June 2004 - 9507EI/5
1-23
2 to 9 Tonne Dumper Instruction Manual
Hydraulic System
The hydraulic system provides power to operate the vehicle
steering and to power the skip elevation.
All dumpers other than the turntable models have a similar
hydraulic circuit layout (see circuit diagrams) and all the
components other than the skip ram, steering ram and the
hydraulic pump are common.
In the case of the turntable dumpers, additional rams are
required to slew the skip to the left or right positions.
The system comprises an engine driven hydraulic pump drawing
oil from a tank located inside the chassis. The tank is fitted with
a suction strainer, an oil level gauge, and a filler/breather cap.
2 to 4 Tonne Hydraulic Circuit
Orbitrol
Control Valve
Hydraulic Tank
Steering Ram
Skip Ram
Hydraulic
Oil Cooler
- if fitted
From
Pump
To
Pump
The pump generates a maximum pressure of 150 bar (2200psi)
on the standard skip dumpers and 170 bar (2500psi) on the
turntable skip dumpers. The system is protected by a relief valve
in the control valve which is set at the same pressure. A return
line filter is fitted to the circuit and is either of the replaceable
cartridge type (Steel Tanks) or the replaceable element type
(Plastic Tanks)
Steering of the dumper is by means of a single hydraulic ram
connecting the front and rear frames, the oil supply to the ram
is controlled by an Orbitrol hydrostatic steering unit. The unit
receives oil via a carry over port in the 3 way control valve and
meters oil to the steering ram as the steering wheel is turned, at
all times.
How the Hydraulics Function
Straight Skips
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