Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C11/00—Trolleys or crabs, e.g. operating above runways
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C19/00—Cranes comprising trolleys or crabs running on fixed or movable bridges or gantries
  • B66C19/002—Container cranes

Definitions

• This invention relates to a crane, particularly though not exclusively a crane that is suitable for use in loading or unloading a vehicle, a conveyor belt or a vessel such as a ship.
• the invention also encompasses a method of operating such a crane.
• Cargo ships form the backbone of worldwide trade, carrying cargo ranging from loose bulk materials to freight containers all over the globe. This cargo can be carried internally within holds that are typically covered by movable hatches, or externally on deck as is common on container ships.
• Each crane typically includes a lifting tackle suspended by wires from a trolley.
• the trolley is movable on an elevated horizontal track defined by a pair of rails supported by a jib or gantry, the trolley spanning the gap between the rails.
• the trolley reciprocates between two positions during an unloading operation, one position being for lifting items from the ship and the other position being for depositing those items at dockside.
• the items may, for example, be deposited onto a vehicle such as a truck or a train, or possibly onto a conveyor belt that carries the items away as they are deposited thereon.
• a loading operation is merely the same operation in reverse.
• Applicant has found old prior art disclosures of cranes in different technical fields that employ more than one tackle but these multiple tackles act on one load and do not teach accelerating a loading or unloading process involving multiple discrete loads. Accordingly, they do not lead to the present invention which involves simultaneous movement of discrete loads to speed the process of transfer.
• UK Patent No. 1,223,379 to Krupp was published in 1971. It discloses an overhead travelling crane for use in the shipbuilding industry, particularly for moving single large pre-constructed sections of a ship which may weigh several hundred tons.
• the crane is on a massive scale: it is in the form of a bridge supported by columns, one at each end, which travel on rails on opposite sides of a dry dock in which a ship is to be built.
• Krupp 's crane provides for turning a single heavy load about either a horizontal or vertical axis, as may for example be necessary to turn a prefabricated ship section through 90° from its orientation on delivery at the shipyard to the orientation required for installation on a ship being built. This is achieved by running two crabs on each side of the bridge, thus making four crabs in total, with the crabs being divided into an upper pair, one upper crab being situated on each side of the bridge, and a lower pair, one lower crab being situated on each side of the bridge. Cables hang from each crab to support the load.
• the Krupp crane is designed for painstaking and careful orientation of single, very large loads, in which it is acceptable to remove and reattach cables as the crabs pass each other.
• the present invention requires no such steps.
• the Krupp crane would not be suitable for dockside use, even if scaled down, because it requires support at both ends of the bridge.
• UK Patent Nos. 907,399 and 972,477, both to Creusot, are a decade older than Krupp. They describe cranes for suspending and tilting a movable ladle in a steelworks.
• the cranes employ an arrangement of three tackles, two mounted on an upper trolley that support the weight of the ladle and one mounted on a lower trolley that controls the tilt of the ladle.
• the trolleys run along respective tracks, the lower trolley running on a track that is narrower than and lies beneath the other track. In this way, during a tilting operation, the inner trolley and its tackle can run inside the tackles suspended from the outer trolley without interfering with the outer trolley or its tackles.
• Creusot documents are concerned with positioning and orienting a single load, which must be moved slowly and precisely. The movements of the various tackles and the range of that movement are therefore constrained. It is also noted that the Creusot cranes would not be suitable for dockside use, even in the unlikely event that a person seeking to load or unload a ship would look to the art of steelmaking for a solution.
• the invention may be described as a method of operating a crane, the method comprising moving goods or commodities in a plurality of loads, wherein: each load is carried by a respective carriage that moves reciprocally with respect to the crane along a respective path to transfer the load and return for a further load; the carriages pass each other as they reciprocate along their respective paths; and at least one carriage changes configuration to avoid collision with another carriage or its load as the carriages pass each other.
• the method is applied to loading and/or unloading a cargo-carrying means such as a ship and so comprises moving cargo in a plurality of loads.
• the invention resides in a crane adapted to move a plurality of loads as when loading or unloading cargo from a cargo-carrying means, the crane comprising a plurality of carriages each movable reciprocally with respect to the crane along a respective path to transfer a load and return for a further load, the carriages passing each other as they reciprocate along their respective paths; and means for changing the configuration of at least one carriage to avoid collision with another carriage or its load as the carriages pass each other.
• the invention also resides in optional features defined in the following specific description and the sub-claims.
• Figure 1 is a cross-sectional end view of a gantry crane having parallel tracks disposed side-by-side, each track supporting a trolley and a tackle
• Figure 2 is a simplified perspective view of a gantry crane having two tackles passing clear of each other in a nested arrangement
• Figure 3 is a cross-sectional end view of the gantry crane of Figure 2, the crane having tracks disposed in a tiered arrangement, where trolleys span the width of the tracks;
• Figure 4 is a side elevation of the gantry crane of Figure 2, showing a collision prevention zone
• Figure 5 is a plan view from underneath of the crane of Figure 2, 3 and 4;
• Figure 6 is a cross-sectional end view of a gantry crane having an inner track, a trolley spanning the width of the inner track, and an outer track comprising two parallel rails, each rail carrying a separate half-trolley or crab; and
• Figure 7 is a cross-sectional end view of a gantry crane as in Figures 2 to 5, but showing a wire arrangement adapted to suit unitised lifts such as containers.
• trolleys 10 run on parallel tracks 11 disposed side by side under a gantry, defining a central vertical plane (not shown) between the tracks.
• Sheaves 12, 13 move with each trolley 10 and support wires which suspend tackles A and B.
• the wires pass over the sheaves 12, 13 and are wound onto drums (not shown) that are independently operable to move the tackles laterally by varying the relative lengths of the two wires that suspend each tackle.
• the wire working from the sheave 12 closer to the central plane takes most of the load on tackle A when tackle A is at the lowered level shown, suitable for picking up and dropping off a load.
• the wire working from the sheave 13 further from the central plane is used to stabilise the load against sway but is also shortened to swing the tackle and lift it outwards and away from the central plane, as shown for tackle B, so as to pass clear of the other tackle when the tackles move past each other.
• This technique for allowing two tackles to share a single crane is advantageous for its simple mechanical design and also because it allows the gantry itself to be of conventional structure. Against this, the two tackles cannot both reach exactly the same point on the central plane and therefore this method is more suitable for less precise work such as the operation of grab lifts for moving bulk commodities from a stockpile or ship's hatch.
• a gantry crane 14 comprises an elevated elongate jib or gantry 15 that extends horizontally in cantilevered fashion from a support offset towards one end.
• the support comprises two pairs of legs 16, the legs of each pair splaying apart towards the ground for stability.
• the gantry 15 is a framework box section of tubular steel elements for strength and lightness.
• the gantry supports an upper pair of rails 17 and a lower pair of rails 18 that respectively define upper and lower tracks in tiered relation.
• Each track supports and is spanned by a respective trolley, the upper track having a relatively wide upper trolley 19 thereon and the lower track having a relatively narrower lower trolley 20 thereon.
• Each trolley 19, 20 supports a respective pair of wires 21 which converge downwardly from sheaves 22 to tackles 23 and 24 respectively.
• the tracks and trolleys 19, 20 are so arranged that the lower track and trolley 20 can pass within the wires 21 that depend from the upper trolley 19, in a nested relationship. As shown in Figures 2 and 4, it is also necessary for the tackle 23 to be lifted above tackle 24 to an extent that permits any load hanging from tackle 23 to clear tackle 24 and its associated wires. However, there is no need to remove a load from either tackle 23, 24 as the trolleys 19, 20 pass each other.
• Safety is, of course, paramount in any crane system.
• the primary safety issue to be considered in practice of the present invention is the risk of a collision between loads, tackles and wires as the tackles move in relation to one another. This can be avoided by electromechanical sensors and cut-outs, microprocessor controlled brakes or other logical switching to the same effect.
• these safety measures can be used to create a 'collision prevention zone' shown in dashed lines to ensure that the tackle 23 and any load supported thereby are progressively lifted by the lower trolley 20 as they reach a minimum separation on approaching tackle 24, so that the tackle 23 is at all times high enough to avoid collision; and if this is not so, the abovementioned safety measures should correct the situation or stop movement of whichever trolley 19, 20 is moving.
• the tackle and any load in motion along the gantry should be fully swung away from the central plane on approaching the other trolley; and if this is not so, the abovementioned safety measures should correct the problem or stop movement of the or each moving trolley.
• Figure 5 shows the trolleys 19, 20 passing each other and also shows how the box structure cf the gantry 15 itself can define the rails 17, 18.
• the rails 17, 18 are four parallel longitudinal members connected at their ends by transverse members 25.
• the legs 16 are attached to the upper rails 17 which are also the outer rails as seen in Figure 5.
• an alternative embodiment of the invention employs an inner trolley 26 running on an inner pair of rails 27 that define an inner track akin to the lower track of Figures 3 and 4.
• FIG 7 a further embodiment of the invention corresponds broadly to the tiered and nested embodiment of Figures 2 to 5 and again like numerals are used for like parts.
• This embodiment is adapted for use with unitised items of standard dimensions such as containers of 12.19 metres (40 feet) in length.
• the tackle commonly has to be lowered into spaces between neighbouring stacked containers on into cellguides in the hold, only as wide as a container itself.
• the upper/outer trolley 32 needs to be wider than 12.19 metres (40 feet) if its wires are to clear the lower/inner trolley 30; but the tackle 33 of the upper/outer trolley 32 has to be brought down to a maximum width of 12.19 metres (40 feet) if it is to reach between the neighbouring containers 34 and lock onto another container 35.
• a wire collector frame 36 is suspended by wires 37 below the point where the narrower lower/inner trolley 30 will clear its lift through the wider tackle 33.
• the aforementioned safety measures can be made more active by providing for automatic control of the path taken by the tackles and hence by any loads that they support.
• This motion could be pre-programmed according to a memorised and possibly standardised pattern of movements appropriate to the loads in question, and/or could be controlled by sensors that monitor the clearance between passing tackles, wires and loads and so enable a microprocessor to determine a safe path.
• the cranes of the invention can also be driven manually, in which case a driver's cab could be attached to or otherwise associated with each respective trolley or crab so as to follow the movement of the respective tackle. If clearances are critical, as may be the case with unitised lifts for example, the cabs could be separate from the trolleys or crabs and could run on further tracks that are independent of the tracks on which the trolleys move. In this case, it would be advantageous to synchronise the movement of a cab to the trolley that the cab commands.
• the means for synchronising cab movement could, for example, be as set out above in relation to the embodiment of Figure 6 for synchronising the movement of the crabs 28.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Ship Loading And Unloading (AREA)
• Carriers, Traveling Bodies, And Overhead Traveling Cranes (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=10805936

Family Applications (1)

Country Status (6)

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Family Cites Families (12)

• 1997
  • 1997-01-14 GB GB9700637A patent/GB2321047A/en not_active Withdrawn
• 1998
  • 1998-01-12 AU AU55667/98A patent/AU5566798A/en not_active Abandoned
  • 1998-01-12 EP EP98900567A patent/EP0952955B1/de not_active Expired - Lifetime
  • 1998-01-12 WO PCT/GB1998/000071 patent/WO1998030485A1/en active IP Right Grant
  • 1998-01-12 DE DE69810075T patent/DE69810075T2/de not_active Expired - Fee Related
• 2000
  • 2000-04-28 HK HK00102594A patent/HK1023551A1/xx not_active IP Right Cessation

Non-Patent Citations (1)

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