Abstract:
Embodiments of collapsible wheels and methods of making collapsible wheels are generally described herein. Other embodiments may be described and claimed.

Description:
RELATED APPLICATION 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/719,634, filed Oct. 29, 2012, the disclosure of which is incorporated by reference. 
    
    
     FIELD 
     The present application generally relates to wheels, and more generally to collapsible wheels and methods of making collapsible wheels. 
     BACKGROUND 
     Some sporting equipment may require a wheeled vehicle for transportation. For example, kayaks may be transported to a river or lake on a wheeled kayak cart. Prior to launching the kayak on water, the kayak cart is removed from the kayak and may be stored on the kayak. The kayak cart may have a frame that is collapsible to reduce the size of the cart when not in use. In another example, an individual playing golf can carry his golf bag on his shoulder, with a golf pull cart or an electric golf cart. Golf pull carts typically have a frame to which two wheels for moving the cart are attached. The frame may also include a handle that is held by an individual for balancing, pulling or pushing the cart, and a platform or base for mounting the individual&#39;s golf bag. The frame may be collapsible to reduce the size of the pull cart when not in use for storage and/or transportation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a wheel according to one embodiment shown in an expanded position. 
         FIG. 2  is a perspective view of the wheel of  FIG. 1  shown in a collapsed position. 
         FIG. 3  is a perspective view of the wheel of  FIG. 1  shown without a tire according to one embodiment. 
         FIG. 4  is a perspective view of the wheel of  FIG. 3  shown in the collapsed position. 
         FIG. 5  is a perspective view of two wheel sections of the wheel of  FIG. 1 . 
         FIG. 6  is a partial front perspective view of the wheel of  FIG. 1  shown in the expanded position. 
         FIG. 7  shows a tire for use with a wheel according to one embodiment. 
         FIGS. 8-9  show sections of the tire of  FIG. 7 . 
         FIGS. 10-11  show mounting of the tire of  FIG. 7  on the wheel of  FIG. 3  according to one embodiment. 
         FIG. 12  shows a wheel section of the wheel of  FIG. 1 . 
         FIG. 13  shows an axle for the wheel of  FIG. 1 . 
         FIG. 14  shows the axle of  FIG. 13  mounted in the wheel of  FIG. 1 . 
         FIGS. 15-18  show the wheel of  FIG. 1  with an expansion and collapsing mechanism according to one embodiment. 
         FIGS. 19 and 20  show a wheel according to another embodiment in an expanded position and a collapsed position, respectively. 
         FIGS. 21 and 22  show a wheel according to another embodiment in a collapsed position. 
         FIGS. 23-25  show the wheel of  FIGS. 21 and 22  in an expanded position. 
         FIG. 26  shows a side view of a wheel according to one embodiment. 
         FIG. 27  shows a side view of a wheel according to one embodiment. 
         FIGS. 28 and 29  show side views of a wheel according to one embodiment in the expanded position and the collapsed position, respectively. 
         FIGS. 30 and 31  show side views of a wheel according to one embodiment. 
         FIGS. 32 and 33  show perspective views of a wheel according to one embodiment. 
         FIG. 34  shows a partial perspective view of the wheel section of a wheel according to one embodiment having a tire section. 
         FIGS. 35 ,  36  and  38  show a wheel according to one embodiment in an expanded position. 
         FIGS. 37 ,  39  and  40  show the wheel of  FIG. 35  in a collapsed position. 
         FIG. 41  shows perspective cross-sectional views of spokes of the wheel of  FIG. 35 . 
         FIG. 42  shows a flow chart of a method to manufacture a wheel according to one embodiment. 
         FIGS. 43 and 44  show a cart for carrying a golf club bag in deployed and stowed positions, respectively, having wheels according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a wheel  100  according to one example of the apparatus, methods, and articles of manufacture described herein is shown. The wheel  100  includes a hub assembly  102  and a tire  104 , at least a portion of which is mounted around the hub assembly  102  for contact with the ground. The wheel  100  also includes an axle  106  over which the hub assembly  102  is rotatably mounted. A wheel  100  or a plurality of wheels  100  may be used on a cart or a vehicle for transporting any object. 
       FIG. 1  shows the wheel  100  in an expanded position. To reduce the size of the wheel  100  for transportation and/or storage, an individual may collapse the wheel  100  to a collapsed position shown in  FIG. 2 . For example, a trunk of an automobile may not have sufficient space to accommodate a pull cart for golf clubs when the wheels  100  of the pull cart are in the expanded position. By placing the wheels  100  in the collapsed position, the pull cart and the wheels  100  may fit inside the trunk of the automobile for transportation. Accordingly, collapsing the wheels from an expanded position to a collapsed position allows the wheels and or any object to which the wheels are attached to occupy less space. Furthermore, as discussed in detail below, each wheel  100  may be removable from a pull cart to further reduce the space that may be occupied by the pull cart and the wheels  100 . 
     Referring also to  FIGS. 3-6 , the hub assembly  102  is shown in the expanded and collapsed positions, respectively. The hub assembly  102  includes a plurality stacked wheel sections  110 . Each wheel section  110  includes a hub section  112  with a central bore  114 . The wheel sections  110  may be concentrically stacked so that the central bores  114  are axially aligned to form an elongated bore for receiving the axle  106 . Each wheel section  110  may include at least one spoke  116  and a rim  118 . In the example of  FIGS. 1-5 , each wheel section  110  has a first pair of spokes  116  that radially projects from the hub section  112  to connect to a first rim  118 , and a second pair of spokes  116  that radially projects from the hub section  112  opposite to the first pair of spokes  116  to connect to a second rim  118 . Each rim  118  receives and supports a section of the tire  104 . Each wheel section  110  may include any number of spokes  116  that extend from the hub section  112  to one or more rims  118 . For example, each rim  118  may be connected to only one spoke  116  or a plurality of spokes  116 . The spokes  116  may be in any shape. For example, each spoke  116  may be straight, bent in one or more locations along the length of the spoke, and/or have a curvature. In the examples of  FIGS. 1-5 , the spokes  116  may be curved so as to function as springs when the wheel  100  is used. Accordingly, when forces are exerted on the rim  118  during the operation of the wheel  100 , the curved shape of each spoke  116  facilitates elastic bending of the spoke  116  such that the spoke  116  provides a shock absorbing function. 
     Each wheel section  110  may be freely rotatable about the axle  106  to allow expansion of the wheel sections  110  from a collapsed position shown in  FIG. 4  to an expanded position shown in  FIG. 3 . The number of wheel sections  110 , the thickness of each wheel section  110 , and/or the radial span of each wheel section  110  may be determined so that in the expanded position of the wheel  100 , a full circular wheel, i.e., about 360°, is defined by the wheel  100  and the rims  118  provide sufficient support for the tire  104  for proper operation of the wheel  100 . Providing sufficient support for the tire  104  at any instant during the operation of the wheel  100  may be defined by the number of contact points between the wheel  100  and the ground. Each rim  118  may be defined as having one contact point, which although referred to herein as a contact point, may represent an area of the rim  118  that contacts the ground. Increasing the number of contact points between the wheel  100  and the ground may increase the stability of the wheel  100 , hence increase the stability of the vehicle, i.e., pull cart, to which to the wheel  100  is attached. 
     The radial span of each wheel section  110  may determine the radial position of each wheel section  110  relative to an adjacent wheel section  110  in the expanded position of the wheel  100  and the number of wheel sections  110  that may be needed. Radial span  119  as shown in  FIG. 5  and as used herein may generally define a length of the rim  118  that contacts the ground during the operation of the wheel  100 . For example, if each rim  118  of a pair of rims  118  of a wheel section  110  define a radial span of about 90°, only two wheel sections  110  may be required so that the rims  118  define a full circle or about 360° without generally any overlap or gap between two adjacent rims  118 ; or each rim  118  may generally define a 90° radial span on a full circle that defines the wheel  100 . In other words, each wheel section  110  may generally define a 180° radial span on a full circle that defines the wheel. In another example, if each rim  118  of a pair of rims  118  of a wheel section  110  has a radial span  119  of about 45°, four wheel sections  110  may be required, i.e., eight rims  118 , so that the rims  118  define a full circle or about 360° without generally any overlap or gap between two adjacent rims  118 . Accordingly, a general configuration of the wheel  100  may be defined by the following example equation: 
     
       
         
           
             
               
                 
                   
                     
                       
                         360 
                         ⁢ 
                         ° 
                       
                       
                         N 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         W 
                       
                     
                     ⁢ 
                     C 
                   
                   = 
                   R 
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     Where W represents the number of wheel sections, N represents the number of opposing rims  118  on each wheel (e.g., N is 2 in the example of  FIGS. 2-5 ), C represents the number of ground contact points, and R represents the radial spacing of each wheel section relative to an adjacent wheel section (in degrees). 
     As described above, increasing the number of contact points between the wheel  100  and the ground may increase the stability of the wheel  100 . Each rim  118  may contact the ground at one contact point. By providing multiple contact points, i.e., multiple rims  118 , which contact the ground at any instant, the stability of the wheel  100  may increase. In other words, increasing the number of contact points with the ground at any instant during the operation of the wheel  100  increases the width of the wheel  100 , thereby increasing the number of wheel sections  110  that may be used to form the wheel  100 . 
     Referring to  FIG. 5 , an example of the wheel  100  is shown where each wheel section has a rim  118  that has a radial span  119  of about 45°. Accordingly, adjacent wheel sections  110  may be generally radially spaced apart by about 45° in the expanded position of the wheel  100  as shown in  FIG. 5 . In the example of  FIG. 5 , four wheel sections  110 , i.e., eight rims  118 , would be required to define a full circle or about 360°. Thus, if the wheel  100  is constructed with four wheel sections  110 , only one rim  118 , i.e., one contact point, contacts the ground at any instant. To increase the stability of the wheel  100 , sixteen wheel sections  110  may be provided as shown in the example of  FIG. 4  so that at any instant during the operation of the wheel  100 , four contact points on the wheel  100  contact the ground, i.e., four rims  118  define the width of the wheel  100 . Any number of wheel sections  110  may be provided for increasing or reducing contact points. For example, twenty wheel sections  110  would provide five contact points with the ground at any instant for the wheel  100 . In another example, twelve wheel sections  110  would provide three contact points with the ground. According to the above, when each rim  118  spans about 45°, at least eight rims  118  may be required so that at any instant during the operation of the wheel  100  one contact point contacts the ground. To increase the number of contact points along the width of the wheel when each rim  118  has a radial span  119  of about 45°, multiples of four wheel sections  110  may be provided. In the example of  FIG. 4 , sixteen wheel sections  110  for the wheel  100  provide four contact points at any instance during the operation of the wheel as shown in  FIG. 6 . 
     Increasing the number of wheel sections  110  may increase the stability of the wheel  100  and/or the amount of weight that the wheel  100  may support. However, increasing the number of wheel sections  110  may also increase the size and/or the weight of the wheel  100  in the collapsed position. Accordingly, the size of each wheel section  110 , and other properties of each wheel section  110  as described herein may be determined depending on the size and load of the cart to which one or more wheels  100  may be attached. 
       FIG. 6  illustrates an expanded position of two wheel sections  110 . The rim  118  of each wheel section  110  includes a radial projection  120 . Referring to  FIGS. 7-11 , the tire  104  may include an inner surface  130  and an outer surface  132 . The outer surface  132  may be smooth or have threads. The inner surface  130  may have any configuration to provide mounting of the tire  104  on the rims  118 . In the examples of  FIGS. 8 and 9 , the inner surface  130  includes a plurality of generally parallel ribs  134  that define a plurality of generally parallel grooves  136  between the ribs  134 . The ribs  134  and the grooves  136  may radially span a portion of the inner surface  130 . In the examples of  FIGS. 8 and 9 , the ribs  134  and the grooves  136  span the entire 360° of the inner surface  130  of the tire  104 . 
     Referring to  FIGS. 10 and 11 , the distance between adjacent grooves  136  generally corresponds to the distance between the projections  120  of adjacent wheel sections  110 . Additionally, the cross-sectional shape of each groove  136  may generally correspond to the cross-sectional shape of the projections  120 . Accordingly, when the tire  104  is mounted on the wheel sections  110 , the projections  120  may engage the grooves  136  and generally fit within the grooves  136 . The projections  120  and the grooves  136  may have any cross-sectional shape. In the example of  FIG. 11 , the projections  120  are shown to have a generally triangular cross-sectional shape and the grooves  136  are also shown to have a generally corresponding triangular cross-sectional shape. Furthermore, the size of the grooves  136  may generally correspond to the size of the projections  120 . For a tire  104  that is constructed from an elastic material such as rubber, the grooves  136  may be alternatively formed to be smaller than the projections  120  so that the grooves  136  elastically expand when receiving the projections  120  to provide a generally formfitting engagement with the projections  120 . The tire may be attached to one or more of the rims  118  such that the tire is maintained in a mounted configuration on the wheel  100  in both the collapsed and expanded positions of the wheel  100 . 
     As described above, each wheel section  110  may be positioned relative to an adjacent wheel section  110  at a certain angle during the operation of the wheel  100  to provide a sufficient number of contact points and generally evenly distributed contact point locations for the wheel  100 . For example, the wheel sections  110  of  FIG. 5  are positioned at about 45° relative to each other in the expanded position to provide four evenly distributed contact points at any instant during the operation of the wheel  100 . The angle between the wheel sections  110  in the expanded position that provides a sufficient number of contact points and generally evenly distributes the contact point locations on the wheel may be referred to herein as the expansion angle. The expansion angle is shown in equation (1) as the variable R. Thus, the expansion angle for the example of  FIG. 5  is about 45°. 
     As described in detail above and with respect to equation (1), the expansion angle may be different depending on the configuration and/or properties of the wheel sections  110 . To limit the expansion of the wheel sections  110  relative to each other and/or to provide positioning of the wheel sections  110  relative to each other at the expansion angle, the wheel  100  may include an expansion angle limiting mechanism by which rotation of each wheel section  110  relative to an adjacent wheel section  110  is limited to the expansion angle. According to one example shown in  FIG. 12 , the angle limiting mechanism includes a radial slot  140  on the hub section  112  of each wheel section  110  and a pin  144  that may be located on the hub section  112  opposite to the slot  142  relative to the central bore  114 . The arc length of each radial slot  140  may be generally no greater than the expansion angle. In the example of  FIG. 12 , the arc length of the radial slot  140  is about 45°, which is the same as the expansion angle. When the wheel sections  110  are assembled as described in detail below, i.e., stacked on top of each other, the pin  144  of each wheel section  110  is placed inside the slot  140  of an adjacent wheel section  110 . Accordingly, when adjacent wheel sections are rotated relative to each other, the pin  144  moves in the slot  140 . However, the radial movement of the pin  144 , which defines the radial movement of the wheel section  110  having the pin  144 , is bound by the arc length of the slot  140 . 
     Each slot  140  includes a first end  150  and a second end  152 . In the collapsed position of the wheel  100 , the pin  144  of each wheel section  110  is located near the first end  150  of the slot  140  of an adjacent wheel section  110 . As the wheel  100  is expanded, the pin  144  moves in the slot  140  from the first end  150  until the pin  144  contacts the second end  152  of the slot  140 . Thus, the slot  140  limits rotation of the two adjacent wheel sections  110  relative to each other to the expansion angle or the radial arc length of the slot  140 . The position of each slot  140  and pin  144  may be determined to allow expanding and collapsing of the wheel  100  as disclosed. In the example of  FIG. 12 , the first end  150  of the slots  140  is generally located along a center longitudinal axis  154  of the hub section  112 . Accordingly, the second end  152  of the slot  140  is located about 45° from the first end  150 . The pin  144  is also located on the center longitudinal axis  154 , but is located opposite to the first end  150  of the slot  140  relative to the central bore  114 . As described in detail below, the arrangement of the pin  144  and the slot  140  as shown in  FIG. 12  provides for each wheel section  110  to be rotated relative to an adjacent wheel section by the expansion angle. 
     After the wheel  100  is expanded, which is defined by each wheel section  110  having the expansion angle relative to an adjacent wheel section  110 , the wheel  100  may be maintained in the expanded position by any type of latching, locking and/or similar mechanisms that prevents the wheel sections  110  from rotating relative to each other. For example, each wheel section  110  may include an aperture (not shown) positioned on the hub section  112  such that when the wheel sections  110  are in the expanded position of the wheel  100 , all of the apertures of the wheel sections  110  are generally aligned to receive a rod (not shown). Therefore, the rod prevents the wheel sections  110  from rotating relative to each other. In another example, a U-shaped bracket (not shown) which has a width that is generally similar to the collective width of the hub sections  112  may be placed over the hub sections  112  to prevent the hub sections  112  from rotating relative to each other. 
     Referring to  FIGS. 13 and 14 , the wheel sections  110  may be rotationally mounted on an axle  106 . The axle  106  may be defined by a cylindrical shaft  160  having a first end  162  and a second end  164 . In the example of  FIGS. 13 and 14 , the axle  106  may further include a mounting bracket  166  having a first bracket section  168  and the second bracket section  170 . The mounting bracket  166  may facilitate mounting or attachment of the wheel  100  to a cart, such as a golf pull cart. The wheel sections  110  may be mounted on the shaft  160  by inserting the shaft  160  from the first end  162  in the central bore  114  of each wheel section  110 . The axle  106  may include a mechanism by which the first wheel section  110  that is mounted on the shaft  160  is held stationary to allow expansion of the wheel  100  from a collapsed position. In one example as shown in  FIG. 13 , the first bracket section  160  includes a pinhole  170  for receiving the pin  144  of the first mounted wheel section  110 . Engagement of the pin  144  in the pinhole  170  of the first mounted wheel section  110  maintains the first mounted wheel section  110  fixed to the first bracket section  160  to allow expansion of the wheel  100  from a collapsed position to an expanded position. After the wheel  100  is expanded, the pin  144  may be removed from the pinhole  170  to allow rotation of the wheel  100  about the shaft  160 . 
     The axle  106  may further include a wheel holding mechanism by which the wheel  100  is maintained on the shaft  160  during the operation of the wheel  100 . The wheel holding mechanism may include any configuration to prevent the wheel  100  from sliding off the shaft  106  or being removed from the shaft  106  during the operation of the wheel  100 . For example, the first end  162  of the shaft  160  may be threaded to receive a correspondingly threaded nut (an example is shown in  FIG. 22 ). The threaded nut increases the diameter of the shaft  160  at the first end  162  to a diameter that is greater than the central bores  114  of the hub sections  112 . Accordingly, the wheel sections  110  are stopped by the nut when reaching the first end  162  of the shaft  160 . 
     In the example of  FIG. 13 , the shaft  160  includes an annular recess  172  at or near the first end  162  of the shaft  160 . As shown in  FIG. 14 , after the wheel sections  110  are mounted on the shaft  160 , a spring clip  174  may be mounted over and pressed onto the shaft  160  so that the spring clip  174  snaps into and remains in the annular recess  172 . The spring clip  174  increases the diameter of the shaft  160  at the first end  162  to a diameter that is greater than the diameters of the central bores  114  of the hub sections  112 . Accordingly, the wheel sections  110  are stopped by the spring clip  174  when reaching the first end  162  of the shaft  160 . The axle  106  may also include a washer  176  or the like mounted between the spring clip  174  and the last mounted wheel section  110 . To provide easier installation of the spring clip  174  into the annular recess  174 , the first end  162  of the shaft may be tapered as shown in  FIGS. 13 and 14  so that pressing the spring clip  174  onto the first end  162  gradually expands the spring clip  172  when being mounted on to the shaft  160 . Thus, the spring clip  174  remains engaged in the annular recess  172  until it is expanded with or without a tool by an individual for removal of the spring clip  174  from the shaft  160 , which then allows removal of the wheel sections from the shaft  160 . At the second end  164  of the shaft  160  an annular shoulder  178  may be provided so that the first mounted wheel section  110  is spaced from the first bracket section  168 . 
       FIG. 2  shows the wheel  100  in the collapsed position having the tire  104  mounted thereon. The tire  104  may be constructed from an elastic material such as rubber. Furthermore, the inner diameter of the tire  104  may be smaller than an outer diameter of a circle defined by the wheel  100  in the expanded position. Accordingly, the tire may be easily mounted over the wheel  100  in the collapsed position. However, the tire  104  may elastically expand when the wheel  100  is expanded. The elastic expansion of the tire  104  may create a restoring force in the tire  104  by which the tire  104  is pressed onto the rims  118  (for example the projections  120  are pressed in the grooves  136 ) to maintain the tire  104  on the wheel  100  during the operation of the wheel  100 . 
     To expand the wheel  100  from a collapsed position to the expanded position, each of the wheel sections  110  may be rotated by hand. In one example shown in  FIGS. 15 and 16 , the wheel  100  includes a hubcap  200  by which the wheel sections  110  may be rotated relative to each other to expand the wheel  100 . The hubcap  200  may include two opposing handles  202  and  204  that can be held by an individual for rotating the hubcap  200 . The hubcap  200  may include a pin (not shown) on an inner surface thereof that may engage inside the slot  140  of the last mounted wheel section  110 . The hubcap  200  may be rotationally mounted on the shaft  106 . Accordingly, when the hubcap  200  is turned about the shaft  106  by an individual, the pin on the inner surface of the hubcap  200  moves in the slot  140  of the first wheel section  110  until the pin engages the second end  152  of the slot  140 . After the first wheel section  110  is turned at the expansion angle, the pin  144  of the first wheel section  110  engages second end  152  in the slots  140  of the second wheel section  110  as described above. Accordingly, further rotation of the hubcap  200  causes the second wheel section  110  to rotate relative to the third wheel section  110  at the expansion angle. Continuing the rotation of the hubcap  200  rotates the remaining wheel sections  110  until the wheel  100  is completely expanded. The hubcap of  200  may be mounted on the shaft  160  between the last mounted wheel section  110  and the spring clip of  174 . When holding the handles  202  and  204 , an individual can also hold the second bracket section  166  to provide leverage when expanding the wheel  100 . 
       FIGS. 17 and 18  show a wheel  400  according to another example. The wheel  400  is similar in certain aspects to the wheel  100 . Accordingly, similar parts of the wheel  100  and the wheel  400  are referred to with the same reference numbers. The wheel  400  includes a plurality of wheel sections  110  that are mounted on an axle  406  (shown in  FIG. 17 ). The axle  406  includes a first end  462  (shown in  FIG. 17 ) and a second end (not shown). The axle  406  receives the wheel sections  110  by being inserted into the central bores  114  of the wheel sections  110 . The second end of the axle  406  includes a base  470  that is larger in diameter than the diameter of the central bore  114  of the wheel sections  110 . Accordingly, when the wheel sections  110  are mounted on the axle  406 , the wheel sections  110  are bound at the second end of the axle by the base  470 . To prevent the wheel sections  110  from being removed from the axle  406  during the operation of the wheel  400 , the second end  462  the axle  406  may be threaded to receive a correspondingly threaded nut  480 . Thus, tightening the nut  480  on threaded first end  462  of the axle  406  prevents the wheel sections  110  from being removed from the axle  406  during the operation of the wheel  400 . Alternatively, the wheel  400  may include a wheel holding mechanism similar to the wheel holding mechanism of the wheel  100  as described in detail above. The wheel  400  includes a hubcap  200  which may be used to expand the wheel  400  from the collapse position to the expanded position as described in detail above with respect to the wheel  100 . 
     Referring to  FIG. 18 , the first mounted wheel section  110  may include two opposing handles  502  and  504  on the central hub section  112  that are position similar to the handles  202  and  204  of the hubcap  200 . Accordingly, an individual can expand the wheel  400  from the collapsed position by holding the handles  202  and  204  with one hand and rotating the handles  202  and  204  in one direction and holding the handles  502  and  504  with the other hand and rotating the handles  502  and  504  in the opposite direction to rotate the wheel sections relative to each other to expand the wheel  400  to the expanded position. The handles  502  and  504  may be part of a hubcap (not shown) that is mounted on the axle  406  before the first mounted wheel section  110  is mounted on the axle  406 . Alternatively as shown in  FIGS. 17 and 18 , the handles  502  and  504  may be an integral part of the first mounted wheel section  110 . 
     Referring to  FIGS. 19 and 20 , a wheel  600  according to another embodiment is shown. The wheel  600  is similar in some aspects to the wheels  100  and  400 . Accordingly, similar parts of the wheels  100 ,  400  and  600  are referred to with the same reference numbers. The wheel  600  includes a plurality of wheel sections  610 . Each wheel section  610  includes a hub section  612  with a central bore (not shown). Each wheel section  610  includes a pair of spaced apart generally straight spokes  616  on each side of the perimeter section of the hub section  612  that project radially outward and connect to a generally curved rim  618 . The distance between each pair of spokes  616  may increase from the huh section  612  to the rim  618 . Accordingly, each pair of spokes  616  and the corresponding rim  618  defines a generally trapezoidal shape. The wheel  600  includes an axle  606  that is mounted through the central bores of the wheel sections  610 . The axle  606  and the mechanisms and methods by which the axle  606  is operatively connected to the wheel and the cart are similar to the axle  106  and  406 . Accordingly, a detailed description of the axle  606  is not provided. 
     Referring to  FIGS. 21-25  a wheel  800  according to another example is shown. The wheel  800  includes a hub assembly  802  and a tire (not shown) that is mounted on the hub assembly  802  as described below. The wheel  800  also includes an axle  806  on which the hub assembly  802  and a tire are rotatably mounted. The hub assembly  802  includes a plurality of wheel sections  810  that are concentrically mounted on the axle  806 . Each wheel section  810  includes a hub section  812  having a central bore  814  for receiving a section of the axle  806 . 
     The tire may be mounted on a plurality of rims  818  that are positioned along a perimeter of a circle  817  that defines a central plane of the wheel  800 . Each rim  818  is generally oriented perpendicular to the circle  817  (shown in  FIG. 24 ) and is convex relative to the hub sections  812 . Accordingly, each rim  818  is concave relative to the tire (not shown) so as to receive a curved section of the tire. Each rim  818  is attached to two spaced apart hub sections  812  by two spokes  816 , respectively. The two hub sections  812  to which a rim  818  is attached with the spokes  816  are spaced apart so that the spokes  816  form a V-shaped support for each rim  818 . For example, as shown in  FIG. 22 , the spokes  816  that support a rim  818  are connected to hub sections  812  are spaced apart by five hub sections  812 . Thus, each hub section  812  has one spoke  816  on one side thereof that partially supports a first corresponding rim  818 , and another spoke  816  on the opposite side thereof that partially supports a second corresponding rim  818 . 
       FIGS. 23-25  show the expanded position of the wheel  800 . The spokes  816  are positioned on the hub sections  812  such that when the wheel  800  is in the expanded position, the spokes  816  are evenly distributed around the wheel, i.e., radially spaced apart on the circle  817  at a similar expansion angle. In the example of  FIGS. 23-25 , the spokes  816  are shown to be generally 30° apart in the expanded position of the wheel  800 .  FIGS. 21 and 22  show the collapsed position of the wheel  800 . To collapse the wheel  800 , the hub sections  812  may be rotated relative to each other until the rims  818  contact each other and prevent further rotation of the hub sections  812 . To expand the wheel  800 , the hub sections  812  may be rotated in an opposite direction relative to each other such that the wheel  800  reaches the expanded position shown in  FIG. 23 . Because each spoke  816  is located on a different hub section  812 , the wheel  800  may require a rotation of less than 180° for expansion from the collapsed position to the expanded position. Accordingly, to expand the wheel  800  from the collapsed position as shown in  FIG. 21 , the spoke  820  is rotated clockwise until the spoke  820  is positioned close to spoke  822  and is prevented from further rotation by an expansion limiting mechanism as described below. Simultaneously, the spoke  824  is rotated clockwise until it is positioned close to spoke  826  and is prevented from further rotation by the expansion limiting mechanism. Thus, the largest rotation of a hub section  812  may be less than 180° to expand the wheel from the collapsed position to the expanded position. 
     To prevent further rotation of the hub sections  812  relative to each other when the wheel  800  reaches the expanded position shown in  FIG. 23 , the wheel  800  may include an expansion limiting mechanism as described above. Accordingly, each wheel section  810  may include a radial slot (not shown) on the hub section  812  and a pin (not shown) that may be located on the hub section  812  opposite to the slot relative to the central bore  814 . The arc length of each radial slot  140  may be generally no greater than the expansion angle. In the example of  FIG. 24  the arc length of the radial slot is about 30°, which is the same as the expansion angle. 
     A tire (not shown) may be mounted on the wheel  800  before or after the wheel is expanded. The tire may be constructed from a solid piece of rubber or other type of plastic material that has sufficient elasticity to allow mounting of the tire on the wheel  800 . Alternatively, the tire may be in the form of an inflatable tube that may be mounted on the rims  818 . Accordingly, the tire may be inflated by an individual before operating the wheel  810 . Alternatively yet, the tire may be attached to one or more of the rims  818  such that the tire is maintained in a mounted configuration on the wheel  800  in both the collapsed and expanded positions of the wheel  800 . 
       FIGS. 26-33  show several exemplary wheels and/or wheel sections according to the disclosure. A wheel section  1010  as shown in  FIG. 26  may include at least one spoke  1016  on each side of a hub section  1012 . The wheel section  1010  also includes a least one rim  1018  attached to each spoke  1016 . Each spoke  1016  and the corresponding rim  1018  generally define a T-shaped spoke and rim assembly. A wheel section  1110  as shown in  FIG. 27  may include at least one spoke  1116  on each side of a hub section  1112 . The wheel section  1110  also includes at least one rim  1118  attached to each spoke  1116 . Each spoke  1116  and the corresponding rim  1118  generally define an L-shaped spoke and rim assembly. According to the exemplary wheel sections  1010  and  1110 , at least one rim and at least one spoke may be attached to each other in any configuration. For example, an end of a spoke may be attached to a center of the length of the rim as shown by the wheel section  1010  to provide a generally T-shaped spoke and the rim assembly. With the exemplary wheel section  1110  however, the end of the spoke is attached to one end of the rim. Therefore, a spoke and a rim may be attached to each other in any configuration and with any type of offset relative to each other. 
       FIGS. 28 and 29  show a wheel  1200  according to another example. The wheel  1200  includes a plurality of wheel sections  1210 , where each wheel section  1210  may have a different configuration as compared to one or more of the other wheel sections  1210 . For example, each wheel section  1210  may have different shaped spokes  1216 . The spokes  1216  may be straight, curved, L shaped, Z shaped and/or have any other shape that may be different from the spokes  1216  of one or more of the other wheel sections  1210 . Depending on the shape of each spoke  1216 , each spoke may have different thickness, may be constructed from a different material and/or have a certain property that may be different from or similar to one or more other spokes  1216  of one or more other wheel sections  1210 . A tire  1204  may be mounted on the wheel  1200  in both the collapsed position in the expanded position of the wheel  1200 . 
       FIGS. 30 and 31  show a wheel  1300  according to another example. The wheel  1300  includes a plurality of spokes  1316 . Each spoke may be flexible so as to deform from an extended position corresponding to the expanded position of the wheel  1300  to a deformed position corresponding to the collapsed position of the wheel  1300 .  FIG. 30  shows an example of the wheel  1300  in the process of being expanded between the collapse position and the expanded position shown in  FIG. 31 . In the extended position of the spokes  1316  as shown in  FIG. 31 , the spokes  1316  have sufficient collective rigidity to support the loads on the tire  1304  and the hub assembly  1302  to provide operation of the wheel  1300  as disclosed. However, the spokes  1316  are flexible so that the wheel  1300  may be collapsed by deforming the spokes  1316  to collapse the wheel  1300 . As shown in the example of  FIG. 30 , the spokes  1316  may be deformed by being bent and stacked on top of each other around the hub  1312 . The spokes  1316  may also provide a shock absorbing function for the wheel  1300 . The wheel  1300  may include a singular hub  1312  to which all of the flexible spokes  1316  are attached. Alternatively, the wheel  1300  may include a plurality of hub sections, where each hub section is rotatable relative to an adjacent hub section to facilitate collapsing and expanding of the wheel  1300  which one or more spokes  1316  may be attached. As shown in  FIGS. 30 and 31 , the wheel  1300  may also include a tire  1304 , which may be similar to the exemplary tires disclosed herein. 
       FIGS. 32 and 33  show a wheel  1400  according to another example. The wheel  1400  includes a hub  1412  to which the rim  1418  is attached. The rim  1418  includes a first rim section  1420  and a second rim section  1422  that are pivotally mounted to the hub  1412  by one or more hinges  1424 . As shown in  FIG. 33 , the first rim section  1420  and the second rim section  1422  can be pivoted at the hinge  1424  to collapse the wheel  1400  from the expanded position shown in  FIG. 32  to a collapsed position (not shown). Thus, the size of the wheel  1400  may be reduced for storage and/or transportation upon collapsing the wheel from the expanded position. 
     Referring to  FIG. 34 , a section of a wheel  1500  according to another example is shown. The wheel  1500  includes at least one spoke  1516  and at least one rim  1518  that is attached to the spoke  1516 . The wheel  1500  may not include a one-piece tire similar to the examples described above. Instead, a tire section  1504  is attached to each rim  1518 . Accordingly, when the wheel  1500  is expanded to an expanded position, the tire sections  1504  collectively define a tire for the wheel  1500 . Therefore, the tire for the wheel  1500  is defined by a plurality of tire sections  1504  and any gaps that may be present between adjacent tire sections  1504 . As with the examples described above, the tire section  1504  may be constructed from an elastic material such as rubber. The tire sections  1504  may then be attached to a rim  1518  with an adhesive, one or more fasteners and/or one or more other types of attachment devices or procedures. 
     Referring to  FIGS. 35-41 , a wheel  1600  according to another example is shown. The wheel  1600  includes a hub assembly  1602 . The wheel  1600  may include a tire (not shown) that may be mounted on the hub assembly  1602 . Alternatively, the wheel  1600  may include e a plurality of tire sections as described above with respect to the wheel  1500 . Alternatively yet, the wheel  1600  may operate without a tire. The wheel  1600  also includes an axle  1606  on which the hub assembly  1602  is rotatably mounted. The hub assembly  1602  includes a plurality of wheel sections  1610  that are concentrically mounted on the axle  1606 . Each wheel section  1610  includes a hub section  1612  having a central bore  1614  for receiving a section of the axle  1606 . 
     The wheel  1600  includes a plurality of rims  1618  that are configured to define a path on a circumferential or circular band  1617  having a width  1619 . The path defined by the rims  1618  may be substantially continuous. The circular band  1617  defines a circular contact area similar to a tire (shown in  FIG. 38 ) between the wheel  1600  and the ground. In the expanded position of the wheel  1600 , each rim  1618  may be oriented such that at least one point on at least one rim  1618  contacts the ground. In one example, each rim  1618  is positioned diagonally on the circular band  1617 . Each rim  1618  may be radially spaced apart from an adjacent rim  1618  as long as the space does not provide a large enough gap to substantially disturb or hinder generally smooth rolling of the wheel  1600  on the ground. Alternatively, each rim  1618  may not have a radial gap relative to an adjacent rim  1618 . Alternatively yet, each rim  1618  may have a radial overlap with an adjacent rim  1618 . In the example of  FIG. 38 , each rim  1618  has a small gap relative to an adjacent rim  1618 . Each rim  1618  may also be curved so that points on adjacent rims  1618  that are spaced apart at a certain angle are located on the circular band  1617 . Thus, as shown in  FIG. 35 , the rim  1618  defines a portion of a path on a generally continuous circle in the expanded position of the wheel  1600 . In other words, the curvature of each rim  1618  may generally follow the curvature for the circle defining a plane of the wheel  1600 . 
     Each rim  1618  is attached to two spaced apart hub sections  1612  by two spokes  1616 , respectively. The two hub sections  1612  to which a rim  1618  is attached with the spokes  1616  are spaced apart so that the spokes  1616  form a V-shaped support for each rim  1618 . For example, as shown in  FIG. 41 , the spokes  1616  that support a rim  1618  are connected to hub sections  1612  are spaced apart by four hub sections  1612 . Thus, each hub section  1612  has one spoke  1616  on one side thereof that partially supports a first corresponding rim  1618 , and another spoke  1616  on the opposite side thereof that partially supports a second corresponding rim  1618 . 
       FIGS. 35 ,  36  and  38  show the expanded position of the wheel  1600 . The spokes  1616  are positioned on the hub sections  1612  such that when the wheel  1600  is in the expanded position, the spokes  1616  are evenly distributed around the wheel, i.e., radially equally spaced apart at a similar expansion angle. In the example of  FIG. 35 , the spokes  1616  are shown to be generally 30° apart in the expanded position of the wheel  1600 .  FIGS. 37 ,  39  and  40  show the collapsed position of the wheel  1600 . To collapse the wheel  1600 , the hub sections  1612  may be rotated relative to each other until the rims  1618  contact each other and prevent further rotation of the hub sections  1612 . Each spoke  1616  may have a certain cross-sectional shape to provide a more compact collapsed position for the wheel  1600 . For example, each spoke  1616  may have a diamond shaped cross-section as shown in  FIG. 41 . Accordingly, when the wheel  1600  is collapsed, each spoke  1616  may be positioned relative to an adjacent spoke  1616  in the complementary or a formfitting manner. Therefore, the spokes  1616  may collectively occupy less space as compared to a scenario where each spoke  1616  has a certain shape that does not lend itself to such complementary fitting with an adjacent spoke  1616 . 
     To expand the wheel  1600 , the hub sections  1612  may be rotated in an opposite direction relative to each other such that the wheel  1600  reaches the expanded position  1612 . Because each spoke  1616  is located on a different hub section  1612 , the wheel  1600  may require a rotation of less than 180° for expansion from the collapsed position to the expanded position as described in detail with respect to the wheel  800 , hence not repeated herein. Thus, the largest rotation of a hub section  1612  may be less than 180° to expand the wheel  1600  from the collapsed position to the expanded position. 
     To prevent further rotation of the hub sections  1612  relative to each other when the wheel  1600  reaches the expanded position, the wheel  1600  may include an expansion limiting mechanism as described above. Accordingly, each wheel section  1610  may include a radial slot (not shown) on the hub section  1612  and a pin (not shown) that may be located on the hub section  1612  opposite to the slot relative to the central bore  1614 . The arc length of each radial slot may be generally no greater than the expansion angle. 
     Similar to the example of  FIG. 34 , each rim  1618  may include a tire section (not shown) that is attached to each rim  1618 . For example, each tire section (not shown) may be a generally rectangular strip of rubber or like elastic materials that is attached to each rim  1618  along the length of the rim  1618 . Thus, each tire section generally follows the orientation and the spatial position of each rim  1618  on the circular band  1617  as described above. Accordingly, when the wheel  1600  is expanded to an expanded position, the tire sections collectively define a tire for the wheel  1600 . As with the examples described above, a tire section may be constructed from an elastic material such as rubber. The tire sections may then be attached to a rim  1618  with an adhesive, one or more fasteners and/or one or more other types of attachment devices or procedures. 
     A tire (not shown) may be mounted on the wheel  1600  before after the wheel is expanded. The tire may be constructed from a solid piece of rubber or other type of plastic material that has sufficient elasticity to allow mounting of the tire on the wheel  1600 . Alternatively, the tire may be in the form of an inflatable tube that may be mounted on the rims  1618 . Alternatively yet, the tire may be attached to one or more of the rims  1618  such that the tire is maintained in a mounted configuration on the wheel  1600  in both the collapsed and expanded positions of the wheel  1600 . 
     Referring to  FIG. 42 , a method  1700  for constructing a wheel according to one example is shown. The method comprises forming a plurality of wheel sections (block  1702 ), and assembling the wheel sections on an axle (block  1704 ). The method  1700  may also include forming a tire (not shown) and/or mounting or attaching a tire on the wheel sections (not shown). A wheel according to the disclosure may be constructed from any metal or metal alloys, plastic, composite materials, wood or a combination thereof. For example, each wheel section such as the wheel sections  110  of the wheel  100  may be formed in one piece from a plastic material by injection molding. In an injection molding process, a mold having a cavity defining a wheel section may be used. Molten plastic material is injected in the mold and cooled. The molded and cooled wheel section is then removed from the mold. The molded wheel section may also be smoothed or cleaned to remove injection molding residue. Alternatively, a wheel section may be constructed by stamping (i.e., punching using a machine press or a stamping press, blanking, embossing, bending, flanging, coining, or casting), forging, machining or a combination thereof, or other processes used for manufacturing metal, composite, plastic or wood parts. Each wheel section may be formed in one piece. Alternatively, components of each wheel section may be formed by processes and materials described herein and assembled to form the wheel section. For example, the wheel section  110  may be formed by assembling a separately manufactured hub section  212 , spokes  216  and rim  218 . A hub section  212 , one or more spokes  216 , and a rim  218  may be attached to each other by one or more adhesives, welding, soldering and/or fasteners. The disclosed materials and/or processes may be used to manufacture any of the disclosed wheel, axle and/or tire components. A tire may be manufactured from an elastic material to provide shock absorption for a pull cart to which one or more disclosed wheels are attached. A tire may be formed from rubber or other plastic materials. A tire may be formed as an inflatable tube or a solid flexible material. 
     Referring to  FIG. 43 , a golf pull cart  1800  for supporting and transporting a golf club bag is shown having wheels  100 . Although the pull cart  1800  is shown with the wheels  100 , any of the wheels described herein may be used with a golf pull cart. The golf pull cart  1800  may include a frame  1810  on which a golf club bag (not shown) may be rested. The golf club bag may also be supported by a bottom support  1812 , a bottom side support  1813  and a top side support  1814 . The frame  1810  may also include one or more straps (not shown) for securing a golf club bag to the frame  1810 . The pull cart  1800  may further include two feet  1820  in  1822  that extend outwardly from the frame  1810  opposite to each other. Each foot supports a wheel  100 . The frame may also include a hinge  1824  having two hinge rods  1826  and  1828  by which the feet  1820  in  1822  may be pivoted and collapsed so that the feet  1820  and  1822  extend along the frame  1810 . The frame  1810  may also collapse at the hinge so as to provide a compact golf pull cart  1800  for transportation to and from a golf course, driving range or any golf related facility. A collapsed golf pull cart  1800  is shown in  FIG. 44 . To further reduce the size of the golf pull cart  1800 , the wheels  100  may be collapsed as described in detail herein. Furthermore, the wheels  100  may be removed from the pull cart  1800  and stored separately. Thus, using the wheels  100  or any of the wheels described herein can reduce the size of any vehicle, such as a golf pull cart, for easier storage and/or transportation. Alternatively, a golf club bag (not shown) may include attachment points or axles for directly attaching two collapsible wheels as described in detail herein to the golf club bag. For example, a golf club bag may be provided with two collapsible wheels that can be stored in one or more pockets of the golf club bag. An individual may carry the golf club bag or attach the two wheels to an axle on the golf club bag, expand the wheels, and pull the golf club bag by using the wheels. The use of collapsible wheels as described in detail herein is not limited to golf pull carts. Collapsible wheels as described in detail herein may be used for kayak carts, grocery carts, small wagons that are typically used by children, any type of luggage, luggage carts, coolers and/or any other wheeled utility cart, trailer, enclosed storage device, or a vehicle. 
     Although a particular order of actions is described above, these actions may be performed in other temporal sequences. For example, two or more actions described above may be performed sequentially, concurrently, or simultaneously. Alternatively, two or more actions may be performed in reversed order. Further, one or more actions described above may not be performed at all. The apparatus, methods, and articles of manufacture described herein are not limited in this regard. 
     While the invention has been described in connection with various aspects, it will be understood that the invention is capable of further modifications. This application is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.