Komatsu Galeo PC138US-8 Shop Manual page 176

SEN02549-02
Swing bleeding valve
Function
When the machine swings, the bleeding valve
q
installed to the pressure reducing valve works
so that the LS pressure rises gradually and the
machine swings smoothly.
Operation
(In fine control operation)
The pressure reducing valve moves to the right
q
and notch (a) connects to the LS circuit. As a
result, pump circuit (PP), bleed-off circuit, and
LS circuit are connected through piston (2).
Bleeding spool (3) moves to the left in propor-
q
tion as swing PPC pressure (PA) rises. In the
fine control area, notch (b) chokes the bleed-
off circuit and determines the intermediate
pressure before the lowered pressure is
applied to pump discharge pressure (PP) and
LS pressure (PLS).
42
10 Structure, function and maintenance standard
Accordingly, the intermediate pressure is set
q
lower than pump discharge pressure (PP) and
raised as bleeding spool (3) moves. As a
result, LS pressure (PLS) rises gradually.
When the lever is in neutral or operated fully,
q
the bleed-off circuit is closed.
PC138US, USLC-8