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AIR BRAKES
A coach equipped with a dual air brake system consists of separate complete systems for the front and
rear service brakes. A separate reservoir and air gauge is provided for each of these systems. A dual treadle
valve is provided for operating the service brake system. In addition to providing excellent service brake
performance, this dual brake system is equipped with safety features which allow the driver to use the emer-
gency stopping system through the service brake treadle valve. In the event there is a failure in the air reserve
for the front brakes, the rear service brakes can still be applied using the treadle valve, since the two service
brake systems operate independently of each other. If there is a failure in the air reserve for the rear service
brake system, the front service brakes and the rear spring brakes can be applied through the treadle valve.
This allows the operator to use a normal method of braking during an emergency situation. However, in the
case of an air reserve failure, the low air pressure warning buzzer will sound and warning light illuminated,
giving an indication that trouble is evident and the respective air gauge located on the dash will indicate
which system has lost air pressure. The coach must not be operated under those conditions, but repaired
before continuing operation.
The rear spring brakes can also be controlled by a dash-mounted valve located on the lower portion of
the instrument panel. These spring brakes cannot be fully released until the air reserve pressure is above 60
PSI. These brakes are in the released position when the control valve is pushed in, and in the applied position
when the control valve is out. In the event there is a loss in air pressure, the valve will automatically move to
the brake applied position and cannot be released until the air reserve pressure has been replenished.
AIR BRAKE ADJUSTMENT
1. Raise the tire off the floor (NOTE: Install jack under the axle, not under the bumper.)
2. Turn the tire and adjust the brake slack adjuster until the brake shoes are tight against the brake drum.
3. Back off the slack adjuster until wheel rotates freely (very little drag).
4. Apply maximum brake application (80 psi) and check brake chamber push rod travel. Readjust, if
travel is greater than 1 1/4 inches.
FRONT & REAR SHOP AIR CONNECTIONS
The coach is equipped with connections valve which are located on the front and rear left hand chassis
outriggers. It allows the air brake reservoirs to be charged with a common type air hose normally used by
service stations and garages. Charging the system in this manner is only a means of providing air pressure
for the air brake system with an inoperable air compressor or without cranking the engine and should only be
used for moving the coach while servicing or in case of emergency.
PARKING
Use the dash mounted valve to apply the rear spring brake when parking the coach.
When the parking brake is applied, and the ignition switch is ON, a dash-mounted yel-
low light labelled PARK will warn the driver that the brake is applied.
CAUTION: Do not attempt to move bus before spring brakes are released.
DRAINING AIR TANKS
Condensation must be drained from all air tanks daily. To drain tanks properly, leave cocks open until all
air escapes and draining stops. NOTE: Daily draining is not required on units equipped with automatic drain
valve or an air dryer. The air dryer removes water, oil and other contaminants before they reach the wet tank.
The automatic drain valve contains a reservoir to collect condensation in the air brake system which ejects
during the on-off cycle of the compressor. On valves with heating elements, freeze up protection is opera-
tional when the ignition is turned on.
PARKING BRAKE
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