Komatsu Galeo PC138US-8 Shop Manual page 118

SEN02548-01
4. When servo piston is balanced
Let us take the area receiving the pressure at
q
the large diameter end of the piston as (A1),
the area receiving the pressure at the small
diameter end as (A0), and the pressure flowing
into the large diameter end of the piston as
(PEN).
If the main pump pressure (PP) of the LS valve
q
and the combined force of spring (4) and LS
pressure (PLS) are balanced, and the relation-
ship is (A0) × (PP) = (A1) × (PEN), servo pis-
ton (12) will stop in that position.
The swash plate of the pump will be held at the
q
intermediate position. [Spool (6) will be
stopped at a position where the distance of the
opening from port (D) to port (E) and the dis-
tance from port (C) to port (D) is almost the
same.]
At this point, the relationship between the pres-
q
sure receiving areas across servo piston (12)
is (A0) : (A1) = 1 : 2, so the pressure applied
across the piston when it is balanced becomes
(PP) : (PEN) C 2 : 1.
18
10 Structure, function and maintenance standard
Force of spring (4) is adjusted in such that the
q
position of the balanced stop of this spool (6)
may be determined when (PP) — (PLS) = 2.2
MPa {22.5 kg/cm
fied value.
2
} at the median of the speci-
PC138US, USLC-8