Komatsu ecot3 PC300LC-8 Shop Manual page 147

10 Structure, function and maintenance standard
q During operation (a work within a scope of dis-
charge by a minimum swash plate angle), the
discharge pressure for the portion of minimum
pump swash plate angle is set to LS pressure
+ P1 pressure.
LS control differential pressure (
q
charge for the portion of minimum swash plate
angle will be equal to P1 pressure.
PC300, 350-8
2.
q
q
q
E
PLS) of dis-
q
q
q
Operation of relief valve
When the cylinder reaches the stroke end, the
main relief valve opens.
The pump delivery (Q) is relieved to the
tank.(See the system diagram)
The pump discharge pressure (PP) and LS
pressure (PLS) become approximately the
same as each has not flow at the upstream
and downstream of the spool, and LS differen-
E
tial pressure ( PLS) becomes 0 kg/cm
As LS differential pressure (
than the LS set pressure of LS valve, LS valve
is actuated to maximize the pump swash plate
angle.
Mechanically, operation of PC valve have the
prevalence to that of LS valve.
The pump is held at a minimum swash plate
angle by the cut-off function of PC valve.
SEN01994-01
2
.
E
PLS) is lower
21