Section E - Hydraulics
Operation Description
General Description
E-15 E-15
9803-9340-8
General Description
The main components of the hydraulic circuit are the tank,
pumps, drive motor(s), loader and excavator valves, filters,
cooler, and rams.
The pumps are driven by the engine and deliver
pressurised oil to the loader and excavator valves and to
the transmission motor(s). When either the loader or
excavator valve is operated, pressurised oil is delivered to
one end of the appropriate ram. The oil forces the ram's
piston along the bore of the ram. When the drive pedal is
operated the transmission pump delivers pressurised oil to
the drive motor which, on 2 wheel drive machines, is
connected to the rear axle. On 4 wheel drive machines,
four hydraulic motors are fitted, one to drive each wheel.
Machine Neutral Circuit
This description should be read in conjunction with the
basic diagram below and the detailed Hydraulic Schematic
Diagrams starting on page E/10-1. The diagram shows the
standard JCB pattern excavator controls. For the optional
ISO pattern controls the excavator spools are in different
positions (refer to detailed diagrams). Otherwise the
circuits are the same.
Oil is drawn from the tank T by the service pump P3. The
pump delivers pressurised oil to the steer priority valve 2
and then to the excavator control valve 4. After passing
through the excavator valve, the oil flows through the
loader valve 5 and then returns to the tank T.
Illustration Key
K Fig 8. ( T E-16)
C Cooler 1 Steer Priority Valve
P1 Transmission Pump 2 Steer Orbitrol Unit
P2 Charge Pump 4 Excavator Valve
P3 Service Pump 5 Loader Valve
M Motor
T
Tank
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