Lifting trolley The present invention relates to a lifting trolley with a raisable lifting platform which is substantially suited for moving and lifting objects which will be heavy or inconvenient for ordinary people to handle. The lifting trolley substantially consists of a vertical and a horizontal frame part which is supported by one or more wheels at the transition between the vertical and horizontal frame parts. The lifting trolley can therefore be moved in the same way as transport trolleys by rotation of the lifting trolley about the wheels' horizontal rolling axis, whereupon the lifting trolley balances on the wheels and is moved by means of the user's muscle power. When the lifting trolley is positioned for loading or unloading, the lifting trolley's frame is rotated about the wheels'rolling axis until the lifting trolley is resting on the frame's horizontal lower frame part possibly in addition to the wheels.

The lifting trolley's lifting platform is further designed and arranged so that it can be brought almost right down to ground level where it is integrated in the lifting trolley's horizontal frame part in such a manner that an object which has to be moved can easily be transferred from ground level, or near ground level, up on to the lifting trolley's horizontal frame part and lifting platform.

Furthermore, the lifting platform is lifted by a drive device which moves the lifting platform via a transmission means in a vertical direction along a guiding or steering means which is provided in connection with the lifting trolley's vertical frame part.

Ordinary transport trolleys are often used to move objects over short distances on smooth or partially uneven surfaces but provide no assistance when the object which has to be moved has to be placed on a level higher than ground level. For this purpose lifting trolleys can be employed which by means of a mechanical device can move an object in a vertical direction between ground level and a desired level above the ground. Such lifting trolleys have a lifting platform, where an object which has to be moved is first placed on the lifting platform, whereupon it can be lifted to the desired level above the ground. If the lifting platform's lower position is at a distance above ground level this means that a user first has to lift the object on to the lifting platform before the lifting platform can transfer the object to the desired level above the ground. Such lifting trolleys, moreover, have to be designed so as to provide good and stable support when an object is lifted

and if the lifting trolley also has to be able to be moved with a load it must be designed so that the load is firmly located on the lifting platform during transport.

There is, however, a need for a device, such as a lifting trolley, which can be used for moving objects and lifting them to a desired level above the ground.

The device must be able to move on a partially uneven surface and must be able to be positioned with a high degree of stability for a lifting operation.

The device's lifting platform must be able to be lowered to a level which is only slightly above ground level so that it will be easy for a user to place an object which has to be lifted on to the platform. The lifting platform should be able to be moved by means of manual or motor power and this should be controlled from the lifting trolley, thus enabling a user to support the trolley when lifting if necessary. If the lifting platform is motor operated, this in turn should be operated by a power supply which is mounted and located on the lifting trolley, thus enabling the trolley to be used independently of any power supply such as, e. g., electric power or the like.

Known technical solutions in relation to devices which can be used both for transporting and lifting objects are described, e. g., in Swedish laid-open patent publication 414759, which concerns a lifting device which can raise and lower parcels or the like by means of mechanical operation and which can be moved. The device consists substantially of a vertical and a horizontal frame part with a guiding or steering means provided on the frame for a lifting platform which moves in a vertical direction. The lifting platform is operated substantially by a manual mechanical arrangement. The device which is described is essentially intended for lifting goods and positioning them for relocation and to a lesser extent for transport of the goods which are lifted. On account of the frame's design and support on four wheels, there will be little possibility of placing large objects on the lifting platform without having to lift them up on to the platform, which will be extremely inconvenient for a user. Furthermore, the device will be sensitive to rough patches and obstacles in the surface since these will create an unstable situation for the lifting device when it is moved. The device is therefore not really suited to cover the requirements described above and the solution will not achieve the same functional advantages as a lifting trolley according to the present invention.

In Norwegian patent application 773574 there is further described a manually drivable transport vehicle with a mechanically raisable and lowerable loading platform, which is also based on a frame supported by four wheels in the rear edge and front edge respectively of the frame's lower horizontal extension.

The device is further provided with a vertically positioned rail as in the solution in the above-mentioned Swedish publication and in connection with this rail there is further provided a screw spindle in the vertical direction which by means of a motor and transmission can be employed to raise and lower a lifting platform along the vertical rail or guide means. The lifting platform is further adapted in size and position to pass through an opening in the lower horizontal part of the frame (as in the solution in the above- mentioned Swedish publication), thus enabling the lifting platform to be moved almost right down to ground level. If, however, one wishes to place a large object on the lifting platform, it will come into conflict with the lifting device's horizontal frame part and the front wheels supporting it. The solution which is described in NO 773574, therefore, like the solution in SE 414759 is not really suited for lifting objects whose dimensions are larger than the lifting platform, or larger than the opening in the lifting device's horizontal lower frame part. In addition, the transport vehicle in NO 773574 will be prone to be unbalanced when it is moved on the four wheels which support the transport vehicle and will therefore only be suitable for lifting and accurately positioning an object.

The present invention relates to a lifting trolley with a raisable lifting platform which is substantially suited for both lifting an object and transporting it over a partially uneven surface. A lifting trolley according to the present invention comprises a substantially L-shaped frame with a substantially vertical frame part and one or more horizontal frame parts at the lower end of the vertical frame part. The horizontal frame part or parts are designed in such a manner that the lifting trolley stands steady in a stationary position and in this position the lifting trolley is substantially supported by the vertical frame part in addition to the wheels which according to the present invention are mounted at the transition between the horizontal and vertical frame parts. The horizontal frame part, furthermore, is of a limited height with the result that any heavy objects do not have to be lifted any substantial distance when they have to be moved from ground level to a lifting platform located in the same plane as the horizontal frame part. In an

embodiment of the present invention the wheels are located on brackets immediately behind the transition between the lifting trolley's vertical and horizontal frame parts, forming a tilting point for the lifting trolley when it is moved. In a further embodiment the wheels may be mounted on the side of the lifting trolley near the transition between the vertical and horizontal frame parts, which may provide slightly better lateral stability, but which also gives the lifting trolley greater width.

The lifting trolley is further provided with a raisable platform which is designed with a horizontal platform part and preferably a vertical platform part which provides support for goods which are placed on the lifting platform during transport. According to the present invention the lifting platform is designed in a known per se manner to be narrower than the opening in the horizontal frame part, with the result that in its lower position the lifting platform is located in the same horizontal plane as the lifting trolley's horizontal frame part. By this means a relatively large transport surface is obtained for goods which have to be moved by the lifting trolley, in addition to which a very low height is obtained (in practice only material dimension in the lifting platform and the lifting trolley's horizontal frame part), which makes it easy to move heavy objects from ground level to the lifting trolley's lifting platform. Furthermore, in its horizontal part the lifting trolley is not supported by wheels or the like and is therefore located very close to ground level.

When an object has to be transported, it can thereby be transferred up on to the lifting platform, where it rests on the lifting trolley's horizontal frame part as well as the lifting platform, both of which are located in the same horizontal plane, providing good stability and support for the object which is placed on the lifting trolley. As with traditional two-wheel trolleys, the trolley can be tilted about the wheel's axis of rotation, with the result that the trolley's horizontal frame part assumes a positive angle relative to ground level and the trolley's vertical frame part is moved to a position which makes it easier for the user to pull or push the trolley during transport.

When and if the object which is transported on the lifting trolley has to be raised to an elevated position, the trolley is tilted back to the starting position about the wheels'horizontal axis until the lifting trolley's horizontal frame part is resting on the ground. The lifting trolley is thereby supported

primarily by the horizontal frame part which provides a highly stable position for the lifting trolley when the lifting platform has to be raised. In a preferred embodiment, moreover, the lifting trolley is provided with a drive device which may be an electric motor, a pneumatic motor, a hydraulic motor or the like, which can raise and lower the lifting platform via a transmission means.

In order to further contribute towards stable raising and lowering of the lifting platform, in a preferred embodiment the lifting platform is provided along its lateral edges with rollers which move along the vertical frame parts of the lifting trolley. In a preferred embodiment, furthermore, the vertical frame parts may be channel sections with their openings facing each other, or angle sections which further help to guide the rollers on the side of the lifting platform. The lifting platform is then moved in a vertical direction along the vertical frame parts and the lifting trolley remains resting in a stable fashion on the lifting trolley's horizontal frame part. In a preferred embodiment the lifting trolley's frame is further provided with the necessary units for operation of the drive device which raises and lowers the lifting platform, such as a hydraulic accumulator, pneumatic accumulator, a battery or the like. The transmission from the drive unit to the lifting platform may be of various types, and the drive body may be a linear actuator such as, e. g., a hydraulic linear motor (possibly telescopic) installed in the lifting trolley's lower frame part, or it may be a rotating motor with a winch drum or the like which can raise or lower the lifting platform via a pulley or the like mounted in the lifting trolley's upper frame part. It is also possible to employ a toothed bar located in the lifting trolley's vertical direction, where the lifting platform is provided with a drive device which moves it along the toothed bar. In this case, however, the lifting platform must be provided with a drive device, thus adding to the weight on the lifting platform, which in turn reduces the maximum load which the platform can lift. Other commonly known drive devices and transmissions may, of course, also be used and will be obvious to a person skilled in the art.

A lifting trolley according to the present invention may further be provided in an embodiment with hinges or the like at one or more points along the vertical frame part, thus making it possible to fold up the vertical frame part to facilitate transport of the lifting trolley, e. g. in the boot of a car. In an embodiment of this kind the transmission between a drive device and the lifting platform should be flexible and a strap, a rope, a wire or the like

which moves between a winch drum mounted in the frame's lower edge, via a pulley mounted in the frame's upper part to the upper part of the lifting platform's vertical part will be capable of satisfying the requirement for flexible transmission, thus enabling the lifting trolley's vertical lifting part to be folded up around one or more hinges.

In a preferred embodiment there is further provided an operating body for the drive device on the vertical frame part of the lifting trolley, at a suitable location for a user. The operating device, however, should not be located in such a manner that it is in the way of the user when the lifting trolley has to be moved. It will therefore be natural to mount the operating device on one of the frame sides, preferably facing away from the side where the lifting platform moves in order to avoid coming into conflict with the lifting platform or the load when it is raised or lowered.

The invention will now be described in further detail in relation to the figures, in which: figure 1 is a perspective view of an embodiment of a lifting trolley according to the present invention; figure 2 is a side view of a further embodiment of a lifting trolley according to the present invention; figure 3 is a side view of the lifting trolley illustrated in figure 2 in the transport position; figure 4 illustrates the lifting trolley shown in figures 2 and 3 in a position where the lifting platform is raised; figure 5 is a rear view of a lifting trolley as illustrated in figures 2 to 4 in an unloaded position where the lifting platform is in the lower position.

In figure 1 an embodiment of a lifting trolley according to the present invention is illustrated where the trolley comprises a substantially L-shaped frame consisting of a horizontal lower frame part 1 and a substantially vertical frame part 3. In the transition between the horizontal frame part 1 and the vertical frame part 3 a wheel is mounted on each side of the frame.

Furthermore, the lifting trolley has a lifting platform consisting of a horizontal part 2 and a vertical part 2', which lifting platform is designed to

be narrower than the internal opening in the horizontal frame part 1, with the result that in its lower position the lifting platform's horizontal part 2 is located in the same horizontal plane as the lifting trolley's horizontal frame part 1. In the embodiment illustrated in figure 1, the horizontal frame part 1 forms only one internal opening where the lifting platform can be located at its horizontal part 2 in the same horizontal plane as the lifting trolley's horizontal frame part 1. In further embodiments the horizontal frame part 1 will be able to be designed as, e. g., two open forks and the lifting platform's horizontal part 2 may have a corresponding fork shape where the lifting platform is designed in such a manner that it fits into the fork-shaped openings in the horizontal frame part 1, with the result that the lifting platform's horizontal part 2 is located in the same horizontal plane as the lifting trolley's frame part 1. This embodiment is particularly suitable for lifting pallets.

In the embodiment illustrated in figure 1, moreover, the lifting platform 2,2' can be raised along the vertical frame parts 3 of the lifting trolley's frame 1,3 and the lifting platform 2,2'is steered by wheels or rollers 4 which are passed along the vertical frame parts 3 on each side of the lifting platform's vertical part. In this case the vertical frame parts may be composed of channel sections where the openings face each other, angle sections or the like which provide adequate steering for the rollers 4 which support the lifting platform 2,2'. In figure 1 rollers 4 are only marked in the upper part of the lifting platform's vertical part 2', while in other embodiments it will be possible to place a plurality of rollers along the vertical part 2'of the lifting platform 2,2'.

The lifting platform 2,2'can further be raised and lowered along the lifting trolley's vertical frame parts 3 by means of a motor 5 with transmission 6.

The motor 5 may, e. g., be a linear actuator, hydraulically or pneumatically driven, it may be an electric motor with a winch with flexible transmission as shown in figures 2 to 5, or the motor 5 and the transmission 6 may be of any other known form which directly or via an element in the upper part 11 of the lifting trolley's frame helps to raise and lower the lifting platform 2,2'along the lifting trolley's vertical frame parts 3. The motor 5 is further driven by an energy accumulator 9, which, e. g., may be a battery, a hydraulic accumulator, a pneumatic accumulator or the like and the motor 5 is further controlled by an operating body 7 which is preferably located on the lifting trolley's

vertical frame parts 3 as illustrated in figure 1. Alternatively, the motor may be remotely controlled or the operating body 7 may be installed in another suitable location in connection with the lifting trolley.

Figure 2 is a side view of a further embodiment of a lifting trolley according to the present invention where the lifting trolley's frame consists of the horizontal frame part 1 and the vertical frame part 3 is resting on the ground supported by the horizontal frame part 1 and the wheels 10. The wheels 10 are mounted on a bracket on the rear of the lower part of the vertical frame part 3, thus making it possible to rotate or tilt the lifting trolley about the wheels'10 horizontal axis, as illustrated in figure 3. Furthermore, as illustrated in figures 1 and 2, a lifting platform is located in its lower position, where the lifting platform's horizontal part 2 is located in the same horizontal plane as the lifting trolley's horizontal frame part 1. Moreover, the lifting platform's vertical part 2'is located against and partly between the lifting trolley's vertical frame part 3, with the result that the vertical frame part 3 supports and guides the lifting platform's vertical part 2'when the lifting platform 2,2'moves vertically along the lifting trolley's vertical frame part 3. As in the embodiment illustrated in figure 1, the embodiment of a lifting trolley illustrated in figures 2,3,4 and 5 is provided with a motor 5 which raises and lowers the lifting platform 2,2'via a transmission means 6 and the motor 5 is driven by an energy source 9 and operated by an operating device 7. In the embodiment illustrated in figures 2 to 5, an electric motor 5 is employed which via a drum releases and retracts a band, a wire or the like which via a pulley or the like in the upper part 11 of the lifting trolley's frame is located from the motor's 5 winch, via the pulley under 11, to the upper part of the lifting platform's vertical part 2'. When the lifting platform has to be raised, which is illustrated in figure 4, the motor 5 is operated by the operating body 7, with the result that the motor 5 winds up the band, wire or the like which constitutes the transmission device 6 on a drum and the transmission device 6 pulls the lifting platform 2,2'up in the vertical direction along the lifting trolley's frame part 3.

In figures 1 to 5 it is further illustrated that the vertical frame part 3 on each side is divided and provided with hinges or the like 8 which permit the vertical frame parts 3 to be divided and the upper part of the vertical frame parts 3 comprising the handle 11 can be tilted about the hinges 8 to a position substantially parallel to the lower parts of the vertical frame parts 3, thus

substantially reducing the height of the lifting trolley with the result that the lifting trolley can be placed, for example, in the boot of a car.

If a plurality of objects have to be transported by the lifting trolley, the lifting platform 2 may be loaded, whereupon it is raised to the desired level above the ground and then the horizontal frame part 1 is loaded, whereupon double the load can be carried compared to a traditional two-wheel trolley.

In the above a brief and exemplified account has been given of the inventive concept and this must not be perceived to be limiting in relation to the invention which is only limited by the following claims. Every change and modification which must be considered obvious to a person skilled in the art must therefore also be considered to be covered by the inventive concept which is indicated in the claims.