Komatsu ecot3 PC300LC-8 Shop Manual page 109

10 Structure, function and maintenance standard
Operation
1) When the control valve is situated at neutral
q The LS valve is a 3-way selector valve, with
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 (self pressure) (PP)
determine the position of spool (6).
q However, magnitude of the output pressure
(PSIG) (called the LS selector pressure) of the
EPC valve for the LS valve entering port (G)
also changes the position of spool (6). (Setting
force of the spring is changed)
Before the engine is started, servo piston (12) is
q
pushed to the right. (See the figure)
q If the control lever is at the neutral position
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)
PC300, 350-8
q
q
q
q
2
}. (It is intercon-
Spool (6) is pushed to the right, and port (C)
and port (D) will be connected.
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.
SEN01993-00
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