Komatsu ecot3 PC300LC-8 Shop Manual page 107

10 Structure, function and maintenance standard
Control of discharge amount
q If the swash plate angle (a) becomes larger,
the difference between volumes (E) and (F)
b ec o me s l ar g er a nd pu m p d el i v e r y ( Q )
increases.
q Servo piston (12) is used for changing swash
plate angle (a).
q Servo piston (12) carries out linear reciprocal
movement according to the signal pressure
from the PC and LS valves.
q This linear movement is transmitted to rocker
cam (4) via slider (13).
q Being supported by cradle (2) on the cylindrical
surface, rocker cam (4) slides on the surface
while continuing revolving movement.
q Space of the pressure receiving area of servo
piston (12) are not identical on the left side and
right side. Main pump discharge pressure (self
pressure) (PP) is always brought to the pres-
sure chamber of the small diameter piston
side.
q Output pressure (PEN) of the LS valve is
brought to the chamber receiving the pressure
at the large diameter piston end.
q The relationship in the size of pressure (PP) at
the small diameter piston end and pressure
(PEN) at the large diameter piston end, and
the ratio between the area receiving the pres-
sure of the small diameter piston and the large
diameter piston controls the movement of
servo piston (12).
PC300, 350-8
SEN01993-00
11