Abstract:
A lifting beam is provided. The lifting beam includes a lower beam and an upper beam arranged above the lower beam; an arranger for arranging the beams in close and releasable engagement with one another; and systems for gripping the load. The gripping systems are kept in an open position when the beams are in engagement with one another, and in a closed position when an engager is released.

Description:
The invention relates to the field of lifting devices, more particularly in gripping systems used in lifting beams. 
     BACKGROUND 
     Lifting beams are intended to carry cumbersome and heavy loads. They should ensure safety of the load and of the operators. However, present safety systems are generally active, i.e. they require the active participation of an operator and this safety system is therefore subject to a risk of human error. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a lifting beam device suitable for solving all or part of the problems mentioned above, notably for ensuring maximum passive safety. 
     A lifting beam device for lifting and/or displacing a load is provided that comprises:
         a lower beam positioned longitudinally;   an upper beam positioned longitudinally above said lower beam;   means for allowing vertical sliding of said beams one relative to the other;   means for arranging the beams in close and releasable engagement with one another; and,   at the longitudinal ends of said lifting beam device, one of the gripping systems for gripping said load,
 
said gripping means
   being maintained in an open position when said beams are engaged with each other,   assuming a closed position when the engagement means are released.       

     The means for arranging the beams in close and releasable engagement with one another advantageously comprise a quarter-turn device rigidly attached to one of the beams and comprising a gib formed with a free end, said gib being provided for engaging with an oblong window of the other beam. 
     In a first embodiment, each longitudinal end of the lower beam bears a transverse girder, a gripping system being jointed in rotation around a longitudinal axis, at each of the ends of said girder, each gripping system comprising:
         a proximal portion, forming a counterweight;   a distal portion forming means for engaging the load, preferably hook-shaped; and,   a sling attached through a first end to the counterweight and through a second end to the upper beam,
 
the sling being dimensioned so as to be tensioned in the closed position and relaxed in the open position.
       

     In a second embodiment, each of the longitudinal ends of the device comprises a gripping system, each of the systems comprising:
         a slide attached to one of the beams, preferably to the lower beam and slidably mounted vertically with respect to the other beam, preferably the upper beam;   a guide forming a guiding rail for a first end of each fixed arm relatively to the other beam;   two arms ( 62 ) symmetrically mounted with respect to each other relatively to a vertical longitudinal plane (P 60 ),   a first end of each arm being provided, guided by said rail;   a preferably hook-shaped second end of each arm forming engagement means for the load;   each arm being jointed in an intermediate point in rotation relatively to said slide, the rail comprising a guiding area designed so as to have the arms swing between an open position and a closed position, when the slide slides relatively to the other beam. Advantageously, the rail comprises another guiding area in which the arm is maintained in its closed position.       

    
    
     
       BRIEF SUMMARY OF THE DRAWINGS 
       Embodiments and alternatives will be described hereafter, as non-limiting examples, with reference to the appended drawings wherein: 
         FIG. 1  is a perspective view of a first embodiment for a lifting beam according to the invention, positioned in an open position on a tank to be displaced; 
         FIG. 2  is a perspective view of a second embodiment for a lifting beam according to the invention, illustrated alone; 
         FIG. 3  is a view of a gripping device, illustrated open, for the lifting beam of  FIG. 1 ; 
         FIG. 4  is a view of a gripping device of  FIG. 3 , illustrated closed, engaged with the tank; 
         FIG. 5  is a view of a gripping device, illustrated open, for the lifting beam of  FIG. 2 ; 
         FIG. 6  is a view of a gripping device of  FIG. 5 , illustrated closed; 
         FIG. 7  is a detailed view of  FIG. 6 , illustrating a safety system; 
         FIG. 8  is a general view of a quarter-turn device for a lifting beam according to an embodiment of the invention, in a locked position; 
         FIG. 9  illustrates the quarter-turn device of  FIG. 8 , in isolation, in a partial sectional view; and, 
         FIG. 10  is a detailed view of  FIG. 9 , illustrating the operation of the quarter-turn device. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a first embodiment for a lifting beam  10  according to the invention. 
     The lifting beam  10  is substantially symmetrical with respect to a vertical longitudinal plane P 10 ; it is also symmetrical with respect to a transverse vertical plane, perpendicular to the longitudinal plane of symmetry P 10 . 
     The lifting beam  10  comprises a lower beam  11  and an upper beam  12 . The beams  11 ,  12  are box girders; they extend longitudinally substantially over the whole length of the lifting beam, one  12  above the other  11 ; they are substantially parallel with each other. Each end  13  of the lower beam  11  bears a transverse girder  14  comprising two plate-formed cheeks  15 , longitudinally separated from each other by an interval  16 . A gripping system  17  is jointed in rotation around a longitudinal axis X 17 , at each of the ends  18  of the girder  14 . 
     The lifting beam  10  is handled by lifting means schematized in the figures by an arrow V; these lifting means may be a crane or a bridge crane, they are attached to the upper beam  12  by a hook and/or lifting slings. 
     As particularly illustrated in  FIGS. 3 and 4 , the gripping system  17  comprises a proximal portion, relatively to the longitudinal plane of symmetry P 1 , forming a counterweight  21 , and, a distal portion forming a hook  22 . In the example of  FIG. 1 , the lifting beam  10  is used for lifting a tank  23 . The tank  23  is equipped with vertical reinforcement plates  24  in which apertures  25  are made. Each hook  17  is provided for engaging with a respective aperture  25 . The upper beam  12  comprises an eyelet  26  extending transversely substantially above each counterweight  21 . A respective sling  27  is attached through a first end to the counterweight  21  and through a second end to the eyelet  26 . 
     The lifting beam  10  further comprises means  30  for having the upper beam  12  and the lower beam  11  engaged with each other. It also comprises, in the vicinity of each of its ends, a guide  31 , designed for ensuring vertical guiding of one of the beams  11 ,  12  relatively to other  12 ,  11 . 
     As particularly illustrated in  FIGS. 8 to 10 , in the described examples, the engagement means  30  comprise a so-called &lt;&lt;quarter-turn&gt;&gt; device  31  extending downwards from the upper beam  12  and provided for engaging with an oblong window formed in an upper footing  33  of the lower beam  11 . 
     The quarter-turn device  31  notably comprises a slide  34 , lower teeth  35  and upper teeth  36 . Each set of teeth  35 ,  36  is formed on the edge of a respective hollow cylinder  37 ,  38 ; the cylinders are positioned coaxially so that the teeth are opposite to each other. Each tooth  39  comprises, along a direction of rotation, identical for both teeth, a vertical front  41  and then a slope  43  surrounding a tip  42 . The set of teeth are positioned so that the tip of a tooth  39  of one of them is facing the slope of a tooth of the other set of teeth. The cylinders bearing the sets of teeth are mounted set in a cylindrical sleeve  40  and form together with this sleeve a fixed portion, relatively to the upper beam  12 , of the quarter-turn device. 
     The slide  34  is provided for axially sliding in the cylinders  37 ,  38  bearing the sets of teeth  35 ,  36 . Its lower end is formed by a gib  51 , of oblong shape, provided for cooperating with an oblong window  32  of the lower beam  11 . Beyond the gib  51 , from bottom to top, the slide comprises a cylindrical pin  52 , a disc-shaped abutment  53 , and then a cylindrical rod  54  slidably mounted in the cylinders bearing the sets of teeth. The slide further comprises a key  55  which extends radially from the rod  54 . The slide thus forms a movable axis able to move upwards and downwards in the fixed portion  37 ,  38 ,  40 . 
     The oblong shape of the gib  51  is such that:
         when it is positioned longitudinally, it may cross the window  32  of the lower beam and,   when it is positioned transversely, as illustrated in  FIG. 8 , it cannot cross the window  32  of the lower beam.       

     The diameter D 52  of the pin  52  is such that the pin may slide in the window  32  of the lower beam  11 . The diameter D 53  of the abutment  53  is greater than the width L 32  of the window  32  of the lower beam  11 , so that the slide  34  cannot penetrate into the beam beyond the pin  52 . 
       FIG. 10  illustrates the operation of the quarter-turn device  30 , by assuming that the device is in a so-called locked position illustrated in  FIG. 8 . In this locked position, the gib  51  is in a transverse position inside the lower beam  11 ; thus, the upper beam  12 , which bears the quarter-turn device, is engaged with the lower beam  11 . The distance LP between the beams is then a first value LP=LP 1 . The key  55  is in a position  55 A, between two teeth of the upper set of teeth  36 . As illustrated in  FIGS. 1 and 3 , the slings  27  are relaxed; the gripping system is in an open position; it remains there as long as the beams  11 ,  12  remain engaged with each other by means of the quarter-turn device. 
     When the lifting means V lift the upper beam  12 , the fixed portion  37 ,  38 ,  40  moves upwards with the upper beam, until the key assumes a position  55 B in contact with the lower set of teeth  35 , at the top of the slope  43  which faces the position  55 A. The pressure exerted by the key  55  on the lower set of teeth, while the upper beam continues its movement upwards, causes displacement of the key, until it assumes a position  55 C, in abutment against a front  41  of the next tooth, at the same time forcing the slide  34  to rotate by an eighth of a turn in the fixed portion. 
     The lifting means V then causing the upper beam  12  to then move down again, the fixed portion  37 ,  38 ,  40  moves downwards with the upper beam while the disc  53  will bear against the lower beam, until the key assumes a position  55 D in contact with the upper set of teeth  36 , at the bottom of the slope  43  which is facing the position  55 C. The pressure exerted by the key  55  on the upper set of teeth, while the upper beam continues its movement downwards, causes displacement of the key, until it assumes a position  55 E, in abutment against a front  41  of the next tooth, at the same time forcing the slide  34  to rotate by an additional eighth of a turn in the fixed portion. 
     Thus, by successively moving upwards and downwards the upper beam it is possible to cause the slide  34  to perform a quarter of a turn, so that the gib is found in a longitudinal position; by raising again the upper beam it is possible to release the gib of the lower beam. The lifting beam  10  may then assume an unlocked position, illustrated in  FIG. 4 , in which the slings  27  are tensioned, driving the counterweights  21  upwards and engaging the hooks  22  into the apertures  25  provided for this purpose in the load  23 . The distance LD between the beams  11 ,  12  then assumes a second value LD=LD 2 , greater than the first distance LD 1 ; the gripping system is in a closed position. 
     When the load is deposited, it is sufficient to cause once again successive upward and downward movements of the upper beam  12  so as to first have the gib penetrate into the window  32  and to have it accomplish again a quarter of a turn. The slings are then relaxed, the hooks  22  swing outwards under the action of their respective counterweights  21 ; the hooks are open and release their engagement with the load. The lifting beam may then be removed leaving the load where it has been deposited. 
     It is noted that each end of the transverse girders  14  comprises a ring  59  for hooking up thereon a rope or a pole, in order to ensure the horizontal positioning of the lifting beam. 
     The method therefore consists in the following steps:
         The lifting beam is first of all brought above the equipment to be handled, here the load which is a tank, for example via a bridge crane and positioned above the load by an operator, for example by means of a pole; and then,   the lifting beam assembly then bears upon the equipment to be handled so as to be released from the quarter-turn system so as to be in an open position which allows, during lifting, tensioning of the slings and consequently obtaining the closing of the gripping system; and then,   the assembly is then lifted and displaced as far as the area provided for depositing thereon the load; and then,   during the deposition of the load, the lifting beam assembly returns for being supported on the latter so as to again be locked in the quarter-turn system and therefore to return to the &lt;&lt;high&gt;&gt; position. It is this return to the high position which has the consequence of relaxing the slings and therefore opening the gripping system, which allows extraction of the lifting beam.       

     A second embodiment of a lifting beam according to the invention will now be described with reference to  FIGS. 2 and 5 to 7 , in that it differs from the first embodiment described earlier. 
       FIG. 2  illustrates a lifting beam  60  which differs from the first embodiment essentially because these gripping systems  61  are cam systems and not with slings. The gripping systems and their operation are illustrated in detail in  FIGS. 5 to 6 .  FIG. 5  illustrates one of the gripping systems  61  in an open position;  FIG. 6  illustrates the same system in a closed position. 
     In this embodiment, the gripping system notably comprises two arms  62  and a slide  63  and a guide  64 . Both arms  62  are positioned symmetrically to each other relatively to the longitudinal plane of symmetry P 60  of the lifting beam  60 . This plane P 60  is the equivalent of the plane P 10  of the lifting beam  10  of the first embodiment. 
     The guide  64  is rigidly attached to the upper beam  12 ; it comprises two rails  64  symmetrical to each other relatively to the longitudinal plane P 60  of symmetry of the lifting beam  60 . As particularly illustrated in  FIG. 7 , each rail  64  comprises, from top to bottom, a first area  641 , substantially vertical, a second area  642  gradually moving away from the plane of symmetry P 60 , and a third area  643 , substantially vertical. 
     The slide  60  is designed so as to vertically slide relatively to the upper beam  12 . In the lower portion, the slide is rigidly attached to the lower beam  11 , so that it slides downwards relatively to the upper beam when the lower beam  11  moves away from the upper beam  12 , and, slides upwards relatively to the upper beam when the lower beam  11  moves closer to it. 
     Each arm  62  comprises a first end  621  provided for covering while being guided thereon, a respective rail  64 . In the illustrated example, the rail has the shape of a window and the end comprises a roller mounted so as to roll along the edges of this window. A second end  622  of the arm  62  comprises a hook shape, adapted so as to engage with a load to be lifted and moved. An intermediate point  623  of the arm is jointed with the slide  63 , around a horizontal axis X 623 . The slide imposes a fixed distance D 623  between this intermediate point and the intermediate point  623  of the other arm  62 . 
     In the open position, illustrated in  FIG. 5 , the first end  621  is in the first area  641  of the rail  64 , so that this first end is close to the first end  641  of the other arm  62 . When the slide  63  slides downwards relatively to the upper beam  12 , the first end  621  of the arms first covers the first area  641  which corresponds to a first vertical travel C 1 . They then cover the second area  642 , covering a second vertical aperture travel C 2 . During the covering of the second area, both first ends gradually move away from each other; this moving away causes rotation of the arms around their respective intermediate point  623 , and therefore the second ends  622  move closer to each other. Thus, when they attain the third area  643 , the second ends are moved away from each other, the hooks are at a reduced distance D 622  from each other, and the gripping device is in the closed position illustrated in  FIG. 6 . 
     When the first ends  621  cover the third area  643 , the distance D 622  between the hook  622  remains constant, all along a third vertical travel C 3 . Thus, when the gripping device is in its closed position, the third travel C 3  forms a safety travel; i.e. if the load or the lifting beam are subject to an impact which would tend to bring both beams  11 ,  12 , closer together, the gripping device remains in a closed position as long as the first ends remain in the third area  643 . 
     Thus, this avoids immediate opening of the gripping system  61  during an impact, the opening and the closing of the latter being accomplished via a guide  63  which gives the possibility of obtaining a safety travel C 3  which, even in the case of an impact, prevents the opening of the gripping system. 
     Further, the advantage of this guiding system with a cam is also the fact that it provides firm attachment of the elements of the gripping system as well as a significant reduction in the frictional stresses which consequently are negligible. This has the consequence of complete and secured alternation of the gripping system. 
     Of course, the invention is not limited to the examples which have just been described. 
     Thus, in a closed position, provision may be made so that the hooks are further away from each other than in the open position, the hooks being provided turned oppositely to each other.