Komatsu PC200-8M0 Shop Manual page 163

402 Hydraulic system, Part 2
Functions and operation by valve
Introduction of LS pressure
LS: Abbreviation for Load Sensing
1. Main pump
2. Main spool
3. Pressure compensation valve
4. Valve
5. Check valve
6. LS circuit
7. LS shuttle valve
Function
The upstream pressure (spool meter-in down-
q
stream pressure) of pressure compensation
valve (3) is transmitted and led to LS shuttle
valve (7) as LS pressure.
q Connected to actuator port (B) through valve
(4), and makes LS pressure C actuator load
pressure.
In main spool (2), leading hole (a) with a small
q
diameter also acts as an orifice.
q LS pressure works as source pressure when
closing unload vale while control lever is oper-
ated, and this pressure also functions as oper-
ating pressure when pressure compensation
valve is compensated.
PC200, 200LC, 220, 220LC-8M0
Operation
When main spool (2) is operated, the pump
q
pressure is transmitted to port (c) through lead-
ing hole (a) and is led to LS circuit.
When the pump pressures rises to reach the
q
load pressure of port (B), check valve (5)
opens and the pressurized oil flows.
SEN06120-00
21
10-402