Abstract:
A lift for maneuvering a heavy manway cover, the lift including a wheeled base and a generally horizontal arm connectable to the cover. A pair of spaced lifts connecting the arm to the base and a shaft rotatably held within the arm. A wheel crank connected to the shaft to rotate the shaft in a pivotable connection on the end of the shaft. Wherein the shaft having a first position wherein the cover is held against rotation and a second position wherein the weight of the cover allows the cover to pivot under the shaft while an axis of the cover rotates from being perpendicular to the arm to being parallel to the arm.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    U.S. Provisional Application for Patent No. 61/520,712, filed Jun. 14, 2011, with title “Method and Device for Removal of Vertical Manway Cover” which is hereby incorporated by reference. Applicant claim priority pursuant to 35 U.S.C. Par. 119(e)(i). 
     
    
     STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to a handling heavy equipment including steel manway doors. 
         [0005]    2. Brief Description of Prior Art 
         [0006]    It is common to provide lift equipment. But in inaccessible areas it is often still necessary to lift heavy objects via manual lifting. An example of manual lifting is moving manway covers (doors) on hemi-head style feedwater heaters. Currently these covers must be maneuvered by hand. These manway covers can weigh as much as 500 lbs. and handling them is a safety concern. The spaces covered by manway doors are sometimes considered to be confined spaces and as such present a significant safety hazard to the workers. 
         [0007]    As will be seen from the subsequent description, the preferred embodiment for the present invention overcome shortcomings of this prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    Briefly stated, the present invention is directed to a device and method for the removal of manway covers (doors) such as might be used on feedwater heaters. 
         [0009]    A lift for maneuvering a heavy manway cover is disclosed. The lift includes a wheeled base and a generally horizontal arm connected to the cover; a pair of spaced lifts connecting the arm to the base and a shaft rotatably held within the arm; a wheel crank connected to the shaft to rotate the shaft and a pivotable connection on an end of the shaft. The shaft has a first position wherein the cover is held against rotation, and a second position wherein the weight of the cover allows the cover to pivot under the shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows a side view of the preferred embodiment of the present invention, a device for removal of vertical manway cover. 
           [0011]      FIG. 2  shows an overhead view of the device of  FIG. 1 . 
           [0012]      FIG. 3  shows an end view of the device of  FIG. 1 . 
           [0013]      FIGS. 4A and 4B  show details of the device. 
           [0014]      FIG. 5A  shows an overhead view of the device in operation. 
           [0015]      FIG. 5B  shows a side view of the device in operation. 
           [0016]      FIG. 6  shows further details of the device. 
           [0017]      FIG. 7  shows a partial view of the device end shaft. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    In accordance with the present invention,  FIG. 1  shows a lift device  100 . The lift device  100  is shown with a load such as a cover D from a manway that allows access into a space S such as a heater. The space S is shown with walls cut away and the cover D in place in the manway. The lift  100  includes an arm  102 , such as a horizontal lift tube arm, and rotatable shaft  104 . The rotatable shaft  104  includes a pivotable connection  106  that is boltable to the load such as cover D. The lift  100  includes a base  110  and an upright post  112  that has handles  116 . The base  110  includes pivotable wheels  120  that allows a user to maneuver the base  110 , each wheel  120  can include a lock  122 . Each wheel  120  includes an attachment point such as opening  124  that allows for steering of the wheel  120 . The lift  100  includes a drive link actuator such as a hydraulic cylinder  130  and a second drive link actuator such as screw lift  140 . The hydraulic cylinder  130  and screw lift  140  act together as a pair to position the arm  102  through a range of positions as shown in  FIG. 5   b . The lift  100  includes a hand wheel crank  150  that controls the rotational position of shaft  104  and thereby the position of the load, cover D. The hand wheel crank  150  controls the shaft  104  through a geared transmission  152 . The position of the cylinder  130  is controlled by a pump handle  160 , pressure tank  162  and hose  164 . The cylinder  130  is connected to the horizontal arm  102  at a pivot point  170 . The rotational position of the screw  140  is controlled by bar  172  that inserts into openings  176 . 
         [0019]      FIG. 2  shows a view of the lift  100  from above. The lift  100  includes a base  110  and the base  110  includes a pair of spaced legs  200  and  202 . Each leg  200 ,  202  includes a pair of lock pins  208  that can lock legs  200 ,  202  in positions as shown in  FIG. 5A . The lift  100  includes a bar  210  that engages opening  124  to steer each wheel  120 . In  FIG. 2  the cover D is in the process of being removed, once the cover D is detached it must first be pushed into the space S shown as cutaway walls in cross section. FIG.  2  shows that as the cover D is removed a significant pinch point develops between the wall of space S and the cover D. 
         [0020]      FIG. 3  shows a rear view of the lift  100  in use. This view shows a possible shape of manway cover D. The manway cover D can be a shape such as an oval with a long axis representing the width and a short axis representing the height, for example. 
         [0021]      FIG. 4   a  shows a view from above of details of the lift  100  with the base portion removed. The arm  102  holds a rotatable shaft  104  with bearings  400 . The geared transmission  152  converts rotational movement of the hand wheel crank  150  into rotation of the shaft  104 . The shaft includes a pivotable connection  106  that can pivot from the position shown in  FIGS. 4   a  and  4   b  to the position shown in  FIG. 6  with the cover in a vertical orientation under the shaft  104 . 
         [0022]      FIG. 4   b  shows a side view of the arm  102  and a joint such as pivot connection  106 . The pivot connection  106  includes a pin  406  that connects a plate  408  to the end of the shaft  104 . The pin  406  is threaded and is attached using a nut  414  and washer  416 . The pin  406  forms a central axis  420  about which the plate  408  and any attached load D can pivot. The plate  408  is part of a coupling  422  having a flat surface that rests upon a flat surface of shaft  104 . When the shaft  104  is rotated from the position shown in  FIG. 4   b  to the position in  FIG. 6  the weight of the load cover D will cause the plate  408  to pivot about the end of shaft  104  to the position in  FIG. 6 . 
         [0023]      FIG. 5   a  shows a view of the lift  100  from above. The pins  208  can be removed and the legs  200 ,  202  can be positioned in any position A, B, C and the pins  208  replaced into holes in the base  110  to hold the legs  200 ,  202  in position.  FIG. 5   b  shows a side view of the lift  100  and shows that the arm  102  can be moved through a range of upward and downward motions keeping the arm  102  level, this motion range is shown by arrow X. The arm  102  can also move through a range of angular motions shown by arrow Y. 
         [0024]    Arm  102  in an isolated view to show additional features.  FIG. 6  shows that the cover D has pivoted from the unstable vertical position shown in  FIG. 1  to a generally horizontal position of  FIG. 6 . The plate  408  rotates out of alignment with the axis of the arm  102  through an angle Z of approximately 90°. 
         [0025]      FIG. 7  shows a partial view of the end of shaft  104 . The end of the cylindrical shaft  104  includes a clearance area  701  that creates a flat planer surface  703  that allows the coupling  422  to rotate relative to the shaft  104 . The coupling  422  also includes a flat surface  710 . The flat surface  703  of the cylinder  104  mates with the flat planer surface  710  of the coupling  422  and the flat surfaces are held together with pin  406  which forms a pinned planar connection having the central axis  420  about which the coupling  422  and cover D can rotate. The flat surfaces  703 ,  710  are held together with a pressure that forms a light friction fit joint. As the shaft  104  rotates from the position shown in  FIGS. 1 and 7  to the position in  FIG. 6  the coupling will at first rotate with the shaft  104  in a direction parallel to the shaft rotation about its own axis, but then the weight of the cover D will overcome the friction of the flat surfaces joint  703 ,  710  and the cover D will continue to rotate with the shaft  104  but will also rotate about the central axis  420 . This controlled rotation allows a user to orient the cover D so that the long axis of the cover, which initially perpendicular to the arm  102 , aligns with the arm  102  with the narrow width of the cover D presented to the opening. The coupling  422  includes fasteners such as screws  725  to attach the coupling  422  to the cover D. 
         [0026]    In operation, the lift  100  is positioned and the coupling plate  408  can be attached to the cover D such as by bolting  725  the coupling plate  408  to the cover D. Then the cover D is released from the space walls S and in the case of the manway covers D on hemi-head style feedwater heaters, the cover D is pushed into the space S as shown in  FIG. 2  by rolling the entire lift  100  toward the space S. The cover D is elongated as shown in  FIG. 3  and is somewhat unstable in the vertical position shown in  FIGS. 2 and 3 . The next step is to turn the hand wheel crank  150  which rotates the shaft  104  and therefore the pivot connection  106  and the cover D. As the cover D rotates through 90 degrees the weight of the cover acts on the connection  106 . As the connection turns through the same angle the cover D turns from the position shown in  FIG. 3  first to a position where the long axis of the cover D is pointing nearly downward, then the connection  106  allows the weight of the cover D to pivot the connection  106  to the position shown in  FIG. 6  with the plate  408  below the shaft  104 . In the process of turning during removal, the cover D goes from a first position where the long axis of the cover D is perpendicular to the long axis of the arm  102  as shown in  FIG. 1 , to a second position where the cover D is under the arm  102  and the long axis of the cover D is parallel to the longitudinal axis of the arm  102 . As can be seen in  FIG. 6  it may be necessary to lift the cover D upward in direction X to get it out of the space S. The arm  102  can be lifted in a level orientation by turning the screw  140  with bar  172  and by lifting the arm  102  with cylinder  130 . When the cover D is lifted to align with the opening in the space S it can be removed from the space by backing the lift  100  up. 
         [0027]    In many cases there will be obstructions to moving the lift  100  and in such cases the legs  200 ,  202  can be positioned as shown in  FIG. 5   a . Once the cover D is off the space S an operator can enter the manway. Once work is complete the cover D can be replaced simply by reversing the steps used to remove it. 
         [0028]    A key advantage of the invention is that it allows an operator to remove and replace the cover D without ever touching it. While replacing the cover D it may be necessary to lower the cover D, see lower position of cover D in  FIG. 5   b  within the space S to get the weight of cover D to rotate about pinned planar connection  106  to go from position shown in  FIG. 6  back to the original position shown in  FIG. 1 . 
         [0029]    Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the invention should be determined by the appended claims in the formal application and their legal equivalents, rather than by the examples given.