Antilock Modulator (M-32Qr); Inversion Valve (Tr-2, Tr-3); Inline Quick Release Valve (Qr-L); Emergency Door Opening Valves - PREVOST H3-41 Maintenance Manual

SECTION 12: BRAKE AND AIR SYSTEM
13.13

ANTILOCK MODULATOR (M-32QR)

The M-32QR (quick release) antilock system modulator is high capacity,
on/off air valve that incorporate a pair of electrical solenoids for control. The
solenoids provide the electro-pneumatic interface between the antilock
controller electronics and the air brake system. The modulator is used to
control the braking function on individual or dual service actuators during
antilock activity.
Maintenance and repair information on the antilock modulator valve is
supplied in the applicable booklet, found on your Technical Publications
USB flash drive, under reference number Bendix SD-13-4870.
13.14

INVERSION VALVE (TR-2, TR-3)

The TR-2 & TR-3 valves are normally open, pilot-operated, inverting, on-off,
two-way valves. As control pressure is reduced to the point that the piston
return spring or springs overcomes the force on the control piston, the valve
will deliver full supply pressure at the delivery port.
Maintenance and repair information on the antilock modulator valve is
supplied in the applicable booklet, found on your Technical Publications
USB flash drive, under reference number Bendix SD-13-4650.
13.15

INLINE QUICK RELEASE VALVE (QR-L)

The QR-L quick release valve is a quick release valve. Its purpose is to
"speed up" the release of air from air lines and devices it is attached to.
Although primarily intended to enhance air system performance by rapidly
exhausting supply or control air pressure from vehicle air lines, it can be
used in a variety of different applications. It is uniquely suitable as an air
system performance enhancement due to its 0 psi crack and differential
pressure. Supply and delivery pressure is the same throughout the air
pressure range.
Maintenance and repair information on the inline quick release valve is
supplied in the applicable booklet, found on your Technical Publications
USB flash drive, under reference number Bendix SD-03-906.

14. EMERGENCY DOOR OPENING VALVES

Two emergency door opening three-way valves
are installed on passenger coaches. One is in
the front service
accessible. The other one is on the R.H. side
lateral console, close to the entrance door.
When used, the valve releases pressure in the
door locking cylinder, thus allowing the door to
be manually opened.
24 PA1621 Maintenance Manual All Series | Revised June 2020
compartment, readily
FIGURE 16: THREE WAY VALVE

14.1.1 Interior Valve Maintenance

When needed, this valve can be changed
according to the following procedure:
12186