Abstract:
An improved wheeled hand cart assembly has a tiltable lifting platform associated with a trailing platform so that separate loads may be transported on each platform. The lifting cart structure comprises a generally conventional L-shaped configuration having a pair of wheels mounted on a common axis, for rolling the lifting cart about. The lifting cart is tiltable about the wheel axis to retain and transport a load. The trailing cart comprises a support platform having a forward end coupled to the lifting cart for pivoting about an axis parallel to the common axis of the wheels, a rearward end portion supported on a caster-like wheel assembly for rolling from place to place in coordination with the spaced-apart wheels and a locking assembly for locking the lifting cart in a tilted position relative to the trailing cart.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to portable hand carts of the type having a lifting platform used for wheeling temporary loads from place to place on the floor/ground. More specifically, the invention relates to improved hand carts of this type having expanded capacity in the form of a trailing platform for transporting additional load material which may be more permanently associated with the cart. 
     2. Description of the Related Art 
     Wheeled, portable hand carts of generally L-shaped configuration have been well-known in the art for many years. Such carts conventionally have a pair of axially spaced-apart wheels attached to the body of the cart near the juncture of the long and the short legs of the L-shape. 
     The shorter leg of the “L” generally serves as a lifting platform that is placed on the ground or floor in horizontal alignment and then slipped under a movable load to lift it above the floor so that both the cart and the load which is cradled in the inner angle of the L-shape, may be wheeled from place to place. The longer leg of the conventional L-shape is substantially vertical when the lifting platform is horizontal, and serves as a lever/handle to facilitate tilting the lifting platform and pushing/steering the cart on its wheels. 
     However, the known design of such carts tends to restrict them to use with loads that are inherently temporary and that must be removed from the lifting platform to permit transporting of other loads on the same platform. This restriction in the number and size of loads that can be carried by carts of known design is particularly unacceptable for many applications in which a temporary load such as a receptacle drum or container must be used together with an ancillary portable load such as a pump or vacuum or power unit that is preferably associated with the cart on a relatively “constant” basis. 
     The present invention addresses these considerations by providing a conventional upright wheeled handcart with a trailing platform that is particularly suited to carry a relatively “constant” load along with the cart without interfering with the use of the conventional temporary lifting platform. 
     SUMMARY OF THE INVENTION 
     The improved wheeled hand cart assembly of this invention incorporates a tiltable wheeled lifting platform associated with a wheeled trailing platform that in combination permit transporting temporary interchangeable loads on the lifting platform together with other, relatively heavy, “constant” loads on the trailing platform. The cart assembly incorporates a lifting cart structure of generally L-shaped configuration wherein the short leg of the L-shape acts as a lifting platform and the longer leg of the L-shape serves generally as the handle portion of the cart in conventional manner. A pair of axially spaced-apart wheels are rotatably mounted on a substantially common axis on the lifting cart, close to the juncture of the longer leg and the short leg, so that the lifting cart may be rolled from place to place on the floor or ground with a load cradled within the juncture of the longer leg and the short leg. 
     The improvement of this invention resides in a trailing cart structure comprising a support platform member having a forward end portion coupled to the lifting cart structure for pivoting about an axis substantially parallel to the common axis of the wheels, and a rearward end portion supported on one or more swivel-caster-like wheel assemblies for rolling from place to place in coordination with the spaced-apart wheels. These and other and further features and advantages of this invention will be made more apparent to those having skill in this art, by reference to the following specification considered in conjunction with the accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of an improved hand cart assembly in accordance with this invention, shown in its at rest position, bearing two separate loads 
         FIG. 2  is a side elevation view of the improved hand cart assembly of  FIG. 1 , shown in normal position for transporting its loads; 
         FIG. 3  is a is a partial pictorial representation of the cart assembly of this invention showing the latching mechanism used to maintain the cart in the position shown in  FIG. 2 ; and 
         FIG. 4  is section view of the cart of this invention taken through line  4 — 4  of  FIG. 1  with representations of the loads omitted, for clarity. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIGS. 1 and 2  of the drawings, the improved hand cart assembly  10  of this invention may be seen to comprise a substantially conventional L-shaped upright lifting cart structure  20  coupled to a generally horizontal trailing cart structure  30 . A substantially “constant” or auxiliary load element  100  is shown mounted on trailing cart  30 , while a removable, “temporary” load element  150  is shown positioned on lifting cart  20 . Constant load  100  may be, for example, a pump or a filtration unit that is required to be transported, regularly, from place to place for use where liquids, for example, are being withdrawn and/or filtered at one location for transport to another in a container such as transient load element  150 . In this regard, it will be understood that the pump unit represented by load element  100  will be connected to a source of liquid [not shown] by an inlet hose or pipe [not shown], while the container represented by load element  150  will be connected while on the cart assembly to load element  100  by suitable connecting elements such as conduits  200  of any acceptable form. Aside from being shown to illustrate their relative positions and use in connection with this invention, elements  100 ,  150  and conduits  200  form no part of this invention. 
     Lifting cart structure  20  may be seen to include a lifting platform  21  which corresponds to the shorter leg of the L-shape, and a lever/handle portion  22  corresponding generally to the longer leg of the L-shape. Conventional hand grips  28  are provided at the uppermost ends of handles  22  to facilitate manual handling of the cart assembly. A pair of axially spaced-apart wheels  23  are mounted for rotation at opposite ends of an axle  24  which is coupled to lifting cart structure  20  close to the generally right-angle juncture  25  of the lifting platform  21  and the lever/handle  22 . In a conventional manner, lifting platform  21  is used by placing it flat on the floor or ground  250  on which a temporary load element  150  is supported, and then slipping it under the load element between the bottom of the element and the ground. When the load element  150  has been positioned on platform  21 , lever/handle  22  is used as a lever to tilt platform  21  to the position shown in  FIG. 2 , so as to cradle element  150  within the inner right angle formed by the juncture  25  of the lifting platform  21  and the lever handle  22 . 
     Trailing cart structure  30  includes a platform surface element  31  having one or more forwardly extending connecting arms  32  [shown more clearly FIG.  4 ] that terminate in journal bearing sleeves  33  coupled to common axle  24  on lifting art structure  20 . Bearings  33  and arms  32  couple trailing cart  30  to lifting cart  20  so that the axial centerline of cart  30  [running from the forward end to the rearward end] is maintained in substantial right angle alignment with the axis of axle  24 . 
     Accordingly, cart assembly  10 , although defined by two pivotally connected cart elements  20  and  30 , maintains both elements at all times in substantially linear fore and aft alignment so that the cart assembly may be maneuvered readily backward and forward through use of lever handle  22  as a steering means. Although two connecting arms  32  and two spaced apart bearings  33  have been shown for illustrative purposes only, it will be understood readily by those having ordinary skill in the related art, that a single arm and single bearing may be used if desired, to achieve the same coupling function. 
     The rearward end of trailing cart platform member  31  is supported above the floor  250  by one or more swivel caster wheel assemblies  34 , dimensioned to support platform member  31  substantially parallel to floor  250 . Most desirably, caster assembly  34  is of the well-known and readily available locking type, to facilitate tilting lifting cart  20  relative to trailing cart  30 . That is, when the caster wheel is locked so as to resist rolling of trailer cart  30 , the trailing cart will remain substantially stationary so that the handles  22  of the lifting cart may be pulled back to tilt the lifting cart without movement of the trailing cart. In this context, a lockable caster is one having any conventional form of selectively activatable brake mechanism to prevent or substantially resist rotation of the caster wheel about its axis. It should be noted at this point that the horizontal surface of platform  31  may be may be supported at the same height above floor  250  as axle  24 , or it may be higher or lower as desired, subject to the choice of any obvious form and shape of the structure attaching platform  31  to coupling sleeves  33 , such as arms  32 . 
     While trailing cart element  30  may be seen to remain supported on and substantially parallel to the floor or ground  250  at all times during normal use, it can be seen also that lifting cart  20  may be tilted readily about axle  24  independently of cart element  30  using lever/handle  22 , so as to bring cart  20  into a tilted position relative to cart element  30  [as shown in FIG.  2 ] wherein a load  150  standing on lifting platform  21  will be cradled within the inner right angle formed by the juncture  25  of lifting platform  21  and lever handle  22 . 
     For convenience of use, when lifting cart  20  is locked in the position shown in  FIG. 2 , the handle grips of handles  22  preferably should lie close to a vertical plane extending vertically upward from the rearmost end of trailing cart  30 . This will allow a user to maneuver the cart assembly freely with reduced likelihood that the rearmost end of cart  30  will interfere with the user&#39;s feet or legs. 
     To facilitate handling and wheeling about of the cart assembly  10  with a load supported on cart element  20 , it has been found to be desirable to provide for releasable latching of cart element  20  to cart element  30  in one or more positions.  FIG. 3  illustrates a preferred latching mechanism  60  having a first separable latching element  61  mounted on trailing cart structure  30 , and a second separable latching element  62  mounted on the lifting cart structure  20 . The two latching elements releasably engage each other in one or more positions so as to lock the two cart elements  20 ,  30  in a desired given position. The two cart elements are latched into the desired position when the lifting cart structure has been tilted about axle  24  so as to bring the first and second latching elements into proper alignment. The first separable latching element  61  may be fixedly attached to trailing cart  30  in any suitable manner, as by bolting it or welding it in place; it includes a curved track surface  63  which is dimensioned to form an arc of a circle having the axis of common axle  24  as its center. One or more holes  64  extend radially inward from track surface  63 , defining circumferentially spaced apart stop surfaces, i.e. diametrically opposite interior wall surface portions of holes  64 , to engage the end of mating latching element  62  between the surfaces. 
     Latching element  62  can be seen to be a pin or bolt mounted to slide substantially radially relative to one of the lever handles  22  so as to enter hole  64  telescopically when the first and second latching members  61 ,  62  have been brought into proper alignment. In this regard, proper alignment is achieved as the result of tilting of cart  20  relative to cart  30 . Slidable pin  62  is coupled to the handles  22  of lifting cart  20  by means of a spanning brace  27  extending between the handles. Pin  62  is resiliently biased to enter hole  64  under the resilient force of a compression spring  65  when pin  62  and hole  64  are aligned. However, it will be obvious in view of this disclosure that other forms of biasing may be adopted or may be dispensed with entirely in favor of selective manual engagement of latching pin  62  within latching hole  64 . 
     It will now be understood that latching elements  61 ,  62  are mounted to cart elements  20 ,  30  respectively so that the tip of latching rod  62  slides along curved track surface  63 , as cart  20  is tilted about axle  24 , and that cart  20  then becomes locked to cart  30  in a desired given position when latching member  62  is inserted into latching opening  64  and becomes locked between opposed inner wall surface portions of opening  64 . It will be further understood that one or more spaced-apart openings  64  may be provided to allow cart  20  to be latched into one or more tilted positions relative to cart  30 . 
     To allow for release of latching bolt element  62  from engagement with the abutment surfaces of latching opening  64 , slidable element  62  includes a manually actuated latch release handle  66  mounted near one of the free ends of lever handle  22 . Release handle  64  may be coupled to withdraw latch element  62  from abutment opening  64  in any convenient manner as, for example, by any well-known eccentric linkage coupled to a rod  67  as shown in  FIG. 3 , or by any other known and available means such as a telescopic cable coupling of the type commonly used for the remote operation of camera shutters. 
     Although a preferred embodiment of the invention has been illustrated and described, it will be obvious to those having skill in this art that various other forms and embodiments of the invention now may be visualized, readily, by those having skill in this art, without departing substantially from the spirit and scope of the invention set forth in the accompanying claims.