Komatsu PC20R-8 Shop Manual page 71

2. BASIC PRINCIPLE
1) Control of pump swash plate angle
. The pump swash plate angle (pump discharge amount) is so controlled that the LS differential pressure DP
which is the difference between the pump discharge pressure P
control valve (actuator load pressure), is maintained at a constant level.
(LS differential pressure DP
. If the LS differential pressure DP
plate angle becomes larger, and if it becomes higher, the pump swash plate angle becomes smaller.
M For the details of this action, refer to the descriptions of «HYDRAULIC PUMP».
PC20R-8 PC27R-8
=Pump discharge pressure P
LS
becomes lower than the setting pressure of the LS valve, the pump swash
LS
Control valve
Pump passage
Main pump
Min.
∆
P
LS
LS valve
Differential pressure
large (high)
TCC valve
Pump pressure high
and the LS pressure P
P
± pressure P
P LS
Actuator
P
LS
LS passage
Max.
Servo piston
Differential
pressure
small (low)
Pump
pressure low
at the outlet port of the
LS
).
RKP00651
,
LS
10-53