BENDIX ATR1DC User Manual
®
Bendix® ATR-1DC™ AntiLock Traction Relay Valve
SD-13-4811A
TRACTION CONTROL
SOLENOID
MOUNTING
BRACKET
SUPPLY
PORT
(2)
CONTROLLER
MOUNTING HOLES (4)
DELIVERY
PORT (4)
SECONDARY
CONTROL
PRIMARY
CONTROL
PORT
4 1
(1)
2 PIN SOLENOID
CONNECTOR
DESCRIPTION
The A TR-1DC™ antilock traction relay valve is a specialized
air brake valve developed for use on Bendix antilock/traction
equipped vehicles. The ATR-1DC™ valve can be used on
straight trucks, buses and tractors. Although this valve, in
combination with the appropriate controller, can be used
in any Bendix antilock traction equipped brake system, it
was developed for use in systems that were built to comply
with Federal regulations effective 3/1/98.
It is a combination of four separate valves working in a single
housing. A Bendix® R-14™ service relay is the base valve,
fitted with a modified cover containing two double check
valves and a traction control solenoid. In addition, the
A TR-1DC™ valve also incorporates a relay piston drain, which
continually allows system contamination to be drained from
the relay exhaust port. (Refer to Service Data Sheet for
more information.)
The ATR-1DC™ valve contains both air and electric
components to provide the service braking and traction
control (differential braking) functions. The traction function
of the ATR-1DC™ valve is enhanced to allow coordination
with the air suspension system of a 6x2 vehicle.
A Bendix antilock traction controller , such as the EC-16™ or
EC-17™, can be mounted to the A TR-1DC™ valve or a cover
AUXILIARY
CONTROL
PORT
2 1
(1)
PORT
4 2
(1)
COVER PLATE FOR
REMOTE MOUNT
REVERSE
ANGLE
VIEW
REMOTE MOUNT A TR-1DC™ VALVE
FIGURE 1 - ATR-1DC™ ANTILOCK TRACTION RELAY VALVE
plate can be installed and the antilock controller mounted
elsewhere on the vehicle. When an ATR-1DC™ valve is
combined with an antilock traction controller the resulting
assembly is referred to as a antilock traction assembly or
A T -1DC™.
The ATR-1DC™ valve replaces the standard relay valve used
to control the rear axle service brakes and performs the
standard relay function. Like the standard relay valve it
replaces, the ATR-1DC™ valve (sometimes with attached
antilock controller) is normally mounted near the service
brakes it serves. A mounting bracket, furnished with the
valve, permits either frame or cross member mounting. All
air connections on the ATR-1DC™ valve are identified with
cast, embossed letters for ease of identification and
installation. The letter identification and air line connections
are shown below for reference.
EMBOSSED ATR-1DC AIR CONNECTION IDENT .
Supply (to reservoir) SUP
Delivery (to brake Chamber) DEL
Primary Control (to brake valve rear delivery) 4 1
Secondary Control 4 2
(to brake valve front delivery)
Optional Auxiliary 2 1
(connected to air suspension control)
1
™
CONTROLLER
EC-16
ATR-1DC
ANTILOCK
TRACTION
FIGURE 2 - TYPICAL A T -1DC™ ANTILOCK TRACTION ASSY.
™
RELAY
VALVE
The A TR-1DC™ valve is part of the R-12™ family of relay valves
which includes the R-12™, R-14™, BP-R1™, AR-1™& A TR-1
valves. The internal components of the relay portion of all of
these valves are similar and in many cases interchangeable
with the R-12™ valve and therefore the same basic
components are used to service all of them. The A TR-1DC
valve is available with various crack pressures to
accommodate specific applications, however the standard
is 4 psi, achieved without any added spring.
OPERATION
GENERAL
While the A TR-1DC™ valve is an antilock-traction relay valve
its true function is that of an air brake relay valve. Because
the A TR-1DC™ is essentially a relay valve, with a traction
control function, the following description of operation
describes its operation as a relay valve and its function in
the traction control system. The full operation of the
antilock system and separate antilock components and their
operation is not addressed in this publication. For a
description of antilock operation, refer to the appropriate
Service Data Sheet covering the electronic controller used
with the A TR-1DC™ valve (e.g. SD-13-4785 for the EC-16
electronic controller, or SD-13-4788 for the EC-17™ electronic
controller). Other useful information on antilock system
components may be downloaded from www.bendix.com. For
example: SD-13-4793 (M-21
™
modulators), SD-13-4870 (M-32™ and M-32QR™ antilock
modulators), SD-13-4754 (WS-20™ wheel speed sensors),
and SD-13-4860 (WS-24™ wheel speed sensors).
™
SERVICE BRAKES - APPL YING
Reservoir air pressure is present at the supply port (SUP)
and at the relay inlet and exhaust valve. Reservoir air
pressure also flows from the supply port through internal
™
and M-22™ antilock
™
EC-16™ OR EC-17
CONTROLLER
SOLENOID
CONNECTOR
BLEND BACK
PISTON
RELAY PISTON
RELAY PISTON
SPRING
(IF USED)
RESERVOIR
SUPPLY PORT
™
TRACTION CONTROL SOLENOID
EXHAUST PORT
INLET-EXHAUST
VALVE
WHEEL SPEED
SENSOR
SECONDARY
SERVICE PORT
PRIMARY
SERVICE PORT
CHECK VALVES
DELIVERY
PORT
BRAKE VALVE
(SHOWING
DELIVERY AIR
LINES ONLY)
AIR BAG
DOUBLE
BRAKE
CHAMBER
TONE RING
FIGURE 3 - SECTIONAL A T -1DC™ ANTILOCK TRACTION ASSEMBLY
2
EC-16™ OR EC-17
CONTROLLER
SOLENOID
CONNECTOR
™
TRACTION CONTROL SOLENOID
SECONDARY
SERVICE PORT
BRAKE VALVE
(SHOWING
DELIVERY AIR
LINES ONLY)
BLEND BACK
PISTON
DOUBLE
CHECK VALVE
“B”
RELAY PISTON
SUPPLY PORT
INLET-EXHAUST
VALVE
FIGURE 4 - SERVICE BRAKE APPLICATION
EXHAUST PORT
body and cover passages to the supply of the normally closed
(NC) traction control solenoid.
Brake application air from both the rear and front axle circuits
of the brake valve enters the A TR-1DC™ valve's primary and
secondary control ports. Secondary control pressure flexes
double check valve diaphragm “A” causing it to seal the air
passage leading to the solenoid and opening the passage
AIR BAG
PRIMARY
SERVICE PORT
DOUBLE
CHECK VALVE “A”
BRAKE
CHAMBER
DELIVERY
PORT
TONE RING
WHEEL SPEED
SENSOR
leading to double check valve “B”. Primary control air flows
to double check valve diaphragm “B”. Because primary
control pressure, from the foot valve, is 2 to 4 psi greater
than secondary control, double check valve diaphragm “B”
flexes in response to primary control and seals the air
passage leading to the secondary control. Air flows past
double check valve diaphragm “B” and through a passage in
the cover to the top of the service relay piston. In response
EC-16™ OR EC-17
CONTROLLER
SOLENOID
CONNECTOR
BLEND BACK
PISTON
DOUBLE
CHECK VALVE
RELAY PISTON
SUPPLY PORT
FIGURE 5 - SERVICE BRAKES HOLDING
™
“B”
INLET-EXHAUST
TRACTION CONTROL SOLENOID
VALVE
EXHAUST PORT
DELIVERY
PORT
SECONDARY
SERVICE PORT
PRIMARY
SERVICE PORT
DOUBLE
CHECK VALVE “A”
BRAKE VALVE
TONE RING
HELD IN
APPLIED
POSITION
AIR BAG
BRAKE
CHAMBER
WHEEL SPEED
SENSOR
3
EC-16™ OR EC-17
CONTROLLER
SOLENOID
CONNECTOR
™
TRACTION CONTROL SOLENOID
SECONDARY
SERVICE PORT
BRAKE VALVE
(RELEASED)
BLEND BACK
PISTON
DOUBLE
CHECK VALVE
“B”
RELAY PISTON
SUPPLY PORT
FIGURE 6 - SERVICE BRAKES RELEASING
INLET-EXHAUST
VALVE
EXHAUST
PORT
DELIVERY
to air pressure, the relay piston drain valve flexes and seals
the drain passage leading to the relay exhaust.
Simultaneously the relay piston moves into contact with the
exhaust portion of its inlet and exhaust valve. With the
exhaust passage sealed, continued movement of the piston
unseats the inlet portion of the inlet and exhaust valve,
AIR BAG
PRIMARY
SERVICE PORT
DOUBLE
CHECK VALVE “A”
BRAKE
CHAMBER
PORT
TONE RING
WHEEL SPEED
SENSOR
allowing supply air from the reservoir to flow out the A TR-1DC
valve's delivery ports to the brake chambers.
SERVICE BRAKES - HOLDING
Air pressure being delivered to the brake chambers is also
present beneath the relay piston. When air pressure above
and below the relay piston is equal, the piston moves
™
EC-16™ OR EC-17
CONTROLLER
SOLENOID
CONNECTOR
BLEND BACK
PISTON
DOUBLE
CHECK VALVE
RELAY PISTON
SUPPLY PORT
FIGURE 7 - SERVICE BRAKES - APPLYING (PRIMARY CIRCUIT DELIVERY FAILED)
™
“B”
INLET-EXHAUST
TRACTION CONTROL SOLENOID
VALVE
EXHAUST PORT
DELIVERY
PORT
SECONDARY
SERVICE PORT
PRIMARY
SERVICE
CONTROL LINE
FAILURE
DOUBLE
CHECK VALVE “A”
BRAKE VALVE
DELIVERY AIR
LINES ONLY)
TONE RING
(SHOWING
AIR BAG
BRAKE
CHAMBER
WHEEL SPEED
SENSOR
4
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