BACKGROUND ART A requirement exists for an efficient portable lifting device that has a large load and lifting height capability but is sufficiently compact to be stored in a closed orientation in a confined space, such as inside the spare wheel of a vehicle. Two existing jack types are the cantilever jack and the scissor jack. Whilst the cantilever jack can be produced in a compact form it has a limited lifting capacity and suffers from serious inherent instability during lifting. In particular the load lifted by the cantilever jack is effectively supported at a single point. This requires the jack to be carefully positioned in relation to the lifting point on the vehicle to avoid the sideways load during lifting exceeding the frictional resistance between the jack and the supporting surface. There is however no way for a user to be positively guided in this positioning. This problem is exacerbated by the lifting point on the vehicle not moving directly upward during lifting by a jack. The lifting point moves along an arc toward the vehicle as the vehicle is raised and an allowance for this movement must be made during initial positioning of the jack.

Scissor jacks offer a more stable configuration but are not particularly compact. Additionally, conventional scissor jacks lift perpendicularly to the supporting surface so that some side loading is introduced as the lifting point of the vehicle follows the arcuate path described above.

A requirement also exists for a tool that is capable of providing a multiplicity of functionalities in use, yet is sufficiently compact to be stored in a confined space. This requirement is particularly apparent in applications such as the replacement of vehicle wheels where one or more conventional tools are required to remove hubcaps and/or wheel nuts, and

to operate the vehicle jack. Typically the conventional tools required to provide the multiplicity of functionalities for these purposes are not sufficiently compact to be stored in a confined space, such as inside the spare wheel of the vehicle.

DISCLOSURE OF THE INVENTION It is an object of this invention to provide a portable lifting device that will meet the above requirement and overcome one or more of the above disadvantages. It is a further object of this invention to provide a multifunctional tool for use with the portable lifting device that will meet the above requirements.

In a first aspect, this invention provides a portable lifting device comprising upper and lower third-order levers pivoted about a common fulcrum, the upper lever being adapted at its free end to support a load, and the lower lever being pivotally connected at its free end to a base; actuating means arranged between the upper and lower levers for simultaneously moving the upper and lower levers relative to each other, the actuating means comprising a screw and upper and lower arms each having respective first and second ends, the respective first ends of the upper and lower arms being pivotally interconnected, the second end of the upper arm being pivotally connected to the upper lever between the fulcrum and the free end of the upper lever, and the lower arm being pivotally connected to the lower lever such that its second end extends beyond the lower lever and is slidably supported for movement during relative movement between the upper and lower levers, and said screw acting between said common fulcrum of the upper and lower levers and the pivotal interconnection of the first ends of the upper and lower arms to effect said relative movement.

Preferably, the second end of the lower arm is slidably supported by the base. The second end of the lower arm preferably includes a guiding formation which captively interengages with a track formation on the base to provide the slidable support. The guiding formation and track formation can for example, be formed by a pin and channel arrangement.

In the preferred form of the invention, the channel in the base is formed by the edges of the base extending upwardly and inwardly.

Preferably, the position of the pivotal connection between the lower arm and the lower lever is selected to maintain the free end of the upper lever directly over the extend of the base during relative movement. In the preferred form of the invention the free end of the upper lever is maintained within about 30 mm of being directly over the pivotal connection between the lower lever and the base.

A nut which threadingly engages the horizontal screw is preferably mounted at the pivotal interconnection between the first ends of the upper and lower arms.

In one form of the invention the upper and lower levers are substantially the same lengths. It is also preferred that the upper and lower arms are substantially the same lengths.

It is further preferred that the upper and lower arms are shorter than the upper and lower levers.

The upper and lower levers preferably have a generally U-shaped cross-section and are arranged with the upper and lower arms such that in a closed configuration the upper and lower arms nestingly engage and at least partially contain the upper and lower arms and the screw.

The lifting device of this invention preferably provides for the free end of the upper lever to move from being about 50 mm from the base to being about 360 mm from the base.

This provides a corresponding lifting range from the ground for the lifting device.

In a second aspect, this invention provides a multifunctional tool for use with a portable lifting device, said tool comprising first and second outer arms pivotally liked to the first and second opposite ends of a central member, a first tool formed at the free end of said first outer arm and a second dissimilar tool being formed at the free end of said second outer arm wherein the respective first and second outer arms can be pivoted between respective first positions in which they extend divergently from said central member and respective second positions in which they are generally aligned and at least partially coextensive with the central

member.

Preferably, in the respective first positions, the respective first and second outer arms extend in substantially opposite directions. The opposite directions are preferably generally perpendicular to the central member.

In the preferred form, the central member has a substantially channel shaped cross- section and in the respective second positions the respective first and second outer arms extend at least partially within the central member. More preferably the first and second outer arms are substantially accommodated within the central member.

The invention will now be described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an elevation of the portable lifting device according to this invention in a first lowered position; Figure 2 is an elevation of the portable lifting device shown in Figure 1 in a semi- raised position; Figure 3 is an elevation similar to Figure 1 showing the lifting device in a fully raised position; Figure 4 is an end view of the lifting device corresponding to Figure 1; Figure 5 is an end view of the lifting device corresponding to Figure 2; Figure 6 is an end view of the lifting device corresponding to Figure 3; Figure 7 is a perspective view of the lifting device corresponding to Figures 1 and 4; Figure 8 is a perspective view of the lifting device corresponding to Figures 2 and 5; Figure 9 is a perspective view of the lifting device corresponding to Figures 3 and 6; Figure 10 is a graph showing a plot of the position of the lifting point of the lifting device with respect to the lower pivot point as a function of the height of the lifting point.

Figure 11 is a side view of a multifunctional tool according to an embodiment of this

invention in an open configuration; Figure 12 is a side view of a multifunctional tool illustrated in Figure 11 in an alternative open configuration; and Figure 13 is a side view of the multifunctional tool illustrated in Figure 11 in a closed configuration.

BEST MODES FOR CARRYING OUT THE INVENTION As shown in Figures 1 to 10, the portable lifting device or jack 2, in accordance with the invention generally comprises upper and lower third-order levers 3, 4 pivoted about a common fulcrum 5. The upper and lower levers 3, 4 have substantially identical lengths.

The upper lever 3 is provided with a groove formation 6 at its free end for the lifting of a load (not shown). The groove formation 6 generally corresponds at least approximately to the profile of a lifting point on a vehicle (not shown).

The lower lever 4 is pivotally connected at 7 by its free end to a base 8 which supports the jack 2 on a surface. Upper and lower arms 9, 10 are pivotally connected about a nut 11 that threadingly engages a screw 12 to form actuating means. The upper and lower arms 9, 10 are respectively pivotally connected at 13, 14 to upper and lower levers 3, 4. The upper and lower arms 9, 10 have substantially identical lengths and are shorter than the lengths of the upper and lower levers 3, 4. The screw 12 extends through a bush 15 at fulcrum 5 and has a hexagonal formation 16 provided for engagement by a tool or handle such as described later. It will be apparent that upper and lower levers 3, 4 and upper and lower arms 9, 10 form a parallelogram bisected by the horizontal screw 12. The screw 12 is rotatably supported by bush 15 which does not engage the thread so that rotation of the screw shortens or lengthens the horizontal diagonal of the parallelogram to simultaneously move the upper lower levers 3, 4 relative to each other. This corresponds to the raising and lowering of the free end of upper lever 3. The lower arm 10 extends beyond lower lever 4 to be slidably supported by base 8. The end 17 of lower arm 10 includes a transversely extending pin 18 which is captively engaged at each side by tracks 19 formed in the base. The tracks 19 are formed by the edges of the base extending upwardly at 20 and inwardly to provided flanges

21. As will be seen from the drawings showing the different positions of the track, the pin 15 traverses the length of slots tracks 19 as the jack is moved from the fully retracted position shown in Figure 7 for example to the fully extended position shown for example in Figure 9.

The upper and lower levers 3, 4 have a generally U-shaped cross-section. As best seen in Figures 1, 4 and 7 the upper and lower levers 3, 4 and upper and lower arms 9, 10 are dimensioned and arranged such that in the lowered or closed configuration the upper and lower levers 3, 4 nestingly engage and substantially surround the upper and lower arms 9, 10 and screw 11. This provides the jack 2 with a small overall height in the lowered or closed configuration.

It will be apparent that the operation of the jack 2 is generally similar to conventional scissor jacks. It will be appreciated however, that the mechanical advantage provided by the upper and lower third-order levers 3, 4 enable the lifting device 2 of this invention to lift loads more efficiently than conventional devices such as scissor jacks. The increase in lifting efficiency provided by the upper and lower third-order levers 3, 4 allows for corresponding reductions in the overall size and weight of the jack 2. More specifically, the jack 2 of this invention may be produced in compact sizes such that its overall length and height in a closed orientation are sufficiently small to be accommodated in a confined space, such as inside the spare wheel of a vehicle. Additionally, the support of the extension of lower arm 10 provided in track 19 considerably enhances the stability of the jack 2 without compromising the compactness of the jack 2 in a closed configuration. The jack of this invention thus combines the stability of a scissor jack with the compactness of a cantilever jack.

Another particular advantage achieved by the configuration of this invention is that the position of the free end of upper arm 3 is maintained very close to directly above the lower pivotal connection 7 between lower arm 4 and base 7 and approximates the movement of the vehicle lifting point during lifting. The following table shows the horizontal distance of the lifting point from the vertical plane intersecting the pivotal axis 7 between lower lever

4 and base 7 for a series of heights of the free end from a surface supporting the base 7. The direction to the left as viewed in Figure 1 is positive or "forward" away from the operator or toward the vehicle. The data in the table is shown graphically in Figure 10.

Free End Horizontal Free End Height in mm Position in mm -0.8 57 -0.5 60 1.3 80 3 100 10.8 200 18.2 300 21.1 330 26.8 360 28 363 As best seen from the graph, the position of the free end or lifting point is maintained within less than 30 mm of the vertical plane of the lower pivotal point at all times. In addition the lifting point of the jack follows a path gradually moving toward the vehicle so as to approximate the accurate path typically followed by vehicle lifting points as the vehicle is raised. This reduces sideways loading and provides for considerable stability of the jack. In particular the need for significant frictional resistance between the base of a jack and the supporting surface is avoided.

As illustrated in Figures 11 to 13, a multifunctional tool 102 in accordance with a preferred embodiment of the present invention generally comprises first and second outer arms 103,104 pivotally linked to the respective first and second opposite ends of a central member 105. The central member 105 is configured to have a generally U-shaped cross- section such that it substantially accommodates both the first and second arms 103,104 when they are folded inwardly towards its centre.

A first tool 106 is provided at the free end of the first outer arm 103 and a second dissimilar tool 107 is provided at the free end of the second outer arm 104. In the illustrated embodiment, the first tool 106 comprises a hexagonally shaped fitting (not shown) for driving the screw of a jack of the type shown in Figure 1 to 10. The second tool 107 comprises a conventional screw driver fitting.

Figure 11 illustrates the multifunctional tool 102 in an open configuration whereby either the first tool 106 or second tool 107 may be operated with the arms 103, 104 and member 105 arranged linearly.

Figure 12 illustrates the multifunctional tool 102 in an alternative open configuration whereby either the first tool 106 or second tool 107 may be operated with the two arms 103, 104 and member 105 arranged as a crank. It will be appreciated that this configuration is particularly advantageous in applications such as the removal or tightening of vehicle wheel nuts and driving the screw of the jack of Figures 1 to 10.

Figure 13 illustrates the multifunctional tool 102 in a closed configuration wherein the first and second outer arm 103, 104 have been folded inwardly towards the centre of the central member 105. As discussed above, the central member 105 has a generally U-shaped cross-section such that it substantially accommodates both of the first and second outer arms 103,104 when they are folded inwardly towards its centre. It will be appreciated that the at least partial nesting of the first and second outer arms 103, 104 inside the central member 105 provides a multifunctional tool 102 that has small overall dimension in a closed configuration.

Additionally, it will be evident from Figure 13 that in the closed configuration the end of screw driver 107 overlies the adjacent end of hexagonal fitting 106. Thus if outer arm 104 is retained in the closed configuration the end of screwdriver 107 retains hexagonal fitting 106 and hence outer arm 103 in position. This facilitates simple mounting of the tool 102 to a vehicle by a single fastening extending through or around central member 105 and outer arm 104 without permitting any movement or rattling of the parts of the tool.

The present invention provides multifunctional tools that are sufficiently compact in a closed configuration to be accommodated in a confined space, such as inside the spare wheel of a vehicle.

The above preferred embodiments of the present invention have been described by way of example only and modifications are possible within the scope of the invention.