5-10t Internal Combustion Counterbalance Forklift Truck Operation & Maintenance Manual
The main oil circuit for hydraulic system turns to be complicated as double pump and steering oil
circuit are applied. O-ring is used for the joint of oil pipe, for sealing, typical of a very satisfactory
sealing property, to ensure the oil sealing.
The hydraulic oil drained from the rear pump is directly sent to multi-way valve, while the hydraulic
oil drained from the front pump (the main pump) is divided into two circuits through bypass valve,
namely for the steering and cargo loading-unloading tasks.
The abovementioned hydraulic oil used for cargo loading-unloading work flows into the multi-way
valve and is added together with the return oil drained from the rear pump to be supplied for the
purposes of cargo lift and tilt. When multi-way valve is under the status of middle position, these
hydraulic oils return to oil tank through multi-way valve.
When lift control lever is pulled, the oil from the multi-way valve reaches the lower part of the lift
cylinder piston through limiting valve, and drives the piston rod. When lift control lever is pushed,
the oil circuits between the lower part of the lift cylinder position and the oil tank are connected. Due
to the deadweights of piston rod, fork carriage, and fork, etc, the piston begins to drop, and in this
case, the speed of return oil flowing back through multi-way valve is adjusted by limiting valve.
When tilt lever is operated, the hydraulic oil from the main pump reaches the certain side of the tilt
cylinder piston and drives the piston to act, while the oil on the other side will be pushed out by
piston, and return to oil tank through multi-way valve.
7.10 Maintenance
7.10.1 Disassembly of Multi-way Valve
Disassemble the multi-way valve from the forklift truck and clean its external part.
(1)Remove the connecting blots, for respective plates of multi-way valve to be taken apart, but don’t
lose the springs on the one-way valve and the bonding face.
(2)Demount the screw on one side of the slide valve head and the bolt with hexagonal slot on the
cover side, and detach the slide valve including rubber cup, o-ring, and sealing plate altogether from
the valve body.
(3)Put the slide valve on the bench vice, loosen off the connecting bolt for the cover, and then detach
the spring and the spring seat. Also demount the spring and the valve core inside the tilt auto-locking
valve, from the tilt slide valve mounted with tilt auto-locking valve.
7.10.2 Reassembly of Multi-way Valve
Clean all the detached parts using mineral oil, and examine whether or not burr or score is present, to
be replaced if required. The valve body and the slide valve, as well as the slide valve and the valve
core shall be properly wrapped up after assembly, to be wholly replaced if required.
(1)Clamp the slide valve using bench vice, and then fit in the valve core and the spring. Pay attention
to the direction of valve core.
(2)Fit in the o-ring, rubber cup, sealing plate, and spring seat, as well as spring and spring seat, to be
mounted in this sequence into the back end of the slide valve. Tighten the connecting bolts at a 25～
32N·m torque, after they and the cover are properly assembled.
(3)Insert the slide valve assembly (one-plate valve) properly assembled into the valve body and fit in
the cover, to be connected using the bolts with hexagonal slot (the tightening torque for the bolts as
9～11N·m).
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