Abstract:
In general, the present invention provides a platform truck. More specifically, the present invention provides a platform truck comprised of a base member, a handle, a pair of swivel caster wheels depending from the bottom surface back end of the base member, a pair of swivel-lock caster wheels depending from the bottom surface front end of the base member, and a user-activated actuator assembly carried on the bottom surface of the base allowing the front swivel-lock casters to be switched between a unidirectional position and swivelable position to more easily negotiate tight turns and doorways is disclosed. Also included is a handle that is stowable within the base portion of the platform truck so that the platform truck may include one or two handles, whereby a handle may be included on one or both ends of the platform truck.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to platform hand trucks, and more particularly, a platform hand truck having an actuator allowing the front casters to be switched between a fixed position and a swivel position to more easily negotiate tight turns and doorways. 
       BACKGROUND OF THE INVENTION 
       [0002]    Platform trucks are well known in industry for moving loads that cannot be easily transported by hand. A typical platform truck includes a generally rectangular, flat, material-supporting surface having two swivel casters positioned at the handle or rear end of the truck and two unidirectional, non-swiveling, wheels at the front end of the platform truck. This configuration is advantageous for carrying heavy loads because it prevents the front casters from following the terrain while allowing the operator to control the path of the swiveling casters with the handle. However, this configuration is difficult to maneuver in tight areas where loads are often transported due to the requirement that the rear of the platform truck be pivoted around the front wheels, placing the center of the turning radius in between the front unidirectional wheels. Thus, in these situations it is advantageous for the front casters to swivel along with the rear casters. 
         [0003]    Thus, it has been suggested in the prior art to construct the platform truck so that the handle can be moved from one end of the platform truck to the other. In these platform trucks, a post receptacle is provided at each corner of the platform for receiving the ends of an inverted U-shaped handle. In this manner, when a user needs a rear steer platform truck, the handle can be placed at the rear of the platform truck near the swiveling casters; and if the user needs a front steer platform truck, the handle can be placed at the front of the platform truck near the unidirectional wheels. However, these constructions have proven to be cumbersome and unreliable as the handles commonly get bent or sprung and are difficult, if not impossible, to move from one end of the platform truck to the other. 
         [0004]    It has also been suggested in the prior art to provide selectable swiveling casters on a platform truck which allow the front casters to swivel or lock in a unidirectional position. For example, some platform trucks provide a spring loaded pin mounted on each caster wheel that engages a notch thereon to prevent that front caster wheel from swiveling when it is desired to lock it in place. Unfortunately, to release the front casters the user has to physically pull a ring at each front caster wheel, requiring the user to step away from the handle, thereby releasing control of the load. Resetting the caster to a locked position is even more cumbersome for the user, requiring the user to orient the caster so that the pin can be re-engaged to the notch. Therefore, what is lacking in the art is a platform truck that includes a user-friendly means of locking and unlocking the caster wheels of the platform truck from the operating position of the platform truck. 
         [0005]    Thus, the need exists for a platform truck having an actuator positioned conveniently at the handle end of the truck which allows the front casters to be switched between a fixed position and a swivel position to more easily negotiate tight turns and doorways. The platform truck should also include a more convenient construction for switching the handle from one end of the platform truck to the other, which eliminates the need to remove the handle from the platform truck. The handle should also be stowable in the platform truck itself for ease in loading and unloading the platform truck. 
       SUMMARY OF THE INVENTION 
       [0006]    In general, the present invention provides a platform truck. More specifically, the present invention provides a platform truck comprised of a base member, a handle, a pair of swivel caster wheels depending from the bottom surface back end of the base member, a pair of swivel-lock caster wheels depending from the bottom surface front end of the base member, and a user-activated actuator assembly carried on the bottom surface of the base allowing the front swivel-lock casters to be switched between a unidirectional position and swivelable position to more easily negotiate tight turns and doorways is disclosed. Also included is a handle that is stowable within the base portion of the platform truck so that the platform truck may include one or two handles, whereby a handle may be included on one or both ends of the platform truck. The base includes a front end and a back end, each having pockets formed therein, a top surface for receiving items thereon, a bottom surface, and generally vertically oriented opposed sidewalls extending downwardly from the top surface about the periphery of the base member. The handle includes a hand grip portion and opposing arms, with the lower ends of the opposing arms constructed and arranged to be carried within the pockets on the base member. Each of the front end swivel-lock caster wheels include a mounting member attached to the bottom surface of the base member, a fork connected to the mounting member for swiveling movement upon a swivel bearing along a substantially vertical axis, a locking pin for engaging and disengaging the swivel bearing to allow for swiveling or unidirectional movement, and a castor wheel supported by the fork for rotation about a horizontal axis. The actuator assembly is comprised of a first end, central portion attached to the base member forming a pivot point, and a second end. The first end is positioned between the pair of swivel-lock caster wheels and each locking pin is connected thereto. The second end extends horizontally beyond and through the back end sidewall. The back end sidewall includes a retainer thereon, allowing the second end of the actuator arm to move in a plane parallel to the base member. The positioning of the second end of the arm to a swiveling position withdraws the locking pins from the swivel bearing on each pair of swivel-lock caster wheels to allow for swiveling movement of the wheels; and positioning of the second end of the arm to a unidirectional position locks the locking pins onto the swivel bearing on each pair of swivel-lock caster wheels to allow for only unidirectional movement of the wheels. 
         [0007]    Accordingly, it is an objective of the present invention to provide a platform truck having an actuator allowing front casters to be switched between a fixed position and a swivel position. 
         [0008]    It is another objective of the present invention to provide a platform truck providing a stow position for the handle within the base member. 
         [0009]    It is yet another objective of the present invention to provide a platform truck where the base member further includes sockets on the front and/or rear end sidewall(s) such that a handle arm can be removably attached thereto in a generally vertical position for manipulating the platform truck. 
         [0010]    It is a further objective of the present invention to provide a platform truck where the base member further includes pockets on the front and/or rear end sidewall(s) such that a handle arm can be removably attached thereto in a generally horizontal position for storage of the handle arm. 
         [0011]    It is yet a further objective of the present invention to provide a platform truck having a stow position for a handle which removes it as an obstacle for large loads on the base member, but keeps the handle with the platform truck for when the emptied platform truck needs to be relocated. 
         [0012]    It is still a further objective of the present invention to provide a platform truck that includes an actuator arm that is activated by a user&#39;s foot to allow engagement or disengagement of the locking pin on each of the front end swivel-lock caster wheels. 
         [0013]    Still a further objective of the present invention is to provide a platform truck having a foot actuated means to switch between a unidirectional movement and a swivelable movement of the front end swivel-lock caster wheels so that the user does not have to let go of the handle. 
         [0014]    It is yet a further objective of the present invention to provide a platform truck that allows for ease of operation in a straight line and ease of turning in tight corners in an instance. 
         [0015]    An even further objective of the present invention is to provide a platform truck that overcomes the prior art, whereby a user would have to manually pull a ring at each front swivel-lock caster wheel, left and right, in order to engage or disengage the loading pin to allow for unidirectional or swivelable movement of the front wheel. The present invention only requires the movement of an actuator arm at the handle end of the platform truck to switch between unidirectional or swivelable movement of the front wheels. 
         [0016]    It is still yet another objective of the present invention to provide back end swivel castor wheels with a wheel brake. 
         [0017]    Still yet another objective of the present invention is to provide a platform truck that includes a platform portion constructed of plastic having a metal frame underneath for support of the plastic platform. 
         [0018]    Still yet a further objective of the present invention is to provide a platform cart wherein the plastic platform includes integrally formed gussets and ribs for strength and rigidity. 
         [0019]    Other objects and advantages of this invention will become apparent from the following description taken in conjunction with any accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. Any drawings contained herein constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0020]      FIG. 1  is a bottom perspective view of the platform truck of the instant invention; 
           [0021]      FIG. 2  is a side view of the instant invention; 
           [0022]      FIG. 3  is a perspective view of the back swivel caster wheel of the instant invention; 
           [0023]      FIGS. 4A and 4B  are perspective views of the pair of front swivel-lock caster wheels of the instant invention; 
           [0024]      FIG. 5  is a top view of the swivel-lock caster wheel of the instant invention; 
           [0025]      FIG. 6  is a back end view of the instant invention; 
           [0026]      FIG. 7  is a bottom view of the instant invention; and 
           [0027]      FIG. 8  is a perspective view of an alternative embodiment of the instant invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred, albeit not limiting, embodiment with the understanding that the present disclosure is to be considered an exemplification of the present invention and is not intended to limit the invention to the specific embodiments illustrated. 
         [0029]    As shown in  FIGS. 1-8 , the platform truck  1  is comprised of a base member  10 , a handle  50 , a back end pair of swivel caster wheels  70 , a front end pair of swivel-lock caster wheels  80 , and a user activated actuator assembly  110  allowing for unidirectional or swivelable movement of the front end swivel-lock caster wheels  80 . As shown in  FIGS. 1 and 2 , the base member  10  consists of a front end  12 , back end  14  having opposing sockets  28  formed therein, a top surface  16  for receiving items thereon, and a bottom surface  18 . The top surface  16  includes a peripheral edge  20  and generally vertically opposed sidewalls  26  extending downwardly from peripheral edge  20 . The base member  10  can be constructed from steel or plastic having varying sizes depending upon load capacity, which is discussed later. The handle  50  provides a handle bar portion  52  and opposing aims  54  with lower ends  56  constructed and arranged to be carried within the sockets  28  on the base member  10 . Each lower end  56  of the arm  54  in the handle  50  includes a spring pin  64 . The back end sockets  28  on the base member  10  have an aperture  30  thereon to cooperate with the spring pin  64  on the lower end  56  of the handle arms  54 , thereby retaining the handle  50  in place on the base member  10 . The handle  50  further includes a cross-piece  60  attached between the arms  54  to provide strength and stability to the handle  50 . The cross-piece  60  includes a hanger  62  thereon for hanging and receiving items such as tools, bungee cords, or the like. 
         [0030]    As shown in  FIG. 2 , a side view of one embodiment of the present invention is illustrated. In this embodiment a back end pair of swivel caster wheels  70  depend from the back end  14  bottom surface  18  of the base member  10 , and a pair of front end swivel-lock caster wheels  80  depend from the front end  12  bottom surface  18  of the base  10 . As shown in  FIG. 3 , the back end swivel castor wheels  70  include a wheel brake  72 . As shown in  FIG. 1 , the front end pair of swivel-lock caster wheels  80  is comprised of a mounting member  82  attached to the bottom surface  18  of the base member  10 . More specifically, as shown in  FIGS. 4A, 4B, and 5 , a fork  84  is connected to the mounting member  82  for swivelable movement about a swivel bearing  86  in a generally vertical axis  88 . A locking cylinder  90  is integrally secured to the mounting member  82  for locking the bearing support  87  to the mounting member with the locking pin  91 . The locking cylinder is preferably formed from a tubular section of metal and may contain keyways, guides or the like to orient to the locking pin as it traverses the bore of the tubular member. The locking pin  91  is selectively engagable and disengagable to lock or allow free turning of the swivel bearing  86  for swivelable or unidirectional movement of the caster wheel. The locking pin  91  preferably includes a yoke  93  for attachment to the locking and unlocking linkage. A caster wheel  92  supported by the fork  84  allows for rotation about a horizontal axis of rotation  94 , the horizontal axis of rotation  94  being spaced behind the swivel bearing  86  when the castor wheel  92  is in a trailing position. The front end swivel-lock caster wheels  80  are manipulable between a unidirectional movement and swivelable movement using the actuator assembly  110 . Additionally, the pair of front swivel-lock caster wheels  80  consist of a left wheel  100  and right wheel  102 , the locking pin  91  on the corresponding left or right wheel,  100  and  102 , is positioned opposite the peripheral edge  20  on the base member  10 , or more specifically towards the center of the base member  10 , more aptly shown in  FIG. 7 . 
         [0031]    As shown in  FIGS. 6 and 7 , the user operated actuator assembly  110  is carried on the bottom surface  18  of the base member  10  and connected to the locking pin  91  on each of the front end swivel-lock caster wheels,  100  and  102 , permitting for unidirectional or swivelable movement of the front end swivel-lock caster wheels  80 . The actuator assembly  110  includes an actuator arm  112  having a first end  114 , central portion  116  attached to the bottom surface  18  of the base member  10  forming a pivot point  120 , and a second end  118 . The first end  114  is positioned between the front end swivel-lock caster wheels  80 , and each locking pin  91  on each of the front end swivel-lock caster wheels  80  is connected to the first end  114  of the actuator arm  112  via drag links  126 . The drag links  126  are preferably formed as flat elongated metal pieces suitable for fitting within the yoke  93  of the pin  91 . Alternatively, cables or the like may be utilized without departing from the scope of the invention. The second end  118  extends horizontally beyond and through the back end sidewall  24  of the base member  10  and is moveable in a horizontal plane parallel to the base member  10  between a swivelable position  124  and unidirectional position  122 . The movement of the second end of the arm  118  to a swivel position  124  withdraws or unlocks the locking pin  91  from the swivel bearing  86  on each of the front end swivel-lock caster wheels  80  to allow for swivelable movement  124  of the front end swivel-lock caster wheels  80 . The movement of the second end arm  118  to a unidirectional position  122  locks the locking pin  91  onto the swivel bearing  86  on each of the front end swivel-lock caster wheels  80  to allow for unidirectional movement  122  of the front end swivel-lock caster wheels  80 . It is contemplated that the actuator arm  112  can be activated by a user&#39;s foot to allow engagement or disengagement of the locking pin  91  on each of the front end swivel-lock caster wheels  80 . Having a foot actuated means to switch between a unidirectional movement  122  and swivelable movement  124  of the front end swivel-lock caster wheels  80  allows the user to keep hold of the handle  50  while operating the platform truck  1 . 
         [0032]      FIG. 8  shows the platform truck  1  having the handle assembly  50  in a stowed position. The base member  10  includes opposed pockets  32  on the front end sidewall  22  such that the handle arms  54  can be removably attached to the pockets  32  in a stowed position. A platform truck  1  having a stow position for a handle  50  removes the handle  50  as an obstacle for large loads that exceed the base member surface area, but keeps the handle  50  with the platform truck  1  for when the emptied platform truck  1  needs to be relocated. In addition, sockets  28  may be provided on the front sidewall of the base member  10  to allow the handle to be switched from one end of the cart to the other. 
         [0033]    Referring to  FIGS. 1-8 , various embodiments of the platform truck are illustrated. The base member  10  of the platform truck  1  is contemplated as being constructed of either steel ( FIGS. 1 and 7 ) or plastic ( FIGS. 2, 6, and 8 ). The steel base member is contemplated as a 30×60 inch heavy duty base member or a 24×48 inch regular duty base member. The heavy duty steel platform truck is rated for a capacity load of approximately 2,000 lbs. The regular duty steel platform truck is rated for a capacity load of approximately 1,000 lbs.  FIG. 8  shows a plastic base member construction. The plastic base member is contemplated as a 30×60 inch heavy duty base member, a 24×48 inch regular duty base member, as well as a 24×36 inch regular base member. The heavy duty plastic platform truck is rated for a capacity load of approximately 2,000 lbs. The regular duty 24×48 inch and 24×36 inch plastic platform trucks are rated for a capacity load of approximately 1,000 lbs. Strength for supporting the heavy loads is provided by the downwardly extending peripheral edge  20  along with a sub-frame  150  ( FIG. 1 ). The sub-frame  150  is constructed as a series of rectangular metal members  152  welded together to create a structural member to which the casters are secured. In this manner, the platform truck can utilize a plastic bed while still providing structural integrity for heavy loads. The plastic bed can never rust and does not need to be painted. Typically, loads being moved onto and off of the bed destroy the surface finish on metal flatbed carts allowing rust to form and requiring painting. In the preferred embodiment, the plastic bed is formed by the process of blow molding or injection molding, however, roto-molding may be utilized without departing from the scope of the invention. Additionally, because of the added load capacity between the heavy duty platform truck and the regular duty platform truck, it is contemplated that the heavy duty platform truck is equipped with heavy duty casters with a metal core and urethane low profile tires. The regular duty platform truck is equipped with normal duty casters with a plastic core and urethane, regular profile tires. 
         [0034]    All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. 
         [0035]    It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein. 
         [0036]    One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.