PREVOST X3-45 Multiplex, Maintenance Manual

Page: 458 / 1422

Section 12: BRAKE AND AIR SYSTEM
PA1562
8
Pay particular attention to the internal passages.
Inspect all parts for damage and replace if
necessary.
6. AIR GAUGES (PRIMARY, SECONDARY
AND ACCESSORY)
The air pressure gauges, located on the
dashboard (see
"Operator's Manual" ), are
connected to the DC-4 double check valve,
located on the pneumatic accessory panel in the
front service compartment.
The latter is connected to the air lines running
from the primary and secondary air tanks, as
shown on the pneumatic system diagram
provided in the technical publications box. The
accessory air gauge is connected to the
accessory air tank using the drain valve
connector. The vehicle should never be set in
motion until the buzzer alarm and warning lights
turn off, i.e. when air pressure registers at least
66 psi (455 kPa). Moreover, if pressure drops
below 66 psi (455 kPa), the
"Low air pressure"
warning lights will turn on, and the "Low air
pressure" buzzer will sound. Stop the vehicle
immediately, determine and correct the cause(s)
of pressure loss. Check the gauges regularly
with an accurate test gauge. Replace the gauge
with a new unit if there is a difference of 4 psi
(27 kPa) or more in the reading.
7. AIR FILTER/DRYER
FIGURE 6: HALDEX AIR FILTER DRYER
12194
The air filter/dryer is located in front of rear
wheelhousing above drive axle (Fig. 1, 2 & 6).
Its purpose is to remove moisture that could
damage the air system before the air enters the
system reservoir. The air filter/dryer also filters
the air to remove dirt, compressor oil, and other
contaminants that can damage the system.
Change cartridge every 100,000 miles (160 000
km) or once every two years, whichever comes
first. The air dryer may be purged for mainte-
nance purposes using the remote drain valve
located in the engine compartment and
accessible through the engine compartment
R.H. side door. The valve is positioned close to
the L.H. side of door opening (Fig. 3). The air
filter/dryer has a built-in governor to maintain the
system between 108 psig and 123 psig.
Maintenance and repair information is supplied
in the maintenance information annexed to this
section.
7.1 AIR FILTER/DRYER PURGE TANK
A tank is supplied to purge the air filter/dryer to
remove moisture and contaminants.
8. AIR LINES
Copper piping, nylon-reinforced tubing, and
flexible hoses are used to connect the units in
the pneumatic system, including air brake
system, suspension system and accessory
systems such as the entrance door, fresh air
damper cylinder, air horns, etc. Furthermore, the
nylon tubing is color coded to ease identification.
Refer to the following table for the complete
color identification code. Service instructions for
each type of air line are also provided under the
applicable headings.
Color Circuit
Red Secondary
Green
Primary and Delivery
Yellow Parking Brake
Blue Suspension
Black Accessory
Brown Trailer
Brake
8.1 COPPER PIPING
A heat dissipation copper piping assembly is
used to dissipate the heat coming from the
compressor before it enters the air filter/dryer.
Connections should be checked for leakage at
least every 6,250 miles (10 000 km) or twice a
year, whichever comes first. Tighten or replace
when necessary. When replacing copper piping,