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RESERVOIR
FIGURE 4 BALANCED POSITION
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 following tests and inspections at the prescribed
intervals. If the M-12
/M-12R
™
described, or if leakage is excessive, repair the valve or obtain
a replacement from any authorized Bendix parts outlet.
EVERY THREE MONTHS, 25,000 MILES, 900 OPERATING
HOURS, OR DURING THE VEHICLE CHASSIS
LUBRICATION INTERVAL, MAKE THE VISUAL
INSPECTIONS IN THE SERVICE CHECKS
EVERY YEAR, 100,000 MILES, OR 3,600 OPERATING
HOURS, PERFORM THE OPERATIONAL AND LEAKAGE
TESTS
SERVICE CHECKS
1. Remove any contaminants and visually inspect the valve's
exterior for excessive corrosion or physical damage.
4
EXHAUST
SOLENOID
SUPPLY
SOLENOID
SUPPLY
EXHAUST
modulator fails to function as
™
DOUBLE
CHECK
BRAKE
VALVE
CONTROL
PISTON
DELIVERY
SERVICE BRAKE
CHAMBER
2. Inspect all air lines connected to the M-12
modulator for signs of wear or physical damage. Replace
as necessary.
3. Test air line fittings for excessive leakage and tighten or
replace as necessary.
OPERATIONAL AND LEAKAGE TEST
OPERATIONAL TEST
1. Apply and release the brakes several times and check
for prompt application and release at each wheel. If the
response at the wheels is "sluggish," check for a kinked
or obstructed air line leading to or from the M-12
M-12R
™
modulator.
2. Road test the vehicle to determine proper modulator
operation. The system can be tested by making an
aggressive stop from a vehicle speed of 20 mph. When
an aggressive stop is made, solenoid pulsation creates
an audible burst of air, which can be heard from outside
the vehicle.
LEAKAGE TEST
1. Build air system pressure to governor cut out. With the
service brakes fully applied, coat the exhaust port with
a soap solution. A 1" bubble in 3 seconds is permitted.
Coat the outside of the modulator body to check for seal
ring leakage. No leakage is permitted.
TRAILER
CONTROL
/M-12R
™
™
™
/
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