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5-10t Internal Combustion Counterbalance Forklift Truck Operation & Maintenance Manual

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When engine is flamed out, the steering wheel is controlled depending on manual force, to drive
the  rotor through  valve  core,  poking  pin,  and  universal  driving  shaft  and  to  press the oil  from
one cavity of the steering cylinder into the other cavity, through, to drive the steering wheel, so
as to achieve manual steering (d in Fig 6-4). Oil is supplied from oil tank through one-way valve
for oil supply.
BZZ1-model  steering unit used for this  forklift truck is an open-core nonreactive type, namely
the  external  force  acted  on  the  steering  wheel  cannot  be  transmitted  to  steering  wheel.  The
driver has no road sense.
6.1.3 Application Requirements
(1) Installation
When steering unit is installed, it shall be ensured that it shall be concentric with the connecting
shaft assembly on the lower end of universal joint, and axial clearance shall exist, to avoid valve
core  from  being  jammed  up,  and  it  is  required  to  examine  whether  or  not  steering  wheel  can
reset flexibly.
For pipeline installation, the “Inlet” marked at the joint of steering unit shall be connected with
the oil pipe from oil pump, while the marked “Return” is to be connected with oil tank, and the
marked  “Left”  and  “Right”  shall  be  respectively  connected  with  the  left  cavity  and  the  right
cavity of steering cylinder.
The  allowable  flow  rate  for  oil  suction  pipe  is  1-1.5m/s,  while  the  allowable  flow  rate  for
pressure oil pipe and return oil pipe is 4-5m/s, and the test pressure for high-pressure hose shall
not be lower by 1.5 times than the maximum operating pressure.
The section of oil tank position shall be higher than the mounting position of steering unit, and
oil suction pipe shall be inserted into the oil level, thus to be able for oil supply during manual
steering, and at the same time to be able to avoid blending of air into oil.
To facilitate safety and repair, it is recommended to set a pressure gauge adapter in the place of
oil inlet for steering unit, so that the pressure gauge can be installed.
(2)Range of Oil Temperature: -20

℃

～

+80

℃

Normal Oil Temperature: +30

℃

～

+60

℃

(3)Selection of Oil Used: N46 or N32 Hydraulic Oil
(4)Filtration:  The  filtration  precision  for  oil  liquid  into  steering  unit  is  30μm,  and  it  shall  be
ensured that the return oil of steering unit has a 0.2-0.3MPa back pressure, to prevent backflow
of oil into oil tank during manual steering.
(5)All  the  pipelines  in  the  system  shall  be  cleaned  up,  and  the  oil  tank  shall  be  closed,  to
minimize oil pollution.
(6)Test Run: Test Run: Prior to operation oil tank shall  be cleaned, and oil shall  be  injected to
the maximum oil level. Loosen the threaded joint for the cylinder, for the oil pump to operate at
low speed for air bleed, until the outgoing oil contains no foam anymore.
Remove the connection between piston rod and steering wheel, and turn the steering wheel, for
piston to reach the leftmost or the rightmost position (staying to be avoided at the two extreme
positions, and then further add oil into the oil tank up to the maximum oil level.
Tighten  all  the  threaded  connection  places  (tightening  under  pressure  to  be  avoided),  connect
the piston rod, and examine whether or not the work of steering system is normal under various
working  conditions.  It  is  required  to  search  for  the  causes  carefully  when  heavy  steering  or
malfunction is found. It is not allowed to turn the steering wheel forcibly, and moreover to take
it apart in a hurry, to prevent the damage of parts for the steering unit.