Wheelchair reconfiguration methods

Abstract

Methods are disclosed, according to the present invention, which enable reversible reconfiguration of a wheelchair by a user between a.) an original load-bearing configuration utilizing the conventional caster wheels of the wheelchair, and b.) a modified load-bearing configuration which confers improved functionality to the wheelchair, especially for traversing difficult or uneven terrain.

Claims

1. A method of enabling integration of a wheelchair with a pair of wheelchair-adapting implements, each one of the pair wheelchair-adapting implements comprising an arm configured for extending an area over which the wheelchair is capable of contacting a ground surface beneath the wheelchair, the wheelchair comprising a frame and a pair of primary caster wheels connected to the frame, the method including outfitting the wheelchair or the pair of wheelchair-adapting implements with a pair of load transitioning mechanisms, each one of the pair of load transitioning mechanisms being adapted for: 1.) unilateral connection of one of the pair of wheelchair-adapting implements to a side of the frame of the wheelchair to interpose a first load transitioning mechanism between a first wheelchair-adapting implement and a first side of the frame of the wheelchair, and to interpose a second load transitioning mechanism between a second wheelchair-adapting implement and a second side of the frame of the wheelchair; 2.) deployment of the pair of wheelchair-adapting implements, together being capable of fully supporting the forward portion of the load carried by the wheelchair while each one of the pair of wheelchair-adapting implements is separately connected to the frame of the wheelchair and capable of load-bearing contact with the ground surface beneath the wheelchair; 3) preparation for transitioning from having the pair of wheelchair-adapting implements deployed to having the pair of wheelchair-adapting implements disengaged; 4.) disengagement of the pair of wheelchair-adapting implements to enable disconnection of each one of the pair of wheelchair-adapting implements from the frame of the wheelchair; wherein the method enables substantially simultaneous operation of the pair of wheelchair-adapting implements.

2. The method of claim 1, further including configuring the first wheelchair-adapting implement with a first auxiliary wheel and configuring the second wheelchair-adapting implement with a second auxiliary wheel to achieve a desired orientation of the first auxiliary wheel and of the second auxiliary wheel relative to the wheelchair during deployment of the first auxiliary wheel and the second auxiliary wheel for load-bearing contact with the ground surface beneath the wheelchair.

3. A method of enabling reconfiguration of a wheelchair between: a.) an original configuration having a pair of primary caster wheels of the wheelchair bearing a forward portion of a load carried by the wheelchair, and b.) a modified configuration having the pair of primary caster wheels of the wheelchair substantially elevated and relieved from bearing the forward portion of the load carried by the wheelchair, having each one of a pair of auxiliary wheel assemblies separately connected to either a first side of the wheelchair or a second, symmetrically-opposing side of the wheelchair, the pair of auxiliary wheel assemblies being maintained in a deployed disposition in which they are capable of bearing the forward portion of the load carried by the wheelchair, the method including equipping at least one of the wheelchair or the pair of auxiliary wheel assemblies to enable connection, simultaneous deployment, simultaneous disengagement, and removal of the pair of auxiliary wheel assemblies in conjunction with use of the wheelchair while the wheelchair is carrying a seated occupant.

4. The method of claim 3, including operatively connecting at least one switch to enable alternation of the wheelchair between the original configuration and the modified configuration, said alternation being effectuated upon toggling of the switch followed by rearward shifting of the load carried by the wheelchair.

5. The method of claim 3, including configuring the pair of auxiliary wheel assemblies to achieve a desired orientation thereof relative to the wheelchair upon alternating the wheelchair to the modified configuration.

6. The method of claim 3, including configuring at least one of the wheelchair or the pair of auxiliary wheel assemblies to enable securing of the pair of auxiliary wheel assemblies in a stowed location of the wheelchair.

7. The method of claim 3, including a step of providing: 1.) a first load transitioning mechanism capable of deploying and disengaging a first wheelchair-adapting implement as a result of activating the first load transitioning mechanism and shifting the load carried by the wheelchair in a rearward direction, and 2.) a second load transitioning mechanism capable of deploying and disengaging a second wheelchair-adapting implement as a result of activating the second load transitioning mechanism and shifting the load carried by the wheelchair in a rearward direction.

8. The method of claim 3, wherein, while in the modified configuration, upon activation of a load transitioning mechanism each one of the pair of primary caster wheels remains substantially elevated wherein rearward shifting of the load carried by the wheelchair results in lowering of the pair of primary caster wheels to transition the wheelchair to the original configuration.

9. The method of claim 8, wherein, while in the original configuration, activation of the load transitioning mechanism and reclining of the wheelchair results in elevating of the pair of primary caster wheels to transition the wheelchair to the modified configuration.

10. The method of claim 3, including a step of equipping each one of the pair of wheelchair-adapting implements with a ground-contacting member, each ground-contacting member being adapted for contacting a ground surface beneath the wheelchair.

11. The method of claim 10, each ground-contacting member comprising a wheel.

12. The method of claim 10, including configuring each one of the pair of wheelchair-adapting implements to achieve a predetermined orientation thereof relative to the wheelchair while the wheelchair is maintained in the modified configuration.

13. A method of enabling reconfiguration of a wheelchair between: a.) an original configuration having a pair of primary caster wheels of the wheelchair supporting a forward portion of a load carried by the wheelchair, and b.) a modified configuration having a first wheelchair-adapting implement maintained in a deployed disposition to support the forward portion of the load carried by the wheelchair, the method including a step of providing a first load transitioning mechanism adapted to be interposed between a first side of the wheelchair and the first wheelchair-adapting implement, the first load transitioning mechanism comprising a switch, the first load transitioning mechanism capable of being advanced through an operation sequence from a deployment stage to a pre-release stage in response to toggling of the switch, the first load transitioning mechanism being capable of supporting loading placed thereupon by a single side of the wheelchair, wherein the pair of primary caster wheels are maintained substantially elevated while in the modified configuration, and wherein the pair of primary caster wheels remain substantially elevated upon advancement of the first load transitioning mechanism from the deployment stage to the pre-release stage in response to toggling of the switch.

14. The method of claim 13, including a step of configuring the first load transitioning mechanism to be capable of releasing the first wheelchair-adapting implement from the deployed disposition as a result of toggling the switch and shifting the load carried by the wheelchair substantially rearward, wherein the method enables transitioning of the wheelchair to the original configuration while the wheelchair is carrying a seated occupant.

15. The method of claim 13, including a step of configuring the first load transitioning mechanism to maintain the pair of primary caster wheels of the wheelchair substantially elevated during the modified configuration upon advancement of the first load transitioning mechanism from the deployment stage to the pre-release stage in response to toggling the switch.

16. The method of claim 13, including a step of configuring the first load transitioning mechanism to be capable of deploying the first wheelchair-adapting implement as a result of toggling the switch during the original configuration and reclining the wheelchair, wherein the method enables transitioning of the wheelchair to the modified configuration while the wheelchair is carrying a seated occupant.

17. The method of claim 13 wherein the method enables transitioning through an operation sequence to enable connection, deployment, disengagement, and removal of the first wheelchair-adapting implement, the operation sequence including a pre-deployment stage and the pre-release stage.

18. The method of claim 13 including a step of disposing the switch in proximity to the wheelchair, the switch being capable of initializing the first load transitioning mechanism to become responsive to rearward shifting of the load carried by the wheelchair, wherein, upon toggling the switch during the modified configuration, the pair of primary caster wheels remains substantially elevated, and rearward shifting of the load carried by the wheelchair results in lowering of the pair of primary caster wheels to transition the wheelchair to the original configuration and, wherein, upon toggling of the switch during the original configuration, reclining of the wheelchair results in elevating of the pair of primary caster wheels to transition the wheelchair to the modified configuration.

19. The method of claim 13, including a step of configuring at least one of the wheelchair or the first wheelchair-adapting implement to enable securing of the first wheelchair-adapting implement in a stowed location of the wheelchair.

20. The method of claim 13 including a step of providing a second load transitioning mechanism adapted to be interposed between a second side of the wheelchair and a second wheelchair-adapting implement, the second load transitioning mechanism being capable of deployment and disengagement in synchrony with deployment and disengagement of the first wheelchair-adapting implement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which:

(2) FIG. 1A shows a wheelchair occupant holding an adapting member equipped with a protract/retract-type transitioning mechanism and a large caster wheel implement while seated in a wheelchair outfitted with a mounting member. The wheelchair in FIG. 1A is in its original load-bearing configuration.

(3) FIG. 1B shows the wheelchair occupant leaning forward and connecting the adapting member to the mounting member with the protract/retract-type transitioning mechanism in the attach/release stage of operation.

(4) FIG. 1C shows the wheelchair occupant manipulating a sliding knob on the adapting member to put the protract/retract-type transitioning mechanism in the pre-deployment stage of operation.

(5) FIG. 1D shows the wheelchair occupant sitting upright and beginning to perform a wheel-stand maneuver to effectuate the transition of the protract/retract-type transitioning mechanism to the deployment stage of operation.

(6) FIG. 1E shows the wheelchair occupant sitting upright with the wheelchair in the modified load-bearing configuration and with the protract/retract-type transitioning mechanism in the deployment stage of operation after the user has performed the wheel-stand maneuver.

(7) FIG. 2 is a perspective view of an unoccupied wheelchair outfitted with a separable-type adapter having a mounting member and an adapting member, the adapting member equipped with a caster wheel implement.

(8) FIG. 3 displays the coupling relationship of the mounting member and the adapting member of the inserting embodiment adapter having a protract/retract-type transitioning mechanism, showing both the mounting member and the adapting member detached from the wheelchair.

(9) FIGS. 4A and B show a wheelchair being outfitted with an asymmetric apparatus having a single clamp, a rotary clutch-type transitioning mechanism, and a single caster wheel assembly wherein the asymmetric apparatus is releasably affixed to a forward portion of the left side of the frame of the wheelchair.

(10) FIG. 5 shows a wheelchair outfitted with a symmetric apparatus having dual left and right clamps, a rotary clutch-type transitioning mechanism, and a single caster wheel assembly wherein the symmetric apparatus is releasably affixed to forward portions of the left and right sides of the frame of the wheelchair.

(11) FIGS. 6A-D are side views of a wheelchair and clamping-type adapter having a rotary clutch-type transitioning mechanism during the four stages of the cyclic operation sequence (6A: attach/release stage, 6B: pre-deployment stage, 6C: deployment stage, and 6D: pre-release stage).

(12) FIGS. 7A-3 show a wheelchair occupant reconfiguring a wheelchair equipped with left and right ratcheting pawl-type transitioning mechanisms having forward-inserting couplings adapted to receive left and right caster wheel implements.

(13) FIGS. 8A-F are side views of the wheelchair equipped with ratcheting pawl-type transitioning mechanisms during the cyclic operation sequence, including steps for actuating additional binding means.

(14) FIGS. 9A-D show several useful applications of load transitioning mechanisms in conjunction with ground-contacting implements.

(15) FIG. 10 is a diagram summarizing the reconfiguration capabilities enabled by the load transitioning mechanism.

(16) FIGS. 11A-D are simplified diagrams comparing a protract/retract-type mechanism, a rotary clutch-type mechanism, and a ratcheting pawl-type mechanism as the three mechanisms are transitioned through the operation sequence.

DETAILED DESCRIPTION OF THE DRAWINGS

(17) The drawings described hereinafter are intended for the purpose of illustration rather than limitation.

(18) To facilitate understanding of the figures, structural elements located on the right side of the wheelchair as well as any attachments thereto, from the perspective of an occupant of the wheelchair, have been labeled with the suffix R following the numeral corresponding to the structural element. Similarly, structural elements located on the left side of the wheelchair and any attachments thereto have been labeled with the suffix L following the numeral corresponding to the structural element. In cases where the aforementioned labeling convention does not aid in understanding a particular figure, the suffix has been omitted and only the numeral has been used. For example, the left-side rear drive wheel is referred to by label 120L, and the right-side rear drive wheel is referred to by label 120R; however, in a side-view illustration wherein 120L cannot be visibly distinguished from 120R, the rear drive wheels are collectively referred to by using label 120.

(19) FIG. 1A depicts an occupant seated in a wheelchair 100, holding an adapting member 140 equipped with a large caster wheel 142 having a diameter of 8 inches. The wheelchair 100 has footrest 103 which, in this illustration, is in its lowest possible position relative to the ground surface 150. The wheelchair 100 also comprises rear drive wheels 120L and 120R of a diameter between about 20 and 26 inches, pivotable front caster wheel assemblies 108L and 108R (not visible) comprising primary caster wheels 106L and 106R (not visible) each having a diameter between about 3 and 5 inches, and left and right forward structural frame portions 102L and 102R. Rear drive wheels 120L and 120R support a rearward portion of the load carried by the wheelchair, including both a portion of the weight of a seated occupant (not shown) and a portion of the weight of the wheelchair itself. The wheelchair 100 is propelled, steered and slowed by the occupant gripping the rear drive wheels 120L and 120R or pushrims 122L and 122R (not visible) attached to said rear drive wheels 120L and 120R and applying muscle-derived force thereagainst to control the movement of the wheelchair 100. In an original, unadapted configuration, primary caster wheels 106L and 106R contact and roll over the ground surface 150 and support a forward portion of the load carried by the wheelchair, including both a portion of the weight of the occupant and a portion of the weight of the wheelchair itself. Load-bearing, in the original, unadapted configuration, is thus shared among primary caster wheels 106L and 106R and rear drive wheels 120L and 120R. As the wheelchair moves in a desired direction, the primary caster wheels 106L and 106R passively align in an orientation such that the horizontal rotational axis of each of the primary caster wheels 106L and 106R trails behind the vertical pivot axis of its respective pivotable caster assembly. As a result, the pivotable portion of each caster wheel assembly pivots about its respective vertical pivot axis in response to changes in the direction of the wheelchair enacted by the user.

(20) The wheelchair 100 is configured with mounting member 110 secured to the left forward structural frame portion 102L of the wheelchair 100. Securing of the mounting member 110 to the left forward structural frame portion 102L may be accomplished by welding, bolting, or clamping, to establish a stable, permanent or semi-permanent attachment capable of withstanding vibration and which is intended to be subjected to substantial leverage and torsion. An ideal attachment of any adaptive implements to the wheelchair, by way of the mounting member, does not risk bending, denting, or otherwise deforming the structural frame portion of the wheelchair; in the depiction, the mounting member 110 comprises an upper attachment clamp 114 and a lower attachment clamp 116 for the purpose of distributing forces over as long of a length of the forward region of the wheelchair as reasonable without adding significant weight to the wheelchair and while maintaining the aesthetic appeal of the ultralight wheelchair frame. Right forward structural frame portion 102R does not have an attached mounting member, although it would suitably accommodate a mounting member of mirror-image construction in comparison to that of mounting member 110. The mounting member 110 is attached to left forward structural frame portion 102L such that it occupies a space immediately above caster cylinder 107 which houses bearings and fastening elements to enable primary caster wheel assembly 108L to pivot freely in all directions.

(21) FIG. 1B depicts the seated wheelchair occupant leaning forward and placing the adapting member 140 in a coupled position relative to the mounting member 110. With his left hand, the user is also pulling inwardly on expansion pin assembly lever handle 124 to secure the inserted position of an expanding insertion pin (not shown) relative to the mounting member 110; the coupling or union established therein prevents relative lateral movement between the adapting member 140 and the mounting member 110, yet permits relative rotational movement therebetween. Input knob 126 is seen in its forwardmost position.

(22) In FIG. 1C, the user is pushing with his right hand, in the rearward direction, against the input knob 126 to switch the mechanism of the adapting member to an internal pre-deployment stage, after which action the input knob 126 will return to its forwardmost position.

(23) FIG. 1D shows the user sitting upright, preparing to perform a wheel-stand maneuver. At this moment, the large caster wheel 142, primary caster wheels 106L (visible) and 106R (not shown), and rear drive wheels 120L and 120R are all in contact with the ground surface 150. Also, at this time, the primary caster wheels 106L and 106R are bearing a portion of the load carried by the wheelchair, which includes both the weight of the occupant and the wheelchair itself. The adapting member 140 and the large caster wheel 142 are non-load-bearing and are upwardly and downwardly rotatable about the axis of the expanding insertion pin (not shown).

(24) Illustrated in FIG. 1E, as the user controllably leans his torso backwards while pushing forwardly against the upper regions of rear drive wheels 120L and 120R, the large caster wheel 142 remains in contact with the ground surface 150 and the primary caster wheels 106L and 106R become elevated from the ground surface 150 so that they no longer bear any portion of the load that is carried by the wheelchair. The primary caster wheels 106L (visible) and 106R (not shown) as well as the footrest 103 are all transitioned to an increased vertical position relative to the ground surface 150, thereafter leaving substantially more clearance beneath these forward structures of the wheelchair 100. As a result of this increased clearance, obstacles laying on or contained within the ground surface 150 may be more readily traversed over by the user, who also experiences decreased rolling resistance and increased forward stability with now having the mechanism in the deployment stage and the wheelchair in a modified load-bearing configuration.

(25) Removing the adapting member 140 and caster wheel 142 from the wheelchair 100 is accomplished by carrying out the sequence depicted in FIGS. 1A through 1E in reverse order, which ultimately results in transitioning the mechanism from the deployment stage to the attach/release stage and subsequently decoupling the adapting member 140 from the mounting member 110 to return the wheelchair back to its original, unadapted load-bearing configuration wherein the primary caster wheel assemblies 106L and 106R contact and roll over the ground surface 150 and support the forward portion of the load carried by the wheelchair.

(26) FIG. 2 displays a similarly-configured wheelchair 100 left unoccupied and with an attached adapting member 140 equipped with a large caster wheel 142. The wheelchair 100, in this depiction, is presently maintained in the modified load-bearing configuration, with the mechanism of the adapter in the deployment stage of operation. A curved tubular support member 230 interconnects the pivotable caster assembly 240 to the mechanism portion 200 adapting member 140. The curved tubular support member 230, which disposes the pivotable caster assembly 240 at a central forward location relative to the wheelchair 100, may also serve as a caster positioning means. By loosening tube clamp 232 and caster mounting block 226 in relation to the curved tubular support member 230, rotation of the curved tubular support member 230 may be performed in either direction and may be used to alter both the pitch orientation and the roll orientation of the pivot axis of the pivotable caster assembly 240. This method, used in conjunction with rotational adjustment of the mounting member 110 about the left forward structural frame portions 102L of the wheelchair 100 and vertical adjustment of the caster cylinder 224 relative to the caster mounting block 226, permits a high degree of adjustability of the adaptive implement (the pivotable caster assembly 240) relative to the wheelchair 100. It is to be understood that alternative provisions for attachment, adjustment, release, and other operations of the adapter may be utilized without departing from the scope of the invention as claimed, and that additional attachment assemblies may be present, as desired, also without departing from the scope of the invention as claimed.

(27) FIG. 3 displays a separated view of the adapting member 140 and the mounting member 110, indicating the manner and direction in which the expanding insertion pin 340 inserts into tubular receptacle 382 of the mounting member 110. Other elements of the adapting member 140 and the mounting member 110, which were implied though not described in previous figures, are also clearly visible in FIG. 3. The mounting member 110 comprises an upper fastening body 360, an upper arcuate fastening element 362, a lower fastening body 366, a lower arcuate fastening element 368, fastening bolts 364A and 364B, a rigid structural plate 370, structural plate bolts 372A and 372B, and a bearing plate 374. A tubular receptacle 382 projects through an aperture in bearing plate 374 and also through an aperture in rigid structural plate 370, and is fastened on both sides by receptacle nut 380A.

(28) The adapting member 140 comprises a load-transfer assembly 310, a solid body 312, and connector bolts 316A and 316B to connect the load-transfer assembly 310 to the solid body 312. To aid in rigidizing and ensuring the integrity of the bolted connection between the load-transfer assembly 310 and the solid body 312, a pair of saddle washers 314 are placed therebetween. Projecting through an aperture in the solid body 312 is an expanding insertion pin 340 operatively connected to a cam assembly 320, which is actuated by user manipulation of the lever handle 124. Upon inserting the expanding insertion pin 340 into the tubular receptacle 382 of the mounting member 110 and subsequently pulling back on the lever handle 124, the expanding insertion pin 340 establishes and maintains a secure grip within the tubular receptacle 382 to effectively secure the adapting member 140 to the mounting member 110. By virtue of the strong union created between the adapting member 140 and the mounting member 110, the adapted wheelchair is capable of withstanding the torsional strain and asymmetric loading placed thereupon during normal use, and rotation of the adapting member 140 about the axis of the expanding insertion pin 340 is sufficiently isolated to ensure that the adapting member 140 may be transitioned without being hindered by any torsional strain and asymmetric loading placed upon the adapting member 140 as a result of a load borne completely or in part by the adapting member 140.

(29) Adjustments made at the union between the expanding insertion pin 340 and the cam assembly 320, such as by turning the lever handle 124 around a threaded end (not shown) of the expanding insertion pin 340, serve to amplify the pressure established between the expanding insertion pin 340 and the inner surface of the tubular receptacle 382 to further unify the adapting member 140 with the mounting member 110. As a result, during transition and while in the operative state, most if not all wiggle, vibration and play between the adapting member 140 and the mounting member 110 is eliminated during normal use of the adapted wheelchair. While traversing over ground surfaces, the occupant of the wheelchair 100 experiences a very solid and secure ride due to the tightly unified adapting member 140 and wheelchair 100.

(30) The adapting member 110 additionally comprises a moveable bearing assembly which comprises a cylindrical bearing element 350. Upon the user manipulating the input knob 126 by pushing it in the rearward direction, the cylindrical bearing element 350 moves, linearly, in the forward direction or in the rearward direction, depending on the current operational stage of the load-transfer assembly 310. Repeated manipulation of the input knob 126 alternates the position of the moveable bearing assembly 348 between a forward position and a rearward position.

(31) Projecting through the bearing plate 374 and into the rigid structural plate 370 is an adjustment bolt 390. Upon removal of the adjustment bolt 390, the bearing plate 374 may be rotated about the axis of the tubular receptacle 382 relative to the rigid structural plate 370, after which the adjustment bolt 390 may be reinserted and tightened into one of the three other adjustment holes to alter the effective angle created between an attached adaptive implement (in this case, the caster wheel) and the wheelchair 100 upon deploying the adapting member 140 into the deployed state.

(32) It is important to note that the aforementioned arrangement of the cylindrical bearing element 350, the load transfer assembly 310, the solid body 312, the expanding insertion pin 340, the mounting member 110, and all fastening and clamping means associated therewith, allows for sufficient movement of the cylindrical bearing element 350 so that it may readily engage with and disengage from the nested groove 378, and wherein the adapting member 140 is releasably securable to the mounting member 110 such that the adapting member 140 is maintained in a position and orientation relative to the wheelchair while in the load-sharing state, preferably through many cycles of attaching, operating, and releasing the adapting member 140 relative to the mounting member 110. In the process, all torsional strain and loading experienced by the adaptive implement attached thereto is borne by the foregoing elements, especially due to the asymmetric loading experienced as a result of the independent lateral attachment to the wheelchair 100. The success with which the design, construction, and choice of materials hold up to this anticipated asymmetric strain will impact the performance, safety, and longevity of the apparatus as well as the proper functioning of the mechanism employed to carry out the transitioning thereof through all stages of the operation sequence.

(33) During the attach/release stage, as well as during transition into and out of the attach/release stage, the cylindrical bearing element 350 slides in an arcuate path in contact with or in close proximity to the arcuate bearing surface 396 of the bearing plate 374. The rotational axis at the center of the expanding pin 340 serves as a fulcrum around which the adapting member 140 rotates; the shape of the arcuate bearing surface 396 may thus be defined as an arc having a radius equal to the distance from the axis 384 of the expanding insertion pin 340 to the nearest contact point of the cylindrical bearing element 350 while the load-transfer assembly 310 is in the attach/release stage or during transition into or out of the attach/release stage. Furthermore, to ensure maximum contact of the cylindrical bearing element 350 with the contact surfaces of the nested groove 378, the deepest point of the nested groove may be defined by the distance from the axis 384 of the expanding insertion pin 340 to the nearest contact point of the cylindrical bearing element 350 while the load-transfer assembly 310 is in the deployment stage.

(34) During the deployment stage, as well as during the pre-release stage, the cylindrical bearing element 350 is disposed in the nested groove 378 of the bearing plate 374. Upwardly directed force (due to downward loading on the front end of the wheelchair) is leveraged about the axis 384 of the expanding pin 340 and transferred downwardly against the lower bearing surface 376 of the nested groove 378. Supporting of a load by the adapter apparatus 180 relies on the integrity of the elements of the moveable bearing assembly 348 as they transfer the load from the adapting member 140, through the cylindrical bearing element 350, to the bearing plate 374.

(35) FIGS. 4A and 4B show the wheelchair prior to and after affixing an asymmetric, fully-removable, clamping-type adapter to the right side of the frame of the wheelchair, said adapter comprising a rotary clutch-type transitioning mechanism acting as a singular joint between a clamp assembly and an adaptive caster wheel assembly. FIG. 4A depicts the wheelchair 100 ready for attachment of a clamping-embodiment apparatus 400 having an asymmetric (one-sided) structure. Caster wheel assembly 440 having large caster wheel 442 is connected to the transitioning mechanism assembly 402 by the extension arm 450. It is important to note that the embodiment disclosed in FIG. 4A is absent a laterally-inserting positive locking pin assembly and alternatively comprises a bolt (not shown) which secures solid body 460 to cylindrical housing 470 and which defines an axis of relative rotation therebetween. Clamp collar 430 adjustably secures the cylindrical housing 470 to tube clamp 420. A positioning collar 410R which is affixed to the lateral portion 102R of the wheelchair 100 enables a user to repeatably attach, remove and re-attach the clamping-embodiment apparatus 400 by affixing tube clamp 420 in a predetermined position and orientation relative to the wheelchair 100. Control knob 166 is shown in its most forward position, corresponding to an internal state of disengaging spring pressure; thus the mechanism is in the attach/release stage of operation.

(36) FIG. 4B depicts the wheelchair 100 having the asymmetric (one-sided) caster wheel apparatus of FIG. 4A in the attach/release stage, with the adaptive caster wheel 442 resting on the ground surface yet bearing no load and with the control knob 166 in its most forward position, corresponding to an internal state of disengaging spring pressure with the mechanism in the attach/release stage of operation. The disengaging spring pressure urges the movable roller bearings toward a disposition free from any binding contact between the fixed portion of the transitioning mechanism assembly 402 and the movable portion thereof. The clamping-embodiment apparatus 400, in this stage of operation, is ready for either: a.) detachment from the wheelchair 100, or b.) transitioning to the pre-deployment stage.

(37) FIG. 5 depicts the wheelchair 100 having a symmetrically-attaching caster wheel apparatus 500 comprising a single transitioning mechanism assembly 502 in conjunction with a curved extension arm 552 which adjoins two symmetrically opposing clamps 520L and 520R configured for attachment to both the left and the right sides of the wheelchair frame. The adaptive caster wheel 442 is supporting the forward portion of the load carried by the wheelchair 100, whereas the primary caster wheels 106L and 106R of the wheelchair 100 are substantially elevated above the ground surface 150 and thus fully relieved of any loading.

(38) The auxiliary caster wheel assemblies of FIGS. 4A, 4B, and 5 comprise a wheel 442 that is substantially larger than that of the primary caster wheels 106L and 106R, such as at least about 5 inches in diameter, or at least about 6 inches in diameter, or at least about 8 inches in diameter, or at least about 10 inches in diameter, or at least about 12 inches in diameter. Depending on the terrain a user desires to traverse, it may also be useful for the auxiliary caster wheel 442 to be substantially wider, such as at least about 10 percent wider than the primary caster wheels, in order to increase the surface area of the region of contact with the ground surface. Useful widths of the auxiliary caster wheel 442 may be at least about 20, 40, 60, 80, 100, 120, 140, 160, or 180 percent wider than the primary caster wheels. Extremely wide auxiliary caster wheels may have a ground-contacting tread region up to 200 percent, up to 300 percent, or up to 400 percent or more of the width of the primary caster wheels.

(39) FIGS. 6A-D are lateral views of the wheelchair 100 and the clamping-embodiment apparatuses of FIGS. 4A, 4B, and 5, illustrating the positioning thereof, with respect to the ground surface, during transitioning through the four stages of operation. FIG. 6A shows a lateral view of the clamping-embodiment apparatus 400 secured to the wheelchair at the location defined by a positioning collar, with the control knob 166 in its most forward position so that the internal spring state is biased towards maintaining release of the binding elements from contact and thus no load transfer to the apparatus. The control knob 166 is shown in a forward rotational position corresponding to an internal state of disengaging spring pressure (the attach/release stage of operation). Control knob 166 receives manual input force enacted by the user for transferring said manual input force to effectuate a state alternation of the force sustainment subassembly which, as a result, is selectably toggled between a first biasing state and an opposing second biasing state. Alternation between the two opposing internal states of spring pressure enables the user to prepare or arm the mechanism so that the overrunning clutch (not visible) of the transitioning mechanism will subsequently be alternated in its capacity for load-bearing torque transmission upon the user performing the wheel-stand maneuver.

(40) FIG. 6B shows a lateral view of the clamping-embodiment apparatus 400 with its wheel resting on the ground surface yet bearing no load and with its control knob 166 in its most rearward position so that the internal spring state is biased towards establishing contact of the binding elements; in this pre-deployment stage, the mechanism is thus prepared for transition to the deployment stage of operation. Engaging spring pressure, as a result of the user having manipulated the control knob 166, causes the internal overrunning clutch (not shown) to allow downward rotation of the rotatable portion of apparatus 400, while preventing rotation thereof in the opposite direction. A reclining action or wheel-stand maneuver, whether it be performed by an assistant or, preferably, by the occupant of the wheelchair, is necessary at this point to lift the front end of the wheelchair 100 to create a gap 300 beneath the primary caster wheels 106 and, at the same time, causes downward rotation of the rotatable portion of the apparatus.

(41) FIG. 6C shows a lateral view of the clamping-embodiment transitioning apparatus 400 in the deployment stage of operation, during which the apparatus is deployed and load-bearing and the primary caster wheels 106 are substantially elevated from contact with the ground surface, after the wheelchair 100 has been reclined substantially to elevate the primary caster wheels 106 off the ground surface 150. While in the pre-deployment stage of operation (previously shown in FIG. 6B), upon reclining the wheelchair sufficiently to cause a travel-limiting element (not shown) to contact a forward limit stop (not shown), the rotatable portion of the clamping-embodiment apparatus 400 is subsequently maintained in the position shown in FIG. 6C and is substantially prevented from attaining any change in position relative to the structural frame of the wheelchair 100. The forward portion of the load that was previously supported by the primary casters while the wheelchair was in its unadapted state is now distributed to the auxiliary caster wheel 442. Auxiliary caster wheel 442 is now in full contact with the ground surface. The control knob 166 remains in its most rearward position until the user manipulates it with a forward push using the hand, thumb or fingers.

(42) FIG. 6D shows a lateral view of the clamping-embodiment apparatus 400 in the pre-release stage of operation, during which the apparatus is load-bearing and the primary caster wheels 106 are substantially elevated from contact with the ground surface, with the control knob 166 in its most forward position so that the internal spring state is biased towards releasing the binding elements from load-bearing contact. Only upon the user reclining the wheelchair substantially will such release of the binding elements occur, after which event the primary caster wheels 106 will drop back down into contact with the ground surface, thereby completing the cyclic operation sequence and returning the wheelchair to its original load-bearing configuration; the clamping-embodiment apparatus 400 may now be removed from the wheelchair 100.

(43) In FIG. 7A, the occupant is shown utilizing the wheelchair 100 while in its original, unadapted load-bearing configuration, having the rear drive wheels 120L and 120R and primary caster wheels 106L and 106R in contact with the ground surface 150. Ratchet pawl-type transitioning mechanism assemblies 700L and 700R are shown semi-permanently affixed to opposing left and right forward regions of the wheelchair 100. Dual adaptive caster wheel implements 710L and 710R, stowed beneath the seat, are visible. FIG. 7B more clearly shows the stowed positioning of the adaptive caster wheel implements 710L and 710R, as visible from behind the wheelchair 100.

(44) FIG. 7C shows the user positioning male coupling member 702L affixed to a rotatable portion of ratchet pawl-type transitioning mechanism assembly 700L, in preparation for connecting adaptive caster wheel implement 710L thereto.

(45) FIG. 7D shows the user reaching behind the wheelchair 100 to remove adaptive caster wheel implement 710L from its stowed position (on the right side, beneath the seat).

(46) In FIG. 7E, the user is shown attaching adaptive caster wheel implement 710L to male coupling member 702L. FIG. 7F is an enlarged view showing the coupling relationship of the adaptive caster wheel implement 710L with the male coupling member 702L. Male coupling member 702L comprises anti-rotation key 704, which slides into keyway 714 notched into opening 712 at the end of adaptive caster wheel implement 710L.

(47) Also shown in FIG. 7F are quick-release clamping collar 720 and adjustment collar 730. Adjustment collar 730 is used to adjust the roll axis of caster wheel assembly 740 so that it trails properly while deployed. Quick-release clamping collar 720 enables the user to releasably secure the adaptive caster wheel implement 710L to the male coupling member 702L after sliding the opening 712 thereover.

(48) Also visible in FIG. 7F is biasing switch lever 750, which is operatively connected to the internal transitioning mechanism for the purpose of biasing a movable pawl bearing toward and away from engagement with a bearing surface. Additionally, FIG. 7F shows binding cam lever 760 which is operatively connected to a tensioning skewer projecting internally to the internal transitioning mechanism for the purpose of enabling the user to releasably draw the movable pawl bearing into a position of maximum binding engagement with the bearing surface.

(49) Not visible in FIG. 7F, but readily visible in FIGS. 7G-7J is external cam binding assembly 770 affixed to quick-release clamping collar 720 for the purpose of enabling the user to establish binding force between the wheelchair frame and the adaptive caster wheel implement 710L to further unify the caster wheel implement 710L with the wheelchair. Alternatively, an additional clamp may be used in place of external cam binding assembly 770 to similarly unify the caster wheel implement 710L with the wheelchair.

(50) In FIG. 7G the user prepares the right-side male coupling member 702R for receiving the right-side adaptive caster wheel implement 710R (not visible).

(51) FIG. 7H shows the user manipulating switch lever 750 to place the load transitioning mechanism into the pre-deployment stage of operation, after which time the user performs the wheel-stand maneuver (shown in FIG. 7-I), effectuating the transition to the deployment stage of operation wherein the primary caster wheels 106L and 106R are elevated from contact with the ground surface.

(52) In FIG. 73, the user is shown manipulating the binding cam lever 760 while the load transitioning mechanism is in the deployment stage of operation. Also, at this time, the user may rotate the external cam binding assembly 770 affixed to quick-release clamping collar 720 to establish additional binding force between the wheelchair frame and the adaptive caster wheel implement 710L to further unify the caster wheel implement 710L with the wheelchair.

(53) FIG. 8A shows a side view of the wheelchair 100 equipped with ratcheting pawl-type transitioning mechanism 700 during the attach/release stage of the cyclic operation sequence. The pawl-type transitioning mechanism 700 comprises biasing switch lever 750 in its forward (disengaging) position, binding cam lever 760 in its unbound position, and external cam binding assembly 770 in its unbound position. Coupled with the pawl-type transitioning mechanism 700 is adaptive caster wheel implement 710 having caster wheel 442 elevated from contact with the ground surface 150, as it is free to rotate in both the upward and downward directions without any engagement occurring within the mechanism. The mechanism is thus in the attach/release stage of the operation sequence.

(54) In FIG. 8B, the pawl-type transitioning mechanism 700 is shown in the pre-deployment stage of the operation sequence, now having the biasing switch lever 750 oriented in its rearward (engaging) position. The caster wheel 442 is contacting the ground surface 150 as a result of the user allowing the adaptive caster wheel implement 710 to rotate downward about the joint axis of the pawl-type transitioning mechanism.

(55) Upon the user performing the wheel-stand maneuver, the pawl-type transitioning mechanism 700 enters the deployment stage of the operation sequence, shown in FIG. 8C, wherein the adaptive caster wheel implement 710 bears the forward portion of the load carried by the wheelchair and wherein the primary caster wheels 106 of the wheelchair 100 remain elevated from contact with the ground surface 150.

(56) In FIG. 8D, the wheelchair 100 is shown in the modified load-bearing configuration while also having the binding cam lever 760 in its bound position and while also having the external cam binding assembly 770 in its bound position, for rigidly unifying the adaptive caster wheel implement 710 with the frame of the wheelchair 100. In other words, the mechanism is in the deployment stage of the operation sequence in conjunction with enhanced binding capabilities.

(57) FIG. 8E shows the wheelchair 100, still in the modified load-bearing configuration while now having the binding cam lever 760 in its unbound position and while also having the external cam binding assembly 770 in its unbound position, for releasing the adaptive caster wheel implement 710 from its rigid unification with the frame of the wheelchair 100. Further, the biasing switch lever 750 is oriented in its forward (disengaging) position, in preparation for the user to perform the wheel-stand maneuver to effectuate alternating the wheelchair from the modified load-bearing configuration to the original load-bearing configuration. The mechanism, as depicted in FIG. 8E, is thus in the pre-release stage of the operation sequence.

(58) FIG. 8F shows the wheelchair 100 after the user has performed the wheel-stand maneuver to alternate the wheelchair from the modified load-bearing configuration to the original load-bearing configuration; the mechanism is returned to the attach/release stage of the operation sequence. At this stage, the user may now lift the adaptive caster wheel implement 710 so that it rotates upward about the joint axis of the pawl-type transitioning mechanism 700, after which the user may de-couple the adaptive caster wheel implement 710 from the wheelchair 100 and return it to a stowed position, if desired.

(59) FIG. 9A shows the wheelchair 100 outfitted with dual, left and right adaptive caster wheel implements 710L and 710R, with the wheelchair 100 in the modified load-bearing configuration wherein the primary caster wheels 106L (not visible) and 106R are elevated from contact with the ground surface 150.

(60) In FIG. 9B, the wheelchair 100 is outfitted with dual, left and right omniwheel implements 910L and 910R which enable movement of the wheelchair in all directions by virtue of a plurality of rollers disposed concentrically around the axis of rotation of the wheels. The primary caster wheels 106L and 106R are elevated from contact with the ground surface 150.

(61) In FIG. 9C, the wheelchair 100 is outfitted with a single, symmetrically-disposed adaptive caster wheel apparatus 920 having dual, left and right support arms 922L and 922R which couple with left and right transitioning mechanism assemblies 700L and 700R. The primary caster wheels 106L and 106R are elevated from contact with the ground surface 150.

(62) In FIG. 9D, the wheelchair 100 is outfitted with dual, left and right ski implements 930L and 930R which enable movement of the wheelchair over snow, ice or sand. The primary caster wheels 106L and 106R are elevated from contact with the ground surface 150.

(63) FIG. 10 summarizes the reconfiguration capabilities enabled by the load transitioning mechanism, wherein a reconfigurable wheelchair 1000 is capable of being outfitted with a variety of wheelchair-adapting implements which confer special functionalities and an extended wheelbase. A user is thus enabled to reconfigure the wheelchair among a dual caster wheel mode 1010, a dual omniwheel mode 1020, a single caster wheel mode 1030, and a dual ski mode 1040.

(64) FIGS. 11A-D are simplified diagrams comparing a protract/retract-type mechanism, a rotary clutch-type mechanism, and a ratcheting pawl-type mechanism as the three mechanisms are transitioned through the operation sequence. Each mechanism type is shown with a singular, central joint axis 1100A, 1100B, and 1100C, respectively. Each mechanism type is also shown having a fixed joint member 1110A, 1110B, and 1110C, respectively, and a rotatable joint member, 1120A, 1120B, and 1120C, respectively. The protract/retract-type mechanism comprises a linearly-displaceable cylindrical bearing 1130. The rotary clutch-type mechanism comprises a plurality of cylindrical roller bearings 1140A, 1140B, and 1140C which are rotationally displaceable. The ratcheting pawl-type mechanism comprises a pawl bearing 1150 which is hingedly-displaceable about its own axis of rotation. Directional arrows in each diagram indicate the direction in which each bearing type is enabled to move as a result of a sustained urging force applied thereto.

(65) In FIG. 11A, all three mechanisms are shown in the attach/release stage of the operation sequence, having the rotatable joint member rotated in an upward angular orientation relative to the fixed joint member. As the directional arrows indicate, each bearing type is enabled to move away from a position of load-bearing engagement.

(66) In FIG. 11B, all three mechanisms are shown in the pre-deployment stage of the operation sequence, still having the rotatable joint member rotated in an upward angular orientation relative to the fixed joint member, after the user has manipulated the biasing switch to enable a sustained application of engaging force to the movable bearing. As the directional arrows indicate, each bearing type is enabled to move in the opposite direction toward a position of load-bearing engagement. At this stage, each mechanism is prepared or armed for alternating the wheelchair from the original load-bearing configuration to the modified load-bearing configuration.

(67) In FIG. 11C, all three mechanisms are shown in the deployment stage of the operation sequence, after the user has performed the wheel-stand maneuver to effectuate a change in the angular orientation of the rotatable joint member relative to the fixed joint member. The sustained urging force applied to each bearing type enables movement thereof into a position of load-bearing engagement, thereby maintaining the relative angular orientation of the rotatable joint member and the fixed joint member and keeping the primary caster wheels of the wheelchair elevated from the ground surface.

(68) FIG. 11D shows all three mechanisms in the pre-release stage of the operation sequence, after the user has manipulated the biasing switch to enable a sustained application of disengaging force to the movable bearing. As the directional arrows indicate, each bearing type is enabled to move toward the position of load-bearing engagement, as previously shown in FIG. 11A, although each mechanism type continues to support the weight placed thereupon. At this stage, only upon the user performing the wheel-stand maneuver will the relative angular orientation of the rotatable joint member and the fixed joint member be permitted to change, thereby alternating the wheelchair from the modified load-bearing configuration back to the original load-bearing configuration.

Example I

(69) An exemplary apparatus was built and configured for the purpose of lengthening the effective wheelbase of the wheelchair and also for decreasing the rolling resistance experienced by the user, especially while traversing over ground substrates such as sand, gravel, woodchips, grass, and snow. The apparatus comprises a single adaptive caster wheel implement which attaches to the left side of a wheelchair so that it may perform in conjunction with, though operated independently of, any additional adaptive implement that may be usefully attached to the right side of the wheelchair. The apparatus may, alternatively, be attached to the left side of the wheelchair without any adaptive implement attached to the right side of the wheelchair.

(70) While attached to the wheelchair in a unilateral manner, the opposing side of the wheelchair frame remains relatively free from obstruction, thereby enabling a user or occupant of the wheelchair to pass his or her body into or out of a seated position in the wheelchair while the apparatus is attached to the wheelchair, if he or she so desires.

(71) The exemplary apparatus comprises an adapting member comprising a caster assembly that is substantially larger and more robust than the original primary caster assemblies that are permanently integrated with the wheelchair, and includes a 50 mm wide, 8-inch diameter pneumatic tire fitted over an aluminum wheel hub. This tire was chosen because, when inflated, it exhibits excellent rolling resistance on both rugged surfaces and smooth surfaces alike, and provides sufficient grip against paved surfaces to help prevent flutter of the caster assembly when approaching vehicle speeds of around 8 MPH or 12 KmPH, which is average human running speed.

(72) The exemplary apparatus also comprises a mounting member, which is semi-permanently clamped onto a forward lateral support of the frame of the wheelchair such that it occupies the space immediately above the left-side primary caster assembly of the wheelchair. The mounting member remains affixed to the wheelchair at all times and is unobtrusive to the user's arms, legs, and feet, and outerwear at times when an adapting member is decoupled from the mounting member.

(73) The mounting member comprises two tube clamps and a primary structural plate; all fabricated out of 6061 aluminum and secured using stainless steel machine screws. A hollow receiver socket, comprising a threaded outer surface, is secured inside an opening cut through the primary structural plate by tightening threaded nuts on opposing sides of the hollow receiver socket. A bearing element, composed of aluminum bronze and comprising four adjustment holes, is affixed to the primary structural plate and is secured against the primary structural plate by one of the threaded nuts and is rotationally secured by a bearing fastening bolt. Loosening of the bearing fastening bolt permits rotation of the bearing element about the axis of the hollow receiver socket; a defined operation angle of the adapting member is dependent upon which adjustment hole is occupied by the bearing fastening bolt in securing the bearing element to the primary structural plate.

(74) The bearing element of the mounting member further comprises a disengagement region and a nested engagement region, both which have been ground and polished to allow for a moveable bearing element of the adapting member to slide smoothly along the disengagement region and into and out of the nested engagement region.

(75) The adapting member is primarily composed of 6061 aluminum, and comprises several position adjustment means. First, the position of the caster assembly is connected to and may be rotatably and longitudinally adjusted relative to a curved support arm. Second the support arm is connected to and rotatably and longitudinally adjustable relative to a solid connector body. Third, the curved support arm itself serves as a means for changing the effective pitch orientation of the caster assembly.

(76) The adapting member further comprises a protract-retract mechanism which is contained within a tubular housing body, the tubular housing body bolted to the solid connector body. An outer portion of the protract-retract mechanism is affixed to the inner surface of the tubular housing body with a set screw. The protract-retract mechanism is slidingly toggled by the user or occupant by pushing rearwardly against a slider knob. Movement of an input element of the protract-retract mechanism switches an output element between a protracted position and a retracted position which, in turn, alternates an internal slider, composed of low-friction wear-resistant Nylatron rod, between a first position and a second position. While in the first position, the internal slider applies linear pressure against the moveable bearing element to urge it towards a disengaged position. If the apparatus is currently in an operative state, toggling the internal slider to the first position will pre-dispose the moveable bearing element to move into the disengaged position to occupy the disengagement region at the instant the user or occupant performs a wheel-stand maneuver or otherwise elevates the front end of the wheelchair.

(77) While in the second position, the internal slider removes linear pressure against the moveable bearing element and thus permits it to move towards an engaged position. If the apparatus is currently in an inoperative state, toggling the internal slider to the second position will pre-dispose the moveable bearing element to move into the engaged position to occupy the nested engagement region at the instant the user or occupant performs a wheel-stand maneuver or otherwise elevates the front end of the wheelchair.

(78) The speed and force with which the moveable bearing element moves into and out of the nested engagement region depends largely on the amount of biasing force that is applied against the moveable bearing element in either direction. In the case of the exemplary apparatus, two internal extension springs, disposed on opposite sides of the moveable bearing element, were selected according to characteristics (length, diameter, and extension force) that would produce maximum travel, urging force, and speed in both directions upon the user or occupant toggling the internal slider between the first position and the second position and performing a wheel-stand maneuver or otherwise elevating the front end of the wheelchair. Through experimentation, it was observed that if the spring forces applied to opposing sides of the moveable bearing element were not properly balanced, the moveable bearing element would fail to move into or out of the nested engagement region upon toggling the internal slider and performing a wheel-stand. Once this balance was achieved, however, the apparatus has demonstrated very reliable operation with only occasional cleaning and lubrication necessary.

(79) An insertion pin with a diameter of inch, integrated with the adapting member, is removably insertable into the hollow receiver socket of the mounting member, which comprises a smooth interior surface. Upon full insertion, the adapting member is situated in the correct lateral position relative to the wheelchair, and the moveable bearing element of the adapting member is situated in the correct location against the disengagement region of the bearing element. To further enhance the integrity of the connection of the adapting member to the mounting member, the insertion pin comprises expandable rings which are expanded within the hollow receiver socket upon the user or occupant applying force against a cam-action lever handle operatively connected to an inner rod of the insertion pin. The user or occupant, upon coupling the insertion pin into the hollow receiver socket, actuating the protract-retract mechanism, and performing a wheel-stand, may enhance the grip of the coupling by applying force against the cam-action lever handle in order to use the apparatus in rigid union with the wheelchair so that minimal wiggle or play is observed between the mounting member and the adapting member.

(80) Actuating the biasing mechanism (to pre-dispose the load-transfer assembly toward the opposite load-bearing state) is quick and easy for the user to perform, as the actuator knob is well within arm's reach.

(81) To convert the wheelchair from its original mode to the adapted mode, the user inserts the expanding pin of the adapting member into the receptacle of the mounting member and, after manually actuating the biasing mechanism, he effectuates the transition to the adapted mode by reclining the wheelchair backward so that the primary caster wheels of the wheelchair are elevated approximately 1 inches above the ground surface. An audible click is heard as the moveable bearing element moves into the nested engagement region of the bearing surface. The user then further secures the adapting member to the mounting member by pulling the cam-action expansion pin lever in towards the body of the adapting member. The caster wheels remain elevated approximately 1 inches above the ground surface during travel in all directions and do not add rolling resistance or otherwise interfere with the performance of the wheelchair in its adapted mode, as the large forward caster wheel now shares, with the wheelchair, the load distributed towards the front of the wheelchair. As a result, the user has been able to use his adapted everyday wheelchair to venture out with relative ease over terrain such as at parks, playgrounds, trails, and over heavily weathered pavement, all which would otherwise pose significant difficulty and safety risk. The user has furthermore enjoyed the maneuverability, in all directions of travel, afforded by the adapted wheelchair while the user traverses over both indoor and outdoor surfaces.

(82) The exemplary apparatus has been used in conjunction with an Invacare Top End titanium rigid-style wheelchair, and has performed exceptionally well on outdoor surfaces including sand, gravel, wood chips, smooth pavement, rugged weathered pavement, city sidewalks, and snowy neighborhood streets.

Example II

(83) Dual (left and right) adaptive caster wheel apparatuses, each having a load-transitioning mechanism which separably integrates with a caster wheel implement, were built and configured for the purpose of lengthening the effective wheelbase of the wheelchair and also for decreasing the rolling resistance experienced by the user, especially while traversing over ground substrates such as sand, gravel, woodchips, grass, and snow.

(84) Both apparatuses were configured to be removably and adjustably affixed to the tubular frame of a Ti-Lite TRA rigid-style ultralight titanium wheelchair by way of mounting clamps which were semi-permanently affixed onto the left and right forward lateral supports of the tubular frame of the wheelchair; each device occupies a space immediately above a primary caster wheel assembly on its respective side of the wheelchair. The load transitioning mechanism of the device remains affixed to the wheelchair at all times and is unobtrusive to the user's arms, legs, and feet, and outerwear, including while any adaptive implements are decoupled from the load transitioning device.

(85) Both apparatuses were further configured to receive any one of a variety of adaptive implements, most notably a selection of attachable all-terrain caster wheel implements adapted for use in urban, suburban, and rural environments encountered in the State of Wisconsin.

(86) Early prototypes of the mechanism were constructed to be capable of withstanding torque in excess of 300 ft-lbs. Provisions were made to clamp the fixed portion of the load transitioning mechanism to the tubular frame of the wheelchair, as well as to form a coupling on the rotatable portion of the mechanism in a manner which exhibits minimal wiggle or play. Also, for each device, a cylindrical aluminum outer casing was fabricated and secured, using a series of set screws, to fit tightly over and completely enclose the load transitioning mechanism.

(87) Internally, each roller clutch has a plurality of cylindrical rollers which function as movable bearings that are selectably wedged between a hardened steel outer casing and a hardened steel inner load transfer spindle, depending on the rotary position of a control dial. The control dial was adapted to receive a first arm of a torsion spring, with the opposing second arm of the torsion spring projecting out of the outer casing through an elongated passageway machined out of the outer casing. The passageway was dimensioned so as to limit the rotational travel of the second arm of the torsion spring in both directions while allowing sufficient clearance for the second arm of the torsion spring to freely travel between both ends of the passageway.

(88) Notches at the opposing ends of the passageway receive the second arm of the torsion spring upon the user manipulably forcing the second arm therein. The torsion spring, which is maintained centrally within the cylindrical outer casing by a cylindrical nylon shaft, behaves in conjunction with the notches of the passageway as a simplistic yet effective means for biasing the control dial (and thus the cylindrical roller bearings) in either an engaging direction of rotation or a disengaging direction of rotation. When the torsion spring is disposed in the first notch of the passageway, the spring is deflected to wind up and, in effect, applies a sustained urging force in a forward direction to cause the control dial to rotate in the engaging direction. When the torsion spring is disposed in the second notch of the passageway, the spring is deflected to wind down and, in effect, applies a sustained urging force in a reverse direction to cause the control dial to rotate in the disengaging direction. When the torsion spring is disposed at a location in the passageway between the first notch and the second notch, the torsion spring is relaxed.

(89) A spherical knob was fitted to the end of the second arm of the torsion spring to achieve a compact yet comfortable means for the user to manipulate the position of the arm. A mechanism was later devised which employs dual, opposing torsion springs which act in a similar fashion to enable the user to control the direction in which urging force is sustained throughout the operation sequence of the load transitioning mechanism.

(90) As a system, the pair of opposing load transitioning assemblies has performed exceptionally well in conjunction with the rigid-frame wheelchair on outdoor surfaces including sand, gravel, wood chips, smooth pavement, rugged weathered pavement, city sidewalks, and snowy neighborhood streets, while enabling the user to alternate his wheelchair between a modified configuration intended for outdoor, rugged terrain and the original, unadapted configuration which is ideally suited to indoor environments.

(91) Each apparatus was built, with load-bearing capacity in mind, for attachment to one side of the wheelchair so that it may perform safely and reliably in conjunction with, though operated independently of, the apparatus attached to the opposing side of the wheelchair.

(92) To convert the wheelchair from its original configuration to the adapted configuration, the user first positions the left and right load transitioning devices such that their rotatable extension members are oriented upward so that a male end of each extension member is ready to couple with the end socket of the respective attachable caster wheel implement. The user secures the coupling by tensioning a quick-release collar to constrict the end socket around the male portion of the rotatable extension member.

(93) Next, the user manually actuates the force-sustaining subassembly of each transitioning device by pushing the knob in a forward direction and securing the arm of the torsion spring into the forward notch of the passageway, and he subsequently lowers both attachable caster wheel implements until they contact the ground surface. The user effectuates the transition to the adapted configuration by reclining the wheelchair backward so that the primary caster wheels of the wheelchair are elevated and maintained approximately 1 inches above the ground surface. The user then further secures the adapting member to the mounting member by rotating a cam-action tensioning assembly, attached to the extension arm of each caster wheel implement, in a downward direction so that it compresses firmly against the forward frame tube of the wheelchair. The caster wheels remain elevated above the ground surface during travel in all directions and do not add rolling resistance or otherwise interfere with the performance of the wheelchair in its adapted mode, as the large forward caster wheel now bears the load distributed towards the front of the wheelchair.

(94) To remove the attachable caster wheel implements from the wheelchairthat is, to convert the wheelchair from the adapted configuration back to the original configurationthe user rotates the cam-action tensioning assembly on each caster wheel implement in an upward direction so that it decompresses against the forward frame tube of the wheelchair. The user then manually actuates the force-sustaining subassembly of each transitioning device by removing the knob and spring arm from the forward notch of the passageway and disposing the knob and spring arm in the opposing, rearward notch; at this time the load transitioning device will continue to bear the load distributed toward the front of the wheelchair. Upon the user reclining the wheelchair backward so that the primary caster wheels of the wheelchair are elevated slightly, the user effectuates the transition to the original configuration, with the primary caster wheels of the wheelchair instantly lowered down into contact with the ground surface as the user brings the wheelchair into its upright, unreclined position. The user is then able to lift both caster wheel implements upward, release constricting tension on the quick-release collars, and subsequently detach both caster wheel implements from the rotatable extension members of their respective load transitioning devices.

(95) Having the load transitioning device affixed to the wheelchair and ready to receive the attachable caster wheel implement, the user has benefited from improved versatility. As needed, the user quickly outfits the wheelchair with dual caster assemblies that are substantially larger and more robust than the original primary caster assemblies that are permanently integrated with the wheelchair, and includes a 50 mm wide, 8-inch diameter pneumatic tire fitted over an aluminum wheel hub. This tire was chosen because, when inflated, it exhibits excellent rolling resistance on both rugged surfaces and smooth surfaces alike, and provides sufficient grip against paved surfaces to help prevent flutter of the caster assembly when approaching vehicle speeds of around 8 MPH or 12 KmPH, which is about average human running speed. Other wheel arrangements have been used, including: a 75 mm wide, 8-inch diameter pneumatic tire fitted over an aluminum wheel hub; and a 35 mm wide, 6-inch diameter soft-roll solid caster having an aluminum hub and connected to a shock-absorbing suspension caster assembly.

Example III

(96) An early prototype was devised having an integrated 8-inch caster wheel assembly, load-transitioning mechanism, and releasable clamp assembly, which was built and configured for the purpose of lengthening the effective wheelbase of an everyday wheelchair and also for decreasing the rolling resistance experienced by the user, especially while traversing over ground substrates such as sand, gravel, woodchips, grass, and snow.

(97) The apparatus was configured to be removably and adjustably affixed to the tubular frame of either an Invacare Top End Terminator Titanium wheelchair or a Ti-Lite TRA rigid-style ultralight titanium wheelchair by way of a hinged clamp adapted to be quickly and securely affixed onto the left forward lateral support of the tubular frame of the wheelchair; the device occupies a space immediately above the left-side primary caster wheel assembly of the wheelchair. The load transitioning mechanism, clamp assembly, and caster wheel assembly may thus be removed from one wheelchair and attached to the other if so desired. An ABS plastic tube clip mounted atop the rear axle beneath the seat of the Ti-Lite TRA wheelchair serves as a useful means for stowing the apparatus beneath the seat of the wheelchair while not in use.

(98) Internally, the mechanism has a single, toothed pawl which incrementally engages with a toothed torque wheel at every 5 degree of rotation in a first direction for load-bearing purposes, whereas the toothed pawl does not load-bearingly engage with the torque wheel in the opposing direction of rotation and permits free rotation thereof in said opposing direction. The toothed pawl is disposed within its own recess which has been bored into the steel casing surrounding the mechanism, the toothed pawl capable of rotating about its own axis of rotation projecting centrally through the bored recess and parallel to the major axis of rotation of the mechanism itself.

(99) A solid elastomeric force sustainment element, composed of cast polyamide (nylon) plastic having a modulus of elasticity of about 2.8 GPa (0.410.sup.6 psi), was fabricated to have a cylindrical shaft which fits tightly and rotates within a circular hole drilled through a cover plate of the casing. On a first end of the cylindrical shaft, projecting into the casing and contacting a side region of the toothed pawl, is an eccentric oval-shaped cam portion, also composed of nylon plastic. The opposing end of the cylindrical shaft, projecting to the exterior of the casing, is affixed to a manipulable lever. The cam rotates in a direction corresponding to rotation of the lever about an axis passing centrally through the cylindrical shaft of the force sustainment element, selectively applying or removing urging force maintained against the pawl by the nylon cam portion, thus enabling the user to repeatably toggle the mechanism between an engaging state and a disengaging state by manipulably imparting rotation to the cam portion, via the lever, between two opposing positions.

(100) Due to the snug fit of the cylindrical shaft within the circular hole of the cover plate as well as the eccentric placement of the cam relative to the axis of the cylindrical shaft, the manipulable lever holds its engaging and disengaging positions without being forced out of position, thus serving as a reliable control switch to control the internal state of the mechanism. The holding power of the control switch, as just described, furthermore overcomes an opposing spring pressure applied against the toothed pawl by a disengaging compression spring disposed internally.

(101) The elasticity of the solid elastomeric force sustainment element is critical to the capacity for the mechanism to successfully transition through the cyclic operation sequence. After clamping the apparatus to the wheelchair and rotating the manipulable lever to toggle the mechanism to the engaging state, that is, with the mechanism is in the pre-deployment stage, the cam portion of the solid elastomeric force sustainment element maintains pressure against the toothed pawl to force the teeth of the pawl to be seated into the grooves between the teeth of the torque wheel. As the user reclines the wheelchair to impart rotation of the movable portion of the apparatus relative to the fixed portion, the cam portion compresses sufficiently to permit a slight amount of rotation of the pawl necessary for the teeth of the torque wheel to advance to the next incremental position of rotation relative to the teeth of the pawl.

(102) With the apparatus clamped to the wheelchair frame, upon the user reclining the wheelchair, relative rotation between the clamp assembly (the fixed portion) and the caster wheel assembly (the movable portion) causes the torque wheel to rotate relative to the toothed pawl as far as the external rotation-limiting detent will allow. Subsequently, upon the user resting his or her weight towards the forward end of the wheelchair, the toothed pawl becomes fully engaged with the torque wheel so that relative rotation in the first direction is inhibited and the forward portion of the wheelchair load is supported as a result of the load being transferred from the torque wheel, through the toothed pawl, to the recess in which the toothed pawl is seated. The user may further secure the joint by actuating a releasable cam-lever tensioner having a steel rod which projects through the casing and which is adapted to draw the toothed pawl tightly against the torque wheel, thereby eliminating any play or wiggle that would otherwise tend to occur during use of the apparatus while the wheelchair user traverses irregular terrain.

(103) To convert the wheelchair from its original configuration to the adapted configuration, the user first clamps the apparatus to a forward region of the frame of the wheelchair. The forward region may be specially adapted for receiving the clamp, such as with a pair of semi-circular adapting shims, to establish a compatible outer diameter of the forward region to which the clamp may be secured.

(104) Next, the user manually actuates the manipulable lever in an engaging direction by pushing the lever rearward, and he subsequently lowers the apparatus until the caster wheel contacts the ground surface. The user effectuates the transition to the adapted configuration by reclining the wheelchair backward so that the primary caster wheels of the wheelchair are elevated and maintained approximately 1 inches above the ground surface. The user then further secures joint of the mechanism by tightening a cam-action tensioning assembly, which draws the toothed pawl tightly against the torque wheel. The caster wheels of the wheelchair remain elevated above the ground surface during travel in all directions and do not add rolling resistance or otherwise interfere with the performance of the wheelchair in its adapted mode, as the large forward caster wheel now bears the load distributed towards the front of the wheelchair.

(105) To remove the attachable caster wheel implement from the wheelchairthat is, to convert the wheelchair from the adapted configuration back to the original configurationthe user first loosens the cam-action tensioning assembly of the mechanism to release its pulling force upon the toothed pawl. The user then manually actuates the control switch of the mechanism in a disengaging direction by pushing the lever forward to fully release engaging pressure placed upon the toothed pawl; at this time the apparatus will continue to bear the load distributed toward the front of the wheelchair, due to high frictional forces maintained between the toothed pawl and the torque wheel as a result of the forward weight supported by the apparatus. Upon the user reclining the wheelchair backward so that the primary caster wheels of the wheelchair are elevated slightly, the frictional forces between the toothed pawl and the torque wheel are relieved and the internal disengagement spring forces the toothed pawl away from contact with torque wheel so that, as the user subsequently brings the wheelchair into its upright, unreclined position, the primary caster wheels of the wheelchair are instantly lowered down into contact with the ground surface; thus the user effectuates the transition back to the original load-bearing configuration. The user is then able to lift the caster wheel implement upward and unclamp and detach the caster wheel implement from the frame of the wheelchair.

(106) The user, having a complete spinal cord injury at the level of the sixth thoracic vertebra, has no motor or sensory function in his legs and in the lower half of his torso, and has benefited from the smoother riding characteristics and the added forward stability that result from attachment of the apparatus to his wheelchair. With the adaptive caster wheel deployed, the user has avoided being forwardly tumbled or ejected from the seated position and has furthermore been able to allocate more time towards enjoying and viewing the surrounding landscape while propelling the wheelchair forward, such as around his neighborhood and at a nearby state park, with less time directed towards observing and avoiding the small bumps, cracks, tree roots, and other obstacles that would otherwise put him at significant risk of falling out of his wheelchair. REMARKS

(107) The foregoing described embodiments depict different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively associated such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as associated with each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being operably connected, or operably coupled, to each other to achieve the desired functionality.

(108) When introducing elements of aspects of the invention or the embodiments thereof, the articles a, an, the, and said are intended to mean that there are one or more of the elements. The terms comprising, including, and having are intended to be inclusive and mean that there may be additional elements other than the listed elements.

(109) Having described aspects of the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of aspects of the invention as defined in the appended claims. As various changes could be made in the above compositions, products, and methods without departing from the scope of aspects of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. Reference to particular illustrative embodiments should not be construed as limitations. The inventive devices, products, and methods can be adapted for other uses or provided in other forms not explicitly listed above, and can be modified in numerous ways within the spirit of the present disclosure. Thus, the present invention is not limited to the disclosed embodiments.