H
y
dra
u
lic
s
9803/
3280
Issue
1
Component Location
Component Key:
T
Hydraulic Tank
P1
Hydraulic Pump (main section)
P2
Hydraulic Pump (secondary section)
1B
Hose - High Pressure Carry Over
3
Loader Valve Block
4
Excavator Valve
5
Auxiliary Valve
6
Return Line Filter (inside hydraulic tank)
7
Steer Circuit Priority Valve
13
Return Line Check Valve
26
Hydraulic Oil Cooler
62
Hydraclamp exhaust hose
Neutral Circuit Description
Fixed Flow - Double Pump
Oil is d raw n from t he hyd raulic t ank
T
b y t he
hydraulic pump. The pump has two sections,
P1
and
P2
.
The hydraulic pump is mounted on the rear of the
g earb o x and is d riven b y t he eng ine via a
driveshaft.
Oil from the larger section
P1
flows direct to the
loader valve
3
. Oil from pump section
P2
, flows to
steering priority valve
7
, and in neutral circuit flows
through the priority valve to the auxiliary valve
5
and then to join the flow from
P1
at the loader
valve.
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.
On sideshift machines only, hydraclamp exhaust
ho se
62
is f it t ed . The ho se c o nnec t s t he
hydraclamp spool directly into the exhaust circuit.
This prevents the clamps from ‘locking-up’ when
the sideshifting operation is required.
3 -
4
3 -
4
B
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