle damage and/or personal injury.

CAUTION

REPLACE ONLY WITH

ETRAC ENABLED ECU

REFERENCE BW2921

Bendix®

eTrac

CAUTION

REPLACE ONLY WITH ETRAC

ENABLED ECU

REFERENCE SD-13-21021

FIGURE 2 - EITHER BENDIX® eTrac™ SYSTEM CAUTION LABEL MAY BE LOCATED ON THE ECU

• Dash-Mounted Mud/Snow Switch (Not shown.)

• Bendix FCS-9700 Solenoid Valve: Energized by the

ECU, this normally-open valve moves to the closed

position when the Bendix eTrac system is active (and

remains on ve (5) seconds after the traction event

ends). See SD-03-10433 for more information about

this valve.

• Bendix® R-12® Relay Valve: This is the “dump” valve

used for venting the Bendix eTrac system. During the Normal Mode this relay valve is used to

provideanopenchannelfortheinationanddeation

of the tag axle suspension air bags (to maintain equal

pressure with the drive axle suspension air bags).

™

See Figure 3.

During the Bendix eTrac system Active Mode, the relay

valve isolates the rest of the air suspension system from the tag axle suspension air bags and “dumps” the air pressure from them. The air is exhausted through the relay’s exhaust port. See Figure 4.

During the Pressure-Limiting Mode, the control port

of the “dump” valve receives air pressure from the

backfeedvalve.Thisre-inatesthetagaxlesuspension

air bags as required. See Figure 5.

See SD-03-1064 for more information about this valve.

• Bendix® DC-4® Double-Check Valve: This valve

toggles based on the higher supply pressure.

When in Normal Mode the double-check valve allows

the delivery from the solenoid valve to hold the tag axle suspension air bags open to the same pressure as the drive axle suspension air bags. See Figure 3.

In the Active Mode, the control air from the solenoid

valve to the “dump” valve ends, and the air is vented back — through the double-check valve — and out of the solenoid valve exhaust. See Figure 4.

During the Pressure-Limiting Mode, the double-check

valve allows air pressure from the backfeed valve to

thecontrolportofthe“dump”valve.Thisre-inates

the tag axle suspension air bags as required.

See Figure 5.

See SD-03-2202 for more information about this valve.

• Bendix® RV-3™ Valves: Typically used for pressure

reduction in air brake systems, this valve provides two special functions: It operates as a backfeed valve, and it also operates as a pressure-limiting valve. See

SD-03-3515 for general information about this valve.

NOTE: When replacing the valves used in this system, it is important to replace ONLY like for like

part numbers (or direct replacement parts as veried

by Bendix.) In particular, the system upper pressure limit for the drive axle suspension air bags is predetermined by the OEM, and this upper pressure limit

determines the specic Bendix RV‑3 valves that must

be used to avoid damage to the drive train.

NOTE: In the case of the valve used to backfeed the Bendix eTrac system, it is necessary to install the valve as shown in the system diagrams, and not to follow the port designations (such as SUP for supply, etc.) cast into the valve housings.

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