Patent Publication Number: US-9901498-B2

Title: Compact wheelchair assembly with removable wheels and methods therefor

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a continuation under 35 USC § 120 of, and thus claims priority to, U.S. application Ser. No. 14/518,641, filed Oct. 20, 2014, which is incorporated by reference for all purposes. 
    
    
     BACKGROUND 
     Technical Field 
     This disclosure relates generally to personal transport devices, and more particularly to wheelchairs. 
     Background Art 
     For many people, wheelchairs are their only mode of transportation. Many elderly, injured, or disabled people use wheelchairs as their primary (or only) mode of transportation. While providing much needed transportation to their patients, many wheelchairs are quite large and bulky. While some wheelchairs are collapsible so they can be stowed when not in use, their large bulk frequently results in difficulty in loading a chair into a vehicle or otherwise stowing the chair. 
     It would be advantageous to have an improved wheelchair that was more compact in design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 2  illustrates a side elevation view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 3  illustrates another side elevation view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 4  illustrates a front elevation view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 5  illustrates a rear elevation view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 6  illustrates a bottom plan view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 7  illustrates a top plan view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 8  illustrates another perspective view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 9  illustrates yet another perspective view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 10  illustrates yet another perspective view of one explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIGS. 11 and 13  illustrate an explanatory rear-wheel assembly in accordance with one or more embodiments of the disclosure. 
         FIG. 12  illustrates an explanatory rear-wheel assembly disassembled in accordance with one or more embodiments of the disclosure. 
         FIG. 14  illustrates an explanatory rear wheel assembly in another disassembled configuration in accordance with one or more embodiments of the disclosure. 
         FIG. 15  illustrates an explanatory front wheel assembly in accordance with one or more embodiments of the disclosure. 
         FIG. 16  illustrates an explanatory front wheel assembly disassembled in accordance with one or more embodiments of the disclosure. 
         FIG. 17  illustrates a front elevation view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 18  illustrates a rear elevation view one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 19  illustrates a bottom plan view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 20  illustrates a top plan view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 21  illustrates a side elevation view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 22  illustrates another side elevation view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 23  illustrates a perspective view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 24  illustrates another perspective view of one explanatory wheelchair with its wheels removed and in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 25  illustrates a top plan view of one explanatory wheelchair with its wheels removed and in a fully collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 26  illustrates a bottom plan view of one explanatory wheelchair with its wheels removed and in a fully collapsed position in accordance with one or more embodiments of the disclosure. 
         FIG. 27  illustrates one explanatory wheelchair with its wheels removed and in a fully collapsed position in a package in accordance with one or more embodiments of the disclosure. 
         FIG. 28  illustrates a prior art wheelchair in a package. 
         FIG. 29  illustrates another rear wheel assembly in accordance with one or more embodiments of the disclosure. 
         FIG. 30  illustrates another rear wheel assembly in a pivoted position in accordance with one or more embodiments of the disclosure. 
         FIG. 31  illustrates yet another explanatory wheelchair in accordance with one or more embodiments of the disclosure. 
         FIG. 32  illustrates yet another explanatory wheelchair in a partially collapsed position in accordance with one or more embodiments of the disclosure. 
         FIGS. 33-50  illustrate various ornamental appearances of wheelchairs and chassis configured in accordance with one or more embodiments of the disclosure. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present disclosure. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Embodiments of the disclosure are now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” Relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, reference designators shown herein in parenthesis indicate components shown in a figure other than the one in discussion. For example, talking about a device ( 10 ) while discussing figure A would refer to an element,  10 , shown in figure other than figure A. The term “substantially” and the term “about,” as used herein, are intended to refer to a desired orientation inclusive of manufacturing tolerances. Accordingly, a “substantially” orthogonal angle with manufacturing tolerances of plus or minus two degrees would include angles of between, and including eighty-eight to ninety two degrees. It is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating the embodiments described below with minimal experimentation. 
     As noted above, while some wheelchairs are collapsible, they can be quite bulky even when in their collapsed states. Embodiments of the present disclosure contemplate that one of the reasons for this bulk in the collapsed state is due to the fact that the wheels and hubs extend outwardly from the frame, thus adding length and width to the collapsed chair. When the wheels remain on the chair in the collapsed state, the overall length and width of the object remains quite large. This large size presents problems. 
     The inventors have discovered that one such problem is that of shelf space in retail outlets. Embodiments of the disclosure contemplate that many retailers, including drug stores, big box stores, and other retailers generally do not put wheelchairs on their shelves—even in the collapsed state—because the accompanying packaging is just too large. For example, most packaged wheelchairs, even when packaged in their collapsed state, at a minimum measure about thirty-two inches by twenty-three inches by nine inches. 
     Embodiments of the present disclosure make it economically possible for retailers to place wheelchairs on their shelves by providing a wheelchair assembly that, when in its collapsed and packaged state, is dramatically smaller than are prior art chairs. In one embodiment, this reduction in dimension is provided by way of rear wheels that extend outwardly from the rear of the chair to offer increased stability, but that are removable from the chair when the chair is to be collapsed for stowage. Illustrating by example, in one embodiment, a chair in accordance with one or more embodiments of the disclosure, when in the collapsed state, can easily fit within a package measuring twenty-three inches by twenty-one inches by nine inches. This results in a thirty-four percent reduction in size over prior art designs when in the collapsed configuration. Embodiments of the disclosure contemplate that many retailers are more than willing to put packages having these reduced dimensions on their shelves. Accordingly, embodiments of the disclosure provide a benefit to both consumer and retailer. The consumer is benefitted by having an increased number of retail outlets in which to purchase a wheelchair. The consumer is additionally benefitted by having a wheelchair that is far smaller than prior art designs when in the collapsed position. The retailer benefits because they have a new product that can be displayed on shelves without consuming too much space. 
     In one embodiment, a wheelchair includes a chassis defining a seat, a backrest, one or more armrests, and an undercarriage. The wheelchair can also include one or more front caster wheels that are coupled to, and selectively detachable from, the undercarriage of the chassis. 
     The wheelchair can also include one or more rear wheel assemblies. Each rear wheel assembly can comprise a rear wheel, an axle, and a mounting post extending distally from the axle at a substantially orthogonal angle relative to the axle. In one embodiment, one or more quick release devices are used to selectively couple each mounting post to the undercarriage so that each rear wheel assembly is selectively detachable from the undercarriage. When the rear wheel assemblies are detached from the undercarriage, the chassis can be folded into a collapsed position. In one embodiment, once folded, the chassis can be placed into a package measuring less than twenty-three inches by twenty-one inches by nine inches such that a drugstore or retailer can present the package on a retail shelf in accordance with their maximum sizing requirements. 
     Turning now to  FIGS. 1-10 , illustrated therein are various views of a wheelchair  100  configured in accordance with one or more embodiments of the disclosure.  FIG. 1  illustrates a perspective view of the wheelchair  100 , while  FIGS. 2-3  illustrate side elevation views of the wheelchair  100 .  FIGS. 4-5  illustrate front and rear elevation views of the wheelchair  100 , while  FIGS. 6 and 7  illustrate top and bottom plan views of the wheelchair  100 .  FIGS. 8-10  each illustrate alternate perspective views of the wheelchair  100 . While some features of the wheelchair  100  described below are functional and utilitarian, it is noted that the wheelchair  100  also includes novel and non-obviousness ornamental appearance features as well. These ornamental features, being shown in  FIGS. 1-10  by illustration, will not be further described in this specification. 
     As shown in  FIGS. 1-10 , the wheelchair  100  includes a chassis  101 . In one embodiment, the chassis  101  is constructed from a tubular metal, such as steel or aluminum. In the illustrative embodiment of  FIGS. 1-10 , the chassis defines a seat  102 , a backrest  103 , one or more armrests  104 , 105 , and an undercarriage  106 . 
     In one embodiment, the seat  102  and the backrest  103  can comprise a layer of organic, inorganic, or organic/inorganic blended fabric spanning two side portions of the chassis. Illustrating by example, in this embodiment the seat  102  is defined by a layer of material  107  that spans two horizontal side members  108 , 308 . The layer of material  107  and the two horizontal side members  108 , 308 . In this illustrative embodiment, the layer of material  107  and the two horizontal side members  108 , 308  define a first plane. 
     Similarly, in this embodiment the backrest  103  is defined by another layer of material  109  that spans two vertical side members  110 , 111 . The layer of material  109  and the two vertical side members  110 , 111  define a second plane. The second plane defines the “rear side”  201  of the chassis  101 . 
     In one embodiment, to assist the user in getting into, and out of, the wheelchair  100 , the layer of material  107  defining the seat  102  includes two handles  112 , 113 . In this embodiment, the handles  112 , 113  are configured as loops that are coupled to the layer of material  107 . A user can grasp these handles  112 , 113  to assist in sliding along the seat  102  of the wheelchair  100 . 
     In one embodiment, the vertical side members  110 , 111  defining the rear side  201  of the wheelchair  100  have extending therefrom two push handles  114 , 115  with which a user can push the wheelchair when a patient is seated on the seat  102 . In this embodiment, to make things more compact when the wheelchair is collapsed, the two push handles  114 , 115  are collapsible, i.e., can fold downward to be adjacent to the vertical side members  110 , 111 . In one embodiment, an upper portion of the vertical side member  110 , 111  folds downward to be adjacent to, and substantially parallel with, a lower portion of the vertical side member  110 , 111 . This results in the two push handles  114 , 115  again being substantially orthogonal with the vertical side members  110 , 111 , but pointing in a direction opposite that in which they are pointing in  FIGS. 1-10 . The collapsed position is shown illustratively in  FIGS. 17-26 . 
     Two locking switch levers  116 , 316  facilitate this selective collapsibility of the push handles  114 , 115 . When the locking switch levers  116 , 316  are pivoted upward, they serve to lock the push handles  114 , 115  in the upright position where they are substantially perpendicular to the two vertical side members  110 , 111 . When pivoted downward, the locking switch levers  116 , 316  allow the two push handles  114 , 115  to fold downward. In one embodiment, the vertical side members  110 , 111  fold approximately at the location of the locking switch levers  116 , 316  so as to cause a portion of each vertical side member  110 , 111  located above the corresponding locking switch lever  116 , 316  to be adjacent to, and substantially parallel with, a lower portion of the vertical side members  110 , 111  disposed below the locking switch levers  116 , 316 . This results in the two push handles  114 , 115  again being substantially orthogonal with the vertical side members  110 , 111 , but pointing in a direction opposite that in which they are pointing in  FIGS. 1-10 . The collapsed position is shown illustratively in  FIGS. 17-26 . 
     In one embodiment, the wheelchair  100  includes one or more wheels. In this illustrative embodiment, one or more front caster wheels  118 , 119  are coupled to, and selectively detachable from, the undercarriage  106 . Similarly, one or more rear wheel assemblies  120 , 121  are coupled to, and are selectively detachable from, the undercarriage  106 . 
     In one embodiment, to provide additional compactness of the chassis  101  when in the folded configuration, yet to provide increased lateral stability between the front and rear of the wheelchair  100 , the rear wheel assemblies  120 , 121  are strategically coupled to the undercarriage  106 . As best shown in  FIGS. 2-3 , in this illustrative embodiment the rear wheel assemblies  120 , 121  are coupled to the undercarriage  106  such that they extend distally away from the rear side  201  of the wheelchair. In this embodiment, the rear wheel assemblies  120 , 121  are coupled to the undercarriage  106  such that they extend distally away from the rear side  201  of the wheelchair  100  at substantially an orthogonal angle. Said differently, in one embodiment the rear wheel assemblies  120 , 121  extend distally, at substantially an orthogonal angle, from the layer of material  109  and the two vertical side members  110 , 111  defining the second plane that defines the rear side  201  of the wheelchair. 
     When viewed in the plan view of  FIGS. 6-7 , it can be seen that in one embodiment the chassis  101 , without the two push handles  114 , 115  and the detachable footrests  122 , 123 , is substantially rectangular in shape. Accordingly, the fact that the rear wheel assemblies  120 , 121  extend distally, at substantially an orthogonal angle, from the layer of material  109  and the two vertical side members  110 , 111  defining the second plane that defines the rear side  201  of the wheelchair means that the two rear wheel assemblies  120 , 121  extend outward from a perimeter defined by this rectangular shape. This configuration provides additional stability for the user when leaning against the backrest  103  while the wheelchair  100  is in use. At the same time, the detachability of the rear wheel assemblies  120 , 121  from the undercarriage  106  means that the depth of the rectangular shape, as viewed in  FIGS. 6-7 , is decreased when the rear wheel assemblies  120 , 121  are removed. Thus, the detachability results in a more compact form factor for the chassis  101  when folded into a collapsed configuration. 
     In one embodiment, each rear wheel assembly  120 , 121  comprises a rear wheel  124 , 125 , an axle  126 , 127 , and a mounting post  128 , 129 . In this illustrative embodiment, the mounting posts  128 , 129  extend distally from the axle  126 , 127  at a substantially orthogonal angle relative to the axle  126 , 127 . In one embodiment, the rear wheel  124 , 125 , axle,  126 , 127 , and mounting post  128 , 129  are perdurably coupled together such that they are only to be separable with the use of tools. For example, while the rear wheels  124 , 125  can be coupled to the axle  126 , 127  by way of a lug nut, in one embodiment this is a perdurable connection in which a tool is required to remove the lug nut. 
     In one embodiment, one or more quick release devices  130 , 131  are used to couple the rear wheel assemblies  120 , 121  to the undercarriage  106 . Accordingly, in one embodiment each mounting post  128 , 129  of each rear wheel assembly  120 , 121  is coupled to the undercarriage  106  by a quick release device  130 , 131  such that the each the one or more rear wheel assemblies  120 , 121  is selectively detachable from the undercarriage  106 . This is shown illustratively in  FIGS. 11-12 . 
     Turning briefly to  FIG. 11 , illustrated therein is one explanatory rear wheel assembly  121 . As shown, the rear wheel assembly  121  includes a rear wheel  125 , an axle  127 , and a mounting post  129 . This particular rear wheel assembly  121  also includes a brake assembly  1101 . In this embodiment, the brake assembly  1101  is coupled to the mounting post  129  of the rear wheel assembly  121 . The brake assembly  1101  comprises a handle  1102  to pivot  1103  to selectively apply stopping friction  1104  to the rear wheel  125  with a mechanical lever  1105 . It is noted that the term “selectively” as used herein means user selectable. For example, the handle  1102  of the brake assembly  1101  can be pivoted  1103  from a first position, where no stopping friction  1104  is applied to the rear wheel  125 , to a second position where the stopping friction  1104  is applied to the rear wheel  125 . The user can select to apply the stopping friction  1104  by selectively pivoting the handle  1102  between the first position and the second position. 
     In this illustrative embodiment, the brake assembly  1101  is attached only to the mounting post of the rear wheel assembly  121 , and not to the undercarriage  106 . Accordingly, when the rear wheel assembly  121  is detached from the undercarriage  106 , the brake assembly  1101  will be detached from the undercarriage as well. This detachment will be shown below with reference to  FIG. 12 . 
     As previously described, a quick release device  131  is used to couple the rear wheel assembly  121  to a tubular post  1106  of the undercarriage  106 . In this illustrative embodiment, the quick release device  131  comprises an extended figure eight clamp  1107  and one or more threaded retention devices  1108 , 1111 , 1112  to couple a first end  1109  of the quick release device  131  to the undercarriage  106  and a second end  1110  of the quick release device  131  to the mounting post  129  of the rear wheel assembly  121 . The quick release device  131  is referred to as an “extended figure eight” clamp  1107  because it includes two open-ended clamping loops  1113 , 1114  that are separated by an offset member  1115 . The offset member  1115  extends one of the open ended clamping loops  1113  from the other open ended clamping loop  1114 . Hence, the “figure eight” defined by the open ended clamping loops  1113 , 1114  is extended by the offset member  1115  to form the extended figure eight clamp  1107 . 
     In one embodiment, the one or more threaded retention devices  1108 , 1111 , 1112  comprise at least a first threaded retention device  1111  to couple the first end  1109  of the extended figure eight clamp  1107  to the undercarriage  106 . A second threaded retention device  1108  is used to couple the second end  1110  of the extended figure eight clamp  1107  to the mounting post  129 . In this illustrative embodiment, a third threaded retention device  1112  is used to couple the first end  1109  of the extended figure eight clamp  1107  to the undercarriage  106  as well. 
     In this illustrative embodiment, the two threaded retention devices  1111 , 1112  coupling the first end  1109  of the extended figure eight clamp  1107  to the undercarriage  106  are perdurable coupling members, which means that they are not to be removed from the undercarriage  106  in normal operation without the use of tools. By contrast, in this embodiment the second threaded retention device  1108  comprises a handle  1116  (better seen in  FIG. 12  below) to enable tool-less rotation of the second threaded retention device  1108  to couple, or release, the second end  1110  of the extended figure eight clamp  1107  to the mounting post  129  of the rear wheel assembly  121 . 
     Turning now to  FIG. 12 , illustrated therein is the rear wheel assembly  121  when removed from the undercarriage  106 . As shown in  FIG. 12 , in one embodiment the second threaded retention device  1108  includes a handle  1116  that has two distally extending finger levers  1216  and a threaded member  1208 . The distally extending finger levers  1216  allow a user to rotate the second threaded retention device  1108  without the use of tools to release it from a coupling device  1207 . For this reason, the second threaded retention device  1108  is referred to as a tool-less retention device that allows quick, tool-less removal of the rear wheel assembly  121  from the chassis  101 . The rear wheel assembly  121  can be reattached to the undercarriage  106  by inserting the mounting post  129  into the second end  1110  of the extended figure eight clamp  1107 , inserting the second threaded retention device  1108  into an aperture  1211  of the second end  1110  of the extended figure eight clamp  1107 , and finger-twisting the threaded member  1208  into the coupling device  1207 . 
       FIGS. 13-14  illustrate a slightly different configuration. Turning now to  FIG. 13 , illustrated therein is another rear wheel assembly  121 . The configuration is the same as that shown in  FIGS. 11-12 , with the exception of the two threaded retention devices  1111 , 1112  coupling the first end  1109  of the extended figure eight clamp  1107  to the undercarriage  106 . Rather than being perdurable connecting members, as was the case in the embodiment of  FIG. 13 , they are instead tool-less threaded retention members. Accordingly, as shown in  FIG. 14 , all three of the threaded retention devices  1108 , 1111 , 1112  can be released without tools to completely remove the extended figure eight clamp  1107  from the chassis  106 , in addition to separating the rear wheel assembly  121  from the chassis. The embodiments of  FIGS. 11-14  are illustrative only, as still other embodiments will be shown with reference to  FIGS. 29-30  below. Still others will be obvious to those of ordinary skill in the art having the benefit of this disclosure. 
     Turning now back to  FIGS. 1-10 , the orientation of the connection of the one or more rear wheel assemblies  120 , 121  to the undercarriage  106 , at least the orientation in one or more embodiments, will be explained in more detail. As can be seen in the figures, in one embodiment each of the one or more quick release devices  130 , 131  are to couple to the undercarriage  106  of the chassis  101  in an orientation that is substantially parallel with the one or more armrests  104 , 105 . This orientation helps to ensure that the one or more rear wheel assemblies  120 , 121  extend distally from the rear side  201  of the chassis  101  at a maximum distance to promote front-to-rear wheelchair stability. 
     In one or more embodiments, as best seen in  FIGS. 2-3 , the one or more quick release devices  130 , 131  are to offset  202  the mounting posts  128 , 129  from the rear side  201  of the chassis  101  by at least one inch. Said differently, in one embodiment the one or more quick release devices  130 , 131  are to offset  202  the mounting posts  128 , 129  from the plane defined by the backrest  103  of the wheelchair  100  by at least one inch. Embodiments of the disclosure contemplate that this distance provides suitable stability for the wheelchair  100  when a person sits in the seat  102  and leans against the backrest  103 . In one embodiment, the one or more quick release devices  130 , 131  are to offset  201  the mounting posts  128 , 129  from the plane defined by the backrest  103 , i.e., the rear side  201  of the chassis  101 , by about two inches. 
     In one embodiment, as best seen in  FIG. 2-3 , the undercarriage  106  defines a first dimension  301  that is oriented substantially parallel to a plane defined by the seat  102  of the wheelchair  100 . The undercarriage  106  also defines a second dimension  302  that is oriented substantially orthogonal with the plane defined by the seat  102  of the wheelchair  100 . In this illustrative embodiment, each of the quick release devices  130 , 131  offsets  202  the mounting post  128 , 129  of each rear wheel assembly  120 , 121  from the plane defined by the backrest  103 , i.e., the rear side  201  of the chassis  101 , by at least one inch. As will be shown in more detail with reference to  FIGS. 17-24  below, in one embodiment when the two push handles  114 , 115  are collapsed as described previously, and the front caster wheels  118 , 119  and rear wheel assemblies  120 , 121  are detached from the chassis  101 , and the chassis  101  is folded to form a folded chassis, both the first dimension  301  and the second dimension  302  are reduced to such an extent that it has a length less than twenty-four inches, a width less than twenty-two inches, and a height less than ten inches. 
     As noted above, in one or more embodiments, the one or more front caster wheels  118 , 119  are additionally removable. Turning now to  FIGS. 15-16 , illustrated therein is one method for removing a front caster wheel  119  in accordance with one or more embodiments of the disclosure. 
     Beginning with  FIG. 15 , a front caster wheel  119  is coupled to the chassis  101 . In this embodiment, the front caster wheel  119  includes a mounting post  1529  extending vertically from the caster  1501  of the front caster wheel  119 . The mounting post  1529  inserts into a sleeve  1507  coupled to the undercarriage  106  of the chassis  101 . A threaded retention device  1508  couples the mounting post  1529  into the sleeve  1507 . In this illustrative embodiment, the threaded retention device  1508  comprises a handle to enable tool-less rotation of the threaded retention device  1508  to couple, or release, the mounting post  1529  within the sleeve  1507 . 
     Turning now to  FIG. 16 , illustrated therein is the front caster wheel  119  when removed from the undercarriage  106 . As shown in  FIG. 16 , the distally extending finger levers  1516  have allowed a user to rotate the threaded retention device  1508  without the use of tools to release it from a coupling device  1607 . The threaded retention device  1508  thus allows quick, tool-less removal of the front caster wheel  119  from the sleeve  1507  of the undercarriage  106 . The front caster wheel  119  can be reattached to the undercarriage  106  by inserting the mounting post  1529  into the sleeve  1507 , inserting the threaded retention device  1508  into an aperture  1611  of the sleeve  1507 , and finger-twisting the threaded retention device  1508  into the coupling device  1607 . 
     Turning now to  FIGS. 17-24 , illustrated therein are views of the chassis  101  once the one or more front caster wheels ( 118 , 119 ), the one or more rear wheel assemblies ( 120 , 121 ), and the one or more detachable footrests ( 122 , 123 ) have been removed from the chassis  101 .  FIG. 17  illustrates a front elevation view of the chassis  101 , while  FIG. 18  illustrates a rear elevation view of the chassis  101 .  FIG. 19  illustrates a bottom plan view of the chassis  101 , while  FIG. 20  illustrates a top plan view of the chassis  101 .  FIG. 22  illustrates a left side elevation view of the chassis  101 , while  FIG. 23  illustrates a right side elevation view of the chassis  101 .  FIG. 23  illustrates a first perspective view of the chassis  101 , while  FIG. 24  illustrates a second perspective view of the chassis  101 . From these various views, when viewed collectively, each and every element of the chassis  101  is visible. 
     Recall from the discussion of  FIGS. 1-10  above that in one or more embodiments, the vertical side members  110 , 111  defining the rear side  201  of the wheelchair ( 100 ) have extending therefrom two push handles  114 , 115  with which a user can push the wheelchair when a patient is seated on the seat  102 . To make things more compact when the wheelchair is collapsed, the two push handles  114 , 115  are collapsible, i.e., can fold downward to be adjacent to the vertical side members  110 , 111 . 
     As shown in  FIGS. 17-24 , in this embodiment an upper portion  2114 , 2215  of the vertical side member  110 , 111  folds downward to be adjacent to, and substantially parallel with, a lower portion  2210 , 2211  of the vertical side member  110 , 111 . This results in the two push handles  114 , 115  again being substantially orthogonal with the vertical side members  110 , 111 , namely, being substantially orthogonal with the lower portions  2210 , 2211  of the vertical side members  110 , 111 . However, they are pointing in a direction opposite that in which they are pointing in  FIGS. 1-10 . This folding is selective by toggling the two locking switch levers  116 , 316  to collapse the push handles  114 , 115  as previously described. 
     Folding down the upper portion  2114 , 2215  of the vertical side member  110 , 111  along with the two push handles  114 , 115  reduces the overall height  1701  of the chassis  101  where the height  1701  is defined by the chassis dimension oriented substantially orthogonally with the seat  102 . This folding is one step in reducing the overall dimensions of the chassis  101 , when completely folded, to be less than twenty-four inches by less than twenty-two inches, by less than ten inches. In one embodiment, the folded chassis reduces to having a length of about twenty-three inches, a width of about twenty-one inches, and a height of about nine inches. 
     In one or more embodiments, the one or more armrests  104 , 105  and the backrest  103  are foldable atop the seat  102 . For example, where the backrest  103  is defined by a layer of material  109 , the material can collapse when the one or more armrests  104 , 105  fold about horizontal tubes  2104 , 2205  disposed at the bottom of the one or more armrests  104 , 105 . Similarly, in one embodiment, the undercarriage  106  can fold beneath the seat  102 . When both the one or more armrests  104 , 105  and the undercarriage  106  are folded atop and beneath the seat  102 , respectively, a folded chassis is formed. One example of such a folded chassis is shown in  FIGS. 25-26 . In this embodiment, two side members  1710 , 1711  of the undercarriage  106  are separated by folding supports  1714 , 1715  that allow the side members  1710 , 1711  of the undercarriage  106  to collapse together beneath the seat. 
     Turning now to  FIGS. 25-26 , illustrated therein is the resulting folded chassis  2500 . The folded chassis  2500  is shown in top plan view in  FIG. 25 , and in bottom plan view in  FIG. 26 . Due to the removal of the one or more front caster wheels ( 118 , 119 ), the one or more rear wheel assemblies ( 120 , 121 ), and the one or more detachable footrests ( 122 , 123 ), and the collapsing of the vertical side members  110 , 111  and push handles  114 , 115 , the folded chassis  2500  advantageously has a length  2501  of less than twenty-four inches, a width  2502  of less than twenty-two inches, and a height  2503  (measured into the page as viewed in  FIGS. 25-26 ) less than ten inches. In this illustrative embodiment, the length  2501  is less than twenty-three inches, the width  2502  is less than twenty-one inches, and the height  2503  is less than nine inches. Advantageously, this allows the folded chassis  2500  to be placed in a package that fits on a retailer&#39;s shelf in accordance with their predefined size requirements. Such a package  2700  is shown in  FIG. 27 . 
     Turning now to  FIG. 27 , this package has a length  2701  of about twenty-three inches, a width  2702  of about twenty-one inches, and a height  2703  of about nine inches. Most drugstore and big-box retailers are more than willing to place packages  2700  of this size on their shelves. Accordingly, a user can see and select the folded chassis ( 2500 ) as an in-store, off-the-shelf purchase. The one or more front caster wheels ( 118 , 119 ), the one or more rear wheel assemblies ( 120 , 121 ), and the one or more detachable footrests ( 122 , 123 ) can be packages separately, stored off-shelf at the retailer, and delivered to the purchaser at check-out. 
     By contrast, as shown in  FIG. 28 , prior art packages  2800  have—at their smallest—a length  2801  of thirty-two inches, a height  2803  of nine inches, and a width  2802  of twenty-three inches. Retailers generally do not allow such package sizes to be placed on their shelves. Accordingly, embodiments of the present disclosure provide over a thirty-percent reduction in package size, advantageously allowing retailers to display previously un-displayable products on their shelves. 
     While removal of the one or more front caster wheels ( 118 , 119 ), the one or more rear wheel assemblies ( 120 , 121 ), and the one or more detachable footrests ( 122 , 123 ) is one way to reduce the folded chassis size, embodiments of the disclosure are not so limited.  FIGS. 29-32  illustrate other techniques for reducing the size of a folded chassis sufficiently to allow retailers to display the folded chassis in a package on their shelves. Still other variations will be obvious to those of ordinary skill in the art having the benefit of this disclosure. 
     Beginning with  FIG. 29 , illustrated therein is one explanatory rear wheel assembly  2921 . As shown, the rear wheel assembly  2921  includes a rear wheel  2925 , an axle  2927 , and a mounting post  2929 . This particular rear wheel assembly  2921  also includes a brake assembly  2911  coupled only to the mounting shaft  2929  of the rear wheel assembly  2921  as previously described. 
     Rather than using a quick release device ( 131 ) to couple the rear wheel assembly  2921  to a tubular post  1106  of the undercarriage  106 , in this embodiment the rear wheel assembly  2921  is coupled to the tubular post  1106  of the undercarriage  106  by a pivotable connector  2904 . The pivotable connector  2904  includes a first portion  2901  and a second portion  2902  that are joined by a hinge pivot  2903 . The first portion  2901  can selectively pivot relative to the second portion  2902  about the hinge pivot  2903  to retract from a first position  2900 , shown in  FIG. 29 , to a second position  3000 , shown in  FIG. 30 . Accordingly, when using the pivotable connector  2904 , each rear wheel assembly  2921  becomes pivotable about the undercarriage  106  from the first position  2900  to the second position  3000  to reduce a second major dimension of the chassis ( 101 ), namely height ( 1701 ). One or more locking mechanisms, similar to locking switch lever ( 116 , 316 ) described above can be used to selectively lock each rear wheel assembly  2921  in either the first position  2900  or the second position  3000 . 
       FIGS. 31-32  illustrate another method of reducing dimensions of a chassis  3101  such that it can fit within a box suitable for a retailer&#39;s shelf. In  FIGS. 30-31 , at least one tube  3102 , 3103  of the chassis  3101  comprises a telescoping tube. Accordingly, a first portion of the tube  3102 , 3103  can slide into, or out of, another portion of the tube  3102 , 3103 . For example, tubes  3102 , 3103  are shown in the extended position  3100  in  FIG. 31 , but are in the retracted position  3200  in  FIG. 32 . This serves to reduce the depth  3201  of the chassis  3101 . One or more quick release mechanisms  3104 , 3105  can be used to lock the tubes  3102 , 3103  in either the extended position  3100  or the retracted position  3200  as desired. Note that while the telescoping tubes are shown being applied to horizontal tubes running parallel to the page to reduce the depth  3201  in this illustrative embodiment, they could also be applied to horizontal tubes running perpendicular to the page to reduce the length as well. They can also be applied to vertical tubes to reduce the height. Of course, combinations of these configurations can be used as well. Still other configurations will be obvious to those of ordinary skill in the art having the benefit of this disclosure. 
     Accordingly, as described above, embodiments of the disclosure provide a wheelchair with selectively detachable, “quick release” wheels that allow the folded chassis of the wheelchair to fit into smaller packaging than in prior art designs. In one embodiment, quick release devices are coupled to rear tubes of the wheelchair, parallel to the armrests in one embodiment. Mounting posts of wheel assemblies then slide into the quick release devices and lock with quick-release, finger-turnable threaded members. In one embodiment, the rear wheel assemblies are offset by about two inches to provide more stability to the chair from front to back. 
     The ability to remove the wheels and/or footrests results in over a thirty percent reduction in shipping volume when the folded chassis is placed within a container. At the same time, the offset from the quick release mechanisms provides a longer wheelbase that would be the case if every dimension of a wheelchair were reduced. Accordingly, a user receives a full size seat and increased stability, all in a package that they can touch and feel on a retailer&#39;s shelf. 
     In one embodiment, to further reduce the size, a brake mechanism can be coupled only to the mounting post of the rear wheel assembly. Accordingly, when the rear wheel assembly is removed, so too is the brake assembly. This results in additional size reduction. 
     Other embodiments—in addition to detachability—are provided as well. For example, in another embodiment, the wheel assemblies are pivotable to reduce chassis size. In still other embodiments, the tubes of the chassis can be telescoping. Other configurations, as noted above, will be obvious to those of ordinary skill in the art having the benefit of this disclosure. 
     While numerous utilitarian features of wheelchairs configured in accordance with one or more embodiments of the disclosure have been described above, each wheelchair has associated therewith a multitude of ornamental design features as well. To be sure, some of the elements associated with embodiments of the disclosure provide both functional and ornamental design features. For example, the removable wheel assemblies, while providing functionality, also create an ornamental design as well. Similarly, the shape of the various chassis configurations, while offering functionality, provide a very unique ornamental design for the wheelchair as well. 
     Turning now to  FIGS. 33-50 , illustrated therein are ornamental design elements of one explanatory wheelchair  100  and chassis  101  configured in accordance with one or more embodiments of the disclosure. The wheelchair  100  and chassis  101  of  FIGS. 33-50  are shown in various configurations. For example, in  FIGS. 33-42 , the wheelchair is shown with its wheel assemblies attached. In  FIGS. 43-50 , the chassis  101  is shown with wheel assemblies detached. 
     In the foregoing specification, specific embodiments of the present disclosure have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Thus, while preferred embodiments of the disclosure have been illustrated and described, it is clear that the disclosure is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present disclosure as defined by the following claims. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present disclosure. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The disclosure is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.