1 - 9
Rams
Boom Lift
Crowd (80 x 40)
(100 x 50)
Compensating (60 x 30)
(50 x 25)
Ram Torque Settings
Piston Head:
Boom Lift
Crowd (80 x 40)
(100 x 50)
Compensating (60 x 30)
(50 x 25)
End Cap:
Boom Lift
Crowd (80 x 40)
(100 x 50)
Compensating (60 x 30)
(50 x 25)
Bore Rod Dia Stroke
mm in mm in mm in
70 2.75 40 1.57 677 26.65
80 3.15 40 1.57 233 9.17
100 3.94 50 1.97 234 9.21
60 2.36 30 1.18 264 10.39
50 1.97 25 0.98 288 11.32
Nm lbf ft Kg fm
405 299 41.3
405 299 41.3
405 299 41.3
300 221 30.6
250 184 25.5
678 500 69.2
678 500 69.2
678 500 69.2
450 331 45.9
400 295 40.8
Section E
Hydraulics
9803/8500
Section E
1 - 9
Issue 2*
Technical Data
General Description
The main components of the hydraulic circuit are the tank, pumps, drive motors, control valves, filters, cooler, and rams. Two
types of control system are used, servo and manual. On servo machines, hydraulic joystick controls are used to operate the
loader and drive functions.
The pumps are driven by the engine and are mounted in tandem. They deliver pressurised oil to the valves and motors.
Servo Machines
When a drive control is operated, oil is fed from the joystick to the transmission pump servo-controls. The pump swashplate
moves to vary or change the flow direction to the motors and hence the speed or direction of rotation. When a loader control is
operated, servo oil is fed from the joystick to a loader valve spool which then moves to direct pressurised oil to operate the
appropriate ram. Relief valves in the loader and transmission circuits prevent system pressure from rising too far.
On machines prior to serial number 678000, hydraulic pressure for the joysticks is regulated by the Pressure Reducing Solenoid
Valve which, together with its associated electrical circuitry, is designed to ensure that the controls cannot be operated without
the operator being seated correctly, with the Safety Restraint Bar in the operating position and the door closed and latched.
On machines from serial number 678000, hydraulic pressure for the joysticks is regulated by the transmission pump charge
valve and is fed to the joysticks via the solenoid operated Brake Valve. The Brake Valve, together with its associated electrical
circuitry, is designed to ensure that the controls cannot be operated without the operator being seated correctly, with the Safety
Restraint Bar in the operating position and the door closed and latched.
Manual Machines
The control levers are mechanically connected to the transmission pump and to the loader valve block. When a drive control is
operated, the pump swashplate is moved to change or reverse the flow direction to the motors. When a loader control is
operated, the loader valve spool moves to direct pressurised oil to operate the appropriate ram. Relief valves in the loader and
transmission circuits prevent system pressure from rising too far.
As an option on machines after serial number 678000, the loader functions can be controlled by dual foot pedals.
A mechanical interlock prevents the controls from being moved unless the Safety Restraint is in the operating position. In
addition, on machines after serial number 678000, solenoid operated lockout valves also prevent the boom service from being
operated until the operator is seated correctly in his seat, with the door closed and latched.
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