Bendix Commercial Vehicle Systems LQ-5 BOBTAIL RATIO VALVE 4/04 - Manual (Page 5)

5
bobtail mode. Upon brake valve release, delivery air pressure
flows back through the LQ-5
™ valve, to the brake valve and
out to atmosphere. Air from the actuators exhausts through
the quick release valve.
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.
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.
PREVENTIVE MAINTENANCE
GENERAL
Perform the following tests and inspections at the prescribed
intervals. If the LQ-5
™ valve fails to function as described or
if leakage is excessive, repair the valve or replace it with a
new or genuine Bendix remanufactured unit, available at any
authorized parts outlet.
Important: Review the Bendix Warranty Policy before
performing any intrusive maintenance procedures. A warranty
may be voided if intrusive maintenance is performed during
the warranty period.
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary. Experience is a
valuable guide in determining the best maintenance interval
for air brake system components. At a minimum, the valve
should be inspected every 6 months or 1500 operating hours,
whichever comes first, for proper operation. Should the valve
not meet the elements of the operational tests noted in this
document, further investigation and service of the valve may
be required.
OPERATION & LEAKAGE TESTS
OPERATION TEST
To properly test the LQ-5 ™ valve, use a pair of test gauges or
gauges of known accuracy.
1. With the trailer supply valve pushed in (tractor-trailer
mode), install two air gauges in the front axle service
system: one between the brake valve and the LQ-5
™
valve and one at a front axle actuator.
2 Build system pressure to governor cut-out setting.
3. Make a service brake application with the foot valve and
have someone observe the gauges. When the gauge
between the foot valve and the LQ-5
™ valve reaches 40
psi, the actuator gauge should read approximately 20
psi (±5 psi).
4. Make a full service brake application. Both gauges should
read the same pressure.
5. With the trailer supply valve pulled out (bobtail mode),
make a 30-40 psi service brake application. Both gauges
should read the same pressure.
6. Remove the test gauges.
LEAKAGE TEST
1. Build system pressure to governor cut-out. With the trailer
supply valve pushed in (tractor-trailer mode), apply a soap
solution to the LQ-5
™ valve exhaust port. The leakage
should not exceed a 1" bubble in less than 3 seconds.