45 - 2
Basic System Operation
Component Identification
A Right hand joystick controller
B Left hand joystick controller
C Operator seat
D Servo pressure supply valve
E Isolation valve solenoid
F Accumulator
G Servo pressure regulating valve
H Servo pressure relief valve
J Loader valve block
K Excavator valve block
L Hydraulic tank
The following section describes the JCB Precision Control
system fitted to machines from January 2003. There is
another JCB Precision Control system fitted to earlier
machines, which is described in a separate section. Refer to
Precision Control (Servo) - Machines up to serial number
931159.
Circuit Description
The JCB Precision Control system facilitates operation of the
backhoe (excavator) via joystick controllers A and B
mounted in the arms of the operator’s seat. Unlike manual
machines the excavator valve spools are moved by hydraulic
pressure and not directly by mechanical levers.
A servo pressure supply valve D maintains a constant supply
of oil at servo pressure to the right and left hand joystick
controllers.
The joysticks each directly operate pressure reducing valves.
These valves in turn operate the excavator valve spools via
hydraulic servo pressure. The interconnecting hoses are
routed to and from the joystick controllers through the
central seat support pillar and then through the cab floor.
The joysticks control the boom, dipper, bucket and slew
functions.
Section D Controls
9803/3280
Section D
45 - 2
Issue 1
Precision Control (Servo)
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