Hydraulics
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
the return line. The check 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
Basic System Operation
Section E Section E
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