Section 12: BRAKE AND AIR SYSTEM
10 X3-45 Commuter PA1593 DOB 2400-2489 Section 12 Updated Sept. 2015
supplied in the applicable booklet annexed at the
end of this section.
Item Description Notes
1 Air Compressor Wabco 636
2 O’Ring
3 Stud (3) M12
4 Flange Nut (3) Torque to 15lb-ft (20 Nm)
5 Nipple (2)
6 Hose Assembly
11.1 COMPRESSOR REMOVAL AND
INSTALLATION
1. Exhaust compressed air from air system by
opening the drain valve of each air tank.
2. Drain the engine cooling system. See
Section 5: "Cooling System".
3. Access the compressor by the engine R.H.
side compartment. Identify and disconnect
all air, coolant and oil lines from the
compressor assembly.
4. Remove the three compressor flange
mounting nuts.
5. Slide air compressor rearward to disengage
the hub from coupling. Remove the air
compressor.
Remove and retain the oil supply tube that
runs between the compressor and the engine
Reverse removal procedure for installation.
12. EMERGENCY/PARKING BRAKE
CONTROL VALVE (PP-1)
A push-pull control valve mounted on the L.H.
lateral console is provided for parking brake
application or release. The spring brakes are
self-actuated whenever the control valve supply
pressure drops below 60 psi (414 kPa). In the
UP position, brakes are ON. In the DOWN
position, brakes are RELEASED. A protective
case around the knob prevents accidentally
releasing the brakes.
FIGURE 10: PP-1 12142
Maintenance and repair information on this valve
is supplied in the applicable booklet annexed to
this section under reference number
SD-03-3611.
Remove the valve the following way:
1. Drain the air system.
2. Access this valve by tearing out the finishing
panel, which holds the controls in place
(Fig. 10).
3. Disconnect the air tubes.
4. Remove the retaining screws.
5. Service or replace the valve.
6. Installation is the reverse of removal.
13. EMERGENCY / PARKING BRAKES
OVERRULE CONTROL VALVE (RD-3)
A RD-3 control valve is used with the parking
brake overrule system. In the case of self-
application of spring brakes due to a pressure
drop, the brakes can be released by holding
down this control valve. Maintenance and repair
information on this valve is supplied in the
applicable booklet annexed to this section under
reference number SD-03-3611.
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