Patent Publication Number: US-2005120518-A1

Title: Caster assembly

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application claims the benefit of and priority of U.S. Provisional Patent Application No. 60/527,085, filed Dec. 3, 2003. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates to caster assemblies and particularly to caster assemblies having a caster wheel that is movable between a retracted position within a housing of the assembly and an extended position outside the housing.  
      Conventional caster assemblies are typically mounted on the bottom of a structure that is desired to be movable. For example, caster assemblies can be positioned on furniture, containers, or any other structure that is to be movable. Display structures in stores are often equipped with caster assemblies. For example, a kitchen or bathroom display that includes a base on which a mock-up of a kitchen or bathroom including cabinets, sink, etc. typically includes caster wheels. The bathroom or kitchen display may be moved easily into a desired position on the store floor by rolling the display on the caster wheels.  
     SUMMARY OF THE INVENTION  
      Conventional retractable caster assemblies, including those on store displays, can be inadequate to support the heavy loads often placed on such casters. Additionally, because of the heavy loads placed on such casters, it may be difficult for a user to operate the mechanism that moves the caster wheel from its retracted position to its extended position. A caster assembly that supports the weight of a structure to which it is coupled and is readily movable from its retracted position to its extended position by a typical user would be welcomed by users of such caster assemblies.  
      In some aspects, the invention provides a caster assembly including a housing, a plate movably positioned within the housing between a retracted position and an extended position, the plate in the extended position being parallel to the plate in the retracted position, a caster wheel rotatably coupled to the plate, and a cam arm pivotally coupled to the housing, wherein the cam arm is pivotable to cam against the plate to move the plate from its retracted position to its extended position.  
      In some aspects, the invention provides a caster assembly including a housing, a plate movable within the housing, the plate having two ends, a caster wheel rotatably coupled to the plate, and a cam arm pivotally coupled to the housing to pivot relative to the housing, wherein the cam arm cams against the plate to move the two ends of the plate vertically downward relative to the housing.  
      In some aspects, the invention provides a method of operating a caster assembly mountable to a structure, the method including mounting the caster assembly to a surface of the structure, the caster assembly including a housing, a plate moveable within the housing, a caster wheel rotatably coupled to the plate, and a cam arm coupled to the housing and engaging the plate, rotating the cam arm to cam the arm against the plate and thereby move the plate relative to the housing from a retracted position to an extended position, wherein the plate in the extended position is parallel to the plate in the retracted position.  
      Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description, claims and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The detailed description of the drawings refers to the accompanying figures in which:  
       FIG. 1  is a perspective view of a caster assembly with a housing shown in a first configuration;  
       FIG. 2  is an end view of the caster assembly with end plates removed, a caster wheel and a plate to which the caster wheel is shown mounted in a retracted position within a housing of the assembly shown in a second configuration;  
       FIG. 3  is an end view of the caster assembly similar to  FIG. 2  showing the caster wheel and plate in an extended position;  
       FIG. 4  is a bottom view of the caster assembly of  FIG. 2  with castor wheels removed, showing two cam arms pivotally mounted within the housing of the caster assembly to move the caster wheels from the retracted position to the extended position;  
       FIG. 5  is a side view of an end plate, which provides an opening in which a cam arm pivots; and  
       FIG. 6  is a plan view of the end plate of  FIG. 5  showing the opening.  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Referring to  FIGS. 1-3 , a caster assembly  10  includes a housing  12  and a plate  14  movable within the housing  12  and including a caster wheel  16  mounted to it. The plate  14  and the caster wheel  16  are movable between a retracted position, as shown in  FIG. 2 , wherein the plate  14  and wheel  16  are positioned substantially within the housing  12  out of contact with the ground when the bottom of the housing  12  rests on the floor or other support surface and an extended position, as shown in  FIG. 3 , wherein the wheel  16  is positioned at least partially outside the housing  12  and supports the caster assembly  10  on the floor or other support surface. The caster assembly  10 , as shown in perspective in  FIG. 1 , includes two caster wheels  16  (only one of which can be partially seen in  FIG. 1 ) attached to the plate  14  (see  FIG. 4 ). However, the caster assembly  10  can include only one caster wheel  16  or more than two caster wheels  16  and still be within the scope of the present invention. Additionally, the caster assembly  10  includes both caster wheels  16  mounted to a single plate  14 . However, each caster wheel  16  could be mounted to its own plate  14  and still be within the scope of the present invention.  
      The caster assembly  10  is mountable to a variety of structures that are to be rolled over a floor or support surface and is mountable on any surface of a structure. The housing  12  can have a variety of configurations to accommodate different structures and applications. For example, one configuration of the housing  12  is shown in  FIG. 1  and a second configuration of the housing  12  is shown in  FIGS. 2-4 . By way of example only, a store display, such as a kitchen or bathroom mock-up, can be supported on the housing  12 . In this way, the caster wheels  16  can be moved to their extended position, lifting the store display off the ground to move the display as desired. Then, when the store display is in its desired position, the caster wheels  16  can be retracted, returning the display to the ground and concealing the presence of the caster wheels  16  within the housing  12 .  
      Referring to  FIG. 2 , the caster assembly  10  includes two cam arms  18  pivotally mounted within the housing  12 . The cam arms  18  are constructed of three pieces of tubing welded together side-by-side. A first tube portion  20  of each cam arm  18  is longer than the remaining two pieces of tubing of each cam arm  18  and extends through openings  22  in end plates  24  of the caster assembly  10  (see  FIGS. 2, 3  and  6 ). The end plates  24  are coupled to the housing  12 , as can best be seen in  FIGS. 1 and 4 . The first tube portions  20  of the cam arms  18  include hex features  26  allowing a user to engage and pivot the cam arms  18  with a hex wrench. By turning the first tube portions of the cam arms  18 , end portions  28  of the cam arms  18  move and cam against a cam surface  30  of the plate  14 . In this way, the cam arms  18  push against the cam surface  30  of the plate  14  forcing it down within the housing  12 .  
      As shown in  FIGS. 2 and 3 , the two cam arms  18 , one mounted on each side within the housing  12 , can be pivoted simultaneously moving each side of the plate  14  simultaneously within the housing  12 . Alternatively, the cam arms  18  can be pivoted one at a time, to lower one side of the plate  14  separately from the other. In their “starting position” ( FIG. 2 ), the cam arms  18  nest in recesses  36  of the plate  14  formed as a result of the “hat-shaped” configuration of the plate  14 . As viewed in  FIGS. 2 and 3 , from the side, the general hat shape of plate  14  is formed by the bends of the plate  14  that create the “brim” of the hat and the recesses  36  in which the cam arms  18  nest when the assembly  10  is in its retracted position ( FIG. 2 ). This produces a relatively low profile assembly.  
      The cam arms  18  are pivoted to cam the end portions  28  against the cam surface  30  of the plate  14  and move the plate  14  and the caster  16  coupled to it from their retracted position, as shown in  FIG. 2 , to their extended position, as shown in  FIG. 3 . As can be seen with reference to  FIGS. 2 and 3 , each cam arm  18  is rotated through an arc of slightly greater than 90 degrees before the end portions  28  of the cam arms  18  abut sidewalls  32  of the housing  12  and can be rotated no further. With the cam arms  18  rotated slightly more than 90 degrees ( FIG. 3 ) from their starting position ( FIG. 2 ), they are held securely in an “over-center” position and cannot freely rotate back toward their starting position because of their abutment against the cam surface  30  of the plate  14 . The weight of the structure being supported by the caster assembly  10  creates an equal and opposite force on the caster wheel  16  and its associated plate  14  pushing back against the end portions  28  of the cam arms  18 . This force prevents the cam arms  18  from freely swinging back from their position, as shown in  FIG. 3 , to their starting position, as shown in  FIG. 2 . With reference to  FIG. 3 , it is also apparent that the cam arms  18  cannot be rotated further outward because of their abutment against the side walls  32  of the housing  12 .  
      As best seen in  FIGS. 5 and 6 , to ensure that this upward force by the caster wheel  16  and its associated plate  14  against the cam arm  18  is maintained, a spring lip  34  of each end plate  24  is bent slightly upwards to act as a spring against which the plate  14  pushes as the cam arms  18  move the plate  14  to its extended position, as shown in  FIG. 3 . As the cam arms  18  are pivoted and reach 90 degrees from their starting position, they slightly deflect the spring lips  34  of the end plates  24 , which then spring slightly back as the cam arms  18  reach their ultimate position, slightly past 90 degrees, as shown in  FIG. 3 . In this way, even if the upward force of the caster wheels  16  and plate  14  against the cam arms  18  is removed (e.g., if a caster wheel  16  hits a hole in the ground over which it is rolling), the spring lips  34  will maintain enough upward force against the plate  14  to prevent the cam arms  18  from unintentionally swinging back toward their starting position and releasing the caster assembly  10  from its extended position.  
      With the caster assembly  10  mounted on a structure, in its retracted position as shown in  FIG. 2 , a user inserts a hex wrench into hex features  26  of the first tube portions  20  of each cam arm  18  and rotates the wrench. This rotates the cam arms  18 , pushing the plate  14  and caster wheels  16  down against the ground. As the cam arms  18  are rotated slightly past their 90 degree positions, they slightly deflect the spring lips  34  of the end plates  24 , which, along with the force of the ground pushing up against the caster wheels  16  and plate  14 , lock the cam arms  18  into their extended positions, as shown in  FIG. 3 . The caster wheels  16  are thus “locked” into their extended positions allowing the structure to which the caster assembly  10  is mounted to be rolled over the ground until a user inserts a hex wrench into the hex features  26  and pivots the cam arms  18  back to their starting positions, as shown in  FIG. 2 . This retracts the plate  14  and its associated caster wheels  16  into the housing  12 .  
      The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. The embodiments described herein are further intended to explain best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention.