Braking; Air Brakes - Blue Bird D3RE 2014 Driver's Handbook Manual

DRIVER'S HANDBOOK

BRAKING

Air Brakes

All Americans equipped with air brakes employ separate 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 the event there is a failure in the air reservoir for the front brakes, the rear ser-
vice brakes can still be applied using the treadle valve, since the two service brake
systems operate independently. If there is a failure in the air reservoir for the rear
service brake system, the front service brakes and the rear spring brakes can be ap-
plied through the treadle valve. This allows the operator to use a normal method of
braking even though part of the system is malfunctioning. However, in the case of
an air reservoir failure, the low air pressure warning buzzer will activate, indicating
trouble, and the respective air gauge on the dash will show which system has lost air
pressure. The bus 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. The spring brakes cannot be fully re-
leased 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 auto-
matically move to the brake applied position and cannot be released until the air
reservoir pressure has been replenished.
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