Abstract:
A trolley assembly ( 200 ) comprising means for supporting a spreader assembly ( 300 ), said means including cables ( 20 ), said spreader assembly ( 300 ) adapted to engage at least one freight device; a first carrier portion and a second carrier portion; the supporting means adapted to connect the spreader assembly ( 300 ) to at least one of said carrier portions and; a trolley separation means for selectively varying the relative position of the first and second carrier portions wherein the adjustment of the trolley separation means is such that the cables ( 20 ) are maintained in a substantially vertical orientation.

Description:
FIELD OF THE INVENTION 
     The invention relates to apparatus, such as hoists and spreaders, required for manipulating freight devices, for example shipping containers and flat racks. Further, the apparatus of the present invention is applicable to the manipulation of multiple freight devices simultaneously. 
     BACKGROUND OF THE INVENTION 
     To increase the economic viability of transporting freight, port authorities invest significant capital into infrastructure to facilitate the efficient loading and unloading of containers from ships at dock. The infrastructure is geared to move said containers to storage facilities ready for delivery via land transport or directly from ships to the land transport. 
     Recently, to increase efficiency and therefore economic viability, inventions facilitating the movement of several containers simultaneously have been developed. One such invention is disclosed in WO 01/98195, the contents of which are incorporated herein by reference. This invention incorporates a spreader having connection to two container engagement frames, which may engage with one or two containers. It follows that this will immediately increase the rate for which a ship may be loaded or unloaded, and therefore the efficiency of the process. 
     A disadvantage of this invention is the connectivity between the spreader and engagement frames. As shown in the various figures of WO 01/98195, the engagement frames are connected to the spreader either by chains or pin-jointed tie rods. 
     If this arrangement were to pick up one container only or two containers of substantially varying weights, then a redistribution of the weight would lead to the spreader listing to one side due to the unbalanced force. Thus, this arrangement is restricted to lifting containers of substantially similar weights. In the loading and unloading procedure however, the only time an operator will be assured of lifting two containers of similar weight will be when the containers are empty. Thus whilst this invention is useful in moving multiple containers, in a practical sense, it may be restricted to the safe movement of empty containers only. 
     This development has been built on by the invention of WO 03/104132, the contents of which are incorporated herein by reference. This invention is an improvement over first in that the connection between the spreader and the container engagement frames is releasably fixed, so removing the degrees of freedom inherent with the use of the chain or pin-jointed tie rods of the previous invention. Further, to prevent the spreader frames from listing, the invention WO 03/104132 provides a hydraulically powered assembly capable of separating the engagement frames, so that adjacent containers do not interfere with each other and are therefore held in a fixed relation to each other. This has the advantage of maintaining a degree of control over the load, which is not possible with the invention of WO 01/98195. 
     Nevertheless, the invention of WO 03/104132 is still subject to existing infrastructure and therefore any imbalance of load through a mismatch of weights of the lifted containers may lead to the same rotation at the point at which the cables engaging the spreader to the hoist are joined. Thus whilst the spreader and engagement frames are stable, the cable would still permit rotation as the unbalanced load is redistributed. As with the previous invention, the redistribution and consequential rotation of the spreader frame may lead to difficulties in placing the containers either on the dock or on a ship. 
     It would be advantageous to have a system whereby containers having a weight differential can be lifted without suffering the detrimental effects of a redistribution of load. 
     SUMMARY OF INVENTION 
     It is therefore an object of the present invention to minimize rotation of the spreader or engagement frames through a load redistribution when lifting containers of differing weight. 
     In a first aspect, the invention provides a trolley assembly comprising means for supporting a spreader assembly, said means including cables, said spreader assembly adapted to engage at least one freight device; a first carrier portion and a second carrier portion; the supporting means adapted to connect the spreader assembly to at least one of said carrier portions and a trolley separation means for selectively varying the relative position of the first and second carrier portions wherein the adjustment of the trolley separation means is such that the cables are maintained in a substantially vertical orientation. 
     In a preferred embodiment, the first and second carrier portions may be discreet trolleys, which may be in rolling engagement with a rail or a crane beam. In a more preferred embodiment, the first and second carrier portions being trolleys may be connected to each other via the trolley separation means. In a most preferred embodiment, the trolley separation means may be one or more actuators, which are capable of selective separation of the trolleys by extension of actuating rams. 
     In an alternative embodiment, the first and second carrier portions may be sheaves mounted within a single trolley. One or both of the carrier portions may therefore be in sliding engagement with the single trolley such that separation of the carrier portions is achieved through sliding the sheaves to the desired position. 
     In a preferred embodiment, the supporting means may be an arrangement of pulleys and sheaves together with a cable set, arranged on the trolley and the spreader assembly whereby the spreader assembly is suspended from the carrier portions by the cables. 
     The cable set may be a plurality of cables whereby the first plurality of cables is connected to a hoist at one end and a first engagement portion at an opposed end, said cables passing through the carrier portion and directing downwards to the engagement portion. Correspondingly the second plurality of cables may span from a second hoist to the second engagement portion via the second carrier portion. 
     Thus, the load carried by the first engagement portion is passed directly to the first carrier, and accordingly the load carried by the second engagement portion is passed to the second carrier portion. Rather than a redistribution of weight about a single cable set suspended from a single trolley, the trolley arrangement for the present invention acts as two distinct trolleys maintaining the cables in a vertical arrangement. The present invention has all the advantages of a unitary structure by maintaining the engagement portions and carrier portions in respective and selectably fixed relation through the separation means. Thus, movement of the containers becomes a single action despite the load bearing arrangement, being in a relatively discreet arrangement. 
     In a second aspect, the invention provides a hoist mechanism for controlling the vertical motion of a duel spreader assembly, said assembly having at least first and second spreader units, said hoist mechanism comprising a hoist drum, a first cable set connecting the first spreader unit to the hoist drum; a second cable set connecting the second spreader unit to the hoist drum, wherein activation of the hoist mechanism causes the hoist drum to rotate, to lift or lower the first and second spreader units simultaneously. 
     Thus, by eliminating the need for a second hoist drum, firstly this has the advantage of not requiring synchronization between hoists operating on the associated spreader units. More importantly, however, there is significant saving in infrastructure in that the cost saving involved with a second hoist drum, a gearbox and cables is substantial. 
     In a preferred embodiment, the hoist drum may be mounted to a fixed structure such as a fixed crane. Thus, cables projecting from the hoist drum may be directed horizontally, then directed downward from the trolley. In an alternative embodiment, the hoist drum may be mounted directly to the trolley and therefore projecting cables vertically downward such that the spreader assembly is directly supported by the hoist. 
     In a third aspect, the invention provides a hoisting system comprising a hoisting means, a spreader assembly, a cable termination assembly and a cable connected at a first end to the hoisting means and connected at an opposed second end to the cable termination assembly. Said spreader assembly engaged with said cables intermediate the hoisting means and termination assembly such that the vertical position of the spreader assembly is determined by activation of the hoisting means, wherein at least one of said cables is connected to the termination assembly via at least one trimming actuator such that the relative position of said at least one cable is selectively adjustable on activation of the trimming actuator and consequently adjusting the orientation of the spreader assembly. 
     It is recognized that a shortcoming of the prior art relating to duel spreader arrangements is the ability to handle the plurality of containers in an individual manner. Whilst in an ideal situation, the freight devices or containers may be positioned on flat ground, perfectly parallel to each other and delivered in an identical orientation, this will not always be the case. The containers may be of different sizes, located on a slope or maybe delivered it to the deck of a listing ship. Thus there will be circumstances when it will be necessary to treat the containers as individual items whilst still maintaining the need to transport them simultaneously. Thus the present invention provides a means by which the orientation of one spreader unit may be adjusted relative to a second spreader unit. This adjustment may be in terms of any one or a combination of relative longitudinal offset, relative inclination in the vertical plane, inclination of both spreader units in the vertical plane, longitudinally and transversely. 
     In a preferred embodiment, each of the cables within the hoisting system may include a trimming actuator whereby adjustment of the relative position of the spreader units is provided for three rotational degrees of freedom and one translational degree of freedom, being vertical position. 
     In a fourth aspect, the invention provides a trimming assembly engaged with a hoisting, system for adjusting the height of a portion of a head frame engaged by said hoisting system, said hoisting system comprising a hoist and a plurality of cables passing from the hoist to the head frame; 
     the trimming assembly comprising 
     at least one trimming cylinder in communication with at least one of said cables; 
     wherein activation of the trimming cylinder lengthens or shortens the path followed by the at least one cable, said lengthening or shortening causing a raising or lower of the portion of the head frame. 
    
    
     
       DESCRIPTION OF PREFERRED EMBODIMENT 
       It will be convenient to further describe the present invention with respective to the accompanying drawings which illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the proceeding description of the invention. 
         FIG. 1  is an isometric view of the hoist mechanism according to one embodiment of the present invention; 
         FIG. 2  is a schematic view of the operation of the single hoist according to another embodiment of the present invention; 
         FIG. 3  is a schematic elevation view of the trimming cylinders according to another embodiment of the present invention; 
         FIG. 4  is an isometric view of the split trolley according to another embodiment of the present invention; 
         FIG. 5  is an isometric view of the duel spreader assembly according to an embodiment of the present invention. 
         FIG. 6  is an elevation view of the hoist mechanism according to a further embodiment of the present invention. 
         FIG. 7  is an isometric view of the trimming cylinders according to a further embodiment of the present invention. 
     
    
    
       FIG. 1  shows the hoist mechanism  5  mountable within a fixed structure (not shown). 
     In broad terms, the hoist mechanism  5  according to this embodiment, comprises a single hoist drum  100 , a split trolley  200 , a duel spreader assembly  300  and an end block assembly  400 . 
     Cables running continuously from the hoist drum  100  to the end block assembly  400  pass through the split trolley  200  and are directed downwards to engage the spreader assembly  300  and terminate at the end block assembly  400 . Thus, rotation of the hoist drum  100 , with the end assembly  400  being essentially fixed, will cause the duel spreader assembly  300  to lift or lower a load attached to this spreader assembly  300 . 
       FIG. 2  shows a schematic view of the operation of the single hoist  100 . In this embodiment, the single hoist comprises a single drum  105  to which cables  10   a,c  for the first carrier assembly  110   a  are attached. Further, a second cable set  10   b,d  also are attached to the single hoist drum  105  and engage the second carrier assembly  110   b . Both cable sets  10   a,b  and  10   b,d  terminate at the end block assembly  400 , which provides a substantially fixed point. 
     Hoist systems of the prior art, for a duel carrier arrangement, will provide two hoist drums, each operating with a single carrier assembly. Thus lifting and lowering of the freight devices attached to the carrier assemblies require synchronization of the two hoist drums to ensure the containers are lifted and lowered at the same rate and from the same position. Whilst a small differential may be accommodated, it is still a technically difficult exercise to synchronize these distinct hoists. 
     This is where the single hoist system according to one aspect of the present invention is of particular advantage. For the manipulation of two or more freight devices, it follows that the loads will travel at the same rate, both vertically and horizontally, and so permit the use of a single hoist drum  105 . By connecting two sets of cables  10   a,c  and  10   b,d , rotation  125  of the single hoist drum  105  will operate both cable sets  10   a,c  and  10   b,d  simultaneously, which will respectively cause both of the carrier assemblies  110   a,b , to move  130   a,b  at the same rate. Thus, so long as the pick-up point of the freight devices for each of the carrier assemblies  110   a  and  110   b  is the same, then it follows that there will be little or no differential between the position of the containers when they are lifted and lowered. 
       FIGS. 1 and 3  also shows the end block assembly  400  according to a further aspect of the present invention. The end block assembly  400  comprises an anchor block  403 , which is fixed to the fixed structure (not shown). Any suitable anchor block  403  will suffice for the present invention so long as it is capable of carrying the loads applied by the cable ends and also accommodating trimming cylinders  405   a,b  which connect the cable ends to the anchor block  403 . The trimming cylinders  405   a,b  may be hydraulically, pneumatically or electrically operated, so long as they are capable of firstly, holding the cable ends in a fixed position resisting the applied loads and when in use, being able to adjust the position of the cable end for any of the activated trimming cylinders  405   a,b.    
     To demonstrate the effect of the trimming cylinders, an example is shown in  FIG. 3 , whereby a trimming cylinder  405   b  is associated with a second carrier assembly  110   b . Extending the ram of the trimming cylinder  405   b  has the effect of extending the length of relevant cable  10   b,d . This has a consequential effect on the position of the second spreader assembly  120   b  by lowering  410  the load carried by the second spreader assembly  120   b . Thus, whilst the single hoist  100  operates to maintain the loads in the same position relative to each other, the trimming cylinders  405   a,b  of the end block assembly  400  operate to make incremental adjustments of the relative position of the loads. 
     Thus, if two freight devices, such as shipping containers, are to be lifted from a ship that may be listing, or from a truck positioned on a slope, then the containers may be engaged and lifted simultaneously by “trimming” the position of each of the spreaders to accommodate the different positions of the containers. On engaging and lifting the containers, the relative position may be adjusted again by the trimming cylinders  405   a,b  to match the conditions of the ground, ship or truck to which the containers will be moved. 
       FIG. 4  shows a duel spreader assembly  300  according to a further aspect of the present invention. Whilst the present invention is useful for single spreader hoist systems, many of the inventive features are particularly useful where a duel spreader is incorporated. To this end, the duel spreader assembly  300  according to one aspect of the present invention is provided to be suspended from a trolley carrier unit for instance the split trolley  200  according to another aspect of the present invention. 
     The duel spreader assembly  300  comprises an upper head frame  305   a,b  mounted to cables  307  projecting from the trolley carrier above. The cables engage with the head frames  305   a,b  through pulleys  308  which permit the cables  307  to pass continuously through. The head frames  305   a,b  are respectively mounted to spreader frames  310   a,b . The spreader frames  310   a,b  are modified in comparison with existing spreader frames in that they include a conventional attachment, such as twist lock, at peripheral corners  330  and, at internal corners  335  of the spreader frames. Thus, the spreader frames  310   a,b  may act individually so that each is attached to a single freight device or alternatively, the spreader frames may be drawn together and connected so as to act as a single spreader frame engaging a single freight device. 
     The adapted spreader frames  310   a,b  are mounted to the head frames  305   a,b  through shear pins  320   a  to  d . Whilst it is possible to mount connection, such as twist blocks, to the header frames  305   a,b  to engage with the spreader frames  310   a,b , the nature of this connection is such that a rapid engagement is not required and can conveniently be done on the ground prior to use. Thus, the use of shear pins  320   a  to  d  provide a convenient and simple means to mount the spreader frames to the head frames. Typically, shear pins of 100 mm diameter can be used, but this will be subject to the loads for which the apparatus is rated, which will be clear to the skilled addressee in the circumstances. 
     A challenge for duel spreader frames of the prior art is how to cope with clearance of adjacent containers held by the duel spreader frames. In the case of the present invention, there are provided in this embodiment, hydraulic actuators  315   a,b,c  located on the head frames  305   a,b . The actuators  315   a,b,c  are arranged to have two outer actuators  315   a,c  acting perpendicular to the major axis of the spreader units and a third inner actuator  315   b  acting within the same plane as the outer actuators  315   a,c , but inclined to the spreader frame main axis. This particular combination of actuators permits a variable range of orientations of the spreader frames to accommodate the different positions of containers to be lifted or lowered. It is recognized that it will not be in every case that containers will be located on flat ground and perfectly square to each other. In situations where the containers are offset or at inclined angles to each other, that the duel spreader assembly  300  according to the present invention, will still be capable of engaging and lifting said containers. 
     For instance where the containers are offset from one another by activating the internal actuator  315   b , the spreader frames will move in opposed directions, co-linear with their major axis, that is one forward and one back. 
     Alternatively, if the major axes of the containers are inclined to each other, so too must the spreader frames be oriented. In this case, the internal actuator  315   b  will be free to move and the first and second outer actuators  315   a,c  differentially activated so as to rotate the spreader frames relative to each other until the desired inclined orientation is achieved. 
     These movements are based upon the spreader frames remaining in the same plane. If, however, the spreader frames need to be outside of a common plane, this may be accommodated according to this embodiment of the present invention. Circumstances where it may be necessary to use the spreader frames in different planes include when containers of different heights must be lifted or where the containers are on a slope, such as for a truck on an incline, or from a ship deck listing to one side. In this case, the portions of the head frames  305   a,b  to which the actuators  315   a,b,c  are attached, are in fact rotatable  325   a,b . Thus, by releasing a brake on the rotatability of these portions  325   a,b , the spreader frames can be hoisted at different heights with the actuators acting to maintain and adjust these height differences. 
     It should be noted that in a further aspect of the present invention, the trimming cylinders of the end block assembly  400  may be used to adjust the height of the spreader frames  310   a,b  so further adding to the flexibility of this embodiment of the present invention. 
       FIG. 5  shows a split trolley  200  according to one aspect of the present invention. Whereas conventional hoisting systems will have a unitary carrier acting as the trolley from which the spreader assembly will be suspended, the present invention in this embodiment provides for two discreet carriers  205   a,b  linked by actuators  210   a,b . The split trolley according to this embodiment is particularly suited for use with a duel spreader arrangement. In such an arrangement whereby spreader frames will separate so as to accommodate side by side containers, trolley carriers according to the prior art are in fixed relation. Therefore as the spreader frames separate, the cables from which the spreader frames suspend will become more and more inclined, leading to greater tension in the cables to accommodate this angle. In the present invention, the actuators  210   a,b  are activated so to separate the discreet carriers  205   a,b  to a position corresponding to the separation of the duel spreader frames such that the cables become substantially vertical. 
     Whilst the trolley units  205   a,b  are discreet units, said carriers are nevertheless linked through the actuators  210   a,b . Thus, movement of the trolley as a whole unit need only rely upon one of said carriers  205   a  to have a motor such that the trolley will run along the crane rails of the fixed structure. To this end the split trolley  200  is in fact divided into a master trolley  205   a  and a slave  205   b , whereby the master trolley  205   a  is motorized having a motor of sufficient capacity to also drive the slave unit. 
       FIG. 6  shows a further embodiment of the present invention, whereby the split trolley involves movable sheaves  355 ,  360 ,  365  within a single trolley carrier  350 . As with previous embodiments, the arrangement includes a trolley  350  from which is suspended, using cables  367 ,  370 ,  375 , a spreader assembly  380 . 
     In the embodiment, a first position of one carrier  365  is shown whereby the corresponding cables  375  are inclined, and so increasing the applied load. The second carrier  355  has cables  367  in the desired position, being substantially vertical, and hence it is desirable to move the first carrier  365  so as to have these corresponding cables  375  also vertical. 
     Hence, the first carrier  365  is moved  385  to a position  360 , whereby the cables are now substantially vertical and thus reducing the load in the cables, and otherwise benefiting from the more desired arrangement. 
     As a further alternative arrangement,  FIG. 7  shows an embodiment of the trimming cylinders  500 . In this arrangement, a hoist drum  510 , controls cables  505   a  to  d . The cables pass through sheaves before progressing to a trolley and head frame (not shown). The intent of trimming cylinders is to vary the length of cables either individually or collectively. In the previous embodiment, this was achieved by extending an in-line cylinder. In this embodiment, the lengthening comes from decreasing the path through which the cable passes. Specifically, the trimming cylinders  520   a  to  d  bear directly on the sheaves  515   a  to  d , and in fact, do not contact the cable. The sheaves  515   a  to  d  are movable subject to the force applied by the cylinders  520   a  to  d . Thus, by retracting the cylinder, the sheaves  515   a  to  d  move  525   a  to  d  accordingly. By moving inwards, the path followed by the cables  505   a  to  d  is shortened, leading to the corresponding portion of the head frame lowering relative to the non-affected cables. Conversely, by extending the cylinder, the sheaves are moved in the other direction, lengthening the path, leading to the corresponding portion of the head frame lifting relative to the remaining portions.