Abstract:
Containers are transported by movement of upper and lower trolleys along vertically spaced travel paths established by laterally spaced rails formed in a boom supported in a horizontal position by suspension cables attached to a frame assembly through which the boom extends horizontally between container receiving and delivery locations.

Description:
STATEMENT OF GOVERNMENT INTEREST 
   The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore. 

   The present invention relates to guided transport of containers between adjacent locations, such as land-based trucks and dockside moored sea vessels. 
   BACKGROUND OF THE INVENTION 
   Current methods and apparatus for transport of containers between ships at port and land-based dockside locations involve use of typical marine terminal cranes having a single rail guided trolleys on a boom extending between such container receiving and delivery locations. Such container transport cranes have facilities involving factors which limit transport rapidity and efficiency with respect to containers. It is therefore an important object of the present invention to provide for more efficient container crane loading and unloading of sea vessels to avoid port traffic delays. 
   SUMMARY OF THE INVENTION 
   Pursuant to the present invention, containers are loaded onto and removed from two trolleys of a single crane to double the rate of container transfer. Such trolleys are respectively guided along upper and lower travel paths vertically spaced from each other along a horizontal crane boom suspended by cables anchored to the upper end of the crane support frame that is positioned by motorized wheel assemblies between container receiving and delivery locations on a land-based surface. Each of such travel paths is established by a pair of rails laterally spaced from each other on the boom positioned so as to extend between the container receiving and delivery locations, at which such as a land-based truck vehicle and a dockside shipping sea vessel are positioned. The vertical spacing between travel paths and the lateral spacing between the boom rails accommodate handling of many containers to be loaded and unloaded without obstruction or delay in transport. 

   
     BRIEF DESCRIPTION OF DRAWING 
     A more complete appreciation of the invention and many of its attendant advantages will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein: 
       FIG. 1  is a perspective view of a container transport crane constructed in accordance with one embodiment of the present invention; 
       FIG. 2  is an end view of the crane shown in  FIG. 1 , as viewed from a container receiving or delivery location; 
       FIG. 3  is top plan view of the crane shown in  FIG. 1 ; 
       FIG. 4  is a side elevation view of the crane illustrated in  FIGS. 1-3 , positioned between typical container receiving and delivery locations; 
       FIGS. 5 and 6  are partial sections views respectively taken substantially through section lines  5 — 5  and  6 — 6  in  FIG. 3 ; and 
       FIG. 7  is a partial section view substantially taken through section line  7 — 7  in FIG.  5 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring now to the drawing in detail,  FIGS. 1 ,  2  and  3  illustrate a container transfer crane generally referred to by reference numeral  10 . Such crane  10  includes a vertical support frame  12  to which a horizontal boom  14  is connected by pairs of cables  16   a  and  16   b.  Such cables  16  are fixedly anchored to an upper rectangular end portion  18  of the support frame  12 , having four vertical gantry legs  20  extending downwardly therefrom. The boom  14  includes a pair of rails  22  interconnected in laterally spaced relation to each other at their forward and rear ends by end connectors  24  and  26 . The frame anchored cables  16   a  and  16   b  are connected to the rails  22  adjacent to their forward and rear ends so that the boom  14  is supported in a horizontal position extending through the upper end portion of the support frame  12  in contact with the gantry legs  20 . 
   The crane  10  is moved to a position on a land-based surface as shown in  FIG. 4  by motorized wheel assemblies  28  at the bottom of the gantry legs  20 , between a land-based delivery location and a dockside location  32  along a body of seawater  34 . The crane  10  is moved to such position by the motorized wheel assemblies  28  so as to transfer containers between delivery vehicle trucks  36  and a shipping sea vessel  38  located in the seawater  34  at the dockside receiving location  32 . Container loads are thereby readily transferred by means of the crane  10  between the delivery vehicle trucks  36  respectively moved to positions between the crane legs  20  and the receiving shipping vessel  38  as hereinafter explained. 
   The rails  22  of the boom  14  as shown in  FIGS. 5 ,  6  and  7  have upper rail tracks  40  formed in the top edges thereof, while confronting lower trolley rail tracks  42  are formed in the lower inside portions sides of the rails  22  adjacent the bottom thereof. The upper rail tracks  40  receive wheels  44  of an upper trolley  46 , as shown in  FIGS. 1 ,  3 ,  4  and  5 , while the lower rail tracks  42  receive wheels  60  of a lower trolley  50  as shown in FIG.  6 . The upper and lower trolleys  46  and  50  are thereby readily displaceable longitudinally along the boom  14  between the opposite end connectors  24  and  26  at the vertically spaced levels of the upper and lower rail tracks  40  and  42 . 
   Pivotally suspended from a cross-bar portion  52  of the upper trolley  46  between its side portion  54  on which the wheels  44  are mounted as shown in  FIG. 5 , is a spreader element  56 . Loaded containers are adapted to be attached to such spreader  56  for transport by the upper trolley  46  along an upper travel path on the boom  14  between its opposite ends and for pivotal displacement relative thereto for enhancing reception and delivery. The lower trolley  50  is also provided with a cross-bar portion  58  between side portions on which the wheels  60  are mounted as shown in  FIG. 6. A  spreader element  62  is pivotally suspended from the cross-bar portion  58  of the lower trolley  50  for reception, delivery and transport of a loaded container  64  for example, between the opposite ends of the boom  14  along the lower trolley travel path established by the rail track  42 . 
   It will be apparent from the foregoing description that the lateral spacing between the boom rails  22  and corresponding dimensions of the trolleys  46  and  50  at different vertically spaced levels enables transport of all containers without obstruction, as well as to accommodate separate upper and lower rail shuttling movement of the trolleys  46  and  50  at the same time with containers thereon. Such shuttling movement of the upper trolley  46  with the container  64  thereon occurs on the rails  22  along the boom  14  as viewed in  FIG. 1  to pass over the lower trolley  50  also moving therebelow along the boom  14 . 
   Thus, both the trolleys  46  and  50  may be utilized with maximum efficiency during a plurality of operational cycles for load transfer in opposite directions along the boom  14 . Accordingly, one of trolley  46  and  50  may be receiving a loaded container on its spreader  56  or  62  at one end of the boom  14  from the vehicles  36  as shown in  FIG. 4 , while the other trolley  46  or  50  at the other end of the boom  14  is positioned for delivery of a loaded container from its spreader  56  or  62  at a ship-side location by drop off of a standard container  64  onto the sea vessel  38  as shown in FIG.  4 . 
   Obviously, other modifications and variations of the present invention may be possible in light of the foregoing teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced; otherwise than as specifically described