Komatsu Galeo PC138US-8 Shop Manual page 113

10 Structure, function and maintenance standard
Control of delivery
If the swash plate angle (a) becomes larger,
q
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.
Servo piston (12) is used for changing swash
q
plate angle (a).
Servo piston (12) carries out linear reciprocal
q
movement according to the signal pressure
from the PC and LS valves.
This linear movement is transmitted to rocker
q
cam (4) via slider (13).
Being supported by cradle (2) on the cylindrical
q
surface, rocker cam (4) slides on the surface
while continuing revolving movement.
Space of the pressure receiving area of servo
q
piston (12) are not identical on the left side and
right side. Main pump discharge pressure
(check valve output pressure) (PP) is always
brought to the pressure chamber of the small
diameter piston side.
Output pressure (PEN) of the LS valve is
q
brought to the chamber receiving the pressure
at the large diameter piston end.
The relationship in the size of pressure (PP) at
q
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).
PC138US, USLC-8
SEN02548-01
13