5-10t Internal Combustion Counterbalance Forklift Truck Operation & Maintenance Manual
7.1 Overview
The hydraulic system mainly includes oil pump composed of front and rear pumps, multi-way valve
(bypass valve and multi-way valve mounted together), steering unit, high/low pressure oil pipe and
joint, etc. Oil pump is a gear pump, mounted on the side face of transmission. When engine runs, it
actuates the oil pump. It sucks out oil from oil tank and transmit it to multi-way valve. The safety
valve inside the multi-way valve is used to maintain the oil pressure of oil circuit within the range of
the specified value, while through the control over the valve stem, the passage of oil circuit inside the
multi-way valve body is changed, to take the control over the cylinder. The oil through bypass valve
to the steering unit is used to control the action of steering cylinder.
7.2 Oil Pump
Oil pump is composed of front and rear pumps. The front pump is the main pump, used for steering,
lift, and tilt, while the rear pump is only used for lift and tilt.
The oil pump is a gear pump, mainly composed of driving gear, driven gear, and pump body, namely
the oil pump includes two gears and some other parts. The driving gear and the driven gear are
engaged. Speaking from the forklift trucks with power brake, the front pump is a duplex pump, while
the small pumps in serial connection are specially applied to oil supply for power brake.
7.3 Multi-way Valve (Refer to Fig 7-1.)
Fig 7-1 Multi-way Valve
Multi-way valve is in a cut type, and it is composed of three major parts including inlet (bypass valve
mounted in the part of inlet), outlet, and slide valve. Three bolts are used to assemble these three
parts together. Bypass valve (in the part of inlet) are mounted together with multi-way valve, for the
structure to be compact and the pipeline to be simple.
A cylinder-shaped main safety valve is available in the part of inlet, used to adjust the oil pressure in
oil circuit. Steering safety valve is also available, for adjusting the oil pressure in the power steering
oil circuit. The limit identifications of the safety valves are marked using red scale lines.
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