Abstract:
A lifting device for suspending a flying form table truss has a horizontal lower truss arm for insertion into the flying truss, a horizontal upper truss arm extending above and parallel to the lower truss arm, an intermediate vertical section connecting one end of the upper truss arm to one end of the lower truss arm, and a trolley, provided with a crane hook connector, on a trolley track extending along the top of the upper truss arm. By adjusting the position of the trolley along the upper truss arm, the crane hook connector can be located above the centre of gravity of the flying form table truss.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to lifting devices for flying form table trusses.  
         DESCRIPTION OF THE RELATED ART  
         [0002]    Flying form table trusses are employed as flying shoring forms in building construction, and are provided with a pair of parallel trusses supporting a table, with bracing between the trusses, and with screw jack legs for supporting the trusses, as disclosed, for example, in U.S. Pat. No. 5,560,160, issued Oct. 1, 1996 to the present inventor, then known as Peter Vladikovic.  
           [0003]    In use, the screw jack legs are supported on a previously cast floor of a building, with the trusses extending upwardly from the screw jacks and supporting the table horizontally on the top of the trusses. After a new floor of the building has been cast on the table, the screwjack legs are released and the flying form table, with its trusses, is withdrawn horizontally from beneath the newly cast floor, and raised by a crane to a position on top of the newly cast floor, ready for the casting of a still further floor.  
           [0004]    It has also been proposed to provide a lifting device with a lower arm for insertion into the flying form table truss, an upper arm extending above and parallel to the lower arm, an intermediate section connecting the upper and lower arms and a crane cable connector on the upper arm.  
           [0005]    It has been found, in practice, that the suspension of the flying form table and this lifting device by a crane is problematical, because it is difficult or even impossible to locate the center of gravity of the flying form table truss and the lifting device, or the lifting device alone, when the flying form table truss is not being lifted, below the outer end of the crane boom.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    The present invention it is based on the concept of providing a lifting device which can be located between the flying form table truss, on the one hand, and a crane cable, on the other hand, which enables a point of connection of the lifting device to the crane cable to be adjustable in position along the lifting device so that it can be adjustably located above the center of gravity of the flying form table truss and the lifting device or of the lifting device alone.  
           [0007]    More particularly, according to the present invention there is provided a lifting device for use in suspending a flying form table truss, the lifting device comprising a lower arm for insertion into the flying form table truss, an upper arm extending above and parallel to the lower arm, an intermediate vertical section connecting one end of the upper arm to one end of the lower arm, and a crane cable connector which is adjustable along the upper arm.  
           [0008]    In a preferred embodiment of the invention, the crane cable connector comprises a crane hook connector mounted on a trolley and the trolley can run along a track extending along the top of the upper arm.  
           [0009]    When the lifting device according to the present invention it is in use, the trolley can be driven along its track so as to correctly adjust the position of the crane hook relative to the flying form table truss and the lifting device and thereby to facilitate correct balancing of the table truss in a horizontal condition while the table truss is suspended from the crane. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The present invention will be more readily understood from the following description of a preferred embodiment thereof given, by way of example, with reference to the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 shows a view in side elevation of a flying form table truss provided with a lifting device according to the present invention;  
         [0012]    [0012]FIG. 1A shows a view in side elevation of the lifting device of FIG. 1 suspended from the cable of a crane;  
         [0013]    [0013]FIG. 2 shows a view in side elevation of the lifting device of FIG. 1 provided with a wireless remote control system;  
         [0014]    [0014]FIG. 3 shows a diagrammatic view taken in vertical cross-section through the apparatus of FIG. 1;  
         [0015]    [0015]FIGS. 4 and 5 show a top plan view and an underneath plan view, respectively, of an upper truss arm of the lifting device of FIG. 2;  
         [0016]    [0016]FIG. 5A shows, in perspective, of a broken-away end portion of the truss of FIG. 4;  
         [0017]    [0017]FIG. 6 shows a top plan view of the lower truss arm of the lifting device of FIG. 2;  
         [0018]    [0018]FIG. 7 shows an underneath plan view of the lower truss arm of the lifting device of FIG. 6;  
         [0019]    [0019]FIG. 7A shows, in perspective, of a broken-away end portion of the truss of FIG. 7;  
         [0020]    [0020]FIG. 8 a view of a truss forming an intermediate section of the lifting device of FIG. 2, taken in the direction of the arrow A 1  of FIG. 2;  
         [0021]    [0021]FIG. 9 shows a view of the intermediate section of FIG. 8, taken in the direction of the arrow A 2  of FIG. 2;  
         [0022]    [0022]FIG. 9A shows, in perspective, of a broken-away end portion of the truss of FIG. 8;  
         [0023]    [0023]FIG. 10 shows a view taken in cross-section along the line  10 - 10  of FIG. 2;  
         [0024]    [0024]FIG. 11 shows a view in side elevation of a trolley forming part of the lifting device of FIG. 1;  
         [0025]    [0025]FIG. 12 shows a view in end elevation of the trolley of FIG. 11; and  
         [0026]    [0026]FIG. 13 shows a view in vertical cross-section of some components of the trolley of FIG. 11. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]    In FIG. 1 of the accompanying drawings, there is shown a flying form table truss indicated generally by reference numeral  10 , and a lifting device embodying the present invention, which is indicated generally by reference numeral  12 .  
         [0028]    The flying form table truss  10  is identical to that disclosed and illustrated in the aforesaid U.S. Pat. No. 5,560,160, the disclosure which is incorporated herein by reference, and will therefore not be described in detail herein. This flying form table truss  10  comprises a pair of elongate, laterally spaced, parallel, vertical support structure truss component  14 , only one of which is shown in the drawings, which support, on their tops, a flying form table indicated generally by reference numeral  16 . Each of these support truss components  14  comprises a vertically spaced pair of longitudinal tubular beams  18 , which are interconnected by angled connecting tubes  20 . The support structure truss components  14  are each supported on three screw jacks  22 .  
         [0029]    The lifting device  12 , which is shown in greater detail in FIG. 2, has a horizontal upper truss arm indicated generally by reference numeral  24 , a lower horizontal truss arm indicated generally by reference numeral  26 , which extends below and parallel to the upper truss arm  24 , and a vertical intermediate section, in the form of an intermediate truss arm indicated generally by reference numeral  28 , which as viewed in FIG. 2 interconnects right hand ends of the upper and lower truss arms  24  and  26 , which ends are opposite from free ends of the upper and lower truss arms  24  and  26 .  
         [0030]    The upper truss arm  24 , the cross-section of which is shown in FIG. 3, is of triangular cross-sectional shape and, as shown in FIGS. 4 and 5, has a pair of lower, horizontally spaced tubular beam members  30 , an upper tubular beam member  32  and angled tubes  34  connecting the lower tubular beam members  30  to the upper tubular beam member  32 . The lower tubular beam members  30  are interconnected by tubular transverse braces  36  and by angled tubes  37 .  
         [0031]    An I-beam  38  (FIGS. 1 and 3) extends longitudinally along the top of the tubular beam  32  on the upper truss arm  24 , and a toothed rack  40  is welded to the I-beam  38  along the top of the I-beam  38 . The I-beam  38  and the rack  40 , which to facilitate illustration of the apparatus have been omitted from FIG. 4, form a track for a trolley or carriage indicated generally by reference numeral  42  which, as described in greater detail below, can be driven to and fro along the I-beam  38  and the rack  40  by an electric motor indicated generally by reference numeral  76  (FIG. 11) controlled by a control unit  45  (FIG. 12). The trolley  42  includes a crane hook connector  44  for connection to the hook (not shown) of a crane cable  43  as shown in FIG. 1A, in which a crane is indicated generally by reference numeral  41 .  
         [0032]    The I-beam  38  is provided with markings in the form of numerals  1 ,  2 , etc., which are spaced apart along the I-beam as shown in FIG. 1 and which are sufficiently large as to be remotely visible, i.e. visible by an operator on the ground. These marking facilitate return of the trolley to a previous position after the lifting device  12 , having been removed from and lifted without the flying form table truss  10 , is re-engaged with the flying form table truss  10  to lift it again.  
         [0033]    The lower truss arm  26  is of triangular cross-section, having a pair of horizontally spaced upper tubular beams  44  (FIGS. 3, 6 and  7 ), which are connected by angled tubes  47  and transverse braces  48 , a horizontal lower tubular beam  46  and angled tubes  49  interconnecting the upper tubular beams  44  and the lower tubular beam  46 .  
         [0034]    The vertical intermediate section  28  (FIGS. 3, 8 and  9 ) is also of triangular cross-section and has a pair of parallel tubular beams  50 , connected by transverse braces  51  and angled tubes  52 , a parallel tubular beam and angled tubes  55  connecting the tubular beams  50  to the tubular beam  54 .  
         [0035]    As shown in FIG. 7A, the lower truss arm  26  has a landing arm indicated generally by reference numeral  82 , which is formed by a pair of posts  84  depending from the beams  44  and a cross-member  86  connected to the lower ends of the posts  84  and extending beneath the beam  46 . This landing arm  82  serves to support the lower truss arm  26  against falling sideways when the lower truss arm  26  is lowered onto the ground.  
         [0036]    The intermediate section  28 , as shown in FIGS. 1 and 9A, is provided with a landing arm, indicated generally by reference numeral  86 , which is similar to the landing arm  82  and which is therefore not described in greater detail.  
         [0037]    As shown in FIGS. 1 and 5A, the end of the upper truss arm  24  adjacent the intermediate section  24  is provided with an inclined triangular plate  90 . Two pairs of connecting lugs  92  are provided at the base of the plate  90 , and a projecting spacer  94  is provided at the apex of the triangular plate  90 .  
         [0038]    The lower truss arm  26 , as shown in FIG. 7A, is similarly provided with a triangular plate  96 , two pairs of connecting lugs  28  and a spacer  100 .  
         [0039]    The intermediate section  28 , as shown in FIGS. 1, 8 and  9 A, is provided, at its ends with triangular plates  102  and  103 , which are provided with connecting lugs  104 .  
         [0040]    By interengaging the connecting lugs  104  of the intermediate section  28  with the connecting lugs  92  of the upper truss arm  24  and the connecting lugs  98  of the lower truss arm  26 , and by inserting connecting pins  106  (FIG. 2) through these interengaged lugs to secure them together, the upper and lower truss arms  24  and  28  are secured to the intermediate section  26 . The spacers  94  maintain the triangular plate  90  parallel to the adjacent triangular plate  102  and th triangular plate  96  parallel to the triangular plate  103 .  
         [0041]    The trolley  42  will now be described with reference to FIGS. 11 through 13.  
         [0042]    As shown in FIG. 13, a pair of spaced vertical side plates  62  are provided at opposite sides of, and spaced from, a drive pinion  63 , which meshes with the rack  40 . The drive pinion  63  is fixed on a drive shaft  64 . The crane hook connector  44  is a triangular plate which projects upwardly at the top of the trolley  42  and is a formed near its top with an opening  67  for receiving a crane hook (not shown) on the crane cable  43 .  
         [0043]    The crane hook connector  44  (FIG. 12) is secured to the side plates  62  by nuts  65  threaded on bolts  66  extending through the side walls  26 , with spacer sleeves  67  on the bolts  66 . The side plates  62  are also connected by bolts  64  extending through brackets  69  welded to the side plates  62 , at the front and rear edges of the side plates  62 , and nuts  75  on the bolts  64 .  
         [0044]    Rollers in the form of flanged wheels  68  (FIG. 13) at opposite sides of a web  70  of the I-beam  38 , underlie and are in rolling engagement with downwardly facing rolling surfaces  71  on the I-beam  38 . The rack  40  and the I-beam  38  form a track extending along the upper arm  24 , and the rolling surfaces  71  therefore extend along opposite sides of this track at the undersides of upper flanges  72  of the I-beam  38 . A pair of the wheels  68  are freely rotatably journalled on each of the side plates  60 .  
         [0045]    Rollers  73  (FIG. 12) on the brackets  69  run along the top of the I-beam  38 .  
         [0046]    The drive shaft  64  is the output shaft of a speed reduction gearing, indicated generally by reference numeral  74  in FIGS. 11 and 12, which is mounted on one of the side plates  62  and interconnects the drive pinion  40  and the electric drive motor  76  (FIG. 11)., provided with a spring-loaded disc brake  77 . The trolley  42  is a commercially available trolley manufactures by Norelco Industries Ltd., of Surrey, B.C., Canada and the disc brake  77  is marketed by Danfoss Bauer Ltd., of Mississauga, ON, Canada under Model No. 005 A 09 5 Nm.  
         [0047]    L-shaped brackets  78  secured to opposite vertical edges of the side plates  62  below the I-beam flanges  72  serve as abutments which, on meeting counterabutments in the form of brackets  80  (FIGS. 1 and 2) secured to the web  70  of the I-beam  38  at opposite ends of the I-beam  38 , limit the movement of the trolley  42  along the I-beam  38 .  
         [0048]    In the embodiment of the present invention illustrated in FIG. 1, the trolley  42  is controlled from a hand-held control unit  120  connected by a control cable  122  to the control unit  45 , and the electric drive motor  76  is supplied with electrical power through a power cable  124  extending from the crane  41 .  
         [0049]    Alternatively, as illustrated in FIG. 2, the trolley  42  may be remotely controlled from a wireless control and transmitter unit  126  transmitting control signals to an antenna  1128  mounted on the lifting device  12  and connected to a power supply and control unit  130  on the upper truss arm  24 .May 16, 2003