RECONFIGURATION MEANS FOR A WHEELCHAIR

Abstract

Means for reconfiguring a wheelchair are disclosed wherein a user or an occupant of the wheelchair is enabled to repeatably alternate the wheelchair between an original load-bearing configuration and a modified load-bearing configuration by engaging and disengaging a ground-contacting adaptive implement operatively connected to a load transitioning mechanism, said load transitioning mechanism adapted for connection to a forward portion of the wheelchair. Embodiments according to the present invention enable an occupant of the wheelchair to alternate the wheelchair, through a cyclic operation sequence, between the original configuration and the modified configuration by toggling of a manipulable switch and subsequent momentary reclining of the wheelchair. The user willfully effectuates a change in the angular disposition of the ground-contacting adaptive implement relative to the wheelchair about a substantially horizontal joint axis wherein in the modified configuration a deployed angular orientation is maintained under load-bearing conditions during travel of the wheelchair in all directions. Embodiments of the present invention enable wheelchair reconfiguration with simplicity of operation while ensuring rigid attachment of a ground-contacting adaptive implement to the wheelchair to confer special functionalities to the wheelchair while preserving comfort and safety for the user while the wheelchair is in the modified load-bearing configuration.

Claims

1. A wheelchair capable of integrating with a load transitioning device for alternating the wheelchair between an original load-bearing configuration and a modified load-bearing configuration, the wheelchair comprising a frame having a front portion, the wheelchair further comprising a pair of symmetrically-opposing rear wheels and a pair of symmetrically-opposing front caster wheels, the pair of symmetrically-opposing rear wheels and the pair of symmetrically-opposing front caster wheels adapted for contact with a ground surface, the pair of symmetrically-opposing front caster wheels adapted for supporting a forward portion of a load carried by the wheelchair while the wheelchair is in the original load-bearing configuration, the load transitioning device comprising a control switch and a joint, the control switch capable of toggling between: a.) a first switch state for preparing the load transitioning device for transitioning of the wheelchair from the original load-bearing configuration to the modified load-bearing configuration, and b.) a second switch state for preparing the load transitioning device for transitioning of the wheelchair from the modified load-bearing configuration to the original load-bearing configuration, the joint configured to enable rotation of an adaptive implement into and out of a deployed position, wherein, in the original load-bearing configuration the pair of symmetrically-opposing front caster wheels of the wheelchair support the forward portion of the load carried by the wheelchair, and in the modified load-bearing configuration the load transitioning device maintains the adaptive implement in the deployed position, and the adaptive implement supports at least part of the forward portion of the load carried by the wheelchair.

2. The wheelchair of claim 1 adapted to secure the load transitioning device to the frame.

3. The wheelchair of claim 2 adapted to dispose the control switch of the load transitioning device substantially behind the front portion of the frame.

4. The wheelchair of claim 1, the adaptive implement comprising a wheel assembly adapted to facilitate movement of the wheelchair over the ground surface while the wheelchair is in the modified load-bearing configuration.

5. The wheelchair of claim 1 adapted to enable stowing of the adaptive implement in a substantially rearward location.

6. A wheelchair reconfiguration system capable of reversibly deploying a load-bearing adaptive implement in a predetermined angular orientation relative to a wheelchair, the wheelchair comprising a frame, the frame having left and right forward portions, the wheelchair further comprising a pair of symmetrically-opposing rear wheels and a pair of symmetrically-opposing front caster wheels for supporting a forward portion of a load carried by the wheelchair while the wheelchair is in an original load-bearing configuration, the wheelchair reconfiguration system comprising: a) an adapting assembly capable of supporting the forward portion of the load carried by the wheelchair; b) a mounting assembly for securing the adapting assembly relative to one of the left and the right forward portions of the frame of the wheelchair in a forward location relative to the frame of the wheelchair; c) a load transitioning mechanism adapted to be operatively interposed between the adapting assembly and the mounting assembly, the load transitioning mechanism comprising a movable bearing, the load transitioning mechanism further comprising a control switch adapted to effectuate movement of the movable bearing about a rotation axis passing through the load transitioning mechanism, the control switch capable of switchably preparing the load transitioning mechanism for alternating the wheelchair between the original load-bearing configuration and a modified load-bearing configuration, the load transitioning mechanism being capable of maintaining the load-bearing adaptive implement in the predetermined angular orientation relative to the wheelchair while the wheelchair is in the modified load-bearing configuration.

7. The wheelchair reconfiguration system of claim 6, the control switch disposed substantially rearward relative to the left and the right forward portions of the frame of the wheelchair.

8. The wheelchair reconfiguration system of claim 6 wherein movement of the movable bearing into and out of a position of load-bearing torque transmission enables alternation of the wheelchair between the original load-bearing configuration and the modified load-bearing configuration, said movement of the movable bearing being capable upon toggling the control switch and subsequently reclining the wheelchair.

9. The wheelchair reconfiguration system of claim 6, the adapting assembly comprising a ground-contacting assembly for contacting a ground surface beneath the wheelchair for extending a region with which the wheelchair contacts a ground surface beneath the wheelchair and for supporting the forward portion of the load carried by the wheelchair to manifest the modified load-bearing configuration of the wheelchair, the ground-contacting assembly adapted to facilitate movement of the wheelchair over the ground surface beneath the wheelchair while the wheelchair is in the modified load-bearing configuration, the pair of symmetrically-opposing front caster wheels of the wheelchair remaining elevated from contact with the ground surface beneath the wheelchair during movement of the wheelchair in all directions.

10. The wheelchair reconfiguration system of claim 9, the ground-contacting assembly comprising a wheel.

11. A switchable load transitioning mechanism for alternating a wheelchair between an original load-bearing configuration a modified load-bearing configuration, the wheelchair comprising a frame having a front portion, the front portion of the frame comprising a pair of symmetrically-opposing forward frame tubes, the wheelchair further comprising a pair of symmetrically-opposing rear wheels and a pair of symmetrically-opposing front caster wheels, the pair of symmetrically-opposing rear wheels and the pair of symmetrically-opposing front caster wheels adapted for contact with a ground surface, the pair of symmetrically-opposing front caster wheels adapted for supporting a forward portion of a load carried by the wheelchair while the wheelchair is in the original load-bearing configuration, the switchable load transitioning mechanism comprising a control switch and a joint, the joint having a substantially horizontal axis of rotation, the joint comprising a fixed portion and a rotatable portion, the rotatable portion of the joint capable of rotating relative to the fixed portion of the joint about the substantially horizontal axis of rotation, the fixed portion of the joint adapted to be fixed relative to the front portion of the frame of the wheelchair, the rotatable portion of the joint adapted to be rotatable relative to the front portion of the frame of the wheelchair, the rotatable portion of the joint adapted for connection of an adaptive implement, the adaptive implement capable of supporting the forward portion of the load carried by the wheelchair while the wheelchair is in the modified load-bearing configuration.

12. The switchable load transitioning mechanism of claim 11, the control switch adapted to be disposed substantially rearward relative to one of the symmetrically-opposing forward frame tubes of the front portion of the frame of the wheelchair.

13. The switchable load transitioning mechanism of claim 11, the control switch being capable of toggling between: a.) a first switch state corresponding to transitioning of the switchable load transitioning mechanism from the modified load-bearing configuration to the original load-bearing configuration, and b.) a second switch state corresponding to transitioning of the switchable load transitioning mechanism from the original load-bearing configuration to the modified load-bearing configuration.

14. The switchable load transitioning mechanism of claim 13, the control switch comprising a handle capable of being rotated about the substantially horizontal axis of rotation of the joint, the control switch configured for receiving a manual force applied against the handle and for transferring said manual force to effectuate toggling between the first switch state and the second switch state.

15. The switchable load transitioning mechanism of claim 11 comprising a movable bearing adapted for movement into a position of engagement between the fixed portion of the joint and the rotatable portion of the joint to transmit torque therebetween about the substantially horizontal axis of rotation of the joint, the movable bearing further adapted for movement out of the position of engagement between the fixed portion of the joint and the rotatable portion of the joint to relieve the mechanism of torque transmission about the substantially horizontal axis of rotation of the joint and to permit relative rotation between the fixed portion of the joint and the rotatable portion of the joint about the substantially horizontal axis of rotation of the joint.

16. The switchable load transitioning mechanism of claim 15 comprising a first spring operatively connected to the movable bearing, the first spring capable of urging the movable bearing out of the binding position, wherein toggling of the control switch to the first switch state enables deflection of the first spring to urge the movable bearing out of the binding position and wherein toggling of the control switch to the second switch state enables relaxation of the first spring to permit movement of the movable bearing toward the binding position.

17. The switchable load transitioning mechanism of claim 16 further comprising a second spring operatively connected to the movable bearing, the second spring capable of urging the movable bearing toward the binding position, wherein toggling of the control switch to the first switch state enables relaxation of the second spring to permit movement of the movable bearing out of the binding position and wherein toggling of the control switch to the second switch state enables deflection of the second spring to urge the movable bearing toward the binding position.

18. The switchable load transitioning mechanism of claim 11 being capable of transitioning the wheelchair from the original load-bearing configuration to the modified load-bearing configuration upon connection of the adaptive implement relative to the front portion of the frame of the wheelchair to operatively interpose the load-transitioning mechanism between the adaptive implement and the frame of the wheelchair, followed by reclining of the wheelchair rearward to: a. rotate the rotatable portion of the joint downward relative to the fixed portion of the joint, b. engage the movable bearing to enable torque transmission between the rotatable portion of the joint and the fixed portion of the joint, c. position the adaptive implement in a predetermined orientation relative to the frame of the wheelchair, and d. elevate the pair of symmetrically-opposing front caster wheels from contact with the ground surface.

19. The switchable load transitioning mechanism of claim 18 being capable of transitioning the wheelchair from the modified load-bearing configuration to the original load-bearing configuration upon reclining of the wheelchair rearward to: a. disengage the movable bearing from torque transmission, b. permit the pair of symmetrically-opposing front caster wheels of the wheelchair to be lowered into contact with the ground surface, after which the rotatable portion of the joint may be rotated upward and the adaptive implement may be disconnected relative to the front frame portion of the wheelchair.

20. The switchable load transitioning mechanism of claim 11, further including a rotation-limiting detent to restrict rotation of the adaptive implement, wherein, during transitioning the wheelchair to the modified load-bearing configuration, the adaptive implement assumes a predetermined angular orientation relative to the frame of the wheelchair.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] 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:

[0080] FIG. 1 shows a wheelchair capable of being reconfigured with dual symmetrically opposing (left and right) adaptive caster wheel assemblies which attach laterally to left and right transitioning mechanism assemblies affixed to opposing sides of the frame of the wheelchair.

[0081] FIGS. 2A and 2B are close-up views of the left-side transitioning mechanism assembly prior to affixing the left-side adaptive caster wheel assembly.

[0082] FIG. 3 shows the wheelchair of FIGS. 1-2B having both adaptive caster wheel assemblies attached and deployed, the wheelchair thus being maintained in a modified load-bearing mode.

[0083] FIGS. 4A and 4B are close-up views of the left-side transitioning mechanism assembly after affixing the left-side adaptive caster wheel assembly and transitioning the apparatus to the deployment stage of operation.

[0084] FIGS. 5A and 5B are exploded views of the right-side transitioning mechanism assembly.

[0085] FIGS. 6A and 6B are sectional views illustrating the cyclic operation sequence as the mechanism is transitioned from a release/attach stage to a pre-deployment stage, then to a deployment stage, then to a pre-release stage, and then back to the release/attach stage.

[0086] FIGS. 7A and 7B 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 transitioning mechanism acting as a singular joint between a clamp assembly and an adaptive caster wheel assembly.

[0087] FIGS. 8A and 8B show alternate arrangements to illustrate structural and functional similarities which exist among a variety of embodiments. FIG. 8B shows how the concept is applicable to adaptive implements other than those comprising wheels, such as ski-type ground-contacting implements.

[0088] FIGS. 9A and 9B display a clamping-type adapter comprising a detent element and a detent bar which limit the range of motion of a moveable portion of the adapter.

[0089] FIGS. 10A-D are side views of the wheelchair and clamping-type adapter during the four stages of the cyclic operation sequence (release/attach stage, pre-deployment stage, deployment stage, pre-release stage).

[0090] FIGS. 11A and 11B depict the attachment of and deployment of forward attaching auxiliary wheel assemblies in an alternate manner. Forward inserting transitioning mechanism assemblies affixed to the left and right sides of the frame of the wheelchair are capable of being rotated into an upward position for connection of the left and right forward attaching auxiliary wheel assemblies, followed by rotation into a downward position for deployment of the auxiliary wheel assemblies.

DETAILED DESCRIPTION OF THE DRAWINGS

[0091] The drawings described hereinafter are intended for the purpose of illustration rather than limitation.

[0092] The term mechanism as used hereinafter refers to an assembly forming a joint, the mechanism assembly comprising: an overrunning clutch comprising a first joint body having a first bearing surface, said overrunning clutch further comprising a second, opposing joint body having a second bearing surface, said overrunning clutch further comprising at least one movable bearing disposed between the first bearing surface and the second bearing surface, the movable bearing being capable of moving into and out of a position of force transmission between the first bearing surface and the second bearing surface; the mechanism assembly further comprising a force sustainment subassembly comprising a manipulable biasing switch and a forward-force sustaining spring, the force sustainment subassembly adapted to be toggled between: a.) a first biasing state, wherein the forward-force sustaining spring is deflected in a forward direction by the manipulable biasing switch to apply a forward sustaining force to the movable bearing to pre-load the movable bearing to enable movement of the movable bearing into a position of load-bearing torque transmission between the first and second bearing surfaces, and b.) a second biasing state wherein the forward-force sustaining spring is relaxed by the manipulable biasing switch to remove the forward sustaining force from the movable bearing to enable the movable bearing to move out of the position of load-bearing torque transmission between the first and second bearing surfaces.

[0093] The terms apparatus and device as used hereinafter refer to an assembly which includes the mechanism described in the preceding paragraph and which further includes: releasable attachment means such as a coupling or a clamp subassembly for connecting the adapter to a frame of a wheelchair; and extended ground-contacting means such as an adaptive wheel, ski, or other implement for conferring modified functionality to the wheelchair.

[0094] 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.

[0095] FIG. 1 depicts a wheelchair 100 having back support 102, seat 104, structural frame 110, foot support 114, rear drive wheels 120L and 120R having a diameter between about 20 and 26 inches, and pivotable front caster assemblies 130L and 130R having a diameter between about 3 and 5 inches. 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 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 132L and 132R contact and roll over the ground surface 50 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 132L and 132R and rear drive wheels 120L and 120R. As the wheelchair moves in a desired direction, the primary caster wheels 132L and 132R passively align in an orientation such that the horizontal rotational axis of each of the primary caster wheels 132L and 132R trails behind the vertical pivot axes 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.

[0096] The wheelchair 100 is configured with transitioning mechanism assemblies 160L and 160R secured to opposing lateral portions 112L and 112R of the structural frame 110 of the wheelchair 100. Securing of the transitioning mechanism assemblies 160L and 160R may be accomplished by welding, bolting, or clamping to the structural frame 110. Each of the transitioning mechanism assemblies 160L and 160R has a generally cylindrical profile and is disposed at a location which does not infringe upon the space normally occupied by the occupant's legs, yet which is within reach so that the occupant may easily toggle or otherwise manipulate a control knob 166 disposed on each transitioning mechanism assembly 160L and 160R. Ideally, the location of each of the transitioning mechanism assemblies 160L and 160R also enables the occupant to easily connect each of two opposing auxiliary caster wheel assemblies 140L and 140R to a transitioning mechanism assembly 160L or 160R on its respective side of the wheelchair 100. Dashed lines in FIG. 1 illustrate the path of lateral insertion which aligns each caster wheel assembly with its respective transitioning mechanism assembly 160L or 160R.

[0097] Each of the auxiliary caster wheel assemblies 140L and 140R comprises a wheel 152 that is substantially larger than that of the primary caster wheels 132L and 132R, 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 152 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 152 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. The auxiliary caster wheel 152 is held within a caster fork 150 which is connected to a pivotable bearing housing 148. The pivotable bearing housing 148 is connected to support arm 146. Support arm 146 is connected to movable rotary support body 142, through which a positive locking pin assembly 144 projects.

[0098] FIGS. 2A and 2B show close-up views of the movable rotary support body 142 of auxiliary caster wheel assembly 140L, while unattached, in its alignment with transitioning mechanism assembly 160L, with transitioning mechanism assembly 160L secured to the lateral portion 112L of the structural frame of the wheelchair. Dashed line 270 indicates the path of lateral insertion which aligns auxiliary caster wheel assembly 140L with transitioning mechanism assembly 160L.

[0099] A lateral enclosure plate 202 having outer aperture 206 is secured to a fixed cylindrical housing 250 with machine screws 204. The fixed cylindrical housing 250 is secured to an inner enclosure plate 230 with machine screws 260, said inner enclosure plate 230, in this illustration, being welded to the lateral portion 112L of the structural frame 110 of the wheelchair 100.

[0100] Secured in place by retention clip 230 and projecting through a central hexagonal aperture of the generally cylindrical-shaped movable rotary support body 142 is positive locking pin assembly 144 comprising a push button 218 which, upon the user applying manual pressure thereto using the hand, thumb, or fingers, allows spherical ball detent 212 to assume a retracted position thereby permitting the cylindrical stem portion 214 of the positive locking pin assembly 144 to pass through the transitioning mechanism assembly 160L and exit aperture 206 of welded enclosure plate 230. Upon fully inserting the positive locking pin assembly 144 into the receiving aperture 206 and upon the user releasing manual pressure from the push button 218, the spherical ball detent 212 assumes via outward spring pressure a protracted position to maintain the positive locking pin assembly 144 in its inserted position relative to the transitioning mechanism assembly 160L. By way of the positive locking pin assembly 144, the auxiliary caster wheel assembly 140L is thus releasably connected to the transitioning mechanism assembly 160L and is reliably maintained in a position relative to the structural frame 110 of the wheelchair 100. Furthermore, the positive locking pin assembly 144 serves as a pivot means comprising a central, generally lateral axis of rotation about which the entire auxiliary caster wheel assembly 140L will rotate as the user carries out the sequence of steps necessary to attach, use, and detach the device.

[0101] Also visible in FIGS. 2A and 2B are the cylindrical portion 214 and the grip portion 216 of the positive locking pin assembly 144. The grip portion 216 has a hexagonal cross-sectional profile and, upon full insertion of the positive locking pin assembly 144 into the transitioning mechanism assembly 160L, mates with and achieves full contact within a hexagonal grip receptacle (not shown) of a load transfer spindle (not shown) to allow torque transmission to occur from the auxiliary caster wheel assembly 140L to an overrunning clutch (not shown) contained within the fixed cylindrical housing 250 of the transitioning mechanism assembly 160L.

[0102] Upon fully inserting the positive locking pin assembly 144 into the transitioning mechanism assembly 160L, travel-limiting element 208 occupies an arcuate travel-limiting passageway 220 of the solid body 220. The arcuate travel-limiting passageway 220 comprises a forward limit stop 224 which defines a rotational endpoint in a first direction of rotation of the auxiliary caster wheel assembly about the central axis of the positive locking pin assembly 144. The arcuate travel-limiting passageway 220 also comprises a rearward limit stop 226 which defines a rotational endpoint in a second direction of rotation of the auxiliary caster wheel assembly about the central axis of the positive locking pin assembly 144.

[0103] An arcuate notch or recess machined into the fixed cylindrical housing 250 forms a handle passageway 240 along which a lever handle 200 travels as the user toggles or otherwise manipulates the control knob 166 to switch the load-bearing state of the overrunning clutch (not shown) contained within the fixed cylindrical housing 250 of the transitioning mechanism assembly 160L.

[0104] In FIGS. 2A and 2B, the control knob 166 and lever handle 200 are shown in a forward rotational position corresponding to an internal state of disengaging spring pressure. Control knob 166 and lever handle 200 serve to receive 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) contained within the fixed cylindrical housing 250 of the transitioning mechanism assembly 160L will subsequently be alternated in its capacity for load-bearing torque transmission upon the user performing the wheel-stand maneuver.

[0105] FIG. 3 depicts the wheelchair 100 with attached auxiliary caster wheel assemblies 140L and 140R after the control knob 166 and lever handle 200 have been manipulated to occupy a rearward rotational position (corresponding to an internal state of engaging spring pressure) and also after the wheelchair 100 has been reclined substantially to elevate the primary caster wheels 132L and 132R off the ground surface 50. This reclining action or wheel-stand maneuver, whether it be performed by an assistant or, preferably, by the occupant of the wheelchair, lifts the front end of the wheelchair 100 to create a gap 300 beneath the primary caster wheels 132L and 132R and, at the same time, causes rotation of the auxiliary caster wheel assemblies 140L and 140R in the first direction of rotation, indicated by direction arrow 60.

[0106] Engaging spring pressure, as a result of the user having manipulated the control knob 166 and the lever handle 200, causes the internal overrunning clutch (not shown) to allow rotation of the auxiliary caster wheel assembly 140L in the first direction of rotation, indicated by direction arrow 60, but prevents rotation thereof in the opposite direction. As a result, upon reclining the wheelchair sufficiently to cause the travel-limiting element 208 to contact the forward limit stop 224 (as previously presented in FIGS. 2A and 2B) the auxiliary caster wheel assembly 140L is subsequently maintained in this position and is substantially prevented from attaining any change in position relative to the structural frame 110 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 assemblies 140L and 140R. Auxiliary caster wheels 152L and 152R, as depicted in FIG. 3, are in full contact with the ground surface.

[0107] FIGS. 4A and 4B show close-up views of the movable rotary support body 142 of auxiliary caster wheel assembly 140L while attached to the transitioning mechanism assembly 160L. The travel-limiting element 208 is nested against the forward limit stop 224 of the movable rotary support body 142. The control knob 166 is occupying the rearward rotational position, corresponding to an internal state of engaging spring pressure.

[0108] FIGS. 5A and 5B show exploded views of a transitioning mechanism assembly 160R aligned with positive locking pin assembly 144 having cylindrical portion 214 and grip portion 216. Near the center of each drawing is fixed cylindrical housing 250 having machine screw holes 524 on its interior side for receiving machine screws 260 for securing the inner enclosure plate 590 (which is analogous to the inner enclosure plate depicted in previous figures) and machine screw holes 526 on its outer side for receiving machine screws 204 for securing the outer enclosure plate 202. The fixed cylindrical housing 250 is intended to be rotationally secured relative to the structural frame 110 of the wheelchair 100, which may be accomplished by means such as welding, clamping, or bolting the fixed cylindrical housing 250 or the inner enclosure plate 590 to the structural frame 110.

[0109] Press-fitted inside the fixed cylindrical housing 250 is an outer bearing member 530 having a plurality of circular depressions 534A, 534B, and 534C. The outer bearing member 530 and the fixed cylindrical housing 250 are secured in alignment by insertion of key 510 into the keyway formed by channel 532 disposed on the outer surface of the outer bearing member 530 and a channel (not shown) disposed on the inner surface of the fixed cylindrical housing 250.

[0110] The outer bearing member 530 is flanked on its outer side by rotary spacer 514 having a spring tab receiver hole 518 and a plurality of alignment projections 516, and the outer bearing member 530 is flanked on its inner side by rotary plate 564 of roller body cage 560. Upstanding elements 562A, 562B, and 562C (not visible) project through the outer bearing member 530. Alignment holes 566 receive the alignment projections 516 to rotationally secure the rotary spacer 514 relative to the roller body cage 560.

[0111] Disposed centrally within the roller body cage 560 is a load-transfer spindle 540 which is cylindrical in shape and comprises a hexagonal grip receptacle 542 configured as a counterpart for receiving the grip portion 216 of the positive locking pin assembly 144.

[0112] Disposed between the upstanding elements 562A, 562B, and 562C are cylindrical roller bearing elements 550A, 550B, and 550C, which are the same length as the load transfer spindle 540 and which are dimensioned so as to remain out of contact with the inner bearing surfaces of the circular depressions 534A, 534B, and 534C while the roller body cage 560 is urged by a second force-sustaining torsion spring 570 in the forward direction (the same direction of rotation as that indicated by direction arrow 60 shown previously in FIG. 3). When the roller body cage 560 is not urged by the second force-sustaining torsion spring 570, a first force-sustaining torsion spring 500 urges the roller body cage 560 in the reverse direction (counter to the direction of rotation indicated by direction arrow 60 shown previously in FIG. 3) so that the cylindrical roller bearing elements 550A, 550B, and 550C are forced into and remain in wedging, load-bearing contact between the outer bearing member 530 and the load-transfer spindle 540. The roller body cage 560 in combination with the cylindrical roller bearing elements 550A, 550B, and 550C, the load transfer spindle 540 and the outer bearing member 530, therefore, form a roller bearing type overrunning clutch.

[0113] First force-sustaining torsion spring 500, having a first tab (not visible) extending into the outer enclosure plate 202 and a second tab 502 extending into the spring tab receiver hole 518 of the rotary space 514, is fitted around mandrel 506. The first force-sustaining torsion spring 500 is preferably pre-loaded such that it tends to impart rotation of the roller body cage 560 in the reverse direction.

[0114] Second force-sustaining torsion spring 570, having a first tab 572 extending into spring tab receiver hole 586 of direction control plate 582 and a second tab 573 extending into spring tab receiver hole 568 of rotary plate 564, is fitted around mandrel 576 and sandwiched between rotary plate 564 of the roller body cage 560 and direction control plate 582.

[0115] Viewing the assembly from the inner side, the first force-sustaining torsion spring 500, as depicted, is wound so that clockwise rotation of the outer enclosure plate 202 prior to assembly causes the first force-sustaining torsion spring 500 to wind up in the clockwise direction so that it will have a tendency to impart clockwise rotation of the roller body cage 560. The second force-sustaining torsion spring 570 is wound in the same direction so that counter-clockwise rotation of the direction control plate 582, resulting from counter-clockwise manipulation by the user, will cause the second force-sustaining torsion spring 570 to wind up in the counter-clockwise direction so that it will have a tendency to impart counter-clockwise rotation of the roller body cage 560. The roller body cage 560 is thus operatively interposed between the first force-sustaining torsion spring 500 and the second force-sustaining torsion spring 570.

[0116] When the direction control plate 582 is placed in its most counter-clockwise position, the second force-sustaining torsion spring 570 applies a maximum amount of counter-clockwise force to the roller body cage 560 and overcomes the pre-loaded clockwise force applied by the first force-sustaining torsion spring 500. In this case, the internal spring state is biased towards moving and maintaining the roller body cage 560 in a rotary position which causes the cylindrical roller bearing elements 550A, 550B, and 550C to bind or wedge between the outer bearing member 530 and the load-transfer spindle 540. If the mechanism is presently in its release/attach stage and the user manipulates the control knob 166 to rotate the direction control plate 582 in the counter-clockwise direction, the mechanism is effectively transitioned to its pre-deployment stage during which it is readied for transitioning to the deployment stage but is not yet bearing any load. Subsequent reclining of the wheelchair 100 then transitions the mechanism to its deployment stage during which it is load-bearing and downward force placed on the forward portion of the wheelchair is transmitted through the elements of the roller bearing type overrunning clutch.

[0117] When the direction control plate 582 is placed in its most clockwise position, the second force-sustaining torsion spring 570 applies a minimum amount of counter-clockwise force to the roller body cage 560, and said counter-clockwise force is readied to be overcome by the pre-loaded clockwise force applied by the first force-sustaining torsion spring 500, in which case the internal spring state is biased towards moving and maintaining the roller body cage 560 in a rotary position which enables the cylindrical roller bearing elements 550A, 550B, and 550C to release from their bound contact between the outer bearing member 530 and the load-transfer spindle 540. If the mechanism is presently in its deployment stage and the user manipulates the control knob 166 to rotate the direction control plate 582 in the clockwise direction, the mechanism is effectively transitioned to its pre-release stage during which it is readied for transitioning to the release/attach stage but the cylindrical roller bearing elements 550A, 550B, and 550C remain in binding contact between the outer bearing member 530 and the load-transfer spindle 540. Subsequent reclining of the wheelchair 100 releases the roller bearing elements 550A, 550B, and 550C from binding contact and, in effect, transitions the mechanism to its release/attach stage during which it is non-load-bearing and downward force placed on the forward portion of the wheelchair is supported by the primary caster wheels 132L and 132R of the wheelchair 100.

[0118] In FIG. 5B, dashed lines are used to indicate the insertion of the spring tabs of the first force-sustaining torsion spring 500 and the second force-sustaining torsion spring 570 in their respective spring tab receiver holes.

[0119] Contained inside a cylindrical recess 584 of the direction control plate 582 is a ball-spring assembly 588 comprising a compression spring 586 and a spherical ball 587, both dimensioned accordingly to provide sufficient holding force against first and second ball receiver depressions 520 and 522, respectively, to maintain the direction control plate 582 in either a discrete forward position or a discrete reverse position yet also allow a user to easily toggle between the two positions by manipulating the control knob 166.

[0120] FIGS. 6A and 6B show sectional views of a transitioning mechanism assembly to illustrate the relative positioning of its moving components as it is transitioned through the four distinct stages of the operation sequence (release/attach stage, pre-deployment stage, deployment stage, pre-release stage). Symbol 600 is included in the diagrams to indicate the rotary position of the hexagonal grip portion 216 of the positive locking pin assembly 144, which corresponds to the rotary position of the support arm 146 as it rotates about the axis of the positive locking pin assembly 144.

[0121] Shown in FIG. 6A is the transitioning mechanism assembly in the release/attach stage 610, with cylindrical roller bearing elements 550A, 550B, and 550C disposed within circular depressions 534A, 534B, and 534C of the outer bearing member 530 and thus free from any bound contact between the outer bearing member 530 and the load-transfer spindle 540. Support arm 146 is free to rotate in either direction about the axis of the positive locking pin assembly 144, as long as the control knob 166 and lever handle 200 are kept in the forward rotational position (corresponding to an internal state of disengaging spring pressure) indicated in FIG. 6A. Also visible in FIG. 6A are: handle passageway 240 along which lever handle 200 travels; fixed cylindrical housing 250; key 510 (for alignment of outer bearing member 530 with fixed cylindrical housing 250); first and second ball receiver depressions 520 and 522; ball-spring assembly 588; and roller body cage 560.

[0122] FIG. 6B illustrates the cyclical operation sequence of the transitioning mechanism assembly, the operation sequence comprising release/attach stage 610, pre-deployment stage 620, deployment stage 630, and pre-release stage 640. Release/attach stage 610 is depicted just as previously shown in FIG. 6A.

[0123] In pre-deployment stage 620, lever handle 200 has been moved by the user to a reverse rotational position (corresponding to an internal state of engaging spring pressure through the roller body cage against the cylindrical roller bearing elements 550A, 550B, and 550C). Support arm 146, still in an elevated position, is now restricted to rotation about the axis of the assembly in the clockwise direction, as the cylindrical roller bearing elements 550A, 550B, and 550C become wedged between the outer bearing member 530 and the load-transfer spindle 540 to prevent rotation of the support arm 146 in the counter-clockwise direction. Rotation of the support arm 146 occurs in the clockwise direction as the user reclines the wheelchairthat is, by performing a wheel-stand maneuver or wheelie, and the load-transfer spindle 540 rotates in the clockwise direction to assume a maximum downward position (defined by the point at which the travel-limiting element (not shown) contacts the forward limit stop) and is maintained in said maximum downward position by the cylindrical roller bearing elements 550A, 550B, and 550C.

[0124] In deployment stage 630, lever handle 200 is maintained in the reverse rotational position (corresponding to an internal state of engaging spring pressure). Cylindrical roller bearing elements 550A, 550B, and 550C are disposed against contact regions of the circular depressions 534A, 534B, and 534C of the outer bearing member 530 and thus maintained in load-bearing engagement between the outer bearing member 530 and the load-transfer spindle 540. Support arm 146 is reliably maintained in a fixed position in both directions about the axis of the positive locking pin assembly 144, as long as the control knob 166 and lever handle 200 are kept in the reverse rotational position.

[0125] In pre-release stage 640, lever handle 200 has been moved by the user to the forward rotational position (corresponding to an internal state of disengaging spring pressure). Support arm 146 is maintained in the lowered position and is supporting the forward portion of the load carried by the wheelchair, while the ground-contacting adaptive implement (not shown) attached to the end of support arm 146 is contacting the ground surface. Due to frictional contact forces between the cylindrical roller bearing elements 550A, 550B, and 550C and the outer bearing member 530 and the load-transfer spindle 540, the disengaging spring pressure is not sufficient to cause the cylindrical roller bearing elements 550A, 550B, and 550C to disengage from their binding interposition between the outer bearing member 530 and the load-transfer spindle 540, thereby enabling continued maintenance of support arm 146 in the lowered position and support of the forward portion of the load carried by the wheelchair as long as the frictional contact forces against the cylindrical roller bearing elements 550A, 550B, and 550C are maintained as a result of forward loading on the wheelchair.

[0126] With the transitioning mechanism in the pre-release stage 640, upon the user reclining the wheelchair, support arm 146 rotates slightly in the clockwise direction about the rotation axis of the assembly to allow the reverse-biased spring pressure to move the cylindrical roller bearing elements 550A, 550B, and 550C, causing them to disengage from said binding interposition between the outer bearing member 530 and the load-transfer spindle 540, instantly allowing free rotation of the support arm 146 in either direction about the axis of the positive locking pin assembly 144. A slight amount of play among roller bearing elements, the outer bearing member 530 and the load-transfer spindle 540 is required to enable said disengagement to occur, and is a phenomenon of roller clutch assemblies which has been usefully exploited in the present invention. Furthermore, reclining of the wheelchair is necessary to effectuate the transition from the pre-release stage 640 to the release/attach stage 610; the wheel-stand maneuver or wheelie is a natural action performed by experienced wheelchair users and has been usefully exploited herein, for both engagement and disengagement of the cylindrical roller bearing elements 550A, 550B, and 550C with the outer bearing member 530 and the load-transfer spindle 540.

[0127] FIG. 7A depicts the wheelchair 100 ready for attachment of a clamping-embodiment apparatus 700 having an asymmetric (one-sided) caster wheel assembly. An adaptive caster wheel 740 is connected to the transitioning mechanism assembly 702 by the extension arm 750. It is important to note that the embodiment disclosed in FIG. 7A is absent a laterally-inserting positive locking pin assembly and alternatively comprises a bolt (not shown) which secures solid body 760 to cylindrical housing 770 and which defines an axis of relative rotation therebetween. A positioning collar 710R which is affixed to the lateral portion 112R of the wheelchair 100 enables a user to repeatably attach, remove and re-attach the clamping-embodiment apparatus 700 in a predetermined position and orientation relative to the wheelchair 100.

[0128] FIG. 7B depicts the wheelchair 100 having the asymmetric (one-sided) caster wheel apparatus of FIG. 7A in the release/attach stage, with the adaptive caster wheel 740 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 which urges the movable roller bearings toward a disposition free from any binding contact between the fixed portion of the transitioning mechanism assembly 702 and the movable portion thereof. The clamping-embodiment apparatus 700 is ready for either: a.) detachment from the wheelchair 100, or b.) transitioning to the pre-deployment stage.

[0129] FIG. 8A depicts the wheelchair 100 having a symmetrically-attaching caster wheel apparatus comprising a single transitioning mechanism assembly 702 in conjunction with two symmetrically opposing clamps configured for attachment to both the left and the right sides of the wheelchair frame. The adaptive caster wheel 740 is supporting the forward portion of the load carried by the wheelchair 100, whereas the primary caster wheels 132L and 132R of the wheelchair 100 are substantially elevated above the ground surface 50 and thus fully relieved of any loading.

[0130] FIG. 8B shows the wheelchair 100 having dual symmetrically opposing ski assemblies 810L and 810R, each separately attached, in conjunction with respective clamps 720L and 720R and transitioning mechanism assemblies 702L and 702R, to the left and the right sides 112L and 112R of the wheelchair frame. The adaptive skis 820L and 820R are supporting the forward portion of the load carried by the wheelchair 100, with the primary caster wheels 132L and 132R of the wheelchair 100 substantially elevated above the ground surface 50 and thus fully relieved of any loading.

[0131] FIGS. 9A and 9B are close-up views of the detached clamping-type apparatus with left-side transitioning mechanism assembly 702L previously shown attached to the left side 112L of the wheelchair 100 in FIG. 8B. Clamp assembly 720L comprises cam-action lever fasteners 912 and 914 which enable the user to releasably secure the clamping type apparatus to the frame of the wheelchair. Disposed between rotatable member 904 and the ski implement (not shown) is support member 812L. A first cylindrical extender 916 of clamp assembly 720L is adjustably secured to a second cylindrical extender 917 of the fixed member 902 with collar 730L which is tightened with collar bolt 918. The directional arrow 910 imprinted on the rotatable member 904 in FIG. 9A indicates the direction in which the rotatable member 904, the support member 812L, and the adaptive implement (not shown) connected thereto will rotate when the apparatus is attached to the wheelchair 100 (not shown) and upon the occupant of the wheelchair performing a wheel-stand maneuver. An external detent element 908, attached externally to the rotatable member 904, limits the rotation of the rotatable member 904 in that it does not permit continued rotation of the rotatable member 904 in the direction of the imprinted arrow 910 upon the external detent element 908 contacting the external detent bar 906 attached externally to the fixed member 902. The internal state of the transitioning mechanism assembly 702L is alternated upon the user or occupant manipulating the control knob 166, operatively connected to the switch subassembly contained within the transitioning mechanism assembly 702L, between a clockwise position and a counterclockwise position.

[0132] FIGS. 10A-D are lateral views of the wheelchair 100 and the clamping-embodiment apparatus 700 illustrating the positioning thereof, with respect to the ground surface, during transitioning through the four stages of operation.

[0133] FIG. 10A shows a lateral view of the clamping-embodiment apparatus 700 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.

[0134] FIG. 10B shows a lateral view of the clamping-embodiment apparatus 700 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 or condition, the mechanism is thus prepared for transition to the deployment stage of operation.

[0135] FIG. 10C shows a lateral view of the clamping-embodiment transitioning apparatus 700 in the deployment stage, during which the apparatus is deployed and load-bearing and the primary casters are substantially elevated from 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.

[0136] FIG. 10D shows a lateral view of the clamping-embodiment apparatus 700 in the pre-release stage, during which the apparatus is load-bearing and the primary casters 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 will drop back down into contact with the ground surface.

[0137] FIGS. 11A and 11B depict the attachment of and deployment of forward attaching auxiliary wheel assemblies 1110L and 1110R utilizing forward inserting transitioning mechanism assemblies 1100L and 1100R secured to opposing lateral portions 112L and 112R of wheelchair 100. Dashed lines in FIG. 11A illustrate the path of longitudinal insertion which aligns forward attaching auxiliary wheel assembly 1110L with forward-inserting transitioning mechanism assembly 1100L. Forward-inserting transitioning mechanism assembly 1100L is shown, while in the release/attach stage, positioned at an angle in which it is fully prepared to receive or couple with the forward attaching auxiliary wheel assembly 1110L. In FIG. 11A, forward-inserting transitioning mechanism assembly 1100R is shown, while in the release/attach stage, positioned at an angle in which it is not fully prepared to receive or couple with the forward attaching auxiliary wheel assembly 1110R (not shown).

[0138] A cam tensioning assembly 1130L comprising a cam body 1132 and a handle 1134 is integrated with the quick-release collar 1112L. Upon coupling the quick-release collar 1112L with the inserting member 1120L and upon subsequently deploying the auxiliary wheel assembly 1110L, as depicted in FIG. 11B, the cam tensioning assembly 1130L may be utilized to apply counter-pressure against the lateral portion 112L of the wheelchair 100. The aforementioned method is used to enhance the rigidity of the union of both auxiliary wheel assemblies 1110L and 1110L with the wheelchair 100.

Example

[0139] Dual (left and right) adaptive caster wheel apparatuses, each having a load-transitioning mechanism which separably integrates with a ground-contacting adaptive 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.

[0140] 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.

[0141] 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.

[0142] Early prototypes of the mechanism were constructed by modifying pre-manufactured stepless roller clutch hand ratchets, each capable of withstanding torque in excess of 300 ft-lbs. Modifications were made to clamp the input end (the handle) of the ratchet to the tubular frame of the wheelchair, as well as to form a coupling on the output end of the ratchet 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 main body of the hand ratchet, and an aluminum cover plate was screwed onto the side opposite the side from which the output shaft of the ratchet projects.

[0143] Internally, each roller clutch ratchet 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 modified 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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 wheels 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

[0153] 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.

[0154] 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.

[0155] 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.