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

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9.1 Overview
Rolling type is applied to lifting system, and the basic type is a two-stage telescopic mast type. The
inner  mast  is  in a  J-shaped  section, while the  C-shaped  section  is applied to outer masts  for all the
5-8t forklift trucks, other than the outmast in a J-shaped section for 10t forklift truck.
9.2 Outer & Inner Mast
The mast assembly is in a two-stage telescopic type including free hoist, and it is composed of inner
mast and outer mast, to be supported with bracket for mast, with the bracket for mast welded on the
bottom  part  of  the  outer  mast,  extended  to  the  axle  housing,  and  connected  together  with  axle
housing, namely the deadweight of mast is supported by axle housing. There is also the bracket for
tilt  cylinder  on  the  outer  mast,  and  the  front  end  of  tilt  cylinder  (namely  the  end  of  piston  rod)  is
connected  with  this  bracket  using  pin  shafts.  The  mast  tilts  under  the  action  of  tilt  cylinder,  for  a
forward tip of 6° and a backward tip of 12°.
9.3 Fork Carriage
Roller  shaft  is  welded  on  the  fork  carriage,  and  the  main  roller  and  its  snap  ring  rolling  on  the
internal surface along the inner mast are mounted on the roller shaft, while the side rollers rolling on
the  inner  side  along  the  inner  mast  are  prized  onto  the  inner  mast  using  bolts,  and  adjusted  by
adjusting shim. In order to prevent the sway of fork beam (support plate, or upper cross beam), two
limit  rollers  are  installed,  and the  limit  rollers  roll  on  the outer  side  face  along  the inner  mast. The
main  roller  bears  the  longitudinal  load,  and  the main  roller  mounted  above  is  exposed  (some  part),
when the Fork rises to the maximum lifting height, while the limit rollers above and the side rollers
below withstand the traverse  load. Enough rigidity and strength  have  been taken  into consideration
about  the  design  of  mast  assembly  and  fork  carriage,  while  operating  stability  has  been  also
considered at the same time.
Besides, the upper and lower cross beams of fork carriage are made of
high-strength  steel,  and  the  fork  carriage  is  made  into  an  integrated
structure,  to  ensure  its  durability.  It  complies  with  ISO  standard
(international standard).
Two forks are loaded on the fork carriage. The forks are made of alloy
steel, and are heat treated.
9.4 Adjustment of Lifting System
9.4.1 Gasket Adjustment for Lift Cylinder Head
When  lift  cylinder,  inner  mast  or  outer  mast  is  disassembled  and
replaced, the stroke of lift cylinder shall be readjusted.
The adjusting method is described as follows:
(1)Load the head of piston rod not added with adjusting shim into the
upper cross beam of inner mast.
(2)Slowly  raise  the  mast  to  the  maximum  stroke  of  cylinder,  and  examine  whether  or  not  the  two
cylinders are synchronous.
(3)Add  the  adjusting  shim  between  the  head  of  piston  rod  for  the  cylinder  that  has  firstly  stopped
movement and the upper cross beam of inner mast. Fig 9-1
Thickness of Adjusting Shim: 0.2