I Caravan Jack Adaptor FIELD OF THE INVENTION [0001] The present invention relates to a jack adaptor, in particular an adaptor that for making a conventional hydraulic bottle jack suitable for use with a caravan. BACKGROUND TO THE INVENTION [0002] Caravan jacks have strict guidelines as laid down in the relevant Australian standards. Available jacks that comply with the standards are either very bulky (typical hydraulic jacks) or very small and inefficient (scissor jacks). Conventional hydraulic bottle jacks are not suitable for use as their saddles are not designed to engage the jacking points of a caravan. [0003] It is desirous to have a caravan jack that complies with the relevant standards and is also compact and easy to use. The jack needs to be small for ready storage and to fit under a caravan with a completely flat tire. The jack must also provide a large lift capacity, suitable mechanical advantage and elevation. No known jacks provide such a combination of features. [0004] The object of this invention is to provide an adaptor to convert a conventional hydraulic bottle jack for use with a caravan whilst maintaining the small size and efficiency of the jack, or at least provides the public with a useful alternative. SUMMARY OF THE INVENTION [0005] In a first aspect the invention comprises an adaptor for a hydraulic bottle jack, comprising a collar for fitting around an extension screw of the jack and a jacking head adapted to engage the split collar and adapted to engage a jacking point of a caravan. [0006] Preferably the collar is a split collar. [0007] Preferably the collar comprises a flange to facilitate manual manipulation of the collar.
[0008] The jacking head may include a ball or a slotted block for engaging the jacking point of the caravan. [0009] It should be noted that any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below as appropriate. BRIEF DESCRIPTION OF THE DRAWINGS [0010] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows. [0011] Figure 1 shows a prior art hydraulic bottle jack used in conjunction with the present invention. [0012] Figures 2A and 2B depict the two halves of a split adaptor collar of the present invention [0013] Figure 3 shows the split adaptor collar being fitted to the extension screw of a prior art jack. [0014] Figure 4 shows the split adaptor collar fitted to the prior art jack. [0015] Figures 5A and 5B shows top and bottom views of a first embodiment of a jacking head that is used to engage a jacking point of a caravan. [0016] Figure 6 shows a jack assembly including a split adaptor collar and a jacking head fitted there to. [0017] Figure 7 shows the jack assembly of Figure 6 with the extension screw of the jack extended. [0018] Figures 8A and 8B show an extension piece. [0019] Figure 9 shows an extension piece fitted to a split adapter collar.
[0020] Figure 10 shows a jack assembly including an extension piece. [0021] Figures 11 A and 11 B show top and bottom views of a second embodiment of a jacking head that is used to engage a jacking point of a caravan. [0022] Figure 12 shows a second jack assembly incorporating the jacking head of Figure 11. LIST OF COMPONENTS 10 hydraulic bottle jack (Prior Art) 12 body 14 ram 16 extension screw 18 saddle 20 split adaptor collar 21 first collar half 22 second collar half 23 body 24 flange 25 bore 28 groove 30 jacking head (first embodiment) 31 body 32 neck 33 ball 34 threaded fixing hole 35 bore 40 extension piece 41 body 42 neck 43 threaded fixing hole 44 bore 50 jacking head (second embodiment) 51 neck 52 block 53 slot 54 threaded fixing hole 55 internal thread 100 jack assembly (first embodiment) 102 jack assembly with single extension (first embodiment) 104 jack assembly with double extension (second embodiment) DETAILED DESCRIPTION OF THE INVENTION [0023] The following detailed description of the invention refers to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration. [0024] In essence the invention provides an adaptor for a hydraulic bottle jack comprising a split collar for fitting around an extension screw of the jack and a jacking head adapted to engage the split collar and also engage a jacking point of a caravan. [0025] Figure 1 shows a conventional hydraulic bottle jack 10 as is well known in the art. Such a jack is not suitable for use with a caravan as its saddle 18 is not designed to engage the jacking point of a caravan. The present invention adapts such a bottle jack to form a jack that is suitable for use with a caravan whilst maintaining the advantageous size and mechanical advantage of the bottle jack. [0026] The bottle jack 10 comprises a body 12 from which a ram 14 extends. An extension screw 16 extends from the ram to allow the height of the jack to be adjusted. Atop the extension screw sits a saddle 18 which engages the object to be jacked up. [0027] The adaptor of the present invention comprises several parts which when fitted together transform a conventional hydraulic jack for use with a caravan. The adaptor includes an optional extension piece to cope with varying heights of caravans and an interchangeable jacking head to cater for the varying forms of caravan jacking points. [0028] Figure 2A and 2B depict a split adaptor collar 20 of the present invention which adapts the extension screw 14 of a jack 10 to allow further components to be readily attached to the jack. The collar 20 comprises first half 21 and second half 22 which when fitted together form a complete collar. The collar 20 includes a body 23 with an inner bore 25 corresponding in size to the extension screw 16 off a jack. A flange 24 located on the lower extremity of the body allows the collar to be manipulated. A groove 28 extends aroudnthe collar to help engage further components as discussed below. [0029] Figures 3 and 4 show the two halves 21, 22 of the split adapter collar coming together around the extension screw 16 of the jack 10. The collar is fitted whilst the extension screw is partially extended such that the collar is held in place between the ram of the jack and the saddle of the jack. [0030] Figures 5A and 5B depict a first embodiment of a jacking head 30 which includes a cylindrical body 31 from which extends a neck 32, on top of which sits a ball 33 which engages a complementarily shaped jacking point of a caravan. The jacking head includes a bore 35 allowing it to be fitted to the split adapter collar to which it is held in place with the aid of a grub screw fitted to threaded fixing hole 34 and engaging groove 28 of the collar. The flange 24 of the adaptor 20 is held to prevent rotation as the jacking head is screwed on or off. [0031] Figure 6 shows a complete jack assembly 100 with an adapter collar 20 and a jacking head 30 fitted. In this view the extension screw of the jack's is only extended as far as is needed to fit the adaptor collar [0032] Figure 7 shows the same assembly as in Figure 6 however the extension screw 16 has been extended from the ram 14 giving the jack assembly a greater height. Typically the extension screw will be rotated to bring the jacking head in contact with the jacking point of the caravan. The adaptor collar 20 does not slide up or down the extension screw as it is extended as the jack saddle 18 is clamped between the collar 20 and jacking head 30. [0033] Figures 8A and 8B depict an extension piece 40 which may be used to increase the height of a jack assembly. The extension piece 40 includes a cylindrical body 41 and cylindrical neck 42. Internal bore 44 and threaded screw hole 43 allow the extension piece to be fitted to an adaptor collar in a similar fashion to a jacking head. A jacking head can then be fitted on the neck 42. An extension piece is shown fitted to an adaptor collar in Figure 9. [0034] A complete jack assembly 102 including an adaptor collar 20, extension piece 40 and jacking head 30 is shown in Figure 10. [0035] A second embodiment of a jacking head 50 is shown in Figure 11 A from above and in Figure 11 B from below and comprises a block 52 with slot 53 fitted above a body 51. The body includes a threaded inside 55 and threaded screw hole 54 allowing it to be mounted to either a collar 20 or extension piece 40. [0036] A complete jack assembly 104 incorporating the jacking head according to the second embodiment 50 is shown in Figure 12. [0037] In a further embodiment (not shown), the split collar 20 is replaced with a non-split collar. To fit the non-split collar the saddle 18 is first unscrewed from the extension screw 16. The non-split collar is then slid over the extension screw and the saddle screwed back in place. [0038] The reader will now appreciate the present invention which provides an adaptor that converts a conventional hydraulic bottle jack for use with a caravan, whilst maintaining the advantages of the bottle jack. [0039] Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field. [0040] In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.