Abstract:
A receiver extends from the top of a retractable wheel assembly to receive the lower end of a jackstand or the like. Upon exerting pressure on a foot operated plate, a wheel is extended from the bottom of a plate and locked in place with a catch to permit transport of a trailer or the like attached to the jackstand. Upon release of the catch, the wheel will retract to bring the plate into contact with the ground and immobilize the trailer.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a retractable wheel assembly for engagement with a trailer jackstand or the like to selectively permit transporting the trailer or immobilizing the trailer. 
         [0003]    2. Description of Related Prior Art 
         [0004]    Relatively light weight trailers usually have an extendable jackstand attached to the tongue, which jackstand includes a wheel to permit manual movement of the trailer. Heavier and/or larger trailers generally include a jackstand mounted on the tongue that has simply the end of a tube or a plate attached to the end of the tube for engagement with the ground. Such trailers are not manually moveable as the end of the jackstand or plate will not readily traverse the ground. 
         [0005]    In order to hook up a trailer to a draft vehicle, the trailer may be manually moved into position if the jackstand includes a wheel. If there is no wheel, the draft vehicle must be maneuvered into a position to permit engagement of a latching mechanism at the end of the tongue with a ball attached to the draft vehicle. This is often a difficult and time consuming task, depending upon the skill of the driver. 
         [0006]    Scaffolding often includes wheels mounted at the bottoms of the uprights to permit transport across the ground into position adjacent a building or the like. Generally, these wheels have mechanical friction locks to prevent unwanted movement of the scaffolding across the ground. However, depending upon the sophistication of the structure of the wheel supporting elements, rotational movement of the wheels about a vertical axis may occur. Sometimes the brakes are less than completely effective. Either of these problems create a safety hazard for personnel on the scaffolding. 
         [0007]    Numerous other structures/apparatus require movement across the ground and a locking mechanism that can maintain the structure stationary on the ground. Furthermore, the transition from a stationary configuration to a mobile configuration must be relatively easy to accomplish and yet be essentially fail safe. To date, various apparatus exists for accomplishing these purposes but most suffer from various functional or structural impediments. 
       SUMMARY OF THE INVENTION 
       [0008]    A retractable wheel assembly includes a housing for supporting an element to permit both moving and anchoring the element. A foot pedal operating a pair of arms pivotally attached to the housing lowers and raises a wheel to raise and lower, respectively, the housing to accommodate moving and anchoring the element. A catch, which may be released by pivotal movement of the foot pedal, retains the pair of arms in the lowered position and extension of the wheel. 
         [0009]    It is therefore, a primary object of the present invention to provide a retractable wheel assembly for an attached element to selectively provide mobility to the element. 
         [0010]    Another object of the present invention is to provide a retractable wheel assembly for an element that is foot operated to raise and lower the wheel. 
         [0011]    Still another object to the present invention is to provide a retractable wheel assembly capable of supporting a significant load in either a stationary or a mobile configuration. 
         [0012]    Yet another object of the present invention is to provide a retractable wheel assembly configurable for attachment to any structure for temporary mobility of the structure and immovably retaining the structure in place between periodic movements. 
         [0013]    A further object of the present invention is to provide a retractable wheel assembly for anchoring an element in place and which is readily configurable to permit movement of the element. 
         [0014]    A still further object of the present invention is to provide a method for selectively moving or anchoring an element in place. 
         [0015]    A yet further object of the present invention is to provide a method for detachably attaching a retractable wheel assembly to an element to permit either moving the element or anchoring the element. 
         [0016]    These and other objects of the present invention will become apparent to those skilled in the art as the description proceeds. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The present invention will be described with greater specificity and clarity with reference to the following drawings, in which: 
           [0018]      FIG. 1  is a side view of a retractable wheel assembly attached to the end of a tongue for a trailer; 
           [0019]      FIG. 2  is a three-quarter isometric view of the retractable wheel assembly; 
           [0020]      FIG. 2A  is an end view of the retractable wheel assembly; 
           [0021]      FIG. 3  is a partial broken side view illustrating the components of the retractable wheel assembly in its stationary configuration; 
           [0022]      FIG. 4  is a partial broken side view of the rotatable wheel assembly in its mobile configuration; 
           [0023]      FIG. 4A  is a partial view illustrating a catch for maintaining the rotatable wheel assembly in its mobile configuration; 
           [0024]      FIG. 5  illustrates angular movement of the rotatable wheel assembly to facilitate movement across the ground of an attached trailer; 
           [0025]      FIG. 6  is a side view of a variant retractable wheel assembly shown in the stationary configuration; 
           [0026]      FIG. 7  is a side view of the variant retractable wheel assembly shown in the mobile configuration; 
           [0027]      FIG. 8  is a top view taken along the lines  8 - 8 , as shown in  FIG. 6 ; 
           [0028]      FIG. 9  illustrates a side view of a yet further variant of the rotatable wheel assembly illustrating it in the stationary configuration; 
           [0029]      FIG. 10  is a partial cross-sectional view taken along the lines  10 - 10 , as shown in  FIG. 9 ; 
           [0030]      FIG. 11  is a side view of the further variant rotatable wheel assembly illustrating it in the mobile configuration; and 
           [0031]      FIG. 12  is a top view of the further variant rotatable wheel assembly. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0032]    Referring to  FIG. 1 , there is shown a retractable wheel assembly  10  positioned on ground  12  and supporting a tongue  14  of a trailer  16 . As illustrated, a shaft  18  extends into and is captured by cup  20  of hitch  22  at the front of tongue  14 . As plate  24  rests upon ground  12 , it serves in the manner of an anchor to prevent movement of tongue  14 . A foot plate  30  is supported upon a pair of arms  32 ,  34 , which pair of arms are rotatable about the axis of shaft  36  mounted within housing  38 . The pair of arms rotatably support wheel  40 . A pivotally mounted catch  42  is mounted intermediate arms  32 ,  34  for selective engagement with plate  24 . 
         [0033]    Referring jointly to  FIGS. 2 ,  2 A and  3 , further details attendant retractable wheel assembly  10  will be described. Retractable wheel assembly  10  may include a cup or cylinder  46  for receiving shaft  18  or other support member. To lock such a support member within cylinder  46 , a pair of diametrically opposed holes  48 ,  50  may be incorporated to receive a pin or the like extending through these holes and through the member to be attached. Plate  24  may include a recess  52  for receiving lip  54  (see  FIG. 1 ) of catch  42 . To retain the lip within the recess, one or more springs  56  maybe incorporated to urge lip  54  into engagement with recess  52 . The opposite end of plate  24  may included and upturned section  58  to enhance movement of the retractable wheel assembly across the ground.  FIG. 3  particularly illustrates shaft  60  in engagement with arms  32 ,  34  for rotatably supporting wheel  40  between these arms. 
         [0034]    Referring jointly to  FIGS. 3 ,  4  and  4 A, the operation of retractable wheel assembly  10  will be described. Once the retractable wheel assembly is in place and in engagement with the element to be moved, an operator places his/her foot upon foot plate  30 . The force exerted on the foot plate will cause a pair of arms  34 ,  34  to pivot downwardly about shaft  36 . As wheel  40  is essentially resting on the ground, as shown in  FIG. 3 , housing about  38  will be raised as a function of the angular movement of the pair of arms about shaft  36 . When pair of arms  32 ,  34  are at their lowest most position adjacent plate  34 , as shown in  FIG. 4 , the wheel will be in its fully extended position and plate  24  will have been raised off the ground. Simultaneously, lip  54  of catch  42  will be brought into engagement with recess  52  defined by plate  24 . To ensure engagement by lip  54  with recess  52 , the edges of the plate defining recess  52  along with the edge of lip  54  maybe beveled to urge counter-clockwise rotation of the catch until the lip comes into engagement with the recess. Thereafter, springs  56  will urge clockwise rotation of the catch to retain lip  54  within recess  52 . In this configuration of catch  42 , wheel  40  will remain in the extended position shown in  FIG. 4 . 
         [0035]    Once the retractable wheel assembly is in position, it can be anchored to the ground in the following manner. Upon release of catch  42  to disengage lip  54  from recess  52 , the weight exerted by housing  38  and any attached element will exert a downward force upon shaft  36 . This downward force will be translated into angular upward movement of pair of arms  32 ,  34  causing shaft  60  to be raised and wheel  40  will become retracted. To prevent an abrupt downward movement of housing  38  and an attached element, a yielding force can be exerted upon foot plate  30  by an operator to promote a relatively slow rise of the pair of arms. 
         [0036]    As illustrated in  FIG. 5 , if retractable wheel assembly  10  is used to support a cup  20  of a hitch  22 , the retractable wheel assembly can pivot about a vertical axis extending through cup  20 . Thereby, an attached trailer  16 , or the like, can be moved forwardly or rearwardly along a curved path as a function of the degree of angular displacement of the retractable wheel assembly relative to tongue  14 . 
         [0037]    Referring jointly to  FIGS. 6 ,  7  and  8 , a first variant  60  of the retractable wheel assembly is illustrated. In this variant, a plate  62  supports a pair of sidewalls  64 ,  66  and includes a central opening  68 . To increase the friction between ground  70  and plate  62 , a plurality of nubbins  72  may be disposed on the under side, as shown in  FIG. 6 . These nubbins may be in the form of spot welds or the like. A bracket  74  includes panels  76 ,  78  interconnected at the upper end with a cross member  80 . A stud  82  extends from panel  76  through sidewall  66  to provide pivotal support for arm  92 . Similarly, a stud  84  extends from panel  78  through sidewall  64  to provide support for arm  90 . Cross member  80  may include a aperture  86  or the like, for securing a cup or cylinder  88  (as shown in  FIG. 6 ) for receiving a jackstand of a trailer or other element to be supported. 
         [0038]    A pair of arms  90 ,  92  are pivotally supported upon the studs  84 ,  82 , respectively. Thereby, these arms are free to pivot about the axis of the lines studs  82 ,  84 . A bolt  94  interconnects the free end of arms  90 ,  92 . An axle  96  extends intermediate the other ends of pair of arms  90 ,  92  to rotatably support a wheel  98 . As shown in  FIG. 8 , the wheel is generally coincident with opening  68  to permit pass through of the wheel. To permit the rotational movement of the pair of arms supporting wheel  98 , a pair of arcuate apertures are disposed in each of sidewalls  64 ,  68  to accommodate arcuate movement of axle  98  there along. 
         [0039]    To retain pair of arms  90 ,  92  in the upper position, as shown in  FIG. 7 , a spring  102  interconnects arm  90  with sidewall  64  and a further spring  104  interconnects arm  92  with sidewall  66 . Thereby, the pair of arms are biased upwardly, as represented by arrow  106 . A foot plate  110  is pivotally mounted on bolt  92  by a cylinder  112  to accommodate pivotal movement of the foot plate relative to bolt  94 . A catch  114  extends downwardly from the cylinder and includes a lip  116 . 
         [0040]    In operation in the quiescent mode, variant  60  has wheel  98  extending downwardly through plate  62  in response to the force exerted by springs  102 ,  104 , as depicted in  FIG. 7 . To raise the wheel and lower plate  62  to ground  70  (see  FIG. 6 ) a force is exerted upon foot plate  110  to cause clockwise pivotal movement of pair of arms  102 ,  104 . Such movement of the pair of arms will cause axle  96  to traverse through arcuate apertures  100  due to pivotal movement about studs  82 ,  84  until the wheel is fully retracted as depicted in  FIG. 6 . To retain the wheel fully retracted, foot plate  110  is pivoted counterclockwise to accommodate passage of lip  116  of catch  114  past edge  118  of plate  62 . Subsequent clockwise movement of the foot plate will cause lip  116  to engage the under surface of the plate, as depicted in  FIG. 6 . This will result in a locking of wheel  98  to the retracted position. To release the wheel and permit downward travel, foot plate  110  is rotated in the counterclockwise direction to withdraw lip  116  from beneath plate  62 . Thereafter, wheel  92  is extended downwardly in response to the force of springs  102 ,  104 . 
         [0041]    Referring to  FIGS. 9 ,  10 ,  11  and  12 , there is illustrated a further variant  120  of the retractable wheel assembly. A housing  122  is mounted upon a plate  124 , which plate may include an upturned section  126 . A cylinder  128 , or the like, may be mounted at the upper end of housing  122  to receive a jackstand or other element to be supported by further variant  120  of the retractable wheel assembly. A bearing  130  may be incorporated intermediate cylinder  128  and housing  122  to permit rotational movement of the cylinder about a vertical axis represented by bolt  132 . Alternatively, the cylinder or other device for receiving and retaining an element may be attached rigidly or removably to housing  122 . Housing  122  includes an end wall  136  extending upwardly from plate  124  and a pair of sidewalls  138 ,  140  interconnecting with the end wall and the plate. Studs  142 ,  144  extend toward one another from respective sidewalls  138 ,  140 . Arm  146  is pivotally mounted on stud  142  and arm  148  is pivotally mounted on stud  144 . These arms may be referred to as a pair of arms. An axle  150  interconnects arms  146 ,  148  and rotatably supports wheel  152 . As illustrated, the pair of arms are configured in the manner of a dog leg. The free ends of the pair of arms supports a footplate  154  pivotally mounted on a bolt  156  interconnecting the pair of arms. A catch extends downwardly from the underside of foot plate  154  and includes a lip  160 . A further bolt or pin  162  interconnects the pair of arms, as illustrated. 
         [0042]    In operation, extension of wheel  152  from the position illustrated in  FIG. 9  is accomplished by exerting a downward force on foot plate  154 . Such downward force will cause pair of arms  146 ,  148  to rotate in a clockwise direction about studs  142 ,  144 . This will result in downward movement of wheel  152  to a position illustrated in  FIG. 11 . By rotating foot plate  154  about bolt  156  in a counterclockwise position, lip  160  of catch  158  will clear edge  164  of plate  124 . Upon subsequent clockwise rotation of the foot plate, lip  160  will come into engagement with plate  174 . To enhance the locking feature of the lip with the plate, the plate may be indented or apertured to receive upwardly extending edge  166  of lip  160 . 
         [0043]    To retract wheel  152 , foot plate  154  is rotated about bolt  156  in a counterclockwise direction which will result in release of lip  160  from plate  124 . Subsequent reduction in downward force on the foot plate will cause pair of arms  146 ,  148  to rotate counterclockwise due to the downward force exerted by housing  136  and the load placed thereon. Such retraction of the wheel will continue until plate  124  becomes supported upon the ground. 
         [0044]    While the above discussion has focused use of the invention in conjunction with a trailer, many other uses exist. For example, the invention can be used to support each of a plurality of upright stanchions of scaffolding. By lowering the wheels of each engaged retractable wheel assembly, the scaffolding can easily be moved to a new location. Thereafter, the wheels can be raised to effectively anchor each of the stanchions on the ground at the new location. It is to be understood that the ultimate user may use the invention with any of a multiple of structures or devices whether normally stationary or mobile.