Service Manual

627333-A 8-1
Air Compressor
AIR COMPRESSOR
The chassis air system consists of an engine mounted,
direct driven air compressor, an air drier and two
storage tanks. The first tank is called a wet tank
because most condensation occurs in this tank as the
air cools from being compressed. The second tank is
called a dry tank since little condensation occurs in that
tank.
From the dry tank, air is sent out to the R-12 relay valve
for service brakes and to the R-14 relay valve for the
parking brakes. Air is sent from the dry tank to the
parking brake and service brake valves in the cab to
serve as “signal” air to control the relay valves.
Air is supplied to the back of the cab and goes to
auxiliary functions in the cab, like the air horn and to the
system requirements such as foam marker systems,
product control valves, boom shut-off, etc. Air to these
auxiliary functions passes through a pressure
protection valve as a safety feature. In the event of a
major air system malfunction (pressure drops to under
4,82 bar (70 psi)), the valve closes off to these auxiliary
functions to reserve remaining air pressure for braking.
AIR COMPRESSOR REMOVAL
m
WARNING: Remove all air pressure from
tanks before disconnecting any air
hoses. Pressurized air can cause serious
personal injury.
m
WARNING: Never open coolant system
when fluid is hot. Hot fluid can cause
serious personal injury.
NOTE: Keep all parts clean from contaminants.
Contaminants may cause rapid wear and
shortened component life.
NOTE: Contain all fluids. Be prepared to collect fluid
with suitable container before opening and
disassembling any component containing
fluids.
Drain coolant from coolant system.
FIG. 1: Disconnect high temperature braided hose
going from compressor to air dryer. Mark and
disconnect coolant lines going to front (1), top (2) and
rear (3) of compressor. Disconnect oil line (4).
FIG. 1
1
4
2
3
N072412002