Komatsu ecot3 PC300LC-8 Shop Manual page 111

10 Structure, function and maintenance standard
3) Action for the direction of minimizing the pump delivery
When LS differential
q
becomes larger (for example, when the area of
opening of the control valve becomes smaller
and pump pressure (PP) rises) because of the
rightward move (it reduces discharge amount)
of servo piston (12), pump pressure (PP)
pushes spool (6) to the right.
q When spool (6) moves, main pump pressure
(PP) flows from port (C) to port (D) and from
port (K), it enters the large diameter end of the
piston.
q Main pump pressure (PP) also enters port (J)
of the small diameter end of the piston, but
because of the difference in area between the
large diameter end and the small diameter end
on servo piston (12), it is pushed to the right.
As the result, servo piston (12) moves into the
direction of reducing the swash plate angle.
As LS selector pressure (PSIG) is input to port
q
(G), setting force of spring (4) is reduced.
PC300, 350-8
pressure (EPLS)
SEN01993-00
15