7
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.
9.
Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored to
their proper operating condition.
OPERATION & LEAKAGE TESTS
Operating Test
To properly test the function of the AR-2
™
valve, a pair of test
gauges or gauges of known accuracy must be used.
1. Install a “tee” at the AR-2
™
valve’s service port and at
one of the delivery ports, then install a gauge in each.
2. Connect the tractor service and emergency “glad hands”
(hose couplings) to dummy connectors, or alternatively,
to a trailer. Build the tractor system air pressure to
governor cut-out and make 4 to 5 full brake applications.
Check the air fittings at the AR-2
™
valve for leakage.
Tighten as needed.
3. With the trailer supply valve (dash control w/red octagonal
button) and system park control (dash control w/yellow
diamond button) activated for tractor/trailer operation,
apply and release the brakes several times and check
for prompt application and release at each wheel. If
prompt reaction is noted at some, but not all wheels,
test the M-21
™
antilock modulator between the AR-2
™
valve and the brake chamber for proper operation. If a
“sluggish” response is noted at all wheels, inspect for a
kinked or obstructed air line leading to or from the AR-2
™
valve. If a complete release of the brakes is noted at
some, but not all wheels, test the M-21
™
antilock
modulator between the AR-2
™
valve and the brake
chamber for proper operation. If an incomplete release
is noted at all wheels, inspect for a kinked or obstructed
air line leading to or from the AR-2
™
valve.
4. Check the AR-2
™
valve’s differential pressure by applying
10 psi to the service port and noting the pressure
registered at the delivery port. Subtract delivery port
pressure from the 10 psi service pressure to obtain the
differential. Compare the measured differential with the
pressure specified for the AR-2
™
valve part number.
NOTE: For AR-2
™
valves not incorporating a relay piston
return spring the measured differential should be
approximately 4 psi. When a spring is in use, the
differential will be higher.
5. Make and hold a full (100 psi or greater) brake application
and note that full pressure is delivered to the brake
chambers.
6. Activate the dash mounted trailer supply valve for bobtail
tractor operation. Then make a slow brake application,
increasing the pressure at the AR-2
™
valve service port
to 20 psi while watching the reaction at the delivery port
gauge. Note that delivery pressure rises to approximately
5 to 10 psi and remains constant while service pressure
continues to rise to 20 psi. Release the application.
7. Make another brake application and slowly increase
the pressure at the AR-2
™
valve service port to between
60 and 70 psi while observing the gauge installed at the
delivery port. Note that when service port pressure rises
to between 20 and 30 psi, delivery pressure begins to
rise above the initial pressure noted in step 6. The rise
of delivery pressure should be at a proportioned rate of
approximately 3 to 1. For example: Each 3 psi increase
at the service port results in a delivery pressure increase
of 1 psi. At 70 psi service port pressure, brake chamber
pressure should be 15 to 25 psi.
8. Make a full brake application and note that both test
gauges register the same pressure. IMPORTANT: If
during testing the service port pressure is SLOWLY
increased from approximately 70 psi to a full (100 psi
or greater) brake application, the AR-2
™
valve MAY begin
to cycle between an apply and exhaust mode. This
