Komatsu Galeo PC138US-8 Shop Manual page 109

10 Structure, function and maintenance standard
Outline
This pump consists of a variable-displacement
q
swash plate type piston pump, PC valve, LS
valve and EPC valve.
Features of double pump system
The common single pump system makes much
q
loss in the pressure compensation valve.
Accordingly, the machine travel speed is
reduced much when the machine is steered.
The double pump system does not make much
q
loss in the pressure compensation valve, since
the right and left travel circuits are independent
from each other. Accordingly, the machine
travel speed is less reduced when the machine
is steered.
The double pump has simpler structure than
q
the tandem pump.
BMP : Breather mounting port
IM : PC mode selector current
OCP : Oil level check port
P1T : Travel deviation control orifice
P2T : Travel deviation control orifice
PA1 : Pump discharge port
PA1C : Pump discharge pressure pickup port
PA2 : Pump discharge port
PA2C : Pump discharge pressure pickup port
PB : Pump pressure input port
PD1 : Case drain port
PD2 : Drain plug
PEN : Control pressure pickup port
PEPB : EPC basic pressure pickup port
PEPC: EPC basic pressure input port
PLS : Load pressure input port
PLSC : Load pressure pickup port
PM : PC mode selector pressure pickup port
PS : Pump suction port
1. Main pump
2. LS valve
3. PC valve
4. PC-EPC valve
5. Shuttle valve
6. No. 1 check valve
7. No. 2 check valve
PC138US, USLC-8
SEN02548-01
9