S Y S T E M S
O P E R A T I O N
A I R S Y S T E M A N D B R A K ES
A I R S U P P L Y F O R T H E A l R S Y S T E M
Air reservoir (3) is fastened to the rear of the
engine end frame under the radiator. Protection
of the reservoir is provided by the crankcase
L O C A T I O N O F A I R R E S E R V O IR
1 . L i n e f r o m g o v e r n o r . 2 . R e l i e f v a l v e ( u n d e r e n g i n e
m o u n t ) . 3 . R e s e r v o i r . 4 . I n l e t f r o m a i r c o m p r e s s o r . 5 .
Check valve. 6. Drain valve.
The air reservoir has drain valve (6), relief valve
(2) and check valve (5) fastened to it.
Water can be drained from the air reservoir when
drain valve (6) is opened. This keeps the water out of
the other components of the air system.
AIR RELIEF VALVE
The air relief valve is fastened to the reservoir. If
the governor does not operate correctly, the relief
valve will open at approximately 1030 kPa (150 psi)
to prevent damage to the air system. The setting of
the relief valve can not be adjusted.
C O M P O N E N T S O F T H E C H E C K V A L VE
1. Seat. 2. Valve. 3. Spring.
The one-way check valve in the system is used to
stop the reverse flow of air from the air reservoir. The
check valve is fastened to the air reservoir.
Air from the air compressor will put spring (3) in
compression and valve (2) will open. This permits air
to flow into the reservoir.
When the air pressure in the reservoir and the
force of spring (3) is more than the air pressure from
the compressor, valve (2) will move against seat (1).
Air can not go from the reservoir to the air
AIR DRYER (Refer to Air Supply Illustration,
The air dryer (10) is installed in the vertical
position in the air line between the air compressor
(1) and the air reservoir (5). The dryer helps reduce
corrosion and prevent possible problems in the air
system, especially the air brake system caused by
moisture in temperatures below 32°F (0°C).
With the use of an air dryer, it is not necessary
to drain the air system reservoirs daily.
The air dryer has a heater and thermostat as-
sembly to keep moisture from freezing in the purge
valve drain when the unit is used in temperatures
of 32°F (0°C) or lower. The 60 watt, 12 or 24
volt DC heater and thermostat assembly has an
operating range between 50°F (10°C) and 85°F
Air, under pressure is sent to the air dryer (10)
from the compressor (1) through supply line (8).
The unsaturated dry air from the air dryer goes
through line (9) to the air reservoir (5).
When the air pressure from the compressor (1)
reaches the high limit setting of the governor (2),
the charge cycle ends and the purge cycle begins.
Air will go from the compressor (1) through un-
loader line (11) to the purge valve in the air dryer
(10). The opening of the purge valve and internal
air dryer operation, permit air pressure in the dryer
to exhaust condensation and foreign material to
the atmosphere. This is referred to as the purge
When air pressure goes below governor (2) limit
setting, the air compressor (1) will again begin
sending compressed air to the air dryer (10)
through supply line (8) and the charge cycle