300HH, 375, 375H, 375HH, 425 AND 425H USER MANUAL R00
SECTION 2
28
1. Engine Air Filter
2. Compressor Air Filter
3. Air Inlet Valve
4. Compressor
5. Engine
Figure 2-8: Air Inlet System—John Deere
N
ORMAL
O
PERATION
– 80
TO
100
PSIG
(5.6
TO
6.9
BAR
)
OR
80
TO
150
PSIG
(5.6
TO
10.3
BAR
)
FOR
H
MACHINES
OR
80
TO
200
PSIG
(5.6
TO
13.8
BAR
)
FOR
HH
MACHINES
When the warm-up control selector valve handle is
moved to the RUN position, the sump pressure rises
above 80 psig (5.6 bar). At this time, the inlet valve
remains fully open for maximum air output. The
engine will continue to run at full speed during this
phase of operation.
M
ODULATION
– 100
TO
110
PSIG
(6.9
TO
7.5
BAR
)
OR
150
TO
165
PSIG
(10.3
TO
11.4
BAR
)
FOR
H
MACHINES
OR
200
TO
220
PSIG
(13.8
TO
15.2
BAR
)
FOR
HH
MACHINES
If the demand on the compressor is less than its
rated capacity, the service line pressure will rise
above 100 psig (6.9 bar) - low or single pressure
rating: 150 psig (10.3 bar) for “H” rating or 200 psig
(13.8 bar) for “HH” dual or high pressure rating. The
pressure regulating valve gradually opens, applying
pressure to the inlet valve piston and pressure
transducer. This causes the inlet valve to partially
close and reduces the engine speed. As the pressure
increases, the inlet valve piston will further close the
inlet valve and the engine speed will decrease until it
reaches its preset idle speed. When the demand on
the compressor increases, the sump pressure falls
below 110 psig (7.6 bar) or 165 psig (11.4 bar) for “H”
machines, or 220 psig (15.2 bar) for “HH” ones. The
pressure regulating valve closes, the air inlet valve
opens fully, and the engine speed increases to its
preset full load rating.
Between the pressure regulating valve and the inlet
valve, there is a small orifice that vents a small
amount of air into the atmosphere when the pressure
regulating valve is open. This allows changes in air
output to conform to air demand. This orifice also
discharges any accumulated moisture from the
regulator.Shutdown
The blowdown valve is normally closed. At shutdown
the back pressure in the compressor inlet signals the
blowdown valve to vent the sump pressure into the
atmosphere.
2.7
AIR INLET SYSTEM,
FUNCTIONAL DESCRIPTION
. The air inlet system consists of
two air filters, a compressor air inlet valve and
interconnecting piping to the engine and the
compressor.
The air filters are three-stage dry element type filters
that are capable of cleaning extremely dirty air.
However, when operating in dirty environments, the
filters should be checked more frequently.
See
on page 64 for Air Filter
Maintenance Procedures.
2.8
INSTRUMENT PANEL
GROUP, FUNCTIONAL
DESCRIPTION
. The instrument panel group
consists of a molded panel containing an: air
pressure gauge, compressor temperature gauge,
ignition/start switch, PowerView, annunciator light,
idle warm-up control, engine shutdown light, engine
warning light, and a wait to start light. A high-low
pressure selector valve is located on the panel for
“H” and “HH” compressors.
1
2
3
4
5
SU_0000668
Summary of Contents for 300HH
Page 17: ...SECTION 1 15 Safety Symbols 2 ...
Page 18: ...SECTION 1 16 Safety Symbols 3 ...
Page 49: ...SECTION 2 300HH 375 375H 375HH 425 AND 425H USER MANUAL R00 47 2 9 WIRING DIAGRAM ...
Page 60: ...NOTES 58 ...
Page 79: ...NOTES ...
