Abstract:
A panel lifting and positioning device for holding, lifting, and positioning sheet material such as, for example, drywall is disclosed. The device is portable, self-powered, and capable of lifting and positioning sheet material at virtually any height and angular orientation through the use of a pressure differential generator on the material-engaging head.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a substantially portable, self-contained and self-powered device for lifting and positioning sheet materials used in the construction industry, such as, for example, drywall, and holding the sheet so that it can be installed as required. Using the device of this invention, a single worker can position and install drywall, even in structures having high or sloped ceilings. When used by two or more workers the speed of installation and completion of the project is significantly enhanced.  
         [0003]     2. Description of the Prior Art  
         [0004]     Within the construction industry, prior art patents disclose and teach a variety of implements for lifting and holding construction materials such as, for example, drywall. While such prior art devices may have proved suitable in years past, today&#39;s construction practices frequently call for higher ceilings, plant shelves, and tray ceiling designs. These more modern interior design and construction techniques have significantly increased the costs associated with handling and installing drywall panels and have actually increased the likelihood of injury when workers are struggling to mount such panels overhead, or at an angle with respect to vertical.  
         [0005]     In addition, most prior art devices useful for lifting and positioning sheet material require the use of fingers or ledges for holding the sheet material. This frequently results in damage, further increasing the costs of construction. Even if the fingers or ledges do not damage the panel, proper placement of the panel for installation is difficult because of the protruding fingers or ledges.  
         [0006]     It is therefore clear that there remains a great need in the art for a device that is capable of lifting, holding and positioning sheet material at virtually any angle between 0 and 180 degrees, wherein such device may be safely operated by one worker within the confines of an interior space. Inasmuch as such devices are typically used before permanent power has been supplied to the space, such a device should be self-powered, and, of course, must be readily movable. As with virtually any article of manufacture, portability from job site to job site is also a desirable asset.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention relates to a lifting and positioning device primarily intended for use with sheet materials used in the construction industry. The device comprises a base, a lift section attached to the base, a boom attached to the top of the lift, a material-engaging head attached to the boom, and a pressure differential generator attached to the material-engaging head whereby the panel may be held thereon for positioning. According to a preferred embodiment, described in detail below, the device further comprises electrically operated control means whereby the worker may raise and lower the lift, raise and lower the boom, articulate the material-engaging head, and actuate the pressure differential generator to hold a panel thereagainst. According to this preferred construction, the control means is powered by one or more batteries mounted on the base.  
         [0008]     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:  
         [0010]      FIG. 1  is a side elevation, partially fragmentary, of a preferred embodiment of this invention with the lift raised.  
         [0011]      FIG. 2  is a rear elevation of the preferred embodiment shown in  FIG. 1 .  
         [0012]      FIG. 3  is a top plan detail of the lift motor.  
         [0013]      FIG. 4  is a side elevation, partially fragmentary, of the lift motor of  FIG. 3 .  
         [0014]      FIG. 5  is a side elevation of the base.  
         [0015]      FIG. 6  is a rear elevation of the base shown in  FIG. 5 .  
         [0016]      FIG. 7  is a partial side elevation of the boom and material-engaging head, showing movement in phantom.  
         [0017]      FIG. 8  is a detail, partially fragmentary, of the boom motor.  
         [0018]      FIG. 9  is a side elevation similar to that of  FIG. 1  with the lift lowered.  
         [0019]      FIG. 10  is a back side elevation of the material-engaging head showing support arms on each side thereof.  
         [0020]      FIG. 11  is a detail side elevation of the material-engaging head, partially in section.  
         [0021]      FIG. 12  is a detail view of a material-engaging head support arm.  
         [0022]      FIG. 13  is a schematic of the control means electrical circuit. 
     
    
       [0023]     Similar reference characters refer to similar parts throughout the several views of the drawings.  
       DETAILED DESCRIPTION  
       [0024]     Before proceeding to a detailed description of the preferred embodiment for the lifting and positioning device of this invention, generally indicated as  20  in the drawing figures, it is to be emphasized that this is merely a preferred embodiment. Numerous changes and modifications are contemplated, as set forth below, and are intended to fall within the scope of the present invention. For example, the lift, generally indicated as  22 , and the boom, generally indicated as  24 , are both illustrated as being of a scissor-jack construction. Equivalent substitutes might include, for example, pneumatic or hydraulic rams, or pulley and cable assemblies. In like fashion, while the lift motor  26 , the boom motor  28 , and the material-engaging head motor  30  in this preferred embodiment are electric screw-thread drives, rams, cables and pulleys, or even eccentric levers may be substituted.  
         [0025]     As will become evident in the following detailed description, left controller  32  and right controller  34  of this preferred embodiment are actually modified power drill housings and circuitry. Other switch devices may be utilized in accord with the example circuit of  FIG. 13  and are intended to be encompassed within the scope of the present invention. Furthermore, primarily for purposes of convenience and portability, this preferred embodiment for device  20  derives its power from a pair of 12 volt batteries  132  and  134  housed within battery box  38 . Clearly, the present invention could be constructed to operate on alternating current by modifying the circuitry and providing a receptacle for the source of such power. In fact, though believed to be somewhat cumbersome, the present invention could be modified for mechanical, pneumatic, or hydraulic operation.  
         [0026]     Referring to the drawing figures,  FIG. 1  illustrates a preferred embodiment for device  20 . As shown therein, device  20  includes a base, generally indicated as  40 , for supporting device  20  on a support surface  42 , and movement across support surface  42  may be accomplished manually with rollers or wheels  44 .  
         [0027]     Lift  22  is mounted on the base  40  and, as shown in the drawing figures, comprises a standard scissor construction in this preferred embodiment of device  20 . The up and down motion of lift  22  is accomplished by lift motor  26 , more fully described below. The lift  22  actually comprises a plurality of lift links  46 , two of which are pivotally attached to base  40  at base pivot points  48 , two of which are attached to base upper frame  50  at base upper frame pivot points  52 , with the remaining scissor pivots indicated at  54 . For up and down operation, lift motor  26  comprises lift motor lower arm  56 , a distal end of which is pivotally attached at base pivot point  48 , and lift motor upper arm  58 , a distal end of which is pivotally attached to base upper frame  50  at lift motor upper arm pivot  60 .  
         [0028]     A fixed boom support  62  extends upwardly from base upper frame  50 , and a pivoting and extendable boom link  64  is provided for raising and lowering boom  24 . As best seen in the view of  FIG. 7 , boom motor  28  is mounted on pivoting and extendable boom link  64  whereby boom  24  may be raised and lowered as indicated in phantom in the view of  FIG. 7 .  
         [0029]     Pivotally mounted at the distal end of boom arm  66  is the material-engaging head, generally indicated as  68 . Articulation of material-engaging head  68  is accomplished by the action of material-engaging head motor  30 . Referring to the view of  FIG. 11 , the pivoting attachment between boom arm  66  and material-engaging head  68  is indicated at head pivot  70 .  FIG. 11  further illustrates the pivoting attachment of head motor rod  72  to material-engaging head  68  at head motor pivot  74 .  
         [0030]     Referring to the views of  FIGS. 10 and 11 , material-engaging head  68  is formed from a sheet of substantially non-porous material  76  and is bounded by head frame  78 . A head channel  80  is provided on the back surface of sheet  76  for attachment of the distal end of the boom arm  66  and of head motor rod  72 . Extending outwardly from the front surface of sheet  76  and around its perimeter is a gasket  82 . An aperture  84  is formed through sheet  76  and, as indicated in phantom in the view of  FIG. 11 , a pressure differential generator is operatively mounted on the back side of sheet  76  in surrounding relation to aperture  84 . Actuation of pressure differential generator  86 , which in this embodiment is a direct current vacuum motor, will draw air inwardly through aperture  84 . Clearly, then, if a sheet of material such as, for example, drywall is disposed in overlying relation to gasket  82 , a pressure differential will be created within the void defined by the material, gasket  82 , and the front surface of sheet  76 , thereby holding and retaining the material on material-engaging head  68 .  
         [0031]     The views of  FIGS. 10 and 12  provide further details with regard to left support arm and right support arm, generally indicated as  88  and  90 , respectively. The support arms  88  and  90  are removably and adjustably attachable to material-engaging head  68  as by inserting their respective support rods,  92  and  94 , into corresponding receiver tubes  96  and  98 . Support rods  92  and  94  are held in position by respective pins  100  and  102 , and the distance that the rods  92  and  94  extend outwardly from material-engaging head  68  is adjustable, independently. In fixed and substantially transverse relation to the distal end of each of the support rods  92  and  94  are corresponding padded arms  104  and  106 . Use of support arms  88  and  90 , though not required, will increase the stability of a sheet of material being lifted and positioned by device  20 .  
         [0032]     Turning to the views of  FIGS. 3 and 4 , it can be seen that in this preferred embodiment for device  20  lift motor  26  will rotate lift rod  108 , and that rotary motion is translated through lift gears or sprockets  110  to result in forward or backward motion (depending upon the direction of rotation of lift rod  108 ) to selectively extend or retract lift motor upper arm  58  by its engagement with lift thread rod  112 .  
         [0033]     As shown in the view of  FIG. 8 , the preferred construction and operation of boom motor  28  is substantially the same as that of lift motor  26 . Rotary motion of boom motor  28  is transferred through boom gears or sprockets  114  to boom thread rod  116 , and this results in corresponding extension or retraction (depending upon the direction of rotation) of pivoting and extendable boom link  64 .  
         [0034]     In like fashion, material-engaging head motor  30  causes rotation of head thread rod  118 , best seen in the view of  FIG. 11 , to articulate material-engaging head  68 .  
         [0035]     Turning to the views of  FIGS. 5 and 6 , further details of the base  40  may be seen. Base  40  includes a bottom frame  120  and a pair of vertical control frames  122  extending upwardly therefrom. A battery support  124  is provided between the vertical control frames  122 , and left and right controllers  32  are removably attachable to the top of vertical control frames  122  by controller mounting bar  126 . A top frame connector  128  extends transversely between and is attached to the distal end of each of the vertical control frames  122  for stability. Controller mounting bar  126  and left and right controllers  32  and  34  attached thereto are removably attachable to base  40  to facilitate the transport of device  20  from one site to another. According to this preferred construction, boom arm  66  is also removably attachable to device  20  at boom arm brackets  130 , best seen in the view of  FIG. 7 . Battery box  38  may also be removed from battery support  124 .  
         [0036]     Turning to the schematic view of  FIG. 13 , one can see that battery box  38 , according to this preferred embodiment, contains left battery  132  and right battery  134 . A standard, pin-type connector is provided for the removal of batteries  132  and  134  from device  20 , and the schematic of  FIG. 13  further illustrates similar pin-type connections for the removal of controller mounting bar  126 . In this preferred embodiment for device  20 , lift motor  26  and boom motor  28  are 24 volt D.C. motors, and material-engaging head motor  30  and pressure differential generator  86  are 12 volt, D.C., motors. Of course, this arrangement is not to be interpreted as limiting the scope of the present invention. As indicated above, different motor sizes could be used, and alternating current could be used. In addition, lift motor  26  is preferably selected as a two-speed motor, but that also is not to be considered as limiting the scope of the present invention.  
         [0037]     All structural elements of this preferred embodiment are preferably formed from aluminum for purposes of weight reduction and strength. Because of the construction of device  20  whereby boom  24 , controller mounting bar  126 , and battery box  38  may be removed, transportation of device  20  in, for example, a standard utility van, is provided. When those elements are removed, the base  40  and lift  22  may be lifted by two persons with relative ease for placement in a transporting vehicle. According to this preferred embodiment, in its fully extended position, as illustrated in the view of  FIG. 1 , a construction panel may be placed slightly more than fifteen feet above the supporting surface. In the fully lowered position shown in the view of  FIG. 9 , the height of device  20  from the support surface is slightly less than four feet. Testing of this device has confirmed that the pressure differential generator  86  will successfully and safely lift and hold a four by eight, one half inch, sheet of drywall weighing approximately forty-six pounds; a four by twelve, five eighths inch, sheet of drywall weighing approximately one hundred thirteen pounds; a four by eight sheet of hardy board; and a four by eight sheet of plywood. In fact, testing has demonstrated that when device  20  is used to lift drywall from a stack of drywall sheets, care must be taken so that only one sheet is lifted. Because of the drywall&#39;s porosity, lifting of two four by eight sheets, simultaneously, can occur.  
         [0038]     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0039]     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall there between.  
         [0040]     Now that the invention has been described,