Komatsu PC200-8M0 Shop Manual page 124

SEN06119-00
1. LS valve
PA : Pump port
PDP : Drain port
PLP : LS control pressure output port
PLS : LS pressure input port
PP : Pump port
PPL : Control pressure input port
PSIG : LS mode selector pilot port
Function
q The LS (load sensing) valve detects the load
and controls the discharge amount.
q This valve controls main pump discharge (Q)
according to differential pressure (
— PLS], called the LS differential pressure (the
difference between main pump pressure PP
and control valve outlet port pressure PLS).
q Main pump pressure (PP), pressure (PLS)
(called the LS pressure) coming from the con-
trol valve output, and pressure (PSIG) (called
the LS selector pressure) from the proportional
solenoid valve enter this valve.
q The relationship between the LS differential
pressure between the main pump pressure
(PP) and LS pressure (PLS) (
(PLS)] and the pump discharge (Q) changes
as shown in the diagram according to LS
selector current (ISIG) of the LS-EPC valve.
If (ISIG) changes from 0 to 1A, setting force
q
the spring changes, too. As the result, the
specified median of the pump discharge vol-
ume switching point changes as shown in the
diagram. It will change in the range of 0.27 to
1.7 MPa {2.78 to 17.75 kg/cm
12
10-401
1.
2.
3.
4.
5.
6.
7.
8.
d
PLS)[= PP
d
PLS) [= (PP) —
2
}.
401 Hydraulic system, Part 1
Sleeve
Piston
Spool
Spring
Sheet
Sleeve
Plug
Locknut
PC200, 200LC, 220, 220LC-8M0
Hydraulic pump