Abstract:
A wheel for a non-motorized vehicle (e.g., a shopping cart) can include a housing assembly and a tread assembly. The housing assembly can be configured to sealingly house electronics or other components. The tread assembly can removably mate with the housing assembly such that the electronics or other components remain closed and/or sealed within the housing assembly when the tread assembly is mated or unmated with the housing assembly.

Description:
RELATED APPLICATIONS 
     This application claims the priority benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/537,715, filed Sep. 22, 2011, titled “WHEEL REPLACEMENT TREADS AND METHODS,” and U.S. Provisional Patent Application No. 61/692,148, filed Aug. 22, 2012, titled “WHEEL REPLACEMENT TREADS AND METHODS,” the entirety of each of which is incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates to replaceable treads for wheels and wheels having replaceable treads usable with non-motorized vehicles. 
     2. Description of the Related Art 
     Non-motorized wheeled vehicles, such as human-propelled carts (e.g., shopping carts), can include two or more wheels. Vehicle wheels incur wear as a result of use or damage. For example, prolonged use of the wheel can cause a tread of the wheel to become worn down. Accordingly, the wheel may need to be replaced. 
     SUMMARY 
     Various embodiments are directed to wheels and wheel treads for non-motorized vehicles (e.g., human-propelled carts). Replacement of vehicle wheels can incur substantial expense, particularly in implementations in which the vehicle wheel includes expensive electronic components (e.g., theft prevention electronics in a shopping cart wheel). Accordingly, in certain embodiments, rather than replacing the entire wheel, the tread of the wheel can be replaced. In certain such embodiments, the tread can be configured to be axially removed and installed on the wheel. 
     Certain wheels require complete or substantially complete removal and/or disassembly of the wheel from the wheeled vehicle in order to replace the treads of the wheels. Furthermore, some wheels may require the disassembly of a sealed portion of the wheel in order to replace the tread. For example, some embodiments may require the opening of a chamber (e.g., in a central portion of the wheel) in order to replace the tread. However, in certain instances, it can be desirable to avoid disassembling certain portions of the wheel to replace the tread. For example, it can be beneficial to avoid opening a sealed chamber containing electrical components disposed in the wheel. 
     In some embodiments, a wheel assembly includes a serviceable tread assembly that is capable of being installed and attached to a non-serviceable housing assembly. As used herein, the term “serviceable” has its ordinary meaning and includes, without limitation, the characteristic of being intended to be replaced during the course of use of the item. As used herein, the term “non-serviceable” has its ordinary meaning and includes, without limitation, the characteristic of not intended to be replaced during the intended course of use of the item. For example, certain components of the wheel may be sealed (e.g., to inhibit contamination) and may be non-serviceable. Non-serviceable also includes situations where a component is not intended to be serviced by an end-user but which may be serviced by a factory-authorized technician or by the manufacturer. In certain instances, the wheel assembly is configured for use on a non-motorized vehicle. For example, the wheel assembly can be configured for use on a locking shopping cart wheel. In some embodiments, the tread assembly attaches to the housing assembly with one or more fastening devices (such as screws, bolts, nails, or otherwise) and/or locking features. In certain configurations, the fastening devices and/or locking features are arranged around the circumference of the tread assembly and/or the housing assembly. 
     In some embodiments, the tread assembly includes a tread and a frame (e.g., support, backbone, lattice, skeleton, spine, or other structural portion). In certain instances, the frame provides support and/or reinforcement for the tread. For example, in certain variants, the frame can be positioned radially inward of the tread and can be configured to bear force (e.g., compressive force) that is applied to the tread. In some implementations, the frame is configured to shape the tread (e.g., a generally cylindrical shape). In certain embodiments, the tread assembly couples with the housing assembly, which can include a hub and a cover. In some embodiments, installation of the tread assembly is facilitated by the structure of the hub and cover components. For example, the hub and cover components can be configured to allow the tread assembly to be slid onto the hub. 
     In certain embodiments, the tread assembly is held in position on the housing assembly by one or more fastening devices and/or locking features. In some cases, the fastening devices and/or locking features are integral with the tread assembly and/or the housing assembly. In certain embodiments, the fastening devices and/or locking features are axially arranged around the inside and/or outside surfaces of the tread assembly and correspond to mating features similarly arranged around the outer circumferential surfaces of the wheel assembly (e.g., the hub). As used herein, the term “axial,” or derivations thereof, has its ordinary meaning and refers to, without limitation, a direction that is substantially perpendicular to a plane in which the wheel rotates. The axial direction may be substantially parallel to or substantially collinear with a rotation axis of the wheel (e.g., within ten to twenty degrees of the rotation axis). In some cases, the tread assembly is maintained on the housing assembly by one or more fasteners. 
     In some embodiments, the tread assembly is configured to be removed from the housing assembly. In certain such cases, the tread assembly can be removed without the need to disassemble the housing assembly (e.g., by separating the hub and the cover). Such a configuration can, for example, facilitate easy replacement of the tread assembly (e.g., due to wear or damage) while preserving the integrity of the housing assembly. For example, a tread assembly that can be replaced without the need to open the housing assembly can maintain the efficiency of the seals on embodiments of the housing assembly that include such seals to protect components (e.g., electronics) located inside the housing assembly. In certain instances, removal of the worn or damaged tread is accomplished by the removal or disengagement of the fastening devices and/or locking features that secure the tread to the housing assembly. In some cases, the removal also includes axially sliding the tread off the mating wheel hub exterior geometry. A new tread assembly can be installed by reversing this procedure. 
     A wheel for a human-propelled cart can comprise a housing assembly having a hub and a cover. The hub can have an inner cavity and can comprise a frame engaging surface having a first mating feature, the inner cavity configured to receive an electrical component and the cover configured to be sealed with the hub, thereby inhibiting access into the inner cavity. In some embodiments, the wheel includes a tread assembly configured to axially receive a portion of the housing assembly, the tread assembly comprising a frame and a tread. The frame can have a tread engaging surface and a hub engaging surface, the hub engaging surface having a second mating feature and being configured to releasably couple with the frame engaging surface of the hub. The tread can be disposed radially outward of the frame and can be configured to engage a surface on which the wheel is configured to roll. The wheel can include a fastener configured to engage the first mating feature and the second mating feature. According to some variants, the tread assembly is configured to removably couple with the housing assembly such that the tread assembly can be axially separated from the housing assembly without unsealing the cover and the hub, thereby facilitating repair or replacement of the tread assembly while maintaining the seal of the cover and the hub. In some embodiments, when the hub engaging surface of the frame is coupled with the frame engaging surface of the hub, the first mating feature and the second mating feature are circumferentially aligned such that the fastener can axially engage the first mating feature and the second mating feature. 
     In some embodiments, at least one of the first mating feature and the second mating feature comprises a radially outwardly-extending flange. The tread assembly can include a frame alignment feature comprising a first tread recess configured to receive the first mating feature. The housing assembly may include a hub alignment feature comprising a first housing recess configured to receive the second mating feature. In some embodiments, the wheel is configured to rotate around a rotation axis, and the hub is configured to be rotated relative to the frame about the rotation axis of the wheel. The frame alignment feature can include a second tread recess oriented substantially perpendicular to and extending generally circumferentially from the first tread recess, the second tread recess being configured to receive the first mating feature when the hub is rotated relative to the frame. The frame alignment feature can include a third tread recess extending in a direction generally axially away from the second mating feature, the third tread recess configured to receive the first mating feature when the hub is rotated relative to the frame such that the first mating feature is generally aligned with the third tread recess. In some embodiments, the hub alignment feature includes a second housing recess generally perpendicular to and extending generally tangentially from the first housing recess, the second housing recess configured to receive the second mating feature when the hub is rotated relative to the frame. The hub alignment feature includes a third housing recess extending in a direction generally axially away from the first mating feature, the third housing recess configured to receive the second mating feature when the hub is rotated relative to the frame such that the second mating feature is generally aligned with the third housing recess. 
     In some embodiments, the tread assembly comprises a first rotational axis and the housing assembly comprises a second rotational axis, the first rotational axis and the second rotational axis being generally collinear when the housing assembly and tread assembly are coupled. The tread can have a tread width, the first mating feature and the second mating feature each can have an axial width that is less than the tread width, and the sum of the axial widths of the first mating feature and the second mating feature can be about equal to the tread width. In some embodiments, the human-propelled cart is a shopping cart. 
     A method of assembling a shopping cart wheel can comprise forming a housing assembly. Forming the housing assembly can include providing a hub having a central cavity, the hub comprising a first mating feature, axially joining a cover with the hub, the cover configured to form a seal between the cover and the hub, thereby inhibiting access by contaminants into the cavity, forming a tread assembly, wherein forming the tread assembly comprises, providing an annular frame comprising an inner surface and outer surface, the inner surface and the outer surface each comprising recesses, the inner surface further comprising a second mating feature, disposing a tread around at least the outer surface of the frame, and engaging the tread with the recesses on the inner surface and the outer surface of the frame, thereby securing the tread with the frame. In some embodiments, the method of assembling a shopping cart wheel includes aligning the first mating feature of the hub with the second mating feature of the frame, receiving the housing assembly into the tread assembly, and securing the housing assembly with the tread assembly. 
     In some embodiments, securing the housing assembly with the tread assembly comprises positioning the first mating feature in a first recess of the frame, wherein the first mating feature comprises a radially outwardly extending flange, positioning the second mating feature in a second recess of the hub, wherein the second mating feature comprises a radially inwardly extending flange, and axially inserting a fastener through the first mating feature and the second mating feature. In some embodiments, the method of assembling a shopping cart wheel further comprises rotating the housing assembly and the tread assembly relative to each other after the housing assembly has been received into the tread assembly. The method of assembling a shopping cart wheel can further comprise axially spacing the first mating feature apart from the second mating feature. 
     A method of repairing a wheel of a shopping cart, the wheel comprising a housing assembly and a tread assembly coupled with a plurality of fasteners located generally around an outer circumferential region of the wheel, the housing assembly coupled with the shopping cart via a caster assembly, the housing assembly comprising a central sealed chamber that includes an electrical component, can comprise removing the wheel from the caster assembly. In some embodiments the method of repairing a wheel of a shopping cart includes loosening the fasteners such that the housing assembly and the tread assembly can be separated, separating the tread axially from the housing assembly without opening the central sealed chamber of the housing assembly, aligning first flanges of a replacement tread assembly with first recesses of the housing assembly, aligning second recesses of the replacement tread assembly with second flanges of the housing assembly, axially sliding the replacement tread assembly onto the housing assembly, securing the fasteners such that the fasteners couple the replacement tread assembly and the housing assembly, and coupling the housing with the caster assembly. 
     In some embodiments, loosening the fasteners comprises rotating the fasteners. The method of repairing a wheel of a shopping cart can further comprise rotating the tread assembly relative to the housing assembly after the replacement tread assembly has been axially slid onto the housing assembly. In some embodiments, the method of repairing a wheel of a shopping cart further comprising radially engaging the first flanges of a replacement tread assembly with the first recesses of the housing assembly, and radially engaging the second recesses of the replacement tread assembly with the second flanges of the housing assembly, thereby providing areas of radial interference between the housing assembly and the tread assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a perspective view of an example of a wheel assembly for a cart, including examples of a tread assembly and a housing assembly. 
         FIG. 2  illustrates a front perspective view of the tread assembly of  FIG. 1 . 
         FIG. 2A  illustrates a rear perspective view of the tread assembly of  FIG. 1 . 
         FIG. 3  illustrates an exploded view of the tread assembly of  FIG. 1 , including a tread and a frame. 
         FIG. 4  illustrates a close-up view of a portion of the frame of  FIG. 3 . 
         FIG. 5  illustrates another close-up view of a portion of the frame of  FIG. 3 . 
         FIG. 6  illustrates an embodiment of the housing assembly of  FIG. 1 , including a hub and a cover. 
         FIG. 7  illustrates a close-up view of a portion of the housing assembly of  FIG. 6 . 
         FIG. 8  illustrates a close-up view of a portion of an embodiment of the hub of  FIG. 6 . 
         FIG. 9  illustrates a close-up view of a portion of an embodiment of the cover of  FIG. 6 . 
         FIG. 10  illustrates an exploded view of an embodiment of the wheel assembly of  FIG. 1 , including the tread assembly of  FIG. 2  and the housing assembly of  FIG. 6 . 
         FIG. 11  illustrates the wheel assembly of  FIG. 10  in a partially assembled state, with the tread assembly coupled with the housing assembly, and a plurality of fasteners in an exploded view. 
         FIG. 12  illustrates the wheel assembly of  FIG. 11  in an assembled state, with a caster and associated hardware shown in an exploded view. 
         FIG. 13  illustrates an exploded view of another embodiment of a tread assembly, including a frame and a tread. 
         FIG. 14  illustrates the tread assembly of  FIG. 13  in an assembled state. 
         FIG. 15  illustrates an embodiment of a wheel hub assembly. 
         FIG. 16  illustrates a close-up view of the hub assembly of  FIG. 15 . 
         FIG. 17  illustrates an exploded view of the tread assembly of  FIG. 14  and the wheel hub assembly of  FIG. 16 . 
         FIG. 18  illustrates a close-up view of protrusions and recesses of the frame of  FIG. 13 . 
         FIG. 19  illustrates a close-up view of protrusions and recesses of the wheel hub of  FIG. 15 . 
         FIG. 20  illustrates a close-up view of one of the protrusions of  FIG. 19  and one of the recesses of  FIG. 18  in a partially assembled state. 
         FIG. 21  illustrates a close-up view of the protrusion and recesses of  FIG. 20  in another partially assembled state. 
         FIG. 22  illustrates a close-up view of the protrusion and recesses of  FIG. 20  in an assembled state. 
     
    
    
     DETAILED DESCRIPTION 
     Non-motorized wheeled vehicles are used in a variety of environments including retail environments (e.g., shopping carts), manufacturing or warehouse environments (e.g., merchandise or industrial carts), travel environments (e.g., luggage or baggage carts at an airport or bus station), medical environments (e.g., hospital carts, medical device carts, wheelchairs, baby strollers), and so forth. Non-motorized vehicles are typically human-propelled, e.g., by a human pushing or pulling the vehicle. The present disclosure describes examples of wheels, treads, and methods for assembling wheels or replacing treads that are usable with non-motorized wheeled vehicles. Many of the examples described herein are in the context of wheels for shopping carts; however, this is intended for facilitating understanding and is not a limitation. 
     With reference to  FIG. 1 , in some embodiments, a wheel assembly can include a tread assembly  10  and a housing assembly  70 . The tread assembly  10  can be configured to mount or otherwise be received at least partly on the housing assembly  70 . The tread assembly  10  can be configured to protect and/or space the housing assembly  10  from a surface on which the wheel assembly rolls. For example, the tread assembly  10  can protect the housing assembly  70  from abrasion due to contact with the surface. 
     With regard to  FIGS. 1-5 , an embodiment of a tread assembly  10  is illustrated. In some embodiments, the tread assembly  10  includes a frame  20  and a tread  60 . In some embodiments, the frame  20  is generally rigid. In some cases, the frame  20  is made of metal (e.g., steel or aluminum) or a polymer (e.g., nylon). The frame  20  and/or tread  60  can include a rotational centerline. In some embodiments, as illustrated in  FIG. 2 , the rotational centerline L of the frame  20  is collinear with the rotational centerline of the tread  60  when the frame  20  is mated with the tread  60 . 
     As shown in  FIG. 3 , the frame  20  can be configured to engage with the tread  60 . The frame  20  can have one or more recessed features  23 . For example, in the embodiment illustrated, the frame  20  can include recessed features  23  that are arranged in a radial pattern around an outer circumference of the frame  20 . As will be discussed in further detail below, the recessed features  23  can engage with corresponding features of the tread, thereby securing the frame  20  and the tread  60 . 
     According to some variants, the frame  20  includes a hub-engaging surface  28  located on the radially-inward surface of the frame  20 . The frame  20  can include first mating features  22 . In some embodiments, the first mating features  22  are located on the hub-engaging surface  28 . In certain variants, such as is shown in  FIGS. 3 and 4 , the first mating features  22  can be one or more radially inwardly-extending flanges  24 . In some embodiments, first mating features  22  are configured to allow for the insertion of a corresponding number of fasteners, such as one fastener per first mating feature  22 . In the illustrated embodiment, the first mating features  22  are generally equally spaced in a radial pattern around an inner periphery of the frame  20 . However, other configurations are contemplated and are included in this disclosure. 
     In some embodiments, the frame  20  includes indentations  25 . In certain instances, the indentations  25  are arranged in a radial pattern around the inner circumference of the frame  20 . One or more of the indentations  25  can span the axial (e.g., parallel to the rotational centerline of the frame) width W of the hub-engaging surface  28 . In some embodiments, one or more of the indentations  25  are located axially-adjacent to the radially inwardly-extending flanges  24 . In such embodiments, the first mating features  22  can comprise a radially inwardly-extending flange  24  and an indentation  25 . The radially inwardly-extending flange  24  and corresponding indentation  25  can each have an axial width that is less than the axial width W of the hub-engaging surface  28 . 
     The tread  60 , or parts thereof, can be made of most any material, such as rubber, plastic, wood, metal, or otherwise. For example, the tread  60  can be a thermo-set material. The tread  60  can be molded onto, injected, fused, welded, or otherwise joined with the frame  20 . In some cases, the tread  60  is formed separately from the frame  20  and then coupled with the frame  20 . In other cases, the tread  60  is formed with the frame  20 . For example, the frame  20  can be molded during substantially the same operation (e.g., injection molding operation) as the tread  60 . In certain instances, the tread  60  covers all exposed outside surfaces of the frame  20 . In some embodiments, the tread  60  is injection molded onto the frame  20 . In certain cases, the tread  60  is secured with/to the frame  20  by adhering with the indentation features  23 . 
     In some implementations, the tread  60  engages with recesses  26  on the frame  20 . For example, the tread  60  can extend around a portion of the sidewall of the frame  20 , such that the tread  60  is located radially outward of the frame  20  and a portion of the tread  60  is engaged with the recess  26 . In certain variants, the tread  60  wraps around a portion of the frame  20 . In certain instances, the tread  60  is joined with the frame  20  with an adhesive (e.g., glue or epoxy), thermal or sonic welding, or otherwise. For example, an adhesive can be applied to an outer surface of the frame  20  and/or an inner surface of the tread  60 . In some embodiments, the outer surface (e.g., tread-engaging surface) of the frame  20  and/or an inner surface (e.g., structure-engaging surface) of the tread  60  can be textured (e.g., dimpled, ribbed, grooved, or otherwise), which can facilitate a connection between the frame  20  and the tread  60 . 
     The tread  60  can include a traction surface  62  configured to engage with a floor or other surface when the non-motorized vehicle (e.g., a shopping cart) is moved. The traction surface  62  can be constructed of the same material as the tread  60  or from a difference material. In some embodiments, the traction surface  62  includes friction features (e.g., channels, protrusions, etc.) configured to facilitate grip between the traction surface  62  and the floor on which it is resting. 
     With regard to  FIGS. 6-9 , an embodiment of a housing assembly  70  is illustrated. As shown, the housing assembly  70  can include a structural hub  80  and a cover  90 . In certain embodiments, the hub  80  and the cover  90  can be assembled together. For example, the hub  80  and cover  90  can be held together by fasteners  50 , which can be arranged in a radial pattern around the circumference of the hub  80  and/or cover  90 . In some embodiments, the fasteners  50  engage with radially outwardly-extending flanges  84 ,  94  on the hub  80  and cover  90  respectively. For example, one or more flanges  94  on the cover  90  can be aligned with one or more flanges  84  on the hub  80  such that a fastener  50  can be extended through apertures in the aligned flanges  84 ,  94 . In some embodiments, the flanges  94  on the cover  90  are symmetrically distributed about the outer circumference of the cover  90 . In some such embodiments, the cover  90  can be attached to the hub  80  in a plurality of relative rotational orientations. In some embodiments, the flanges  94  are asymmetrically distributed about the outer circumference of the cover  90  such that the cover  90  connects with the hub  80  in only one relative rotational orientation. In some such embodiments, rotational alignment of some portion of the hub  80  and/or the contents therein can be consistently aligned with some portion of the cover  90 . In some embodiments, the hub  80  and/or cover  90  can include one or more magnets housed within and/or on the surface of the hub  80  and/or cover  90  (e.g., magnets for use with Hall effect sensors to activate the electrical components within or around the housing assembly  70 ). 
     In some instances, the hub  80  and/or the cover  90  include second mating features  82 . The second mating features  82  can correspond to the features  22  on the inside of the frame  20  of the tread assembly  10 . The illustrated embodiment includes a plurality of second mating features  82  arranged in a radial pattern around the outer circumference of the housing assembly  70 . Other configurations are also contemplated and are part of this disclosure. In some instances, the second mating features  82  include radially outwardly extending flanges  84 . In some instances, the second mating features  82  include radially inwardly extending notches  85 . In some instances, such as in the illustrated embodiment, the second mating features  82  include a combination of radially outwardly extending flanges  84  and radially inwardly extending notches  85 . 
     As shown, the housing assembly  70  can have an axial depth D. In some cases, the second mating features  82  extend less than the entire axial depth D of the housing assembly  70 . In other cases, the second mating features  82  can extend less than the entire axial depth D of the housing assembly  70 . Such a configuration can, for example, provide an improved connection between the housing assembly  70  and the tread assembly  10  when assembled together, as is discussed below. In some implementations, the depth D of the housing  70  is greater than or equal to the axial width W of the frame  20 . 
     In some embodiments, the cover  90  and the hub  80  include rib features  97  and  87  that form a mating channel structure around the inside circumference of the cover  90  and the hub  80 . The rib features  97  and  87  can house a seal (e.g., a rubber or polymeric O-ring), which can be configured to inhibit or prevent moisture or other contaminants from entering the inside of the housing assembly  70  when the hub  80  is assembled with the cover  90 . Such a configuration can, for example, protect devices (e.g., mechanical or electrical components) disposed inside the housing assembly  70 . Examples of such devices can include, for example, a brake mechanism, a two-way communication device, a navigation device, a power generator, a computer processor, a battery, combinations of such devices, or otherwise. Examples of some such devices are discussed in the following: U.S. Pat. No. 8,046,160, titled “NAVIGATION SYSTEMS AND METHODS FOR WHEELED OBJECTS”; U.S. Patent Application Publication No. 2006/0244588, filed Mar. 20, 2006, titled “TWO-WAY COMMUNICATION SYSTEM FOR TRACKING LOCATIONS AND STATUSES OF WHEELED VEHICLES”; and U.S. Patent Application Publication No. 2006/0249320, filed Mar. 20, 2006, titled “POWER GENERATION SYSTEMS AND METHODS FOR WHEELED OBJECTS;” the entirety of each of which is hereby incorporated by reference herein for all it discloses. 
     In certain variants, the cover  90  and the hub  80  are configured to be readily separable from each other. For example, in some implementations, the cover  90  and the hub  80  are configured to be separable after the fasteners  50  are removed. Designs including a separable cover  90  and hub  80  can, for example, facilitate the ability to service, replace, repair, and/or otherwise attend-to the devices in the housing assembly  70 . For example, such designs can facilitate installing a new battery in the housing assembly  70 . Some embodiments have an O-ring or other type of sealing device disposed between, near, or adjacent to the rib features  97  and  87 . 
     In some variants, the cover  90  and the hub  80  are substantially permanently joined. For example, in some embodiments, the channel structure can be at least partly filled with an adhesive (not shown) that, in combination with the surfaces formed by rib features  97  and  87 , substantially permanently joins the cover  90  and the hub  80 . In some embodiments, the adhesive forms a portion of the seal between the cover  90  and the hub  80 . Further, in some such embodiments, the adhesive can inhibit or otherwise discourage disassembly of the housing assembly  70 . 
     Certain embodiments that have substantially permanently joined cover  90  and hub  80  have a longer life expectancy than embodiments in which the cover  90  and the hub  80  are readily separable. For example, embodiments in which the cover  90  and the hub  80  are substantially permanently joined can include a battery having a greater life expectancy, an internal generator and power storage (such as is described in U.S. Patent Application Publication No. 2006/0249320, incorporated by reference herein), and/or intelligent power management circuits utilizing motion sensors, each of which, alone or in combination, can provide a longer life than embodiments in which the cover  90  and the hub  80  are readily separable. 
     As shown in the exploded views of  FIGS. 9-11 , the tread assembly  10  can be installed on the housing assembly  70 . For example, the first mating features  22  of the frame  20  can be aligned with the second mating features  82  of the cover  80  and hub  90  of the housing assembly  70 . In certain embodiments, the tread assembly  10  can be axially slidably mounted on the housing assembly  70  when the tread assembly  10  and housing assembly  70  are moved toward one another in an axial direction AD. In certain such embodiments, the first mating features  22  can be received in the radially inwardly extending notches  85  of the housing assembly  70 , thus providing a circumferential interference, which can inhibit or prevent the tread assembly  10  from rotating relative to the housing assembly  70 . In some embodiments, the flanges  84  are received into the indentations  25  of the frame  20  to provide additional or alternative circumferential interference between the housing assembly  70  and the tread assembly  10 . The first mating features  22  and second mating features  82  can be circumferentially distributed in a symmetric pattern such that the tread assembly  10  can align with the housing assembly  70  in a plurality of relative rotational orientations. In some embodiments, the first mating features  22  and second mating features  82  are asymmetrically circumferentially distributed such that the tread assembly  10  and housing assembly  70  can align in only one relative rotational orientation. In some such embodiments, alignment between certain features (e.g., sensors, mechanical components, electrical components, etc.) within the housing assembly  70  and certain features of the tread assembly  10  can be facilitated. 
     In some embodiments, as illustrated in  FIG. 2A , the tread  60  and/or frame  20  can include one or more mating identifiers  68 . The mating identifiers  68  can facilitate proper orientation of the tread assembly  10  with respect to the housing assembly  70  for connecting the tread assembly  10  to the housing assembly  70 . For example, mating identifiers  68  can be located on the side of the tread  60  that faces the housing assembly  70  before the tread assembly  10  is received onto the housing assembly  70 . In some embodiments, the mating identifiers  68  correspond to the side of the tread assembly  10  opposite the inwardly-extending flanges  24 . 
     In some embodiments, the tread assembly  10  is secured with the housing assembly  70  with fasteners  52  in order to, for example, reduce the chance of unintentional separation and/or to reduce vibration. In some configurations, the housing assembly  70  and/or the tread assembly  10  include indicia to indicate the fasteners  52  that couple the housing assembly  70  with the tread assembly  10 . In certain instances, at least one of the fasteners  52  is configured to discourage tampering with the wheel assembly. For example, at least one of the fasteners  52  can have a non-standard screw driving connection (e.g., a tamper-resistant head). The fasteners  52  can be installed into the tread assembly  10  and housing assembly along the axial direction AD. 
     In some embodiments, a method of installing a tread assembly  10  includes sliding the tread assembly  10  onto the housing assembly  70 . In certain instances, the tread assembly  10  is slid until it is generally fully seated on the housing assembly  70  (e.g., in contact with a positive stop or other feature to denote proper placement). The hub  80  can include one or more hub orientation features  83 , such as one or more protrusions  83  or recesses. In some such embodiments, the tread  60  and/or frame  20  can include one or more tread orientation features  27  (e.g., protrusions and/or recesses) configured to engage with the one or more hub orientation features  83 . Engagement between the tread orientation features  27  and the hub orientation feature  83  can facilitate alignment between the first mating feature  22  and the second mating feature  82 . In some cases, the tread assembly  10  is axially installed (e.g., by sliding) onto the housing assembly  70 . In some embodiments, the method includes securing the tread assembly  10  to corresponding features on the hub  80  with fasteners  52 . According to some variants, the tread assembly  10  can be connected with and disconnected from the housing assembly  70  without unsealing the housing assembly  70  (e.g., without removing the cover  90  from the hub  80 ). 
     In certain embodiments, the method further includes mounting the wheel assembly with a caster  240 , for example as shown in  FIG. 12 . In certain embodiments, the method also includes placing the wheel assembly between end portions  242  of the caster  240 ; placing a first fastener  228  (e.g., a bolt) through the end portions  242  and the wheel assembly; and securing the first fastener  228  with a second fastener  232  (e.g., a nut). In certain instances, the method also includes mating at least one flat portion  235  of an axle  234  of the wheel assembly with a retaining clip  225 . In certain such cases, the method also includes inhibiting rotation of the axle  234 . For example, rotation of the axle  234  can be inhibited by an interference fit between the “U”-shaped side of the retaining clip  225  and at least one of the end portions  242  of the caster  240 . 
     In some embodiments, a method of removing a tread assembly  10  includes substantially the reverse of some of the actions in the above-described method of installing a tread assembly  10 . For example: separating the wheel assembly from the caster  240  (e.g., by loosening fastener  228 ,  232  and removing the fastener  228 ), loosening the fasteners  52 , and axially sliding the tread assembly  10  off of the housing assembly  70 . 
     In some embodiments, a method of manufacturing a tread assembly  10  includes forming a frame  20  and molding a tread  60  onto the frame  20 . Some embodiments include vulcanizing the tread  60 . In some cases, the method includes applying an adhesive to an outer surface of the frame  20 , which can, for example, improve adherence of the tread  60  with the frame  20 . 
     With regard to  FIGS. 13-22 , another embodiment of a tread assembly is illustrated. In some embodiments, the tread assembly  110  includes a frame  120  and a tread  160 . Certain embodiments of the frame  120  are nylon and are injection molded. In some embodiments, the tread  160  is rubber (e.g., ethylene propylene diene monomer (EPDM)). Certain variants of the tread  160  can be over-molded onto the insert ring  120 . As shown in  FIG. 14 , in the assembled tread  110 , the tread  160  can be positioned generally outside and around the frame  120 . For example, the frame  120  can be received in the tread  160 . 
     As illustrated in  FIGS. 14-16 , in certain implementations, the tread insert component  120  has first mating features  122  arranged in a radial pattern and spaced apart from one another in a circumferential direction D C  around an inside circumference of the frame  120 . In some variants, the first mating features  122  correspond to second mating features  182  located on an outer circumference of a wheel hub  180 . The second mating features  182  can be arranged in a radial pattern around the circumference of the hub  180 . The tread assembly illustrated in  FIGS. 13-22  includes a wheel cover configured to mate with the hub  180  that is not shown in the figures. The wheel cover can be configured to mate with the hub  180  to create a seal between the wheel cover and the hub  180 . In some embodiments, the first mating features  122  and second mating features  182  are asymmetrically circumferentially distributed such that the tread insert component  120  and hub  180  can align in only one relative rotational orientation. In some such embodiments, alignment between certain features (e.g., sensors, mechanical components, electrical components, etc.) of the hub  180  and certain features of the frame  120  and/or tread  160  can be facilitated. The first mating features  122  and second mating features  182  can, in some embodiments, be circumferentially distributed in a symmetric pattern such that the insert component  120  can align with the hub  180  in a plurality of relative rotational orientations. 
     As shown in  FIGS. 17 and 18 , in some variants, the first mating features  122  of the frame  120  include protrusions  124  and recesses  125 . In certain embodiments, the second mating features  182  of the hub  180  include recesses  185  and protrusions  184 . The first mating features  122  can be configured and arranged in such a way that the protrusions  124  can be received in the recesses  185  on the hub  180 , thereby allowing the mating engagement of the protrusions  124  and the recesses  185 . Similarly, the protrusions  184  on the hub  180  can be received in the recesses  125  on the insert ring  120 , thereby allowing the mating engagement of the protrusions  184  and the recesses  125 . 
     In certain embodiments, the tread insert  160  can be assembled with the wheel hub  180  by mating (e.g., by sliding) the tread insert  160  onto the hub  180 . For example, the protrusion  124  on the insert  160  can be generally aligned with a portion of the recess  185  of the hub  180 , thereby allowing the protrusion  124  to be slidably received (e.g., axially) in the recess  185 . In some embodiments, the insert  160  is pushed onto the hub  180 . In some embodiments, the tread insert  160  is pushed completely onto the hub. 
     In certain variants, the recess  185  has sufficient axial width (e.g., parallel with the axis of rotation) that the protrusion  124  does not circumferentially interfere with the protrusion  184 , when the protrusion  124  is received in the recess  185 . In some arrangements, when the protrusion  124  is received in the recess  185 , the protrusion  124  has a first axial width and the protrusion  184  has a second axial width, with the first and second axial widths not axially overlapping. 
     As shown in  FIGS. 21 and 22 , in some implementations, the tread insert  160  can be rotated relative to the hub  180 . In some embodiments, the tread insert  160  can be rotated (e.g., in a clockwise direction relative to the hub) until it engages (e.g., abuts or otherwise is stopped by) walls that define the recess  185  of the hub  180 . For example, rotation of the tread insert  160  relative to the hub  180  can cause the protrusion  124  of the insert  160  to be received into a second recess  188  extending perpendicular and generally in a circumferential direction D C  away from the recess  185 . In some configurations, rotation of the tread insert  160  relative to the hub  180  can cause the protrusion  184  of the hub  80  to be received into the second recess  129  on the tread insert  120 . Such a configuration can, for example, increase the strength and/or reduce the likelihood of relative movement of the insert  160  and hub  180 . In some embodiments, the engagement of the insert  160  and the walls of the hub  180  facilitates torque transfer between the insert  160  and the hub  180 . In certain variants, when the tread insert  160  is rotated, the protrusions  124  on the inside circumference are moved near, next to, in front of, and/or behind the protrusions  184  on the outside of the hub  180 . 
     In certain implementations, the protrusions  124 ,  184  include holes  111 . In certain embodiments, when the tread insert component  160  has been rotated to its final position, the holes  111  that pass through each of the protrusions  124 ,  184  will be aligned. In some implementations, fasteners (e.g., screws  52 ) can be driven into the aligned holes  111 , thereby securing the tread insert  160  and hub  180  and/or inhibiting or preventing further relative rotation of the insert  160  and hub  180 . Some variants include a wheel cover with a mating hole (not shown). In some embodiments, the fasteners  50 ,  52  secure the tread insert  160  and hub  180  and wheel cover (not shown). For example, the fasteners  50 ,  52  can pass through a portion of each of the tread insert  160  and hub  180  and wheel cover. Such a configuration can enhance the structural and/or watertight characteristics of the tread assembly. In some embodiments, each of the fasteners  50 ,  52  passes through the wheel cover. In some embodiments, the fasteners  52  used to connect the first mating feature  122  to the second mating feature  182  can have a non-standard screw driving connection (e.g., a tamper-resistant head). 
     In some embodiments, the tread insert  160  can be configured such that the protrusion  124  can be axially spaced apart from the protrusion  184 . In some variations, the protrusion  124  of the tread insert  106  are received by a generally axially oriented third recess  189  of the second mating feature  182 . Such reception of the protrusions  124  can facilitate torque transfer between the protrusion  124  and the walls defining the third recess  189 . In some embodiments, engagement of the protrusion  124  with the third recess  189  can reduce stress on any fasteners  52  used to mate the first mating feature  122  with the second mating feature  182 . 
     Although the present disclosure has been described in terms of certain preferred embodiments and certain preferred uses, other embodiments and other uses that are apparent to those of ordinary skill in the art, including embodiments and uses which do not provide all of the features and advantages set forth herein, are also within the scope of the present disclosure. Components, elements, features, acts, or steps can be arranged or performed differently than described and components, elements, features, acts, or steps can be combined, merged, added, or left out in various embodiments. For example, any or all of the features of the tread assembly of  FIGS. 1-12  can be used with the tread assembly of  FIGS. 13-22 , and any or all of the features of the tread assembly of  FIGS. 13-22  can be used with the tread assembly of  FIGS. 1-12 . Also, the wheels and tread assemblies shown and described herein can be used on any type of non-motorized wheeled vehicle, human-propelled vehicle, or cart such as a shopping cart, a hospital or medical device cart, wheelchair, an equipment cart, and so forth. Indeed, all possible combinations and subcombinations of elements and components described herein are intended to be included in this disclosure. No single feature or group of features is necessary or indispensable for every embodiment. Accordingly, the scope of certain embodiments of the present disclosure is to be defined by the claims that follow and their obvious modifications and equivalents. 
     Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. 
     Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z to each be present. 
     Similarly, while operations may be depicted in the drawings or described in the specification in a particular order, it is to be recognized that such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Additionally, the operations may be rearranged or reordered in other implementations. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.