6
and the vehicle is stopped, or moving at any speed up to 25
mph, the antilock traction controller instantly energizes the
solenoid in the ATR-1
™
valve which then applies air to each
of the rear axle modulators as shown in figure 8. The
modulators are equipped with solenoid valves also and
because they are also controlled by the controller, the
solenoid valves in the appropriate modulator are opened and
closed to gently pump the brake on the spinning wheel only.
This brake application, to the spinning wheel, forces the
differential to drive the stationary or slowly spinning wheel.
OPERATION
Reservoir air pressure is constantly present at the traction
solenoid. When the electronic controller detects wheel spin
it energizes the solenoid and in response the solenoid opens
momentarily. While the solenoid is open, air is delivered
through internal passages to the double check valve. The
check valve diaphragm flexes in response and seals the
passage to the open exhaust of the brake valve. Once past
the double check valve, air from the solenoid flows through
the rest of the valve in the same manner as a normal service
brake application and air is delivered out the delivery ports
of the ATR-1
™
valve.
When the electronic controller de-energizes the solenoid,
air between the solenoid and the double check valve returns
to the solenoid and is exhausted. Air between the relay piston
and double check valve is exhausted at the brake valve while
delivery pressure is exhausted at the main ATR-1
™
valve’s
exhaust port.
PREVENTIVE MAINTENANCE
Important: Review the warranty policy before
performing any intrusive maintenance procedures. An
extended warranty may be voided if intrusive
maintenance is performed during this period.
Because no two vehicles operate under identical conditions,
maintenance intervals will vary. Experience is a valuable guide
in determining the best maintenance interval for a vehicle.
GENERAL
Perform the tests and inspections presented at the
prescribed intervals. If the ATR-1
™
valve fails to function as
described, or leakage is excessive, it should be repaired or
replaced with a new or genuine Bendix remanufactured unit,
available at any authorized parts outlet.
EVERY 3 MONTHS, 25,000 MILES OR 900 OPERATING
HOURS
1. Remove any accumulated contaminates and visually
inspect the exterior for excessive corrosion and physical
damage.
2. Inspect all air lines connected to the ATR-1
™
valve for
signs of wear or physical damage. Replace as necessary.
3. Test air line fittings for excessive leakage and tighten or
replace as necessary.
4. Perform the Leakage Test described in this manual.
EVERY YEAR, 100,000 MILES, OR 3,600 OPERATING
HOURS
1. Perform the Operation and Leakage Tests described in
this manual.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove 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.
3. 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.
4. 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 an AD-IS
™
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommended procedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. 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.
8. Use only genuine Bendix
®
replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
