Abstract:
The invention provides a container crane comprising a frame having a trolley rail along which a trolley travels; said trolley supporting a twin spreader assembly for engaging one or more containers, and; a docking station mounted to said frame; wherein said trolley is arranged to move said twin spreader assembly to the docking station and be placed therein.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to container cranes for the loading and unloading of shipping containers, such as quayside cranes. In particular, the invention relates to the use of twin spreaders on a container crane. 
       BACKGROUND 
       [0002]    The use of twin spreaders is becoming more prevalent so as to increase the rate of movement of shipping containers for loading and unloading. As it is also documented whilst twin spreaders are useful for maximizing capacity, they are not applicable in all instances and so it is important to be able to switch between single and twin spreaders when applicable. Such switching is disclosed in PCT application no. PCT/SG2006/000015 the contents of which are incorporated herein. 
         [0003]    In this document, a flexible arrangement which allows for a twin spreader to be used and then de-coupled to allow for single spreader use in detailed. What is not disclosed is the most efficient way of dealing with the separation of these spreaders and the method of storing said spreaders when not in use. 
         [0004]    A spreader for a 40-foot container and even one extendable for use with a 20-foot container and 40-foot container represents an extremely large piece of equipment which is not easily stored. In a container yard with storage space represents potential opportunities for revenue storing a large piece of equipment like a spreader represents a loss of potential income not to mention logistical issues of being able to provide excess by trucks to a quay crane. Where storage space for equipment is often in non-productive area of a container yard this makes the availability of a spreader to reconnect to form a twin spreader inefficient and a significant detriment from the benefits a twin spreader can provide. 
       SUMMARY OF INVENTION 
       [0005]    In a first aspect, the invention provides a container crane comprising a frame having a trolley rail along which a trolley travels; said trolley supporting a twin spreader assembly for engaging one or more containers, and; a docking station mounted to said frame; wherein said trolley is arranged to move said twin spreader assembly to the docking station and be placed therein. 
         [0006]    In a second aspect, the invention provides a method of operating a container crane, the method comprising the steps of: providing a frame having a rail along which a trolley travels, said trolley supporting a twin spreader assembly for engaging one or more containers; providing a docking station mounted to said frame; moving the trolley along the rail so as to be proximate with the docking station, and; positioning the twin spreader assembly into the docking station. 
         [0007]    Thus a complete solution provided by a combination of a container crane and a docking station mounted directly thereto allows for the twin spreader to access the docking station. It may further allow for the twin spreader to de-couple one spreader for use as a single spreader. The de-coupled spreader may then reside in the docking station in storage until needed again. 
         [0008]    The container crane, and in particular the rail upon which the trolley moves, may have an operational zone within which the trolley operates to engage containers and a maintenance zone for maintenance to the trolley and twin spreader assembly. 
         [0009]    In this embodiment, in the docking station is mounted to the frame proximate to the maintenance zone of said rail. This way, the spreader assembly may undergo maintenance and other activity, in the same way the trolley undergoes maintenance. 
         [0010]    In light of this, it may be advantageous to have the docking station mounted proximate to a maintenance platform of said crane 
         [0011]    In a further embodiment, it may be beneficial to have the docking station move into the operational zone. To this end, the docking station may be movably mounted to the frame such that the docking station is selectively movable from the a position proximate to the maintenance zone to a position proximate to the operational zone 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIGS. 1A and 1B  are elevation views of a container crane system according to one embodiment of the present invention; 
           [0013]      FIGS. 2A and 2B  are elevation views of the container crane system according to  FIGS. 1A and 1B ; 
           [0014]      FIGS. 3A and 3B  are elevation views of the container crane system according to  FIGS. 1A and 1B ; 
           [0015]      FIGS. 4A and 4B  are elevation views of the container crane system according to  FIGS. 1A and 1B ; 
           [0016]      FIGS. 5A and 5B  are elevation views of the container crane system according to  FIGS. 1A and 1B ; 
           [0017]      FIGS. 6A and 6B  are elevation views of the container crane system according to  FIGS. 1A and 1B ; 
           [0018]      FIGS. 7A and 7B  are elevation views of a container crane system according to a further embodiment of the present invention; 
           [0019]      FIGS. 8A and 8B  are elevation views of the container crane system according to  FIGS. 7A and 7B ; 
           [0020]      FIGS. 9A and 9B  are elevation views of the container crane system according to  FIGS. 7A and 7B ; 
           [0021]      FIGS. 10A and 10B  are elevation views of the container crane system according to  FIGS. 7A and 7B ; 
           [0022]      FIGS. 11A and 11B  are elevation views of the container crane system according to  FIGS. 7A and 7B ; 
           [0023]      FIGS. 12A and 12B  are elevation views of the container crane system according to  FIGS. 7A and 7B ; 
           [0024]      FIGS. 13A and 13B  are elevation views of the container crane system according to  FIGS. 7A and 7B , and; 
           [0025]      FIGS. 14A and 14B  are elevation views of the container crane system according to  FIGS. 7A and 7B . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]      FIGS. 1A and 1B  show a container crane, in this case a quayside crane  5  comprising a frame  10  having a twin spreader arrangement  15  supported upon a trolley  20 . The crane operator is located within a cabin  25  which is linked to the trolley  20  and travels  26  along a rail  21  as a single unit. The rail has two zones being an operational zone  16  where the trolley normally operates during the movement of containers, and a maintenance zone  17 , where the trolley is moved so as to undergo maintenance. Mounted proximate to the maintenance zone  17  of the rail  21  of the quayside crane is a docking station  35  mounted to the frame  10  using a docking structure  30 . 
         [0027]      FIGS. 2A and 2B  show the first step of the coupling a twin spreader arrangement  15  whereby the trolley  20  has moved to the maintenance zone  17  of the rail  21  so as to bring the twin spreader  15  proximate to the docking structure  30 . 
         [0028]    The twin spreader assembly  15  includes individual spreaders  40 A,  40 B which in this case involves a master spreader  40 A and a slave spreader  40 B. The two spreaders are so designated because the control systems for connection and manipulation are generally located on the master spreader  40 A with the slave spreader  40 B following the control on the master spreader. 
         [0029]    As shown in  FIGS. 2A and 2B , the respective spreaders  40 A,  40 B are positioned above the docking station  35  and in particular the spreaders located above respective slots  45 A,  45 B within the docking station  35 . 
         [0030]      FIGS. 3A and 3B  show the placement of the spreaders  40 A,  40 B into the respective slots  45 A and  45 B. In this position, the de-coupling procedure can begin.  FIGS. 4A and 4B  show the retraction of the connecting arm  41 , which slides the sheaves and cables  42 B from the slave spreader  40 B onto the headblock of the master spreader  40 A. This leaves the slave spreader  40 B unattached with the master spreader forming a single spreader arrangement. 
         [0031]      FIGS. 5A ,  5 B,  6 A and  6 B show the removal of the single spreader  40 A from the docking station and its movement from the maintenance zone  17  to the operational zone  16 . The de-coupled slave spreader  40 B can now be stored within the docking station and the master spreader removed and brought into action such that the quayside crane now operates in a single spreader mode. 
         [0032]      FIGS. 7A and 7B  show an alternative arrangement of the docking structure  50  whereby the structure  50  is located upon a rail system  55 , such that the docking station  51  is now movably mounted to the frame  10 . To further enhance the efficiency of the system, the docking structure  50 , and so the docking station  51 , maybe moveable upon a dedicated rail  55  so as to bring the docking station within the normal operating range of the quay crane rail  21 . 
         [0033]    In one embodiment, when only one spreader is required, rather than the operator moving the trolley  20  out of the operational zone  16  of the rail  21 , the docking structure  50  can be moved closer and be available to the operator whilst still within a normal operating range. 
         [0034]    In this embodiment, however, the spreader arrangement is moved  19  from the operational zone  16  into the maintenance zone  17 . The docking structure  50  is positioned in a resting zone  18  at the far end of the rail. 
         [0035]    As shown in  FIGS. 8A and 8B  the docking structure may be brought into the maintenance zone  17  from the resting zone  18 . The docking structure  50  moves  56  into position, with  FIGS. 9A and 9B  showing the final position of the docking structure  50  such that the individual spreaders  40 A,  40 B are positioned above the respective slots  60 A,  60 B. 
         [0036]      FIGS. 10A and 10B  show the final position of the twin spreader, similar to that shown in  FIGS. 3A and 3B  whereby the de-coupling procedure can begin.  FIGS. 11 to 14  show the completion of de-coupling, and the removal of the master spreader back into the operational zone  16  ready for single spreader use. 
         [0037]    The docking structure  50  is then moved  70  back to its original position in the resting zone  18 , outside the normal operating range of the trolley taking the slave spreader  60 B with it, until a twin spreader arrangement is required, or if the master spreader needs to be stored or undergo maintenance. Under each of these scenarios, the docking structure can then be returned to the maintenance zone  17  for the appropriate action.