F-1031, Section 2119
Page 17 of 24
Air Compressor Pressure Mode: UNLOAD
The air compressor essentially idles, producing a minimal
pressure (40 psi) to maintain compressor oil flow.
NOTE: The compressor’s clutch shall only be en-
gaged when the Unload / Fixed / Auto switch is in the
“Unload” position and the master air pressure gauge
reads zero psi.
With the compressor engaged, running and the Auto-
Sync control panel switched to “UNLOAD”, the following
occurs:
·
The yellow and black solenoids are NOT energized
and are OPEN.
·
The master pressure gauge registers compressor
sump tank pressure.
·
The shuttle valve is closed. The compressor inlet
pressure is lower than the compressor discharge
pressure.
·
The fixed air regulator and the balance valve are
closed and do not directly influence the air circuit op-
eration.
·
The sizing of the piping and inlet valve limits the pres-
sure produced to 40-50 psi (2.8-3.4 bar).
·
If the compressor discharge air pressure is above 40-
50 psi (2.8-3.4 bar), then the control air closes the air
inlet valve. This causes the control air pressure to
drop below 40-50 psi (2.8-3.4 bar), the control pres-
sure is not high enough to keep the air inlet valve
closed. The air inlet valve opens allowing air into the
compressor raising the control air pressure above 40-
50 psi (2.8-3.4 bar).
NOTE: Control air is always being released and pressure relieved through the air inlet trim valve (AITV) and out
the air bleed outlet. This air release is controlled (limited) by the AITV.
Red Hose
Red Hose
Blue Hose
Gray Hose
Water Pressure
Air Pressure
Y
e
ll
o
w
Ho
s
e
Black Hose
Yellow Solenoid
(Open)
Black Solenoid
(Open)
Master Air Pressure Gauge
Water Pump
Balance Valve
(Closed)
Balance
Trim Valve
(BTV)
Shuttle Valve
(Closed)
Minimum
Pressure
Valve
Air / Oil Separator
Air Inlet
Valve
Air Inlet Valve
from Air Filter
Air Inlet Trim Valve (AITV)
Air Bleed Off
Fixed Air Regulator (Closed)
Oil Scavenger Line
Air Compressor Mode: Unload
(40 psi / 2.8 bar)
Black Hose
Air Discharge
Manifold
(40 psi / 2.8 bar)
Air
Compressor
