Abstract:
A pallet jack includes a hydraulic system that allows for adjustment of the pallet-engaging portion of the jack using a mechanical adjusting system whereby a large variety of pallet sizes can be accommodated. Once the desired width is achieved, the hydraulic system is used to raise the pallet engaging portion of the pallet jack once the pallet is engaged.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the general art of land vehicles, and to the particular field of pallet jack type land vehicles. 
   2. Description of the Related Art 
   Many people must move heavy pallets from one place to another. Truckers must load and unload heavy pallets, personnel in warehouse must move heavy pallets, and the like. Often, a heavy pallet must be loaded onto a pallet jack to be moved. One problem encountered in the use of a pallet jack is the size of the pallet and the size of the jack may be incompatible. That is, the pallet may be too large for the jack or vice versa. In such instances, the jack may be nearly useless, or it may take considerable time to adjust the size of the jack to accommodate the pallet. In either instance, time and/or money is lost. 
   Therefore, there is a need for a pallet jack that can be easily and quickly adjusted to accommodate a pallet. 
   In some cases, the pallet is quite heavy and is not easily moved, even to permit a pallet jack to accommodate the pallet. If a pallet is too heavy, it may not be possible for a pallet jack to be modified to accommodate the pallet. 
   Therefore, there is a need for a pallet jack that can be easily and quickly adjusted to accommodate a pallet, even a very heavy pallet. 
   In some cases, a pallet and a pallet jack are incompatible in two dimensions. That is, the pallet may be too long and too wide for the pallet jack, or vice versa. In such instances, a pallet jack may not be useable at all. 
   Therefore, there is a need for a pallet jack that can be easily and quickly adjusted in more than one dimension to accommodate a pallet. More specifically, there is a need for a pallet jack that can be easily and quickly adjusted in a widthwise direction of the pallet jack to accommodate pallets having a variety of width dimensions. 
   PRINCIPAL OBJECTS OF THE INVENTION 
   It is a main object of the present invention to provide a pallet jack that can be easily and quickly adjusted to accommodate a pallet. 
   It is another object of the present invention to provide a pallet jack that can be easily and quickly adjusted to accommodate a pallet, even a very heavy pallet. 
   It is another object of the present invention to provide a pallet jack that can be easily and quickly adjusted. 
   It is a specific object of the present invention to provide a pallet jack that can be easily and quickly adjusted in a widthwise direction of the pallet jack to accommodate pallets having a variety of width dimensions. 
   SUMMARY OF THE INVENTION 
   These, and other, objects are achieved by a pallet jack that includes a hydraulic system that permits adjustment of the width of the pallet jack whereby the size of the pallet jack can be adjusted to accommodate a wide range of pallet sizes. The pallet jack embodying the present invention can be adjusted in the widthwise direction of the pallet jack so pallets having a variety of widths can be accommodated by the pallet jack. The hydraulic system of the pallet jack embodying the present invention is also used to raise the jack after the jack has been positioned beneath a pallet so the pallet can be easily moved by the jack. 
   Using the pallet jack embodying the present invention will permit an operator to quickly, easily and accurately adjust the size of the pallet jack to accommodate a wide range of pallet sizes, especially a variety of widths. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  is a perspective view of a pallet jack embodying the present invention. 
       FIG. 2  shows a portion of a hydraulic unit used in the pallet jack shown in  FIG. 1 . 
       FIG. 3  is a side elevational view of the pallet jack embodying the present invention with the wheels in a retracted position. 
       FIG. 4  is a side elevational view of the pallet jack embodying the present invention with the wheels in a deployed position. 
       FIG. 5  shows a detail of the hydraulic ram used to move the wheels of the pallet jack between a retracted position and a deployed position with the wheels in a retracted position. 
       FIG. 6  shows a detail of the hydraulic ram used to move the wheels of the pallet jack between a retracted position and a deployed position with the wheels in a deployed position. 
       FIG. 7  is a view of the hydraulic ram used to move the wheels of the pallet jack. 
       FIG. 8  is a view taken along line  8 — 8  of  FIG. 3  and shows the system used to move the forks of the pallet jack in a width direction. 
       FIG. 9  shows a system that can be used to move the pallet-engaging forks in a width direction and is a view taken along line  9 — 9  of  FIG. 1 . 
       FIG. 10  is an elevational view from distal ends of first and second pallet-engaging fork elements, showing the first and second pallet-engaging fork elements extended outwardly. 
       FIG. 11  is an elevational view from distal ends of the first and second pallet-engaging fork elements, showing the first and second pallet-engaging fork elements retracted inwardly. 
       FIG. 12  is a top plan view showing the first and second pallet-engaging fork elements extended outwardly. 
       FIG. 13  is a bottom plan view showing the first and second pallet-engaging fork elements extended outwardly. 
       FIG. 14  is a bottom plan view showing the first and second pallet-engaging fork elements retracted inwardly. 
       FIG. 15  is a side elevational view showing wheels retracted upwardly. 
       FIG. 16  is an elevational view taken along line  16 — 16  of  FIG. 15 . 
       FIG. 17  is a side elevational view showing the wheels extended downwardly. 
       FIG. 18  is an elevational view opposing the view shown in  FIG. 10 . 
       FIG. 19  is an enlarged and fragmentary, schematic representation of portions of the hydraulic system of the pallet jack of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings. 
   Referring to  FIGS. 1 through 19 , it can be understood that the present invention is embodied in a pallet jack  10 . Pallet jack  10  can be adjusted in width dimension as well as in height dimension so pallets of a wide variety of sizes can be accommodated on the pallet jack. 
   Pallet jack  10  comprises a frame unit  12  including a housing  14 , an adjustment mechanism  16  having six components: a first component  18 , a second component  20 , a third component  22 , a fourth component  24 , a fifth component  26 , and a sixth component  28 . First component  18  includes a first end  30 , which is attached to adjustment jack bracket  32 , and a second end  33 , which is attached to mounting bracket  34  which is attached to first fork element  36 . Second component  20  has a first end  40 , which is attached to adjustment jack bracket  32 , and a second end  42 , which is attached to mounting bracket  44 , which is attached to second fork element  46 . 
   First fork element  36  includes a first pallet-engaging fork element  50  with a proximal end  52  movably attached to components  18  and  22  wherein the first pallet-engaging fork element  50  and is movable between a first position shown in  FIGS. 1 ,  5  and  12  spaced outwardly in the direction of a width dimension  53  of the adjustment mechanism  16 , and a second position indicated in  FIGS. 2 and 4  spaced inwardly in the direction of the width dimension  53  of the adjustment mechanism  16 . First pallet-engaging fork element  50  further includes a distal end  54  which is spaced apart from the housing  14  and a length dimension  56  which extends between the proximal end  52  of the first pallet-engaging fork element  50  and the distal end  54  of the first pallet-engaging fork element  50 . First fork element  36  further includes a first surface  58 , which is a top surface when the first pallet-engaging fork element  50  is in a use position, and a second surface  60 , which is a bottom surface when the first pallet-engaging fork element  50  is in the use position. 
   Second fork element  46  includes a second pallet-engaging fork element  64  with a proximal end  66  movably attached to components  20  and  26  wherein the second pallet-engaging fork element  64  is movable between a first position, shown in  FIGS. 1 ,  10 ,  12 , , 13 ,  16  and  18 , spaced outwardly in the direction of the width dimension  53  of the adjustment mechanism  16 , and a second position, shown in  FIGS. 11 and 14 , spaced inwardly in the direction of the width dimension  53  of the adjustment mechanism  16 . Second pallet-engaging fork element  64  further includes a distal end  70 , which is spaced apart from the housing  14 , and a length dimension  72 , which extends between the proximal end  66  of the second pallet-engaging fork element  64  and the distal end  70  of the second pallet-engaging fork element  64 . Second fork element  64  further includes a first surface  74 , which is a top surface when the second pallet-engaging fork element  64  is in a use position, and a second surface  76 , which is a bottom surface when the second pallet-engaging fork element  64  is in the use position. 
   Widthwise movement of the pallet-engaging fork elements  50 ,  64  is indicated in  FIGS. 1 and 10  by double-headed arrows  80  and  82 . 
   A handle unit  90  includes a pivot mount  92  mounted on the frame unit  12  and a handle element  94  which has a proximal end  96  pivotally attached to the pivot mount  92 , a distal end  98 , and a hand grip element  100  mounted on the distal end  98  of the handle unit  90 . As indicated in  FIGS. 2 ,  3  and  19  by double-headed arrow  102 , the handle unit  90  is pivotally movable between a first position, which is upright when the handle unit  90  is in a first condition, and a second position, wherein the handle element  94  is at an oblique angle with respect to the first position when the handle unit  90  is in a second condition. 
   A wheel unit  108  is mounted on the frame unit  12  and includes a pair of wheels  110  mounted on the frame unit  12 . A second wheel  112  is mounted on the first pallet-engaging fork element  50  near the distal end  54  of the first pallet-engaging fork element  50 . A pivot arm  114  is connected to the second wheel  112 . A third wheel  116  is mounted on the second pallet-engaging fork element  64  near the distal end  70  of the second pallet-engaging fork element  64 . A pivot arm  118  is connected to the third wheel  116 . 
   Pallet jack  10  further includes a hydraulic unit  120  as schematically shown in  FIGS. 2 and 19 . The hydraulic unit  130  includes a hydraulic fluid container  140  mounted on the frame unit  12 . The hydraulic fluid container  140  includes a vent valve  142 . 
   A pump element  144  is mounted on the frame unit  12  adjacent to the hydraulic fluid container  140  and is connected thereto. 
   A mechanical connecting arm  150  has a first end  152  connected to the handle unit  90  and a second end  154  connected to the pump element  144 . The mechanical connecting arm  150  is pivotally connected to thereby translate movement of the handle unit  90  into pumping movement of the pump element  144 . 
   A first hydraulic ram element  160  is fluidically connected to the hydraulic fluid container  140  and is movably mounted on the frame unit  12  to move between an extended position and a retracted position. The first hydraulic ram element  160  is connected to the pair of wheels  110  to move the pair of wheels  110  between a retracted position when the first hydraulic ram element  160  is in the retracted position and a deployed position when the first hydraulic ram element  160  is in the extended position. 
   A second hydraulic ram element  170  is fluidically connected to the hydraulic fluid container  140  and is movably mounted on the first pallet-engaging fork element  50  to move between an extended position and a retracted position. The second hydraulic ram element  170  is connected via a pushrod  172  to the pivot arm  114  of the second wheel  112  to move the second wheel  112  between a retracted position, as indicated in  FIGS. 3 ,  5  and  15 , when the second hydraulic ram element  170  is in the retracted position and a deployed position, as indicated in  FIGS. 4 ,  6  and  17 , when the second hydraulic ram element  170  is in the extended position. 
   Similarly, a third hydraulic ram element  180  is fluidically connected to the hydraulic fluid container  140  and is movably mounted on the second pallet-engaging fork element  64  to move between an extended position and a retracted position. The third hydraulic ram element  180  is connected via pushrod  182  to the pivot arm  122  of the third wheel  120  to move the third wheel  116  between a retracted position when the third hydraulic ram element  180  is in the retracted position and a deployed position when the third hydraulic ram element  180  is in the extended position. 
   Fluid hoses, such as fluid hose  190 , and fluid connections, such as fluid connection  192 , are used to effect the fluid connections in the hydraulic system included in pallet jack  10 . 
   Pallet jack  10  further includes a pallet-engaging fork element-moving unit  200  mounted in the frame unit  12 . Unit  200  includes support bars  210  mounted on the frame unit  12  and extending in the direction of the width dimension  53  of the adjustment mechanism  16 , a first bracket  220  movably mounted on the support bars  210  and fastened to the first pallet-engaging fork element  50 , a second bracket  230  movably mounted on the support bars  210  and fastened to the second pallet-engaging fork element  64 , and a means  250  for moving the first bracket  220  and the second bracket  230  toward and away from each other in the direction of the width dimension  53  of the adjustment mechanism  16 . 
   Means  250  may include mechanical elements such as a rack and pinion arrangement  260 , or can be a hydraulic system  270  fluidically connected to the above-described hydraulic system by a fluid conduit  290 . 
   It is understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts described and shown.