Product Manual

Table Of Contents
185 T4F Kubota User Manual 3: Description
02250216-781 R02
Subject to EAR, ECCN EAR99 and related export control restrictions. 23
nents of the compressor. The functional descriptions of
the control system are described by relating them to four
distinct phases of operation. They apply to any control
system with the exception of those with specified pres
-
sures which are dependent on pressure requirements.
The given
values apply to a compressor with an operat-
ing pressure range of 100 to 125 psig (6.9 to 8.6 bar).
3.6.1 Start—0 to 58 psig (0 to 4.0 bar)
When the compressor is started, the receiver tank pres-
sure quickly rises from 0 to 58 psig (0 to 4.0 bar). During
this perio
d the pressure regulator valve is inactive. At this
pressure range the idle warm-up control keeps the inlet
valve closed for engine idle operation. Within 30 seconds
of starting the compressor (the instrument controller
READY status light is on) turn the handle of the warm-up
selector valve (located on the instrument panel) from the
START to the RUN position. The inlet valve is fully open
due to inlet pressure, and the compressor operates at full
capacity. When the compressor operates at full capacity,
the engine runs at full speed.
3.6.2 Normal operation—80 to 100 psig
(5.6 to 6.9 bar)
When the warm-up control selector valve handle is
moved to the RUN position, the receiver tank 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.
3.6.3 Modulation—100 to 125 psig (6.9 to
8.6 bar)
If the demand on the compressor is less than its rated
capacity, the service line pressure will rise above
125 psig (8.6 bar). The pressure regulating valve gradu-
ally opens, applying pressure to the inlet valve piston and
en
gin
e speed control. This causes the inlet valve to par-
tially close and reduces the engine
speed. As the pres-
sure increases, the inlet valve pist
on 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 receiver tank pressure falls
below 125 psig (8.6 bar). 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, ther
e 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 con-
form to air demand. This orifice also discharges any
accumu
lated
moisture from the regulator.
3.6.4 Shutdown
The blowdown valve is normally closed. At shutdown the
back pressure in the compressor inlet signals the blow-
down valve to vent the receiver tank pressure into the
atmosp
here.