Komatsu Galeo PC138US-8 Shop Manual page 115

10 Structure, function and maintenance standard
Operation
1. When the control valve is situated at neutral
The LS valve is a 3-way selector valve, with
q
pressure (PLS) (LS pressure) from the outlet
port of the control valve brought to spring
chamber (B), and main pump discharge pres-
sure (PP) brought to port (H) of sleeve (8).
Magnitude of the force resulting from this LS
q
pressure (PLS), force of spring (4) and the
pump delivery pressure (check valve output
pressure) (PP) determine the position of spool
(6).
Before the engine is started, servo piston (12)
q
is pushed to the left. (See the diagram on the
right)
If the control lever is at the neutral position
q
when the engine is started, LS pressure (PLS)
will be set to 0 MPa {0 kg/cm
nected to the drain circuit via the control valve
spool)
Spool (6) is pushed to the left, and port (C) and
q
port (D) will be connected.
PC138US, USLC-8
q
q
q
2
}. (It is intercon-
Pump pressure (PP) is conducted to the larger
diameter end from the port (K).
The same pump pressure (PP) is conducted to
the smaller diameter end from the port (J).
According to the difference in the areas on
servo piston (12), the pressure moves in such
that the swash plate angle may be minimized.
SEN02548-01
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