Patent Publication Number: US-6902147-B2

Title: Wheeled hydraulic jack with suspensory lifting device

Description:
BACKGROUND OF THE INVENTION 
   (a) Field of the Invention 
   The present invention relates to wheeled hydraulic jacks with a suspensory lifting means, and more particularly to a wheeled hydraulic jack with a suspensory lifting means that utilizes a vertical hydraulic unit for lifting the loading terminal of a pair of cantilever arms. 
   (b) Description of the Prior Art 
   Referring to  FIG. 12 , a wheeled hydraulic jack of the prior art is provided, in the rear portion thereof, with a horizontally laid hydraulic unit  10 . The piston  101  of the hydraulic unit  10  drives a pair of pivotal cantilever arms  20  in a transverse direction to lift the loading terminal of the cantilever arms  20 . Since the hydraulic unit  10  extends horizontally, this conventional wheeled hydraulic jack has long side plates  30  and therefore does not have a compact configuration, as required in some practical applications. 
   SUMMARY OF THE INVENTION 
   Accordingly, the primary objective of the present invention is to provide a wheeled hydraulic jack with a suspensory lifting means in which the hydraulic unit stands upwardly. Two movable tension links, each pivotally mounted on each of pivotal cantilever arms, have the free ends thereof connected with each end of a cross-wise shaft that goes through the piston of the hydraulic unit. The piston of the hydraulic unit moves upwardly and bears against the cross-wise shaft so as to lift the loading terminal of the pivotal cantilever arms, which defines the suspensory means. Since the hydraulic unit stands upwardly, the side plates defining the length of the jack are greatly shortened, therefore attaining a compact configuration for the jack. 
   The secondary objective of the present invention as a wheeled hydraulic jack with a suspensory lifting means is to provide a vertical configuration for the hydraulic unit of a jack, and thereby the piston of the hydraulic unit is not confined within the jack, which allows the installation of hydraulic units of various capacities. 
   It is a further objective of the present invention as a wheeled hydraulic jack with a suspensory lifting means that the hydraulic unit can be an independent module by mounting the components such as hydraulic cylinder, pump unit, oil-ejecting valve, safety valve and the associated oil tubing on a base, which base is directly mounted between the rear sections of the side plates. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the present invention. 
       FIG. 2  is an exploded perspective view of the present invention. 
       FIG. 3  is a side view of the present invention in a lifted state. 
       FIG. 4  is a cross-sectional view of the rear portion of the present invention. 
       FIG. 5  is a top view of the rear portion of the present invention. 
       FIG. 6  is a bottom view of the rear portion of the present invention. 
       FIG. 7  is a top view showing the combination of the movable tension links of the present invention. 
       FIG. 8  is an exploded perspective view of another preferred embodiment of the present invention. 
       FIG. 9  is a top view of a part of the preferred embodiment of the present invention in  FIG. 8 . 
       FIG. 10  is a side view of a part of the preferred embodiment of the present invention in  FIG. 9 . 
       FIG. 11  is a cross-sectional side view of the piston and the cross-wise shaft as shown in  FIG. 10 . 
       FIG. 12  illustrates the combination of a wheeled hydraulic jack in the prior art. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 ,  FIG. 2  and  FIG. 3 , the present invention as a wheeled hydraulic jack with a suspensory lifting means is provided with a hydraulic unit  1  in a vertical configuration. Each of the pivotal cantilever arms  2  of the jack is pivotally connected with a movable tension link  3 , the free end of which is further connected to a corresponding end of a cross-wise shaft  111  of the hydraulic unit  1 . As the piston  11  of the hydraulic unit  1  moves upwardly, the cross-wise shaft  111  bears against the movable tension links  3  correspondingly, which lifts the loading terminal of the pivotal cantilever arms  2  up, as shown in  FIG. 3 . 
   The above-mentioned wheeled hydraulic jack further comprises a main body  4 , which is composed of two side plates  41 . Two pairs of roller wheels  42 ,  43  are respectively mounted underneath the front and rear ends of the main body  4 . The pivotal cantilever arms  2 , bridged by a shaft sleeve  21 , are pivotally mounted on the main body  4  by a shaft  44  which is inserted through the shaft sleeve  21 . One or more than one connecting plates  45  are mounted between the side plates  41  on selected locations to reinforce the structural toughness of the main body  4 . Further, one or more than one barricades  441  are installed on the inner wall of each side plate  41  near the lower edge thereof, for locking the hydraulic unit  1 . Two pivotal links  46  are each pivotally mounted between a lifting base  22  mounted onto the loading terminal of the pivotal cantilever arms  2  and a corresponding side plate  41 . 
   In the above-mentioned wheeled hydraulic jack, a shaft sleeve  21  is integrally mounted on a selected location at the rear portion of the pivotal cantilever arms  2 . The loading terminal of the pivotal cantilever arms  2  is provided with a lifting base  22  for supporting a load. One or more than one connecting plates are mounted between the middle sections of the pivotal cantilever arms  2 . The above-mentioned movable tension links  3  respectively has one end pivotally connected to the pivotal cantilever arms  2  by a dowel  31  and the other end, utilizing a hole  32  thereon, pivotally connected to the cross-wise shaft  111  of the hydraulic unit  1 . As shown by the preferred embodiment, two strengthening plates  33  are each applied to a movable tension link  3 , with one end mounted on the outer face of the movable tension link  3  and another end connected to the corresponding end of the shaft sleeve  21 . Each movable tension link  3  is thereby pivotally sandwiched by a corresponding pivotal cantilever arm  2  and a strengthening plate  33 . This measure strengthens the combination of the movable tension links  3  and the dowels  31 , which prevents the deformation of the dowels  31 . 
   The suspensory lifting means of the present invention adopts a vertical configuration for the hydraulic unit  1 , which allows the freedom of installing hydraulic unit of a variety of capacities, then avoiding the problem of insufficient installation space. 
   The above-mentioned hydraulic unit  1  can be an independent module. That is, the components of the hydraulic unit  1 , such as hydraulic cylinder  13 , pump unit  14 , oil-ejecting valve  15 , safety valve and the associated oil tubing, can all be mounted on a base  12  which is locked at the bottom of a wheeled hydraulic jack by screwing a plurality of screws  47 , through the barricades  441  on the side plates  41 , to corresponding locking holes  121  formed on the base  12 . The base  12  is therefore directly mounted between the rear sections the side plates  41 . 
   This present invention utilizes a hydraulic unit  1  in a vertical configuration to form a suspensory lifting means, which is different from the conventional wheeled hydraulic jacks in that the hydraulic unit extends horizontally. The pivotal cantilever arms  2  are lifted by a suspensory driving means that may house hydraulic unit  1  of a variety of capacities. It is a further advantage that the side plates  41  are significantly shorter than those of the conventional jacks, which greatly reduces the size of a jack and simplifies the structure at the same time. 
   In the above-mentioned wheeled hydraulic jack, a handle seat  48  is pivotally connected to the rear portion of the space between the side plates  41 . The handle seat  48 , coupled with the pump unit  14  of the hydraulic unit  1 , provides the insertion mechanism of a handle bar  49 , which in turn drives the pump unit  14  to actuate the lifting means. This mechanism is the same as that of a wheeled hydraulic jack of the prior art. 
   The cross-wise shaft  111  as disclosed by the above-mentioned preferred embodiment takes the shape of a cylinder. The shaft may also have a square cross-section, being a rectangular bar  111   a , or other cross-sections; this is shown from  FIG. 8  to  FIG. 11  by another preferred embodiment. The rectangular bar  11   a  is provided with a connecting cavity  111   b  and a pin hole  11   c , which are for housing the piston  11  or the extending portion  11   a  of the piston  11 . To assure solid connection of the cross-wise shaft  111  with the piston  11 , a resilient pin  111   d  is inserted through the pin hole  111   c  to a corresponding pin hole  11   b  in the piston  11  (or the extending portion  11   a  thereof) as being received in the connecting cavity  111   b . Further, a fixing pin  111   e  can be installed on each side of the cross-wise shaft  111 , and, corresponding to each fixing pin  111   e , a fixing piece  122  is mounted on the base  12  of the hydraulic unit  1 . Two restoring springs  123  are respectively hooked between a fixing pin  111   e  and a fixing piece  122  on each side of the cross-wise shaft  111 , for accelerating the restoring movement of the cross-wise shaft  111  after the hydraulic unit  1  is relieved. 
   The present invention is described by the preferred embodiments, and it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. For example, the strengthening plates  33  attached on the outer faces of the movable tension links  3  are for structural strengthening, which can be omitted. Any equivalent variation to the strengthening plates  33  is therefore allowed.