Material or article handling – Self-loading or unloading vehicles – Loading or unloading by other carrier or mover means – and...
Reexamination Certificate
2000-05-02
2002-04-23
Keenan, James W. (Department: 3652)
Material or article handling
Self-loading or unloading vehicles
Loading or unloading by other carrier or mover means, and...
Reexamination Certificate
active
06375404
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a loading platform system for mounting on vehicles, especially trucks, comprising a lifting mechanism, an essentially plate-like loading platform for lifting and lowering a load and at least one lift actuator for lifting and lowering the loading platform. The lifting mechanism includes at least one support arm with a first end by which it is supported on the vehicle so as to be pivotable about a first axis of rotation and a second end which is connected pivotally to the first end of a lifting actuator, a second end of the lifting actuator being rotatably supported on the vehicle.
Such a loading platform system is described for example in EP-A-0808747. Loading platform systems have been known in various designs for a long time. They are often used on trucks in order to be able to unload loads carried by the trucks at the destination that is to lower a load from the truck bed to the ground so that the load can then be further moved by other means. The same is true for the loading procedure of a vehicle that is the load is first deposited on the loading platform when disposed at ground level and lifted to the level of the vehicle load bed and finally moved onto the load bed.
In some designs of loading;platform systems, the loading platform is tilted from a horizontal to a vertical position when the loading procedure is completed. In this position, the loading platform can serve additionally as the rear end wall of the load bed or respectively, of a box-like loading space.
In other embodiments of known loading platform systems, that is, so-called folding loading platforms, the loading platform is not tilted from a horizontal to a vertical position and vice versa; rather these loading platforms are folded after the loading procedure and are then moved below the load bed that is below the rear end of a load bed of a truck.
For the lifting and lowering of the loading platform while in a horizontal position for loading a load onto, and unloading a load from, the loading bed of a truck to street level and from the street level to the level of the load bed of the truck, a so-called lifting actuator is utilized which is operated hydraulically, pneumatically, electrically or in some other way. For the tilting of the loading platform, if such possibility is provided, that is, for the opening and closing of the loading space by movement of the platform from the vertical to the horizontal position and vice versa, a tilting arrangement is used which is actuated hydraulically, pneumatically, electrically or in some other suitable way. Loading platform systems of the type described have at least two actuator arrangements, wherein generally the lift actuator arrangement cooperates with one support structure of a lift and tilting structure which is usually, but not necessarily a parallelogram arrangement. The tilting actuator arrangement cooperates with the other support structure of the lift and tilting structure. However, a tilt actuation structure is only provided if a tilting movement from a horizontal position of the loading platform to the vertical positions and vice versa is necessary.
Known loading platform systems encountered substantial problems during loading and unloading that is under the effects of a force which may reach substantial values depending on the weight of the goods to be moved: As a result of the load disposed on the loading platform, the loading platform may bend relative to the loading bed of the truck so that gaps are formed between the loading platform and the load bed in horizontal as well as in vertical directions. Furthermore, those gaps may vary over the width of the load bed opening. As a result, particularly with heavy loads which need to be moved by the loading platform, vertical thresholds are formed between the loading platform and the loading bed so that the load must often be moved across such threshold by a carriage by hand or by other means.
With the solution presented in EP-A-0 808 747 of the assignee of the present invention, the problems described above have been solved that is no vertical or horizontal gaps between the loading platform arranged horizontally relative to the loading bed of a motor vehicle are formed. In addition, the solution has the very positive effect that the loading platform may be very simple in design, and, because of its design, does not provide for an uneven loading of the support structure. As a result, the support structure remains operative over a long period of time and the service requirements could be reduced to a minimum.
In a lifting support structure of such a loading platform system a substantial torque is generated on the lift support mechanism when the loading platform is in a horizontal position already because of the relatively high weight of the loading platform. Consequently, there is a force effective on the support structure with a substantial vertical force component. When the support structure reaches its end position at the level of the loading bed of the truck that is at the maximizing lift travel of the loading platform and the maximizing lift effect of the lift actuator structure, there is still a small vertical threshold between the level of the loading platform and the level of the load bed of the truck. In this respect, it is pointed out that the lifting mechanism with the support arm and the lift actuator including the pivot or, respectively, axis points of the loading platform can actually not be a totally rigid system since, because of design and material reasons, there is always a certain elastic deformation of the individual elements of the lift mechanism. The elements of the lift mechanism therefore act in a way like springs, particularly the support arms. In order to overcome the deformation caused by the spring action which is responsible for the forming of the gap described earlier the lift actuation arrangement is so operated that the loading platform is lifted actually to the same level as the loading bed of the truck so as to overcome deviations caused by the elastic deformation particularly of the support arms of the lifting mechanisms in order to reduce any gap between the loading platform and the loading bed to zero.
This problem is solved by the loading platform system de scribed above in an elegant manner by providing a second support arm which, at its first end, is interconnected with the first support arm and has at its second end, a pivot axis which extends essentially perpendicularly to the two support arms and by way of which the second support arm is rotatably connected to the loading platform. With the two support arms which are interconnected like pincer arms or spring pliers, the lift actuator operation or movement can be completed by way of the spring action of the two support arms until the loading platform reaches the level of the loading bed while the elastic deformation of the lift mechanism is compensated for.
This design is however relatively expensive and complicated although it is very effective.
It is therefore the object of the present invention to provide a loading platform system, whereby the loading platform can be raised in a simple manner exactly to the desired level so that no vertical gap is formed between the loading platform and the loading bed no matter how large the load on the loading platform is. The system should also be easily installable in existing loading platform arrangements.
SUMMARY OF THE INVENTION
In a loading platform system for mounting on a vehicle, comprising a lift mechanism support structure, at least a first support arm having an end pivotally connected to the lift mechanism support structure and pivotally supporting at its other end a loading platform for supporting a load and a lifting actuator connected between the lift mechanism support structure and the other end of the support arm for operating the support arm for lifting and lowering the loading platform, the loading platform is pivotally connected to the second end of the first support arm by way of a spring-loaded guide me
Bach Klaus J.
Keenan James W.
Sörensen Hydraulik, Zweigniederlassung, Ulfborg, Filial af Sören
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