Elevator – industrial lift truck – or stationary lift for vehicle – Industrial lift truck or required component thereof – Having structure allowing propulsion or steering by walking...
Reexamination Certificate
2003-05-06
2004-07-27
Bidwell, James R. (Department: 3651)
Elevator, industrial lift truck, or stationary lift for vehicle
Industrial lift truck or required component thereof
Having structure allowing propulsion or steering by walking...
C187S231000, C414S662000
Reexamination Certificate
active
06766882
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable.
BACKGROUND OF THE INVENTION
Typically, a low lifting floor conveyor truck is provided with a driving unit and a load unit. The driving units bears the driving wheel, which is beared hingedly around a vertical axis and which can be coupled to a corresponding steering appliance, for instance a drawbar. Besides, the motor transmission arrangement as well as the lifting facility for the load unit is disposed in the driving unit. The lifting facility is mostly formed by one or two hydraulic lifting cylinders. The load unit, which normally accommodates the battery for the battery-operated electric motor, is connected to two wheel arms, which form the load fork. The wheel arms are supported on their free ends by load wheels, which on their part are beared on a rocker arm. The rocker arm co-operates with a linkage transmission, which is coupled to the driving unit on the other end, such that upon a height adjustment of the load unit the rocker arm is simultaneously adjusted also, in order to follow up the height movement of the wheel arms. The linkage transmission is mostly designed as a push or pull rod system.
With such linkage transmissions, there is the aspiration to provide an adjustment facility in order to compensate for larger tolerances in production. Because the kinematics is branched into two wheel arm systems, the asymmetries can be compensated by two adjustment facilities. The definite adjustment takes place only after the assembly. The objective of such an adjustment is to maintain the lowered height of the wheel arms in the region of the load wheels. This is particularly necessary when one gets into the pallets in the transverse direction.
It is known to undertake a linkage transmission adjustment with the aid of an eccentric. Another possibility consists in changing the linking of the reversing lever in its position with the aid of plain washers.
The disadvantages in the known systems consist in the increased times required for assembling and adjustment, which by far exceed the coast saving potential of a more coarse manufacture of the single components. Furthermore, the full cylinder lifting range can no more be utilised.
The invention has as an objective to provide a low lifting floor conveyor truck in which adjustment works for the wheel arm kinematics are omitted, but a full lifting range of the lifting cylinder is maintained anyway.
BRIEF SUMMARY OF TH INVENTION
In the invention, a bearing component is linked to the upper end of the lifting cylinder, which is connected with the load unit via a screwed connection, the screwed connection being designed such that it allows a limited relative displacement between bearing component and load unit in its detached state.
Advantageously the rocker arm is provided with a stopping face which co-operates with the bottom side of the load arm. In the lowered height position of the wheel arms the rocker arm rests on the stopping face. The lifting cylinder is supported by the driving unit. Thus, through a relative adjustment between the bearing component and the load unit upon the stopping of the load wheel rocker arm or the arrival of the load wheel on the downward position, respectively, a corresponding compensation can be carried out, before the screw connection is tightened. Preferably the screw connection is designed for non-positive transmission of the lifting forces.
According to one form of the invention, upon the rocker arm acts a push bar, which on its other end is linked to a reversing lever, which on its part is linked to the load unit and to the driving unit.
According to a further form of the invention, the piston rod of the lifting cylinder points in the downward direction and is accommodated in a pocket or the like of the driving unit in an approximately fitting manner. The component is linked to an endside eye of the lifting cylinder jacket.
Preferably the bearing component is an angular-shaped component, which is linked with one leg to one side of the lifting cylinder, and takes its rest against a support face of the load unit with the other leg. Preferably this leg, which has a panel-shaped design, is provided with at least one elongated hole for the purpose of relative adjustment between the bearing component and the load unit. The latter is then provided with a corresponding thread bore for the accommodation of the screw bolt.
In the inventive low lifting floor conveyor truck the lifting range of the lifting cylinder is completely utilised. The delineated adjustment of the linkage transmission preferably takes place at the end of the main assembly. Thereafter, no more adjustment is necessary.
REFERENCES:
patent: 2650733 (1953-09-01), Blatz
patent: 5158639 (1992-10-01), Washizaki
patent: 5468116 (1995-11-01), Reichert et al.
patent: 5918703 (1999-07-01), Nordstrom
patent: 6125971 (2000-10-01), Niebuhr et al.
patent: 6309168 (2001-10-01), Holmes
patent: 6648581 (2003-11-01), Gibson
patent: 23 18 048 (1978-08-01), None
patent: 38 31 375 (1990-03-01), None
Bidwell James R.
Jungheinrich Aktiengesellschaft
Vidas Arrett & Steinkraus P.A.
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