WO2004072502A1

WO2004072502A1 - A joint for transmission of torque

Info

Publication number: WO2004072502A1
Application number: PCT/AU2003/000180
Authority: WO
Inventors: Gary Rigby; Anthony O'donnell
Original assignee: Gary Rigby; Anthony O'donnell
Priority date: 2003-02-12
Filing date: 2003-02-12
Publication date: 2004-08-26
Also published as: AU2003212086A1

Abstract

A joint (10) for transmission of torque between an input shaft (12) and an output shaft (14) of a drive by means of a coil spring (16) for joining the said two shafts (12, 14). The joint (10) also includes a coupling (18) that keep the two shafts (12, 14) continuously engaged during transmission of torque between the shafts (12, 14). The coupling (18) is a spherical ball (22) and socket (26) arrangement with more than half of the spherical ball (22) retained within the spherical socket (26). The coupling (18) enables relative pivoting between the said two shafts (12, 14) and can be arranged to transfer thrust from the output shaft (14) to the input shaft (12).

Description

A JOINT FOR TRANSMISSION OF TORQUE

Field of the Invention The present invention relates to apparatus which enables the transmission of torque over a coupling. In one form the invention relates to a drive joint which has application in marine apparatus. Another form of the invention for torque transmission in a vehicular drive assembly is described. The invention can also find use in aerospace equipment, as well as in electronics and industrial machinery.

Background Art Devices for transmitting torque from one rotating shaft to another are known in the art . Such devices utilise so-called Hooke universal joints or Rzeppa constant-velocity joints to join the rotatable shafts and find application in hand tools such as socket wrenches, shown for example in US6,390, 927, US6,267,681 and US5,458,028. In such devices the coupling joint transfers torque between the shafts, although the performance of both constant velocity and universal joints can suffer if such devices were otorised for constant torque transmission, for example, instead of being merely hand-operated. Under such load conditions, severe strain can be placed on the joint and in particular on any joining pins. In the apparatus disclosed in these prior art documents, the spring portion of the joint is present for stiffening the joint assembly and for maintaining the shaft portions at a predetermined angle to each other.

As a further example of this, US3,122,901 describes a universal joint assembly which delivers power from a tractor to a farm implement. Multiple joints are arranged in series at predetermined angles and a non-rotatable external spring acts as a positioning element to restrain axial movement of the joints in order to maintain the relative axial position of each joint in the series. Torque is transmitted via the universal joints but only over a limited range of relative operating angles, as controlled by the spring, in order to avoid joint damage.

Some known devices for transmitting torque over a joint involve complex linkage arrangements which can be prohibitively costly, for example the use of back-to-back universal joints linked together and located in a housing such as shown in EP407630 in an inboard-outboard boat drive train. In US4,065,941 in a high impact wrench, torque is transmitted through a complicated ball joint arrangement. In this apparatus, the external spring portion is used for providing some flexibility and for returning the shafts into axial alignment after each use.

In US1,485,036 a joint is shown which includes an external spring which transmits the rotational torque of one rotating shaft to a second shaft. The proximate ends of each shaft adjoin a ball which functions to allow the shafts to become angularly displaced with respect to one another. This apparatus is suitable in situations where a positive thrust is applied from a first shaft to the ball and then to the second shaft. However, if one shaft should suddenly have a reverse thrust applied to it, for example when the motor drive attached to the first shaft reverses (eg. when a boat drive or tractor drive is reversed) , or even if the spring should become stretched over time with use, the spring can stretch open sufficiently and the ball can become dislodged from its tensioned position between the two shafts during use, and may not necessarily be received back into that position, causing failure of the joint. Summary of the Invention

In a first aspect the present invention provides a joint for transmission of torque between an input element and an output element, the joint including: - a spring associated with the input and output elements and arranged in use to transfer all of the torque between the elements; and - a coupling defined as part of the input and output elements to enable direct coupling of the elements so that they remain in continuous physical contact with each other during transmission of torque. In a preferred embodiment of the joint of the present invention the coupling couples the elements over a range of axial alignments. In situations where both positive and negative axial thrust is applied to either of the elements, and in situations where the spring becomes stretched with use over time, the coupling remains continuously engaged with each element, and the spring of the joint transfers torque between the elements. Preferably the coupling enables relative pivoting between the input and output elements . Preferably the coupling is arranged in use for transmission of thrust between the elements. Most preferably the joint is used to transmit torque from the input element to the output element and to transmit thrust from the output element to the input element. In this regard, typically the input element is rotatably driven by a drive, and typically the output element transmits this drive to a medium (e.g. a body of water, a road etc) . Preferably the coupling includes a spherical or part- spherical ball and socket coupling. Most preferably the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket. Preferably the ball is joined at one end of the input or output elements and the socket is joined at one end of the output or input elements respectively. Preferably the spring is helical and the coupling is located generally centrally within the spring. Preferably each element has a perimeteral flange projecting out therefrom, intermediate its ends, each flange forming a seat for a respective adjacent end of the spring.

I

Preferably each element is a shaft.

In a second aspect the present invention provides an inboard-outboard drive train for mounting on a boat, the drive train including:

- an input drive element having first and second ends, the first end being adapted for coupling to a drive in the boat; an output drive element having first and second ends, the second end being couplable to a propulsion element; a joint for joining the input drive element second end to the output drive element first end, the joint including a spring for transferring torque from the input drive element to the output drive element and a coupling defined as part of the input and output elements to enable direct coupling of the output drive element to the input drive element so that the elements remain in continuous physical contact with each other during transmission of torque .

Preferably the coupling enables relative pivoting between the input and output elements . Most preferably the coupling is used for transferring thrust from the output drive element to the input drive element.

Preferably the coupling includes a spherical or part- spherical ball and socket coupling. Most preferably the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket. Preferably the ball is joined at one end of the input or output elements and the socket is joined at one end of the output or input elements respectively.

Preferably the spring is helical and the coupling is' located generally centrally within the spring. Preferably the output drive element is disposed in a housing. Preferably the elements are shafts.

Preferably steering and trim control elements are mounted on the boat and operatively coupled to the housing. Preferably the trim control element includes a hydraulic ram. Preferably the steering control element includes an arm mounted to the housing and pivotable with respect to the boat . Preferably the input element is mounted at a thrust bearing disposed at a transom or keel of the boat.

In a third aspect the present invention provides a boat including a bow section, a stern section, a drive, a propulsion element and the inboard-outboard drive train of the second aspect, the drive being mounted at the stern section of the boat, the first end of the input drive element being coupled to the drive, and the output drive element second end being coupled to the propulsion element.

In a fourth aspect the present invention provides a drive apparatus for use in a drive assembly, the apparatus including : a first member having opposing ends; - a joint located at each first member end, each joint including a spring and a coupling portion defined as part of and extending from the first member end; and - respective mounting elements located at a free end of each spring, a coupling portion defined as part of and extending from each mounting element, wherein the springs are arranged for transferring torque between each respective mounting element and the first member, and the coupling portions are arranged to enable direct coupling of each respective mounting element or another member to the first member so that the coupled elements, or coupled element and member, remain in continuous physical contact with each other during transmission of torque. Preferably the couplings enable relative pivoting between the first member and each of the mounting elements or other member. Preferably the or each coupling includes a spherical or part-spherical ball and socket coupling. Preferably the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket. Preferably the ball is joined at one end of the first member or mounting element and the socket is joined at one end of the mounting element or first member respectively. Preferably the or each spring is helical and the or each coupling is respectively located generally centrally within the or each spring. Preferably the mounting elements are annular flanges. Preferably the first member is a shaft. Preferably one mounting element is mounted at a differential of a vehicle and the other mounting element is mounted at a gearbox of the vehicle, with the first member extending between the differential and the gearbox.

Alternatively one mounting element is mounted at a differential of a vehicle and the other mounting element is mounted at a wheel of the vehicle, with the first member extending between the differential and the wheel .

In a fifth aspect the present invention provides a drive apparatus for use in an aircraft drive assembly, the drive apparatus including: a member having first and second ends; and - a joint located at the first end, the joint including a spring and a coupling; wherein the second end of the member is couplable to a propulsion element for providing aircraft motion, the spring is arranged for transferring torque from a drive in the aircraft to the member, and the coupling is defined as an extending part of both the member first end and of the drive to enable direct coupling of the member first end and the drive so that they remain in continuous physical contact with each other during the transmission of torque.

Preferably the coupling enables relative pivoting between the drive and the member. Preferably the coupling is used for transferring thrust from the member to the drive. Preferably the coupling includes a spherical or part-spherical ball and socket coupling. Preferably the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket. Preferably the ball is joined at one end of the member or the drive and the socket is joined at one end of the drive or the member respectively.

Preferably the spring is helical and the coupling is located generally centrally within the spring. Preferably the member is a shaft. Preferably the propulsion element is a propeller.

Brief Description of the Drawings Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of one embodiment of a joint for transmission of torque in accordance with the invention.

Figure 2 shows a side view of the embodiment shown in Figure 1.

Figure 3 shows a perspective view of one embodiment of an inboard-outboard boat drive in accordance with the invention when mounted on a boat .

Figure 4 shows a side part-sectional view of the embodiment shown in Figure 3.

Figure 5 shows a side schematic view of one embodiment of a drive apparatus for use in an aircraft drive assembly in accordance with the invention when mounted at an aircraft gearbox and engine.

Figure 6 shows a perspective view of one embodiment of a drive apparatus for use in a drive assembly in accordance with the invention.

Figure 7 shows a side schematic view of a further embodiment of a drive apparatus for use in a drive assembly in accordance with the invention when mounted in a front wheel drive car.

Figure 8 shows a side schematic view of a further embodiment of a drive apparatus for use in a drive assembly in accordance with the invention when mounted in a front wheel drive car. Figure 9 shows a side schematic view of a further embodiment of a drive apparatus for use in a drive assembly in accordance with the invention when mounted^' in a rear wheel drive car.

Figure 10 shows a side schematic view of a further embodiment of a drive apparatus for use in a drive assembly in accordance with the invention when mounted in a rear wheel drive car.

Modes for Carrying out the Invention Referring to Figures 1 and 2, the present invention according to one embodiment provides a joint 10 . for transmission of torque between an input shaft 12 and an output shaft 14 of a drive. The joint 10 includes a coil spring 16 for joining the input 12 and output 14 shafts, the spring 16 arranged in use to transfer torque from the input shaft 12 to the output shaft 14, for example if the input shaft 12 is caused to rotate by being connected to a motor or other prime mover.

The joint 10 also includes . a coupling 18 for joining the input 12 and output 14 shafts. In some embodiments this coupling can be arranged in use to transfer thrust (or axial force) from the output shaft 14 to the input shaft 12, for example if the output shaft 14 is operatively connected to a source of some kind of frictional resistance, such as a propeller in water or air. As the thrust is transmitted from the output shaft 14 to the input shaft 12 via the coupling 18, the apparatus to which the input shaft 12 is connected can be caused to move, for example through the air or across a body of water. In other embodiments which will be described, the coupling 18 of the joint 10 in use may not transmit thrust at all, for example in some front and rear wheel drive applications of the joint 10 in motor vehicles.

The coupling is a spherical ball and socket coupling 18 which enables relative pivoting between the input shaft 12 and output shaft 14. . In the embodiment of the invention shown in the drawings the coupling is formed at each end of a cylindrical protrusion located at the in use opposing ends of the input 12 and output 14 shafts . The protrusion 20 on the input shaft 12 is joined to the spherical ball 22 and the protrusion 24 on the output shaft 14 is joined to the spherical socket 26 for receiving the spherical ball 22. In an alternative embodiment the spherical socket can be located on the protrusion 20 and the spherical ball on the protrusion 24 to achieve the same functionality. The ball and complementary-shaped socket can be part-spherical in shape, eg. egg or teardrop-shaped. The coupling can also be achieved by any other flexible coupling having retaining means other than a ball and socket.

In the preferred embodiment the spherical ball 22 is retained within the spherical socket 26 because more than half of the exterior of the ball 22 is covered by the socket 26. During assembly of the ball and socket coupling 18, the ball portion is placed in a half-socket and the remainder of the socket is joined about the ball and the two halves of the socket then joined together to form socket 26. Thus the coupling 18 continuously engages each shaft 12,14 during transmission of torque via the associated spring 16.

Typically the protrusions 20, 24 and the ball and socket coupling 18 extend centrally through a core of the coil spring 16, although in other embodiments of the joint 10 the protrusions and coupling can be of -centred. In still further embodiments the protrusions and coupling need not be located within the spring but can be located substantially parallel to and on one side of the spring. In one preferred embodiment shown in Figures 1 and 2 an integral flange 30, 32 of larger diameter than the diameter of each respective shaft 12 , 14 is spaced from in use opposing- ends of each shaft 12, 14 and forms a seat for respective opposing ends 34, 36 of the coil spring 16. The opposing ends 34, 36 of the spring 16 are attached to these integral flanges 30, 32 by welding or other appropriate attachment method. Typically the spring 16 is of substantially larger coil diameter than the protrusions 20, 24 which are enclosed by the spring 16. Typically the spring 16 has a coil diameter approximately equal to the diameter of the integral flanges 30, 32, as shown in Figures 1 and 2.

Referring now to the drawings shown in Figures 3 and 4 the present invention according to one embodiment provides an inboard-outboard drive train 40 for mounting on a boat 42. The drive train includes an input drive shaft 43 having a first 44 and a second 46 end, the first end 44 adapted to be coupled to a drive in the form of an engine mounted in the boat 42. The drive train 40 also includes an output drive shaft 48 having a first 50 and a second 52 end, the second end 52 adapted to be coupled to a propulsion element in the form of marine propeller 54. The drive train 40 also includes a joint 56 for joining the input drive shaft second end 46 to the output drive shaft first end 50, the joint 56 including a coil spring 58 arranged in use to transfer torque from the input drive shaft 43 to the output drive shaft 48 and a coupling arranged in use to transfer thrust from the output drive shaft 48 to the input drive shaft 43.

Typically the coupling is a part-spherical ball and socket coupling which enables relative pivoting between the input drive shaft 43 and the output drive shaft 48. In the embodiment of the invention shown in Figures 3 and 4 the coupling is formed at each end of a cylindrical protrusion located at the in use opposing ends of the input 43 and output 48 shafts. The protrusion 62 on the input shaft 43 is joined to the part-spherical socket 64 and the protrusion 66 on the output shaft 48 is joined to the part- spherical ball 68 for receiving in the part-spherical socket 64. More than half of the body of the part- spherical ball 68 is covered by the complementary-shaped socket 64 so that the coupling remains continuously engaged with each shaft 43,48. The protrusions 62, 66 and the ball 68 and socket 64 coupling extend centrally through a core of the spring 58. In an alternative embodiment, the protrusion on the input shaft can be joined to the spherical or part-spherical ball and the protrusion on the output shaft can be joined to the spherical or part- spherical socket .

In the preferred embodiment an integral flange 70, 72 of larger diameter than the diameter of each respective shaft 43, 48 is spaced from in use opposing ends of each shaft 43, 48 and forms a seat for respective opposing ends 74, 76 of the coil spring 58. The opposing ends 74, 76 of the spring 58 are attached to these integral flanges 70, 72 by welding or other appropriate attachment method.

In the preferred embodiment the output drive shaft 48 is disposed in a cylindrical housing 80 and centred in that housing by water lubricated bearings 82. The housing 80 has a rudder fin 84 fitted on its lower side to facilitate steering of the boat 42. A cavitation plate 86 is located on an upper side of the housing 80 and is joined to the housing by a web 88. Steering (left to right positioning of the drive train 40) and trim control (up or down positioning of the drive train 40) devices form part of the drive train 40 and are mounted on the boat 42 and operatively coupled to the housing 80. The upper surface of the cavitation plate 86 has a curved projection 90 which is slidably receiveable in a close fitting curved sleeve 92 which is itself pivotally joined by support bushes 94 and support sections 95 to the transom 96 of the boat 42. Trim tilt control is effected by remote actuation of a hydraulic ram 98 operatively positioned between and pivotally linked to both the curved sleeve 92 and the upper surface of the cavitation plate 86. Steering control is effected by rotation of the tiller arm 100 to cause the curved sleeve 92 to pivot about the support bushes 94 on axis A-A and deflect the drive train 40 from side to side. Such deflection is facilitated by the pivoting action of the ball 68 and socket 64 joint and the flexible bending afforded by the spring 58. Typically the ball 68 and socket 64 joint is located on the axis A-A (the centreline) of the pivotal support bushes 94 which link the curved sleeve 92 to the boat transom 96. Typically the input shaft 43 is mounted at a thrust bearing 102 disposed at the base of the transom 96 adjacent to the keel 104 and at the stern of the boat 42.

In further embodiments of the drive train, the cavitation plate, web and fin can be of different shapes to those shown in the drawings and the propeller need not be of the marine variety as shown but another suitable type of propeller depending on the fluid conditions and boating requirements. Other arrangements of trim pivoting mechanisms are envisaged which may be of a different arrangement to the pivotable hydraulic ram 98 coupled to sleeve 92 and cavitation plate 86 shown. For example, in the absence of a cavitation plate, an hydraulic ram can also be positioned directly between the shaft housing 80 with the opposing end of the ram joined to a slidable member which can move in a slot projecting from the boat transom ultimately linked to the boat tiller arm. The functionality of a flexible coupling and coil spring in a joint which allows trim and steering movement of the drive train as well as the transmission of torque and thrust remains a common element of all such alternative arrangements. In still further embodiments of the drive the coil spring can be of any appropriate profile depending upon the selected torque (revolutions per unit time) required for the particular application.

In use the joint in the drive train is able to transmit a substantial axial force or thrust in conjunction with the ability to transfer large amounts of torque. A Hooke type universal joint in such an application would experience more variable angular velocity and attendant vibration and a Rseppa constant-velocity type joint would be unable to transmit an axial force. The joint of the invention, unlike a Rzeppa joint, is immune to the effects of vibration in the driven shaft. As shown in the drawings, the joint can also be configured such that it is lubricated by the media in which it is immersed, thus eliminating the requirement for periodic lubrication, and therefore reducing the risk of environmental contamination. The drive joint is simple to manufacture with few moving parts and is therefore simpler to maintain. Because of its simplicity, the drive train can also be of significantly less weight than conventional boat drive trains which can be of importance in racing boats, for example. In use the flexible nature of the coil spring allows the input shaft and the output shaft to be displaced such that the angle between them can be of the order of 45 degrees and still allow full transmission of torque and axial force (thrust) . This gives the drive train the flexibility of being used in either hard water (fully submerged in water) , semi-surfacing or surface piercing applications depending upon the selected trim angle. Present boat drive train apparatus usually only allows a drive to be used in one or other of these situations, for example EP407630 (SAND) is designed to operate in hard water whereas US4976638 (GRINDE) is designed to operate in a surface piercing application.

In a further example of the use of the apparatus of the invention to transfer both torque and thrust, Figure 5 shows a drive apparatus 302 for use in an aircraft drive assembly 300. The drive apparatus 302 includes a member in the form of a shaft 304 which may be a hollow tube or a solid shaft. The shaft 304 has first and second ends and a joint 10 (as described in earlier preferred embodiments) located at the first end. The joint 10 includes a helical coil spring 16 and a spherical or part-spherical ball and socket coupling 18 located inside the spring 16 and extending from the end of the shaft 304.

The coupling 18 of the joint 10 is couplable to a drive in the form of a gearbox 306 and motor 308 co bination in an aircraft. The spring of the joint 10 is arranged for transferring torque from the gearbox 306 and motor 308 to the shaft 304. Typically the spring 16 and coupling 18 also enables relative pivoting between the gearbox/motor 306, 308 and the shaft 304 and is also used for transferring thrust therebetween. The joint 10 may be mounted to the gearbox 306 by any suitable means including bolting or welding of the spring 16 to the gearbox outlet flange, for example. The second end of the shaft 304 is couplable to a propulsion element in the form of a propeller 310 in use for providing aircraft motion and flight .

Further examples of use of the joint 10 for transmission of torque between an input shaft 12 and an output shaft 14 of a drive will now be described where the coupling is not used to transfer thrust (or axial force) from the output shaft 14 to the input shaft 12. Some preferred examples of the use of the joint are shown now in Figures 7 and 8 in a drive assembly for a front wheel drive motor vehicle and in Figures 9 and 10 in a drive assembly for a rear wheel drive motor vehicle. Figure 6 shows a preferred arrangement of drive apparatus 201 for use in a drive assembly 200 of the types shown in Figures 7 to 10. The apparatus 201 includes a first member in the form of a shaft 202 which may be a hollow tube or a solid shaft. The shaft has opposing ends each of which have a joint 10 (as described in earlier preferred embodiments) located thereat. Thus each joint has a helical coil spring 16 and a spherical or part- spherical ball and socket coupling 18 located inside the spring 16 and extending from the ends of the shaft 202. Mounting elements in the form of annular flanges 204 are located at a free end of each spring 16. The flanges 204 provide a means of attaching the drive apparatus 201 to a drive assembly 200, for example to the output flange of a vehicle differential 206 or a vehicle gearbox 208. Typically the flanges 204 have holes 209 for receiving bolts to enable fastening attachment of the flanges 204 to another item.

In this embodiment, the springs 16 are arranged for transferring torque between each annular flange 204 and the shaft 202. The couplings 18 are arranged to couple each respective flange 204 to the shaft 202. In other embodiments the couplings 18 can be coupled to another shaft (or other item, such as a wheel hub) so that for example a number of shafts 202 may be linked together in series depending upon the application.

In use the couplings 18 enable relative pivoting between the shaft 202 and each of the flanges 204 (or other like shafts or other items) . However while the drive apparatus 201 can easily cope with the transmission of thrust, ^"in some applications this is not required. For example in Figure 7 a front wheel drive assembly of a motor vehicle is shown. Drive is supplied to the drive assembly 200 by a motor 210 and gearbox 208 combination. The drive motion passes via a differential 206 of the vehicle into a drive apparatus 201 which features a joint 10 located at either end of a splittable tube or shaft which features sliding spline pins 211 as a means of joining the shaft into one piece. The splines optionally allow a variation in the drive shaft assembly 200 length and can allow some relative axial movement between the two ends of the shaft 202. At the free ends of each joint 10, one of the annular flanges 204 can be mounted to the differential 206 of the vehicle and the other annular flange 204 can be mounted at a wheel 212 of the vehicle so that the shaft 202 extends between the differential 206 and the wheel 212. In a further preferred form shown in Figure 8 a joint 10 is located at either end of a fixed length tube or shaft 214, the shaft 214 having end flanges 216 to which the joints 10 are attached.

In a further preferred form of the invention shown in Figure 10 a rear wheel drive assembly 220 of a motor vehicle is shown. Drive is supplied to the drive assembly 220 from a motor 222 and gearbox 224 combination. The drive motion passes via an outlet flange 226 of the gearbox 224 into a drive apparatus 221 which features a joint 10 located at either end of a tube or shaft 226. The free end 227 of one joint 10 has an annular flange 228 which in use is mounted to the outlet flange 226 of the gearbox 224. The outlet flange 226 is in turn joined to the gearbox 224 by spline pins 229. The free end 230 of the joint 10 located at the opposing end of the shaft 226 is mounted to an inlet flange 232 of the differential 234 of the vehicle so that the apparatus 221 extends between the differential 234 and the gearbox 224. Spline pins 233 mount the inlet flange 232 of the differential 234 to the differential 234. The differential 234 is then attached to the rear wheel of the vehicle. In a further preferred form shown in Figure 9 a drive apparatus 242 includes a joint 10 located at either end of a length of tube or shaft 240. The shaft 240 requires no end flanges to attach the joints 10 thereto, the apparatus 242 being directly welded or formed together. One joint 10 is then attached to the outlet flange 226 of a gearbox 224 and the joint 10 at the opposing end of the shaft 240 is attached to the inlet flange 244 of the differential 246 (inlet flange 244 and differential 246 being shown in hidden detail) . The differential 246 is then attached to the rear wheel 236 of the vehicle.

The materials of construction of the joint 10 can comprise any suitable materials which can be shaped, formed and fitted in the manner so described, such as metal or metal alloy coil springs and a metal ball and socket coupling. Alternatively the joint can be made of hard plastics to give a structurally sound device that can withstand the loads imposed. Because it can be used in a corrosive environment in contact with salt water, it is most preferable that the joint be made of suitably stable materials .

It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms a part of the common general knowledge in the art, in Australia or any other country.

Whilst the invention has been described with reference to preferred embodiments it should be appreciated that the invention can be embodied in many other forms.

Claims

1. A joint for transmission of torque between an input element and an output element, the joint including:

- a spring associated with the input and output elements and arranged in use to transfer all of the torque between the elements; and

- a coupling defined as part of the input and output elements to enable direct coupling of the elements so that they remain in continuous physical contact with each other during transmission of torque.

2. A joint as claimed in claim 1 wherein the coupling enables relative pivoting between the input and output elements .

3. A joint as claimed in claim 1 or claim 2 wherein the coupling is arranged in use for transmission of thrust between the elements.

4. A joint as claimed in claim 3 wherein the joint is used to transmit torque from the input element to the output element and to transmit thrust from the output element to the input element.

5. A joint as claimed in any one of the preceding claims wherein the coupling includes a spherical or part- spherical ball and socket coupling.

6. A joint as claimed in claim 5 wherein the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket .

7. A joint as claimed in claim 5 or claim 6 wherein the ball is joined at one end of the input or output elements and the socket is joined at one end of the output or input elements respectively.

8. A joint as claimed in any one of the preceding claims wherein spring is helical and the coupling is located generally centrally within the spring.

9. A joint as claimed in any one of the preceding claims wherein each element has a perimeteral flange projecting out therefrom, intermediate its ends, each flange forming a seat for a respective adjacent end of the spring.

10. A joint as claimed in any one of the preceding claims wherein each element is a sha t .

11. An inboard-outboard drive train for mounting on a boat, the drive train including:

- an input drive element having first and . second ends, the first end being adapted for coupling to a drive in the boat; an output drive element having first and second ends, the second end being couplable to a propulsion element

- a joint for joining the input drive element second end to the output drive element first end, the joint including a spring for transferring torque from the input drive element to the output drive element and a coupling defined as part of the input and output elements to enable direct coupling of the output drive element to the input drive element so that the elements remain in continuous physical contact with each other during transmission of torque .

12. An inboard-outboard boat drive as claimed in claim 11 wherein the coupling enables relative pivoting between the input and output elements.

13. An inboard-outboard boat drive as claimed in claim 11 or claim 12 wherein the coupling is used for transferring thrust from the output drive element to the input drive element.

14. An inboard-outboard boat drive as claimed in any one of claims 11 to 13 wherein the coupling includes a spherical or part-spherical ball and socket coupling.

15. An inboard-outboard boat drive as claimed in claim 13 wherein the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket .

16. An inboard-outboard boat drive as claimed in claim 14 or claim 15 wherein the ball is joined at one end of the input or output elements and the socket is joined at one end of the output or input elements respectively.

17. An inboard-outboard boat drive as claimed in any one of claims 11 to 16 wherein the spring is helical and the coupling is located generally centrally within the spring.

18. An inboard-outboard boat drive as claimed in any one of claims 11 to 17 wherein the output drive element is disposed in a housing.

19. An inboard-outboard boat drive as claimed in any one of claims 11 to 18 wherein the elements are shafts.

20. An inboard-outboard boat drive as claimed in claim 18 wherein steering and trim control elements are mounted on the boat and operatively coupled to the housing.

21. An inboard-outboard boat drive as claimed in claim 20 wherein the trim control element includes a hydraulic ram.

22. An inboard-outboard boat drive as claimed in claim 20 or claim 21 wherein the steering control element includes an arm mounted to the housing and pivotable with respect to the boat .

23. An inboard-outboard boat drive as claimed in any one of claims 11 to 22 wherein the input element is mounted at a thrust bearing disposed at a transom or keel of the boat .

24. A boat including a bow section, a stern section, a drive, a propulsion element and the inboard-outboard drive train of claim 11, the drive being mounted at the stern section of the boat, the first end of the input drive element being coupled to the drive, and the output drive element second end being coupled to the propulsion element.

25. A drive apparatus for use in a drive assembly, the apparatus including: a first member having opposing ends; a joint located at each first member end, each joint including a spring and a coupling portion defined as part of and extending from the first member end; and respective mounting elements located at a free end of each spring, a coupling portion defined as part of and extending from each mounting element, wherein the springs are arranged for transferring torque between each respective mounting element and the first member, and the coupling portions are arranged to enable > direct coupling of each respective mounting element or another member to the first member so that the coupled elements, or coupled element and member, remain in continuous physical contact with each other during transmission of torque.

26. A drive apparatus as claimed in claim 25 wherein the couplings enable relative pivoting between the first member and each of the mounting elements or other member.

27. A drive apparatus as claimed in claim 25 or 26 wherein the or each coupling includes a spherical or part- spherical ball and socket coupling.

28. A drive apparatus as claimed in claim 27 wherein the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socke .

29. A drive apparatus as claimed in claim 27 or claim 28 wherein the ball is joined at one end of the first member or mounting element and the socket is joined at one end of the mounting element or first member respectively.

30. A drive apparatus as claimed in any one of claims 25 to 29 wherein the or each spring is helical and the or each coupling is respectively located generally centrally within the or each spring.

31. A drive apparatus as claimed in any one of claims 25 to 30 wherein the mounting elements are annular flanges.

32. A drive apparatus as claimed in any one of claims 25 to

31 wherein the first member is a shaft.

33. A drive apparatus as claimed in any one of claims 25 to 32 wherein one mounting element is mounted at a differential of a vehicle and the other mounting element is mounted at a gearbox of the vehicle, with the first member extending between the differential and the gearbox.

34. A drive apparatus as claimed in any one of claims 25 to

32 wherein one mounting element is mounted at a differential of a vehicle and the other mounting element is mounted at a wheel of the vehicle, with the first member extending between the differential and the wheel.

35. A drive apparatus for use in an aircraft drive assembly, the drive apparatus including: a member having first and second ends; and a joint located at the first end, the joint including a spring and a coupling; wherein the second end of the member is couplable to a propulsion element for providing aircraft motion, the spring is arranged for transferring torque from a drive in the aircraft to the member, and the coupling is defined as an extending part of both the member first end and of the drive to enable direct coupling of the member first end and the drive so that they remain in continuous physical contact with each other during the transmission of torque.

36. A drive apparatus as claimed in claim 35 wherein the coupling enables relative pivoting between the drive and the member.

37. A drive apparatus as claimed in claim 35 or claim 36 wherein the coupling is used for transferring thrust from the member to the drive.

38. A drive apparatus as claimed in any one of claims 35 to 37 wherein the coupling includes a spherical or part- spherical ball and socket coupling.

39. A drive apparatus as claimed in claim 38 wherein the socket portion of the coupling encases more than half of the ball therewithin so that the ball is retained within the socket.

40. A drive apparatus as claimed in claim 38 or claim 39 wherein the ball is joined at one end of the member or the drive and the socket is joined at one end of the drive or the member respectively.

41. A drive apparatus as claimed in any one of claims 35 to

40 wherein the spring is helical and the coupling is located generally centrally within the spring.

42. A drive apparatus as claimed in any one of claims 35 to

41 wherein the member is a shaft.

43. A drive apparatus as claimed in any one of claims 35 to 42 wherein the propulsion element is a propeller.