AU2006222533A1 - Manually propelled wheelchair device - Google Patents

Description

WO 2006/094332 - 1 - PCT/AU2006/000187 MANUALLY PROPELLED WHEELCHAIR DEVICE FIELD OF THE INVENTION The present invention relates, generally, to wheeled conveyance 5 assemblies and relates particularly, though not exclusively, to a manually operated wheelchair which can be controlled and steered by either or both arms of an occupant. Throughout the ensuing description the expressions "single-handed occupant(s)" and "two-handed occupant(s)" are intended to refer to persons 10 who have one or two usable hands or arms respectively. BACKGROUND OF THE INVENTION Manually-operated. wheelchairs are well known. Most prior art manually-operated wheelchairs have been designed for two-handed operation 15 by persons, as for example paraplegics, having full or partial use of both hands. Typically, a wheelchair is movably supported by two larger rear wheels and two smaller forward (generally swivel-type) wheels. These wheelchairs are manually-driven or operated by an occupant gripping top portions of the larger rear wheels (or hand-rim assemblies directly connected to the rear wheels) and 20 then pushing the wheels in a desired direction to propel the wheelchair in a chosen direction. If an occupant desires to turn the wheelchair in a particular direction, the larger rear wheel on that side of the wheelchair relevant to the direction of turn is pushed more slowly than the opposite rear wheel, which gradually changes the direction of movement of the wheelchair. Sharp turns 25 are generally accomplished by holding one rear wheel stationary whilst pushing the opposite rear wheel in a desired direction. In some cases both rear wheels are propelled in opposite directions to rotate the wheelchair sharply on the-spot in a desired direction. The smaller forward wheels of the wheelchair generally swivel and follow the arc of rotation of the wheelchair directed by 30 the propulsion applied to the rear wheels. Two-handed manually operable wheelchairs usually include frames which are collapsible for transportation. A common design for a conventional WO 2006/094332 - 2 - PCT/AU2006/000187 collapsible two-handed wheelchair includes side-frames which are mounted to scissor-like cross-frame members which enable the opposing side-frames to be drawn together in close proximity to one another, which results in the overall dimensions of the wheelchair being substantially reduced. This collapsible 5 configuration facilitates portability, ease of transportation and storage in, for example, the boot of a vehicle. A disadvantage associated with one design for conventional two handed manually-driven wheelchairs is that an occupant must use both arms to manoeuvre the wheelchair at all times. This is most disadvantageous when an 10 occupant needs to carry an object from one point to another, for example from a refrigerator to a kitchen table. It is common practice in situations like this for a wheelchair occupant to balance any load he (or she) wishes to carry on his (or her) lap whilst manoeuvring the wheelchair with both arms. A further disadvantage with known designs of conventional two-handed 15 wheelchairs is due to the fact that, since they have two large rear drive wheels independently connected to the wheelchair frame, the muscle power of a single arm can only be delivered to a single drive wheel of the wheelchair. If a wheelchair occupant has one arm stronger than the other, the maximum effort in forward movement of the wheelchair is dependent on that of the weakest 20 arm, otherwise the wheelchair would continually turn if uneven strength was to be continually applied to both wheels. Some manually-driven wheelchairs have also been provided for single handed operation by persons having use of only a single hand. Typically, single-handed manually-driven wheelchairs provide two individually operable 25 and concentrically positioned hand-rim assemblies mounted on the working hand side of the wheelchair. Each hand-rim assembly is adapted to drive one wheel of the wheelchair. A first hand-rim assembly is usually directly mounted to the rim of one large rear wheel of the wheelchair, whilst a second hand-rim assembly, generally located adjacent the first hand-rim assembly, is 30 coupled to the opposite rear wheel and is operable in order to drive the opposite rear wheel from the working-hand side of the wheelchair. A single drive axle couples the hub of the rear wheel located on the non-working-hand side to the WO 2006/094332 - 3 - PCT/AU2006/000187 second hand-rim assembly located on the working-hand side. This arrangement of two hand-rim assemblies located on a single working-side enables an occupant to not only drive the rear wheel adjacent the working hand, but also the opposite rear wheel located on the opposite side of the 5 wheelchair by way of pushing both hand-rim assemblies together or separately in a desired direction. When both hand-rim assemblies are propelled together, the occupant is able to drive the wheel chair in a relatively straight line by using only a single hand. One problem associated with single-handed manually-driven 10 wheelchairs is that they are purposely designed for either left or right handed operation, and not both. Such wheelchairs usually require tooling to convert the wheelchair from left-handed drive to right-handed drive operation, depending on which arm an occupant is able to use. A further disadvantage with such prior art single-handed wheelchairs is that they are sometimes not 15 collapsible or do not collapse to a sufficiently compact state, due to the rigid or semi-collapsible drive axle configuration interconnecting the second hand-rim assembly with the rear wheel located on the non-working-hand side of the wheelchair. Usually, in the case of rigid drive axles, the drive axle extends transverse to the side-frames of the wheelchair in a direction substantially 20 parallel to the direction of collapse of what would normally be a conventional collapsible frame, which opposes the collapsible nature of the wheelchair. Another disadvantage associated with most conventional manually driven wheelchairs, both two-handed and single-handed operation, is that many wheelchair occupants do not have sufficient upper body strength to traverse 25 inclines or other rugged terrain. The general set-up of a conventional wheelchair results in a 1:1 drive propulsion ratio. As such, many wheelchair occupants are limited in terms of their scope of mobility. Wheelchair manufacturers tend to use small castor wheels as means for supporting and rotating the forward section of a wheelchair in response to force 30 applied to the larger rear drive wheels. Castor wheels can easily become jammed or snagged against, for example, small ledges, edges of carpet and/or cracks in pavement. With conventional wheelchairs it is common practice to WO 2006/094332 - 4 - PCT/AU2006/000187 rotate both drive wheels forcefully in opposite directions in order to generate enough rotational force (on a 1:1 drive ratio) at the castor wheels to release the jammed wheel. With conventional two-handed wheelchairs, when occupants try to 5 traverse an incline they have to be sure that they quickly push, release, and then re-engage the wheels to push again, so as to be sure that the wheelchair does not slip backwards down the incline. If instead the wheelchair occupant tries to drive the wheelchair uphill by releasing one arm from one wheel at a time, the wheelchair will pivot and rotate backwards relative to the wheel that is being 10 held firm. Thus, the only way to navigate a conventional two-handed wheelchair uphill is by way of pushing with both hands against both wheels simultaneously. It therefore becomes evident that, if an operator does not re engage and push forward again on the wheels of the wheelchair in a manner which is quick enough dependent on the grade of the incline, the wheelchair 15 will roll backwards down the incline. It is therefore an object of the present invention to provide a manually driven wheeled conveyance, preferably a wheelchair, which can be propelled and steered by either or both arms of an occupant. A further object of the present invention is to provide a manually 20 driven wheeled conveyance, preferably a wheelchair, which can be propelled and steered by either hand of a two-handed person enabling an occupant to use the other hand to carry an object. Yet a further object of the present invention is to provide a manually driven wheeled conveyance, preferably a wheelchair, which can be propelled 25 and steered by a single-handed person and which is configured for both left handed and right-handed drive operation. SUMMARY OF THE INVENTION According to the present invention there is provided a conveyance 30 having a plurality of wheels, preferably a wheelchair, said conveyance including: WO 2006/094332 - 5 - PCT/AU2006/000187 at least two drive axles adapted to be mounted or disposed between said wheels; one of said plurality of wheels defining a first wheel, said first wheel being rotatably mounted to one end of a first of said at least two drive axles; 5 another of said plurality of wheels defining a second wheel, said second wheel being rotatably mounted to one end of a second of said at least two drive axles; a first actuation means associated with said first drive axle, on the opposite end of said first drive axle from said first wheel and proximate said 10 second wheel; a second actuation means associated with said second drive axle, on the opposite end of said second drive axle from said second wheel and proximate said first wheel; wherein said first actuation means is selectively operable to apply a 15 selective relative rotation to said first wheel, and said second actuation means is selectively operable to apply a selective relative rotation to said second wheel. In a practical preferred embodiment said first and second drive axles are mounted or disposed coaxially between said first and second wheels. 20 Preferably said first drive axle is coaxially disposed within said second drive axle. In an alternative practical preferred embodiment, said first and second drive axles are mounted or disposed between said first and second wheels on separate axes. Preferably said conveyance is collapsible to reduce its overall 25 dimensions for ease of portability and/or transportation. It is also preferred that said first and second drive axles are removably mounted or disposed between said first and second wheels In a further practical preferred embodiment, said first and second drive axles each include telescoping sections that are adapted to selectively reduce 30 the overall length of said first and second drive axles to enable an occupant to remove said first and second drive axles from said conveyance. Preferably said telescoping sections of said first and second drive axles each cooperate with at WO 2006/094332 - 6 - PCT/AU2006/000187 least one biasing means which biases said telescoping sections to a fully extended position. It is also preferred that said at least one biasing means biases said first and second drive axles to a fitted position between said first and second wheels of said conveyance, wherein said fitted position of said first 5 and second drive axles is substantially the same as that of said fully extended position. It is further preferred that said first and second drive axles can each be locked in a collapsed position by means of a locking device, to facilitate removal of said first and second drive axles from said conveyance. Preferably said first and second actuation means is coupled to its 10 respective first or second drive axle via at least one gearing assembly. In a practical preferred embodiment, said at least one gearing assembly is disposed within a hub of at least one of said first or second drive wheels. Preferably said at least one gearing assembly is at least one differential. In one embodiment, said at least one differential includes at least two bevel gears associated with at 15 least one pinion gear. In an alternative embodiment, said at least one differential is a planetary gear system including at least one ring gear associated with at least one planet gear and at least one sun gear. In either embodiment, it is preferred that said at least one differential is adapted to provide a 2:1 drive propulsion ratio. 20 In yet a further practical preferred embodiment, each of said first and second actuation means is coupled to its respective first or second drive axle via at least one gearing assembly, preferably at least one differential. Preferably each differential coupled to each of said first and second drive axles can be locked by at least one arrester adapted to be removably attached to said 25 conveyance in order provide a predetermined drive propulsion ratio relative to use of said first and second actuation means. Preferably said predetermined drive propulsion ratio is a 2:1 drive propulsion ratio. It is also preferred that said arresters are adapted to be coupled to said differentials in place of said first and second drive axles when said first and second drive axles are removed 30 from said conveyance. In an alternative practical preferred embodiment, only one of said first and second actuation means in coupled to its respective first or second drive axle via at least one gearing assembly, preferably at least one WO 2006/094332 - 7 - PCT/AU2006/000187 differential, and wherein the other of said first or second actuation means is directly mounted to its respective first or second drive axle. Preferably said first and second actuation means are drive or actuation discs which can each be separately engaged and manipulated by an occupant to 5 each selectively rotate said first and second wheels of said conveyance. Preferably a hand-rail means is associated with each of said first and second wheels. It is also preferred that each of said hand-rail means is removably coupled to its respective first or second wheel. In yet a further practical preferred embodiment, each of said first and 10 second drive axles includes at least one universal joint disposed at or near its outer ends thereof. Said universal joints allowing said first and second wheels to move freely in all directions relative to said first and second drive axles. According to a further aspect of the present invention there is provided an improved drive system for a conveyance having at least one pair of opposed 15 drive wheels, said improved drive system including: at least two axles adapted to be mounted or disposed between said wheels, each of said axles being adapted to be in direct drive connection with opposed ones of said wheels; at least one drive means associated with at least one of said wheels and 20 in drive connection with one of said axles; and means associated with each wheel, for selective manipulation by an occupant of said conveyance, to allow for rotation of said wheels. In a practical preferred embodiment, said at least two drive axles are adapted to be mounted or disposed coaxially between said wheels. Preferably 25 a first of said at least two drive axles is coaxially disposed within a second of said at least two drive axles. In an alternative practical preferred embodiment, said at least two drive axles are adapted to be mounted or disposed between said wheels on separate axes. Preferably said at least two drive axles are adapted to be removably 30 mounted or disposed between said wheels. In a practical preferred embodiment, said at least two drive axles each include telescoping sections that are adapted to selectively reduce the overall length of said at least two drive WO 2006/094332 - 8 - PCT/AU2006/000187 axles to enable an occupant to remove said at least two drive axles from said conveyance. Preferably said telescoping sections of said at least two drive axles each cooperate with at least one biasing means which biases said telescoping sections to a fully extended position. It is also preferred that said at 5 least one biasing means biases said at least two drive axles to a fitted position between said wheels of said conveyance, wherein said fitted position of said at least two drive axles is substantially the same as that of said fully extended position. It is further preferred that said at least two drive axles can each be locked in a collapsed position by means of a locking device, to facilitate 10 removal of said at least two drive axles from said conveyance. Preferably said means associated with each wheel are actuation means which are coupled to opposed ones of said wheels via said at least two axles. Preferably at least one of said actuation means is coupled to its respective drive axle via said at least one drive means. Preferably said at least one drive means 15 is at least one gearing assembly. It is also preferred that said at least one gearing assembly is disposed within a hub of at least one of said wheels. It is further preferred that said at least one gearing assembly is at least one differential. Preferably said at least one differential is adapted to provide a 2:1 drive propulsion ratio. In a practical preferred embodiment, each of said 20 actuation means are coupled to their respective drive axle via at least one gearing assembly. In an alternative practical preferred embodiment, said improved drive system includes two actuation means, and only one of said actuation means in coupled to its respective drive axle via at least one gearing assembly, and wherein the other of said actuation means is directly mounted to 25 its respective drive axle. In a further practical preferred embodiment said actuation means are drive or actuation discs which can each be separately engaged and manipulated by an occupant to each selectively rotate said wheels of said conveyance. In yet a further practical preferred embodiment each of said at least two 30 drive axles includes at least one universal joint disposed at or near its outer ends thereof. Preferably said universal joints allow said wheels to move freely in all directions relative to said at least two drive axles.

WO 2006/094332 - 9 - PCT/AU2006/000187 According to yet a further aspect of the present invention there is provided a conveyance having at least one pair of opposed drive wheels, said conveyance including the improved drive system as described in any one of the preceding paragraphs. Preferably the conveyance is a wheelchair. 5 According to yet a further aspect of the present invention there is provided a dual axle assembly for a conveyance having at least one pair of opposed drive wheels, said dual axle assembly including a first and a second drive axle adapted to be mounted or disposed between said wheels, wherein said first and second axles are adapted to be in direct drive connection with 10 opposed ones of said wheels. In a practical preferred embodiment said first and second drive axles are adapted to be mounted or coaxially disposed between said wheels. Preferably said first drive axle is coaxially disposed within said second drive axle. In an alternative practical preferred embodiment, said first and second 15 drive axles are adapted to be mounted or disposed between said wheels on separate axes. Preferably said dual axle assembly is adapted to be removably mounted or disposed between said wheels. In a practical preferred embodiment said first and second drive axles each include telescoping sections that are adapted 20 to selectively reduce the overall length of said first and second drive axles to enable an occupant to remove said dual axle assembly from said conveyance. Preferably said telescoping sections of said first and second drive axles each cooperate with at least one biasing means which biases said telescoping sections to a fully extended position. It is also preferred that said at least one 25 biasing means biases said dual axle assembly to a fitted position between said wheels of said conveyance, wherein said fitted position of said dual axle assembly is substantially the same as that of said fully extended position. It is further preferred that said first and second drive axles can each be locked in a collapsed position by means of a locking device, to facilitate removal of said 30 dual axle assembly from said conveyance. Preferably each of said first and second drive axles includes at least one universal joint disposed at or near its outer ends thereof. Preferably said WO 2006/094332 - 10 - PCT/AU2006/000187 universal joints allow said wheels to move freely in all directions relative to said dual axle assembly. ADVANTAGES OF THE INVENTION 5 Accordingly, the present invention provides a manually-driven wheeled conveyance, preferably a wheelchair, which can be selectively operated by either or both hands of an occupant allowing the occupant to use a free hand to hold an object, if desired, whilst still being able to control and steer the conveyance from one side with a single hand. The wheeled conveyance of the 10 present invention can be controlled and steered by one or two arms of an occupant by using the actuation means or the drive wheels, either separately or in combination. If one actuation means is held together with its adjacent drive wheel, both drive wheels become joined as one. The resulting action of this function allows the wheeled conveyance to be propelled in a straight line by an 15 occupant using only one arm. Furthermore, the occupant can selectively release his (or her) grip on the actuation means being held together with its adjacent drive wheel and rotate either the actuation means or drive wheel separately, this function providing a means of rotating or steering the wheeled conveyance with a single arm as desired. 20 The wheeled conveyance of the present invention may therefore be used by single-handed occupants having either only a left-arm or a right-arm. Thus the wheeled conveyance is a universal device for a single-handed occupant that does not require any modification to suit a particular arm of an occupant, as the conveyance can be controlled and steered from either side by 25 default. If the wheeled conveyance of the present invention includes differential gearing systems disposed in working relationship with the two drive wheels and actuation means, a means for averaging the strength of both arms of a two handed occupant is provided. If an occupant selectively holds at least one of 30 the two actuation means together with at least one adjacent drive wheel, the power applied by the occupant to both wheels and the at least one actuation WO 2006/094332 - 11 - PCT/AU2006/000187 means held together with the adjacent drive wheel averages the strength of the individual when propelling the wheeled conveyance in a desired direction. If the wheeled conveyance includes differential gearing with a 2:1 drive propulsion ratio the power required to turn the wheeled conveyance by way of 5 the actuation means alone is half that which would be required to apply a turning force to the drive wheels alone. If an occupant selectively rotates the two actuation means in opposite directions they can deliver twice the turning force to the front, preferably castor wheels, of the conveyance which provides greater force to release the front wheels should they become jammed against an 10 object. The wheeled conveyance of the present invention can be used to traverse an incline in the same manner as a conventional conveyance. However, it is also possible with the wheeled conveyance of the present invention for an occupant to release one hand at a time from one wheel held in 15 cooperation with a corresponding actuation means, as the wheel that is no longer grasped is interconnected with the wheel and the adjacent actuation means that are being held firm. Thus an occupant can selectively propel the wheeled conveyance of the present invention up an incline using varying force applied to the wheels and actuation means by one arm at a time. 20 If the axles are embodied to be removably attached to the wheeled conveyance of the present invention the conveyance can include a collapsible frame so that the conveyance can be folded to reduce its overall dimensions for ease of portability and/or transportation and/or storage. Further, by being able to remove the axles of the wheeled conveyance, a pair of arresters or the like 25 can be connected to the wheeled conveyance in place of the axles in order to lock the gearing assemblies of each hub in a constant, preferably, 2:1, drive propulsion ratio relative to use of the actuation means. BRIEF DESCRIPTION OF THE DRAWINGS 30 In order that the invention may be more clearly understood and put into practical effect there shall now be described in detail preferred constructions of a manually propelled wheelchair device in accordance with the invention. The WO 2006/094332 - 12 - PCT/AU2006/000187 ensuing description is given by way of non-limitative example only and is with reference to the accompanying drawings, wherein: Fig. 1 is a front elevational view of a wheeled conveyance made in accordance with a first preferred embodiment of the present invention; 5 Fig. 2 is a cross-sectional view of an improved drive system for the wheeled conveyance shown in Fig. 1; Figs. 3a & 3b are partial cross-sectional views of the improved drive system of Fig. 2, each showing the drive system in a different mode of operation; 10 Fig. 4 is a front elevational view of a wheeled conveyance made in accordance with a second preferred embodiment of the present invention; Fig. 5 is an exploded perspective view of the wheeled conveyance shown in Fig. 4; Figs. 6a & 6b are partial cross-sectional views of an improved drive 15 system for the wheeled conveyance shown in Fig. 4, each showing the drive system in a different mode of operation; Fig. 7 is a partial cross-sectional view of an improved drive system for a wheeled conveyance made in accordance with a third preferred embodiment of the invention; 20 Fig. 8 is a partial cross-sectional view of an improved drive system for a wheeled conveyance made in accordance with a fourth preferred embodiment of the invention; Fig. 9 is an enlarged cross-sectional view of the gearing arrangement of the improved drive system shown in Fig. 8; 25 Fig. 10 Oa is a front elevational view of the wheeled conveyance of Fig. 4, showing the axle assembly removed from the wheeled conveyance so that the wheeled conveyance may be folded for storage or transportation; Fig. 10b is a similar view to that of Fig. 10 Oa, this time showing the wheeled conveyance in a folded position; 30 Fig. 11 a is a cross-sectional view of a preferred axle assembly for use with any one of the wheeled conveyances shown in Figs. 1 to 10b, showing the axle assembly in an extended position; WO 2006/094332 - 13 - PCT/AU2006/000187 Fig. 1 lb is a similar view to that of Fig. 1 la, this time showing the axle assembly in a retracted or collapsed position; Fig. 12 is a partial cross-sectional view of a wheeled conveyance made in accordance with a fifth preferred embodiment of the present invention, 5 showing an axle assembly removed from the wheeled conveyance and in its place a pair of arresters connected thereto, which, in accordance with a further aspect of the present invention, provides a means of manoeuvring the wheeled conveyance at a preferred constant 2:1 drive propulsion ratio by using the hand-rim assemblies of the wheeled conveyance; 10 Figs. 13a & 13b are enlarged cross-sectional views of the respective dashed-line sections of Fig. 12; and Figs. 14a to 14c are cross-sectional views of an alternative preferred axle assembly for use with any one of the wheeled conveyances of Figs. 1 to 10b, showing the axle assembly in various positions. 15 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In Fig. 1 there is shown a wheeled conveyance 10 of any suitable formnn, for example a wheelchair as shown. Wheelchair 10 includes a frame 12 which carries and supports a seat 14, a backrest 16 and a pair of armrests (not shown). 20 Armrests usually extend outwardly from frame 12, near backrest 16, in a direction substantially parallel to the plane of seat 14. Wheelchair 10 may also include a pair of hand-push handles 18 (see for example Fig. 5) disposed at the uppermost points of frame 12 and which may extend outwardly therefrom in a direction substantially perpendicular to frame 12 and away from the rear of 25 wheelchair 10. Mounted to the base of frame 12 are footrests 20 which are disposed in a position suitable to support the feet of an occupant (not shown). Although shown in Fig. 1 as being two separate footrests 20, it should be understood that a single footrest 20 (see Fig. 5) could be included and the invention is therefore not limited to the specific example as shown. 30 Wheelchair 10 includes a first drive wheel 22 rotatably mounted to a first side 24 of frame 12 and a second drive wheel 26 rotatably mounted to a second side 28 of frame 12. First and second drive wheels 22, 26 are WO 2006/094332 - 14 - PCT/AU2006/000187 substantially aligned to rotate about a substantially horizontal common wheel axis 30. A first hand-rim assembly 32 is operably mounted proximate, preferably adjacent, first drive wheel 22 for selective manual operation thereof. A second hand-rim assembly 36 is operably mounted proximate, preferably 5 adjacent, second drive wheel 26 also for selective manual operation thereof. A first elongated, preferably detachable, drive axle member 38 is coupled between first hand-rim assembly 32 and second drive wheel 26. First drive axle member 38 is substantially aligned to rotate about common wheel axis 30. A second elongated, preferably detachable, drive axle member 40 is coupled 10 between second hand-rim assembly 36 and first drive wheel 22. Second drive axle member 40 is also substantially aligned to rotate about common wheel axis 30. The arrangement of first and second drive axle members 38, 40 is such that both together as one unit make up a dual axle assembly 42 which is 15 preferably detachable from wheelchair 10 (see for example Figs. 10 a & 10b). In the preferred embodiments described with reference to the drawings accompanying the present specification first drive axle member 38 is coaxially aligned with second drive axle member 40, and both drive axles 38, 40, together as dual axle assembly 42, are substantially aligned to rotate about 20 common wheel axis 30. As can be best seen in Fig. 2, second drive axle member 40 is preferably housed within first drive axle member 38 such that dual axle assembly 42 includes inner and outer axles coaxially aligned with one another to rotate substantially about common wheel axis 30. Although shown in the drawings as being coaxially aligned, one within 25 the other, it should be understood that first drive axle member 38 and second drive axle member 40 could alternatively be disposed separately, as two separate single axle assemblies 42. Axles 38, 40 could be arranged, for example, parallel to one another such that first drive axle member 38 could rotate about common wheel axis 30, whilst second drive axle member 40 could 30 rotate about a second parallel wheel axis (not shown). In this alternative preferred embodiment (not shown) first and second drive wheels 22, 26 may WO 2006/094332 - 15 - PCT/AU2006/000187 be, for example, disposed offset from one another in order to rotate about separate parallel wheel axes. As shown in Fig. 1, first and second drive axle members 38, 40 are supported and rotatably mounted to frame 12 of wheelchair 10 by bearings 44. 5 Disposed at one end of first drive axle member 38, relative to first side 24 of frame 12, is a first differential gearing assembly 46. Disposed at one end of second drive axle member 40, relative to second side 28 of frame 12 and opposite first differential gearing assembly 46, is a second differential gearing assembly 48. Differential gearing assemblies 46, 48 are preferably housed 10 within first and second hubs 50, 52 (see for example Fig. 5) of first and second drive wheels 22, 26, respectively. As best seen in Figs. 2 to 3b, each differential gearing assembly 46, 48 includes two bevel gears 54 cooperating in working relationship with one pinion gear 56. It should be understood, however, that two pinion gears 56 (as 15 is shown in Fig. 5) could be included and, as such, the invention should not be considered limited to the specific arrangement as shown. Similarly, although embodied as only including a single differential gearing assembly 46, 48 disposed at either side 24, 28 of frame 12, in an alternative embodiment (not shown) more than one differential gearing assembly may be included, if 20 required, without departing from the spirit and scope of the present invention as herein described. As shown in Fig. 1, wheelchair 10 also includes a pair of forward non driven wheels 58. Forward wheels 58 are preferably castor wheels but may be any other suitable wheels that are adapted to swivel and/or turn in order to 25 follow the path directed by propulsion applied to first and second drive wheels 22, 26 by an occupant (not shown). As shown in Figs. 2 to 3b, first and second drive wheels 22, 26 may also each include a hand-rail 34, 35 for selective propulsion to be applied thereto. First hand-rail 34 is integral with or removably connected (see for 30 example Fig. 5) to first drive wheel 22, whilst second hand-rail 35 is integral with or removably connected to second drive wheel 26. First and second hand rails 34, 35 can be used by an occupant (not shown) to selectively propel first WO 2006/094332 - 16 - PCT/AU2006/000187 and second drive wheels 22, 26, instead of directly pushing on first and second drive wheels 22, 26. As can be seen in Fig. 2, first differential gearing assembly 46 interconnects first hand-rim assembly 32 with second drive wheel 26 via first 5 (outer) drive axle member 38. Second differential gearing assembly 48 interconnects second hand-rim assembly 36 with first drive wheel 22 via second (inner) drive axle member 40. The arrangement of first and second hand-rim assemblies 32, 36, first and second drive axle members 38, 40, and first and second differential gearing assemblies 46, 48 provides wheelchair 10 10 with an improved drive system that enables an occupant (not shown) to selectively operate either or both hand-rim assemblies 32, 36 in order to selectively drive either or both interconnected drive wheels 22, 26 from respective sides 24, 28 of wheelchair 10. It should be understood that, although shown as having first drive axle member 38 interconnecting first 15 hand-rim assembly 32 with second drive wheel 26, and second drive axle member 40 interconnecting second hand-rim assembly 36 with first drive wheel 22, either drive axle member 38, 40 could be used to interconnect either hand-rim assembly 32, 36 with respectively opposed drive wheels 22, 26 (see for example Fig. 5 which shows a reverse arrangement of axles 38, 40 to that 20 shown in Figs. 2 to 3b). Reference will now be made to Figs. 3a & 3b in an effort to provide a better understanding of the operation of the improved drive system for a wheeled conveyance, preferably wheelchair 10, of the present invention. In Fig. 3a the power train of the improved drive system of the present 25 invention is shown when a selective (anticlockwise) motion is applied to first hand-rim assembly 32 in the direction of arrow a. As first hand-rim assembly 32 is directly coupled to one bevel gear 54 of first differential gearing assembly 46 this bevel gear 54 rotates with first hand-rim assembly 32 in the direction of arrow a. As this bevel gear 54 is disposed in working relationship with pinion 30 56, pinion 56 is driven by bevel gear 54 in the (clockwise) direction of arrow b. As pinion 56 is also coupled to the remaining bevel gear 54, which in turn is directly coupled to first (outer) drive axle member 38, the (clockwise) rotation WO 2006/094332 - 17 - PCT/AU2006/000187 of pinion 56 in the direction of arrow b causes remaining bevel gear 54 and first drive axle member 38 to rotate (clockwise) in the direction of arrow c. The interconnection of first drive axle member 38 with second drive wheel 26 thus causes second drive wheel 26 to rotate against a surface 60 also in the 5 (clockwise) direction of arrow c. Rotation of second drive wheel 26 in the direction of arrow c causes wheelchair 10 to rotate in a clockwise direction relative to stationary first drive wheel 22. Thus it can be seen that power is applied to second drive wheel 26 from first hand-rim assembly 32 via first differential gearing assembly 46 and first (outer) drive axle member 38 in the 10 direction of arrows x. In Fig. 3b the power train of the improved drive system of the present invention is shown when a selective (clockwise) motion is applied to second hand-rim assembly 36 in the direction of arrow d. As second hand-rim assembly 36 is directly coupled to one bevel gear 54 of second differential 15 gearing assembly 48 this bevel gear 54 rotates with second hand-rim assembly 36 in the direction of arrow d. As this bevel gear 54 is disposed in working relationship with pinion 56, pinion 56 is driven by bevel gear 54 in-the (anticlockwise) direction of arrow e. As pinion 56 is also coupled to the remaining bevel gear 54, which in turn is directly coupled to second (inner) 20 drive axle member 40, the (anticlockwise) rotation of pinion 56 in the direction of arrow e causes remaining bevel gear 54 and second drive axle member 40 to rotate (anticlockwise) in the direction of arrowf The interconnection of second drive axle member 40 with first drive wheel 22 thus causes first drive wheel 22 to rotate against surface 60 also in the (anticlockwise) direction of 25 arrowf Rotation of first drive wheel 22 in the direction of arrowf causes wheelchair 10 to rotate in an anticlockwise direction relative to stationary second drive wheel 26. Thus it can be seen that power is applied to first drive wheel 22 from second hand-rim assembly 36 via second differential gearing assembly 48 and second (inner) drive axle member 40 in the direction of 30 arrows y. If either hand-rim assembly 32, 36 is selectively rotated in a reverse direction to that described above with reference to Figs. 3a & 3b, then the WO 2006/094332 -18- PCT/AU2006/000187 resultant movement of wheelchair 10 would be opposite to that already described. That is to say that selective rotation of first hand-rim assembly 32 in the reverse (clockwise) direction of arrow a will cause second drive wheel 26 to rotate (anticlockwise) against surface 60 in the reverse direction of arrow 5 c which will in turn cause wheelchair 10 to rotate anticlockwise relative to stationary first drive wheel 22. Likewise, motion applied to second hand-rim assembly 36 in the reverse (anticlockwise) direction of arrow d will cause first drive wheel 22 to rotate (clockwise) against surface 60 in the reverse direction of arrowfwhich results in wheelchair 10 rotating clockwise relative to 10 stationary second drive wheel 26. The improved drive system of wheelchair 10 can therefore be selectively used to rotate wheelchair 10 in a desired direction by the use of only a single hand. Wheelchair 10 is also designed to be manoeuvred by two-handed operation. If an occupant (not shown) should choose to use two-hands and, for 15 example, rotate first hand-rim assembly 32 in one direction whilst rotating second hand-rim assembly 36 in an opposite direction, wheelchair 10 will rotate on-the-spot (within its own space). If the gearing of differential gearing assemblies 46, 48 was to be embodied with a preferably 2:1 ratio between pinions 56 and respective bevel gears 54, the effort required to perform this on 20 the-spot rotation would be half that of alternatively directly rotating first and second drive wheels 22, 26 in opposite directions. Thus a 2:1 drive propulsion ratio as a result of this preferable gearing arrangement will result in half the work being required to, for example, release a jammed forward wheel 58 should it become snagged on any object. 25 The improved drive system of the present invention also provides an occupant with a means for driving wheelchair 10 in a straight line by the use of either or both arms. If an occupant should choose to use a single-arm to propel wheelchair 10 in a straight line, that person can do so by holding either one of hand-rim assemblies 32, 36 whilst also holding a corresponding proximate, 30 preferably adjacent, drive wheel 22, 26. If one hand-rim assembly, for example first hand-rim assembly 32, is held together with its corresponding proximate, preferably adjacent, drive wheel 22, 26, ie: first drive wheel 22, by WO 2006/094332 - 19 - PCT/AU2006/000187 selectively applying a driving force to both the hand-rim assembly (32) and drive wheel (22) together, wheelchair 10 can be driven in a straight line as both drive wheels 22, 26 become locked-up as one by way of the interconnection provided by respective drive axle members 38, 40. Therefore, forward or 5 reverse movement of wheelchair 10 can be achieved by the use of only a single arm by selective operation of either of first or second hand-rim assemblies 32, 36 held in co-operation with either of first or second drive wheels 22, 26. If an occupant has use of two-hands, wheelchair 10 enables the occupant to propel and steer wheelchair 10 with one arm whilst leaving one 10 arm free to hold an object if desired. Likewise, a single-handed occupant is also able to propel and steer wheelchair 10 from either side 24, 28 of wheelchair 10 corresponding to the hand they have use of. If a two-handed occupant should choose to propel wheelchair 10 with both arms they can do so equally as well by using first and second hand-rim 15 assemblies 32, 36 alone, or by using first and second drive wheels 22, 26 alone as is conventional. If an occupant chooses to hold at least one of first and second hand-rim assemblies 32, 36 with at least one corresponding proximate, preferably adjacent, drive wheel 22, 26, wheelchair 10 can be propelled as desired whilst also providing a means of averaging the strength of the 20 individual and delivering this average strength to both drive wheels 22, 26. This action is provided by the locked arrangement between respective drive wheels 22, 26, which results in at least one drive wheel 22, 26 receiving a driving force from an occupants arm located on an opposite side 24, 28 of wheelchair 10. 25 In Figs. 4 to 6b there is shown a wheeled conveyance 10, of any suitable type, for example a wheelchair as shown, made in accordance with a second preferred embodiment of the present invention. In Fig. 5 it can be seen that a preferable construction of wheelchair 10 is shown in exploded view in order to highlight the individual components that make up the improved drive 30 system of the present invention. As already discussed, either drive axle member 38, 40 can be interchanged with one another, and in Fig. 5 the axles 38, 40 are shown in a reverse configuration to that of Fig. 2 in order to WO 2006/094332 - 20 - PCT/AU2006/000187 exemplify this option. What is also shown in these Figures is the arrangement of first and second differential gearing assemblies 46, 48 being housed within first and second hubs 50, 52 of first and second drive wheels 22, 26, respectively. Hubs 50, 52 house respective differential gearing assemblies 46, 5 48, each having two bevel gears 54 and two pinions 56, preferably configured in a 2:1 drive arrangement, such that when assembled (Fig. 4) the entire drive arrangement of wheelchair 10 is maintained by way of locking nuts or rings 62. Referring particularly to Fig. 5, it can be seen that first and second hand-rim assemblies 32, 36 are preferably first and second drive discs which 10 can be selectively rotated by either hand of an occupant (not shown). The particular configuration of drive discs 32, 36 is such that, when fitted to wheelchair 10 (see Figs. 6a & 6b), they preferably fit under and within hand rails 34, 35 of first and second drive wheels 22, 26, making it easy for an occupant to selectively grip either or both drive discs 32, 36 and/or hand-rails 15 34, 35, either separately or together. In Fig. 5, unlike in the embodiment of Fig. 2, hand-rails 34, 35 are shown as separate components which can be removably attached to respective drive wheels 22, 26, by way of screws or bolts 37. When attached to drive wheels 22, 26, screws 37 affix hand-rails 34, 35 to drive wheels 22, 26 by way 20 of a series of threaded holes 39 formed in drive wheels 22, 26, and a matching series of integral shoulder sections 43 provided on hand-rails 34, 35. By being removably attachable to first and second drive wheels 22, 26, first and second hand-rails 34, 35 can be selectively removed from wheelchair 10, if necessary, in order to provide, for example, more room for an occupant (not shown) to 25 access and use first and second drive discs 32, 36. When hand-rails 34, 35 are removed from wheelchair 10 and wheelchair 10 is fully assembled a space (see for example the wheelchair 10 shown in Figs. 7 & 8) is provided between first and second drive wheels 22, 26, and first and second drive discs 32, 36, which enables an occupant to more easily selectively operate either a drive wheel 22, 30 26 or a drive disc 32, 36, on their own. The removability of hand-rails 34, 35 is particularly useful for when axle assembly 42 of wheelchair 10 is removed and a pair of arresters 83a, 83b are connected to wheelchair 10 in order to lock WO 2006/094332 - 21 - PCT/AU2006/000187 differential assemblies 46, 48 in a predetermined drive propulsion ratio in accordance with a further aspect of the present invention, as will be described later with reference to Figs. 12 to 13b. In Figs. 6a & 6b the power train of the improved drive system of 5 wheelchair 10 shown in Figs. 4 & 5 is shown in similar (cross-sectional) views to that of Figs. 3a & 3b. In each of these representations the individual components that are each used to apply the power to the respective drive wheels 22, 26 are shown as darker shaded components for exemplary purposes only. 10 In Fig. 6a the power train of wheelchair 10 is shown when a selective (anticlockwise) motion is applied to first drive disc 32 in the direction of arrow a. As before, selective rotation of first drive disc 32 causes a first bevel gear 54 of first differential gearing assembly 46 to also rotate in the direction of arrow a. This bevel gear 54 subsequently rotates pinions 56 (clockwise) in the 15 direction of arrow b. Pinions 56 then rotate remaining bevel gear 54 and first drive axle member 38 in the (clockwise) direction of arrow c, which also rotates second drive wheel 26 in the (clockwise) direction of arrow c, which causes wheelchair 10 to rotate clockwise relative to stationary first drive wheel 22. Should a reverse (clockwise) force be applied to first drive disc 32 in the 20 reverse direction of arrow a wheelchair 10 will rotate in an anticlockwise direction, as already explained with reference to Fig. 3a. In Fig. 6b the power train of wheelchair 10 is shown when a selective (clockwise) motion is applied to second manual drive disc 36 in the direction of arrow d. As before, selective rotation of second drive disc 36 causes a first 25 bevel gear 54 of second differential gearing assembly 48 to also rotate in the direction of arrow d. This bevel gear 54 subsequently rotates pinions 56 (anticlockwise) in the direction of arrow e. Pinions 56 then rotate remaining bevel gear 54 and second drive axle member 40 in the (anticlockwise) direction of arrowf, which also rotates first drive wheel 22 in the (anticlockwise) 30 direction of arrowf, which causes wheelchair 10 to rotate anticlockwise relative to stationary second drive wheel 26. Should a reverse (anticlockwise) force be applied to second drive disc 36 in the reverse direction of arrow d, WO 2006/094332 - 22 - PCT/AU2006/000187 wheelchair 10 will rotate in a clockwise direction as already explained with reference to Fig. 3b. Although shown in Figs. 1 to 6b as including differential gearing assemblies 46, 48 having bevel gears 54 each cooperating with at least one 5 pinion gear 56, the invention is not to be considered to be limited to this particular arrangement of gears. In Fig. 7 one of possibly many alternative preferred differential gearing arrangements for a wheeled conveyance 10 is shown which includes two planetary gearing assemblies 46, 48 arranged at opposite sides 24, 28 of a wheeled conveyance 10. Referring to first planetary 10 gearing assembly 46, it can be seen that first hand-rim assembly 32 is directly coupled to a first sun gear 64. First sun gear 64 is disposed in working relationship with two first planet gears 66, which are inturn disposed in working relationship with one first ring gear 68. As first ring gear 68 is preferably directly coupled to first (outer) drive axle member 38, rotation of 1.5 first ring gear 68 in either an anticlockwise or clockwise direction will cause first drive axle member 38, and interconnected second drive wheel 26, to rotate in the same direction. Thus wheeled conveyance 10 will rotate in either direction relative to stationary first drive wheel 22 as described before with reference to preceding embodiments. 20 Referring to second planetary gearing assembly 48, it can be seen that second hand-rim assembly 36 is directly coupled to a second sun gear 70. Second sun gear 70 is disposed in working relationship with two second planet gears 72, which are in turn disposed in working relationship with one second ring gear 74. As second ring gear 74 is preferably directly coupled to second 25 (inner) drive axle member 40, rotation of second ring gear 74 in either an anticlockwise or clockwise direction will cause second drive axle member 40, and interconnected first drive wheel 22, to rotate in the same direction. Thus wheeled conveyance 10 will rotate in either direction relative to stationary second drive wheel 26 as described before with reference to preceding 30 embodiments. Although shown in Figs. 1 to 7 as including two gearing assemblies 46, 48, one disposed at each side 24, 28 of the wheeled conveyance 10 of the WO 2006/094332 - 23 - PCT/AU2006/000187 preceding embodiments, the invention is not limited to this particular arrangement of gearing assemblies 46, 48. In Fig. 8 one of possibly many alternative preferred gearing arrangements is shown which includes a single gearing assembly 46 disposed at one side 24 of a wheeled conveyance 10. 5 Although shown in Fig. 8 as being disposed at side 24 of wheeled conveyance 10 it should be understood that single gearing assembly 46 may alternatively be located at opposite side 28 of wheeled conveyance 10 and as such the invention should not be considered limited to the specific example as shown. Referring to single gearing assembly 46 (in enlarged view in Fig. 9 and having first drive 10 wheel 22 removed for illustrative purposes only), it can be seen that first hand rim assembly 32 is directly coupled to a first gear 65. First gear 65 is disposed in working relationship with a second gear 67 which is preferably located above first gear 65 but may be located at any other suitable location. Second gear 67 is directly coupled to a third gear 69 via a shaft or axle 71. Shaft 71 15 preferably passes through the hub (not shown) of first drive wheel 22 in order to interconnect first, second and third gears 65, 67, 69 with a fourth gear 73 which in turn is preferably directly coupled to first (outer) drive axle member 38. The arrangement of gears 65, 67, 69, 73 of single gearing assembly 46 facilitates selective rotation of first (outer) drive axle member 38 in response to 20 force applied to first hand-rim assembly 32 in either a clockwise or anticlockwise direction. As first (outer) drive axle member 38 is directly coupled to second drive wheel 26, selective rotation of first hand-rim assembly 32 in turn causes second drive wheel 26 to rotate in either a clockwise or anticlockwise direction. 25 Although wheeled conveyance 10 of Figs. 8 and 9 only includes a single gearing assembly 46 arranged at one side 24 of wheeled conveyance 10, selective rotation of second hand-rim assembly 36 still facilitates rotation of first drive wheel 22 by way of each component being directly coupled to dual axle assembly 42. Instead of having a second gearing assembly arranged at 30 side 28 of wheeled conveyance 10, second hand-rim assembly 36 is directly coupled to second (inner) drive axle member 40 which preferably passes through the hub (not shown) of second drive wheel 26. As second hand-rim WO 2006/094332 - 24 - PCT/AU2006/000187 assembly 36 is directly coupled to second (inner) drive axle member 40 which in turn is directly coupled to first drive wheel 22, a second gearing assembly is not required. Hence, first and second hand-rim assemblies 32, 36, of wheeled conveyance 10 of Figs. 8 and 9, can each be selectively rotated as hereinbefore 5 described and still achieve a similar result. In accordance with the present invention, dual drive axle assembly 42 may be embodied as completely detachable from wheelchair 10. This detachable configuration of dual axle assembly 42 is particularly suitable for a collapsible wheelchair 10 of the type illustrated in Figs. 4 to 6b and 10Oa & 10Ob. 10 To facilitate the collapsible configuration of wheelchair 10, collapsible frame 12 includes front and rear support arms 76, 78 which are pivotally connected together by a series of pivot pins 80, such that frame 12 may be collapsed into the position shown in Fig. 10b. Pivot pins 80 extend centrally through support arms 76, 78, in a direction which is transverse to the longitudinal length of 15 arms 76, 78. Once dual axle assembly 42 has been detached and removed (Fig. 10a), wheelchair frame 12 can be collapsed inwardly in the direction of arrows g into the position shown in Fig. 10b, and in a manner similar to most conventional manually driven wheelchairs with collapsible frames. In Figs. 1 la & 1 lb there is shown two separate representations of a 20 preferred detachable dual axle assembly 42 which is suitable for use with any one of the preferred wheeled conveyances 10 previously described. In Fig. 1 la, dual axle assembly 42 is shown in an extended position which would be substantially the same position to that if fitted to a wheeled conveyance 10. Dual axle assembly 42 includes an outer axle 38 and an inner 25 axle 40 coaxially aligned, one within the other, both adapted to rotate about a common axis. To support inner axle 40 within outer axle 38, bearings 44 are disposed toward the outer edges of inner axle 40 such that inner axle 40 can freely rotate therebetween. Inner axle 40 includes first and second separate sections 40', 40" which 30 are disposed in a telescoping arrangement in order that first (male) section 40' is adapted to be slidably received within second (female) section 40". To bias first section 40' to an extended position of inner axle 40, a first spring 82 is WO 2006/094332 - 25 - PCT/AU2006/000187 disposed within second section 40" of inner axle 40. To maintain first and second sections 40', 40" in drive relationship with one another an inner axle drive pin 41 is disposed to restrict any rotational movement between sections 40', 40" of inner axle 40. Outer axle 38 also includes first and second separate 5 sections 38', 38" which are disposed in a telescoping arrangement in order that first (male) section 38' is adapted to be slidably received within second (female) section 38". To bias first section 38' to an extended position of outer axle 38, a second spring 84 is disposed within second section 38" of outer axle 38. 10 Dual axle assembly 42 includes inner and outer splines 86, 88 for receiving on opposed outer ends respective drive wheels 22, 26 and hand-rim assemblies 32, 36. Although shown in the drawings as having matched inner and outer splines 86, 88 at respective ends of axle assembly 42, it should be understood that the configuration of splines 86, 88, or any other suitable 15 means, may differ in accordance with the configuration of the gearing assemblies 46, 48 to which axle assembly 42 is to be attached. For example, if axle assembly 42 were to be connected to the wheelchair 10 shown in Fig. 12, respective inner and outer splines 86, 88 would not be matched at each end of axle assembly 42, and instead respective ends of inner and outer axles 40, 38, 20 of axle assembly 42, would have opposed male and female inner and outer splines. Similarly, although shown in the drawings as having an inner spline 86 extending beyond the outer peripheral edge of outer spline 88, at each end of axle assembly 42, it should be understood that inner and outer splines 86, 88 may be flush at the outer peripheral edge of axle assembly 42. 25 Dual axle assembly 42 also includes a latching mechanism 90 which is adapted to be operable in order to lock axle assembly 42 into the compressed or retracted position shown in Fig. 1 lb. In a preferred embodiment, latching mechanism 90 can be engaged and pushed into contact with a groove 92 formed on first section 40' of inner axle 40. When required, the ends of axle 30 assembly 42 near inner and outer splines 86, 88 can be held firm and drawn together in the direction of arrows h (Fig. 11 a) in order to retract axle assembly 42 to reduce its overall length. When axle assembly 42 is retracted far enough WO 2006/094332 - 26 - PCT/AU2006/000187 for latching mechanism 90 to be engaged with groove 92, latching mechanism 90 can be pushed into engagement with groove 92 which will maintain axle assembly 42 in the retracted state shown in Fig. 11 lb. Thus, and when required, an occupant of a wheeled conveyance 10 may selectively retract dual axle 5 assembly 42 and lock axle assembly 42 in a retracted state with latching mechanism 90 to selectively detach and remove axle assembly 42 from wheeled conveyance 10 in order to, for example, collapse the same for transportation. Similarly, and when required, an occupant may re-position axle assembly 42 and release latching mechanism 90 in order to return axle 10 assembly 42 to its extended position (Fig. 1 1a) to refit axle assembly 42 to wheeled conveyance 10. In Figs. 12 to 13b, there is shown a wheeled conveyance 10, of any suitable type, for example a wheelchair as shown, made in accordance with a fifth preferred embodiment of the present invention. Although not shown in 15 the drawings, wheelchair 10 is also configured to receive a removable dual axle assembly 42, such as that shown and described with reference to Figs. 11 a & 1 lb. Hence, wheelchair 10 can operate in the same or similar fashion to that described with reference to Figs. 4 to 6b and 10Oa & 10b. In accordance with a further aspect of the present invention, Figs. 12 to 20 13b show the connection of a pair of preferred arresters 83a, 83b to respective differential gearing assemblies 46, 48 of wheelchair 10, instead of a dual axle assembly 42. The connection of arresters 83a, 83b to wheelchair 10 provides wheelchair 10 with a means of locking differential gearing assemblies 46, 48 in a predetermined, preferably 2:1, drive propulsion ratio relative to the selective 25 operation of first and second hand-rim assemblies 32, 36. Referring to Fig. 12, and in the enlarged views of Figs. 13a & 13b, it can be seen that a first arrester 83a (Fig. 13a) can be removably connected to differential gearing assembly 48 of wheelchair 10 at side 28, and a second arrester 83b (Fig. 13b) can be removably connected to differential gearing 30 assembly 46 at side 24 of wheelchair 10. First and second arresters 83a, 83b each include a spline 85a, 85b disposed at one end of an elongated arm 87a, 87b, and a hole 89a, 89b disposed at the other end thereof. Arresters 83a, 83b WO 2006/094332 - 27 - PCT/AU2006/000187 are each removably attachable to wheelchair 10 by way of a screw or bolt 91 a, 91b, which is received in holes 89a, 89b and is used to affix arresters 83a, 83b to sides 28, 24, of frame 12, of wheelchair 10. Screws 91a, 91b being connectable to frame 12, at sides 28, 24, by way of a pair of threaded bosses or 5 captively held nuts 93a, 93b. In the preferred embodiment shown in Figs. 12 to 13b, splines 85a, 85b of arresters 83a, 83b, are matched to the respective differential gearing assembly 48, 46 of wheelchair 10 to which they are removably attachable to, which results in first arrester 83a having a female spline 85a and second 10 arrester 83b having a male spline 85b. It should be understood that splines 85a, 85b could be configured to suit any number of varying differential gearing assemblies 48, 46 and as such the invention is not limited to the specific example provided. When connected to wheelchair 10 (see Fig. 12), arresters 83a, 83b lock 15 differential gearing assemblies 48, 46 relative to frame 12. The locked arrangement of gearing assemblies 48, 46 provides a constant drive propulsion ratio relative to movement of first and second hand-rim assemblies 32, 36. If differential gearing assemblies 46, 48 of wheelchair 10 are embodied with a 2:1 gearing arrangement, selective operation of first and second hand-rim 20 assemblies 32, 36 results in a 2:1 drive propulsion ratio of wheelchair 10. Hence, when arresters 83a, 83b are connected to wheelchair 10, an occupant (not shown) can selectively operate first and second hand-rim assemblies 32, 36 to manoeuvre wheelchair 10, using half the effort to that required to manoeuvre wheelchair 10 by using first and second drive wheels 22, 26. Thus, 25 an occupant can selectively choose to manoeuvre wheelchair 10 by using drive wheels 22, 26 (as is conventional), or instead by using hand-rim assemblies 32, 36 at a 2:1 drive ratio. In Figs. 14a to 14c there are shown various views of a further preferred embodiment of a dual axle assembly 42 made in accordance with the present 30 invention. Dual axle assembly 42 includes inner and outer axles 40, 38, each having respective first and second (female and male) telescoping sections 38', 38", 40', 40", similar to those described with reference to Figs. 1 la & 1 lb.

WO 2006/094332 - 28 - PCT/AU2006/000187 Thus dual axle assembly 42 of Figs. 14a to 14c is also retractable when required by means of sections 38', 38", 40', 40" and first and second springs 82, 84. Where dual axle assembly 42 of Figs. 14a to 14c varies from the axle assembly 42 shown and described with reference to Figs. 1 la & 1 1b, is that 5 axle assembly 42 of Figs. 14a to 14c includes at opposed ends thereof inner and outer axle universal joints 94, 96. The arrangement of inner and outer axle universal joints 94, 96 is such that dual axle assembly 42 has at each end a dual universal joint 98 which enables each end of axle assembly 42 to pivot freely when, for example, a drive wheel 22, 26 (not shown in Figs. 14a to 14c), 10 traverses uneven ground. As can be seen in Fig. 14b, dual axle assembly 42 can freely move relative to dual universal joint 98 which means that inner and outer splines 86, 88 can rotate about a wheel axis 31 which is offset from common wheel axis 30 by an angle a. The magnitude of angle a is dependent on how far inner and outer splines 86, 88 have shifted with respect to inner and 15 outer axles 38, 40 relative to dual universal joints 98. Thus, dual universal joints 98 provide the drive wheels 22, 26 of a wheeled conveyance 10 with the ability to drive through an angle a relative to preferably stationary inner and outer axles 38, 40 of dual axle assembly 42. Although explained in detail as having one dual universal joint 98 20 arranged at each end of dual axle assembly 42, it is to be understood that axle assembly 42 of a wheeled conveyance 10 could include more than one dual universal joint 98 disposed at any suitable location along axle assembly 42. Similarly, if axle assembly 42 was to be embodied as two separate axles aligned, for example, parallel to one another, each axle may include one or 25 more single universal joint disposed at any suitable location. Although not shown, any one of the wheeled conveyances 10 of the present invention could also include a disc brake arrangement disposed at any suitable location in order to facilitate selective braking of the wheeled conveyance 10. In a practical preferred embodiment (not shown) selective 30 brakldng may be effected in association with brake actuators located proximate the armrests of the wheeled conveyance 10 for ease of operation. It should be understood that this is only one of many varying additional arrangements WO 2006/094332 - 29 - PCT/AU2006/000187 which can be included on any one of the wheeled conveyances 10 of the present invention as hereinbefore described. Although the preferred embodiment has been described with reference particularly to a wheelchair 10, it should be understood that the improved drive 5 system of the present invention may also be used with many other types of wheeled conveyance having at least two drive wheels interconnected by at least two drive axles. The drive axles need not be located on a common wheel axes 30, but are preferably located coaxially one within another such that an inner 40 and outer 38 dual axle assembly 42 results which can be removably attached 10 to the wheeled conveyance 10, if required, in order to facilitate, for example, collapse of the wheeled conveyance 10. Finally, it is to be understood that the foregoing description refers merely to preferred embodiments of the invention, and that variations and modifications will be possible thereto without departing from the spirit and 15 scope of the invention.

Claims (62)

1. A conveyance having a plurality of wheels, said conveyance including: 5 at least two drive axles adapted to be mounted or disposed between said wheels; one of said plurality of wheels defining a first wheel, said first wheel being rotatably mounted to one end of a first of said at least two drive axles; another of said plurality of wheels defining a second wheel, said 10 second wheel being rotatably mounted to one end of a second of said at least two drive axles; a first actuation means associated with said first drive axle, on the opposite end of said first drive axle from said first wheel and proximate said second wheel; 15 a second actuation means associated with said second drive axle, on the opposite end of said second drive axle from said second wheel and proximate said first wheel; wherein said first actuation means is selectively operable to apply a selective relative rotation to said first wheel, and said second actuation means 20 is selectively operable to apply a selective relative rotation to said second wheel.

2. The conveyance as claimed in claim 1, wherein said first and second drive axles are mounted or disposed coaxialy between said first and 25 second wheels.

3. The conveyance as claimed in claim 2, wherein said first drive axle is coaxially disposed within said second drive axle. 30

4. The conveyance as claimed in claim 1, wherein said first and second drive axles are mounted or disposed between said first and second wheels on separate axes. WO 2006/094332 - 31 - PCT/AU2006/000187

5. The conveyance as claimed in any one of the preceding claims, wherein said conveyance is collapsible to reduce its overall dimensions for ease of portability and/or transportation. 5

6. The conveyance as claimed in any one of the preceding claims, wherein said first and second drive axles are removably mounted or disposed between said first and second wheels. 10

7. The conveyance as claimed in claim 6, wherein said first and second drive axles each include telescoping sections that are adapted to selectively reduce the overall length of said first and second drive axles to enable an occupant to remove said first and second drive axles from said conveyance. 15

8. The conveyance as claimed in claim 7, wherein said telescoping sections of said first and second drive axles each cooperate with at least one biasing means which biases said telescoping sections to a fully extended position. 20

9. The conveyance as claimed in claim 8, wherein said at least one biasing means biases said first and second drive axles to a fitted position between said first and second wheels of said conveyance, wherein said fitted position of said first and second drive axles is substantially the same as that of 25 said fully extended position.

10. The conveyance as claimed in any one of claims 7 to 9, wherein said first and second drive axles can each be locked in a collapsed position by means of a locking device, to facilitate removal of said first and second drive 30 axles from said conveyance. WO 2006/094332 - 32 - PCT/AU2006/000187

11. The conveyance as claimed in any one of the preceding claims, wherein at least one of said first and second actuation means is coupled to its respective first or second drive axle via at least one gearing assembly. 5

12. The conveyance as claimed in claim 11, wherein said at least one gearing assembly is disposed within a hub of at least one of said first or second drive wheels.

13. The conveyance as claimed in claim 11 or claim 12, wherein 10 said at least one gearing assembly is at least one differential.

14. The conveyance as claimed in claim 13, wherein said at least one differential includes at least two bevel gears associated with at least one pinion gear. 15

15. The conveyance as claimed in claim 13, wherein said at least one differential is a planetary gear system including at least one ring gear associated with at least one planet gear and at least one sun gear. 20

16. The conveyance as claimed in any one of claims 13 to 15, wherein said at least one differential is adapted to provide a 2:1 drive propulsion ratio.

17. The conveyance as claimed in claim 11 or claim 12, wherein 25 each of said first and second actuation means is coupled to its respective first or second drive axle via at least one gearing assembly.

18. The conveyance as claimed in claim 11 or claim 12, wherein only one of said first and second actuation means in coupled to its respective 30 first or second drive axle via at least one gearing assembly, and wherein the other of said first or second actuation means is directly mounted to its respective first or second drive axle. WO 2006/094332 - 33- PCT/AU2006/000187

19. The conveyance as claimed in any one of claims 13 to 16, wherein each of said first and second actuation means is coupled to its respective first or second drive axle via at least one differential. 5

20. The conveyance as claimed in claim 19, wherein each differential coupled to each of said first and second drive axles can be locked by at least one arrester adapted to be removably attached to said conveyance in order provide a predetermined drive propulsion ratio relative to use of said first 10 and second actuation means.

21. The conveyance as claimed in claim 20, wherein said predetermined drive propulsion ratio is a 2:1 drive propulsion ratio. 15

22. The conveyance as claimed in claim 20 or claim 21, wherein said arresters are adapted to be coupled to said differentials in place of said first and second drive axles when said first and second drive axles are removed from said conveyance. 20

23. The conveyance as claimed in any one of claims 13 to 16, wherein only one of said first and second actuation means in coupled to its respective first or second drive axle via at least one differential, and wherein the other of said first or second actuation means is directly mounted to its respective first or second drive axle. 25

24. The conveyance as claimed in any one of the preceding claims, wherein said first and second actuation means are drive or actuation discs which can each be separately engaged and manipulated by an occupant to each selectively rotate said first and second wheels of said conveyance. 30 WO 2006/094332 - 34 - PCT/AU2006/000187

25. The conveyance as claimed in any one of the preceding claims, wherein a hand-rail means is associated with each of said first and second wheels. 5

26. The conveyance as claimed in claim 25, wherein each of said hand-rail means is removably coupled to its respective first or second wheel.

27. The conveyance as claimed in any one of the preceding claims, wherein each of said first and second drive axles includes at least one universal 10 joint disposed at or near its outer ends thereof.

28. The conveyance as claimed in claim 27, wherein said universal joints allow said first and second wheels to move freely in all directions relative to said first and second drive axles. 15

29. The conveyance as claimed in any one of the preceding claims, wherein said conveyance is a wheelchair.

30. An improved drive system for a conveyance having at least one 20 pair of opposed drive wheels, said improved drive system including: at least two axles adapted to be mounted or disposed between said wheels, each of said axles being adapted to be in direct drive connection with opposed ones of said wheels; at least one drive means associated with at least one of said wheels and 25 in drive connection with one of said axles; and means associated with each wheel, for selective manipulation by an occupant of said conveyance, to allow for rotation of said wheels.

31. The improved drive system for a conveyance as claimed in 30 claim 30, wherein said at least two drive axles are adapted to be mounted or disposed coaxially between said wheels. WO 2006/094332 - 35 - PCT/AU2006/000187

32. The improved drive system for a conveyance as claimed in claim 31, wherein a first of said at least two drive axles is coaxially disposed within a second of said at least two drive axles. 5

33. The improved drive system for a conveyance as claimed in claim 30, wherein said at least two drive axles are adapted to be mounted or disposed between said wheels on separate axes.

34. The improved drive system for a conveyance as claimed in any 10 one of claims 30 to 33, wherein said at least two drive axles are adapted to be removably mounted or disposed between said wheels.

35. The improved drive system for a conveyance as claimed in claim 34, wherein said at least two drive axles each include telescoping 15 sections that are adapted to selectively reduce the overall length of said at least two drive axles to enable an occupant to remove said at least two drive axles from said conveyance.

36. The improved drive system for a conveyance as claimed in 20 claim 35, wherein said telescoping sections of said at least two drive axles each cooperate with at least one biasing means which biases said telescoping sections to a fully extended position.

37. The improved drive system for a conveyance as claimed in 25 claim 36, wherein said at least one biasing means biases said at least two drive axles to a fitted position between said wheels of said conveyance, wherein said fitted position of said at least two drive axles is substantially the same as that of said fully extended position. 30

38. The improved drive system for a conveyance as claimed in any one of claims 35 to 37, wherein said at least two drive axles can each be locked WO 2006/094332 - 36 - PCT/AU2006/000187 in a collapsed position by means of a locking device, to facilitate removal of said at least two drive axles from said conveyance.

39. The improved drive system for a conveyance as claimed in any 5 one of claims 30 to 38, wherein said means associated with each wheel are actuation means which are coupled to opposed ones of said wheels via said at least two axles.

40. The improved drive system for a conveyance as claimed in 10 claim 39, wherein at least one of said actuation means is coupled to its respective drive axle via said at least one drive means.

41. The improved drive system for a conveyance as claimed in any one of claims 30 to 40, wherein said at least one drive means is at least one 15 gearing assembly.

42. The improved drive system as claimed in claim 41, wherein said at least one gearing assembly is disposed within a hub of at least one of said wheels. 20

43. The improved drive system for a conveyance as claimed in claim 41 or claim 42, wherein said at least one gearing assembly is at least one differential. 25

44. The improved drive system for a conveyance as claimed in claim 43, wherein said at least one differential is adapted to provide a 2:1 drive propulsion ratio.

45. The improved drive system for a conveyance as claimed in any 30 one of claims 39 to 44, wherein each of said actuation means are coupled to their respective drive axle via at least one gearing assembly. WO 2006/094332 - 37- PCT/AU2006/000187

46. The improved drive system for a conveyance as claimed in any one of claims 39 to 44, including two actuation means, wherein only one of said actuation means in coupled to its respective drive axle via at least one gearing assembly, and wherein the other of said actuation means is directly 5 mounted to its respective drive axle.

47. The improved drive system for a conveyance as claimed in any one of claims 39 to 46, wherein said actuation means are drive or actuation discs which can each be separately engaged and manipulated by an occupant to 10 each selectively rotate said wheels of said conveyance.

48. The improved drive system for a conveyance as claimed in any one of claims 30 to 47, wherein each of said at least two drive axles includes at least one universal joint disposed at or near its outer ends thereof. 15

49. The improved drive system for a conveyance as claimed in claim 48, wherein said universal joints allow said wheels to move freely in all directions relative to said at least two drive axles. 20

50. A conveyance having at least one pair of opposed drive wheels, said conveyance including the improved drive system as claimed in any one of claims 30 to 49.

51. The conveyance as claimed in claim 50, wherein said 25 conveyance is a wheelchair.

52. A dual axle assembly for a conveyance having at least one pair of opposed drive wheels, said dual axle assembly including a first and a second drive axle adapted to be mounted or disposed between said wheels, wherein 30 said first and second axles are adapted to be in direct drive connection with opposed ones of said wheels. WO 2006/094332 -38- PCT/AU2006/000187

53. The dual axle assembly as claimed in claim 52, wherein said first and second drive axles are adapted to be mounted or coaxially disposed between said wheels. 5

54. The dual axle assembly as claimed in claim 53, wherein said first drive axle is coaxially disposed within said second drive axle.

55. The dual axle assembly as claimed in claim 52, wherein said first and second drive axles are adapted to be mounted or disposed between 10 said wheels on separate axes.

56. The dual axle assembly as claimed in any one of claims 52 to 55, wherein said dual axle assembly is adapted to be removably mounted or disposed between said wheels. 15

57. The dual axle assembly as claimed in claim 56, wherein said first and second drive axles each include telescoping sections that are adapted to selectively reduce the overall length of said first and second drive axles to enable an occupant to remove said dual axle assembly from said conveyance. 20

58. The dual axle assembly as claimed in claim 57, wherein said telescoping sections of said first and second drive axles each cooperate with at least one biasing means which biases said telescoping sections to a fully extended position. 25

59. The dual axle assembly as claimed in claim 58, wherein said at least one biasing means biases said dual axle assembly to a fitted position between said wheels of said conveyance, wherein said fitted position of said dual axle assembly is substantially the same as that of said fully extended 30 position. WO 2006/094332 - 39 - PCT/AU2006/000187

60. The dual axle assembly as claimed in any one of claims 57 to 59, wherein said first and second drive axles can each be locked in a collapsed position by means of a locking device, to facilitate removal of said dual axle assembly from said conveyance. 5

61. The dual axle assembly as claimed in any one of claims 52 to 60, wherein each of said first and second drive axles includes at least one universal joint disposed at or near its outer ends thereof. 10

62. The dual axle assembly as claimed in claim 61, wherein said universal joints allow said wheels to move freely in all directions relative to said dual axle assembly.