H
y
dra
u
lic
s
9803/
3280
Issue
1
Component Location
Component Key:
T
Hydraulic Tank
P
Hydraulic Pump (engine driven)
1B
Hose - High Pressure Carry Over
3
Loader Valve Block
4
Excavator Valve
6
Return Line Filter (inside hydraulic tank)
7
Steer Circuit Priority Valve
13
Return Line Check Valve
26
Hydraulic Oil Cooler
Neutral Circuit Description
Fixed Flow - Single Pump
Oil is drawn from the hydraulic tank
T
by the single
stage hydraulic pump
P
. The pump is mounted on
the rear of the gearbox and is engine driven via a
driveshaft.
Pressurised oil from the pump flows to steering
priority valve
7
, and in neutral circuit flows through
the priority valve to the loader valve
3
.
From the loader valve neutral gallery, oil flows via a
high pressure carry-over line
1B
to the excavator
valve
4
.
Some of the exhaust oil flows directly back to the
tank through an in-tank filter
6
, and some of the
exhaust oil returns to tank via the hydraulic oil
cooler
26
.
To help prevent excavator dipper ram and loader lift
ram cavitation, there is a check valve
13
fitted to
t he ret urn line. The c hec k valve raises
approximately 5 bar (75 lbf/in
2
) of pressure in the
line, which improves the operation of the respective
anti-cavitation valves.
3 -
2
3 -
2
B
a
sic
S
yst
e
m
O
p
e
ra
tio
n
S
e
c
tio
n E
S
e
c
tio
n E