Bridge crane

Abstract

A bridge crane for loading and unloading containers or packing crates into and from a vessel comprises a support structure including a horizontal girder on which one or more carriages are supported for movement each provided with hoisting and propelling devices. A positioning member is also supported for movement along the girder independently of the carriage and is provided with sighting means for determining the position of the positioning member along the girder with respect to the vessel therebelow. A device which may be in the form of an arm for actuating a switch is mounted on the positioning member to halt the carriage at a predetermined distance from the positioning member. In the case where two carriages are provided, one is superimposed on the other and is capable of travelling in a vertical plane therewith and therepast with a load suspended therefrom.

Description

The invention relates to a bridge crane in particular for loading and unloading containers or packing crates, the load being unloaded or loaded from and into a vessel respectively by means of at least one carriage adapted to travel over the girder of the bridge crane and provided with hoisting and propelling devices.

As the carrying capacity of modern container ships is considerable and as there is a tendency even to increase said carrying capacity, and as the harbour fees are very high, there is a need for load handling cranes having a greater capacity for loading and unloading vessels in order to shorten the lay time of the vessels.

Inasmuch as the number of load handling cranes positioned alongside a vessel cannot be increased indefinitely, and the rate of hoisting as well as the speed of the carriage in the cranes used so far cannot be increased indefinitely, also on account of the fact that hereby swaying of the hoisting cables is intensified, so that the time gained by the higher speed is lost again, it is not possible to increase the unloading and loading capacity in this way to a much greater extent.

It is therefore the object of the present invention to find new ways to increase the loading and unloading capacity of a crane, with the possibility of operating said crane fully automatically.

It has appeared that with the load handling cranes used so far, in which the operator travels with the carriage, much time is lost in causing the carriage come to a stop with such accuracy above the vessel that in lowering the hoisting ropes the spreader suspended from said ropes accurately engages the locks of the container, in the vessel or that the container suspended from the spreader accurately slides along the guide ways in the vessel, or is accurately positioned on a container already loaded in the vessel.

According to the present invention, an arrangement is provided by which the aforesaid period of time is appreciably shortened and which also permits fully automatic operation.

This arrangement according to the invention comprises a positioning member adapted to travel over the girder, and provided with sighting means for fixing the position of the positioning member on the girder with respect to one or more points of a vessel, while means are provided to stop a carriage at a predetermined distance from said positioning member.

In this manner in arrested position the carriage will be automatically in the correct position above a stack of containers in a vessel, while this position can be determined when the carriage is still travelling, and this position can be corrected just before the carriage is coming to a stop, and even thereafter the position can be corrected during lifting and lowering operations, so that any motions of the vessel can be followed as it were.

Advantageously, according to the invention, there may be provided two carriages movable on vertically spaced apart tracks formed on the girder, the lowest point of the one carriage with the load suspended therefrom in the topmost position being at a higher elevation than the highest point of the other carriage, so that the carriages are permitted to pass each other in superimposed relationship.

In this manner the capacity of the crane can be doubled, as it were, since a container can be unloaded from the vessel with one carriage, and simultaneously the other carriage can place a container unloaded from the vessel on a truck on the dock, for instance, while the carriages operate in the same vertical plane, so that in unloading or loading a plurality of loads from or in the same position in the vessel, containers from or in the same stack, for instance, the entire crane need not to be displaced at every turn.

The means for stopping a carriage may comprise a projecting bracket on the positioning member, which bracket can cooperate with a switch, or a member operating a switch, on the carriage.

In an alternative embodiment, the means for stopping a carriage comprises a counting device on each carriage and a counting device in the positioning member with which the respective positions of a carriage and the positioning member on the girder can be determined, and a computer connected to said counting devices, which at a predetermined distance between the carriage and the positioning member produces a control signal in order to stop the carriage. Advantageously, in using two carriages the computer may be connected in such a way with the hoisting device of at least the upper carriage that at a predetermined distance between the two carriages it is ensured that before the carriages pass one another, or lie above one another, the hoisting device of the upper carriage has hoisted the load to its highest position. Owing to these last measures there is thus obtained an automatic safeguard against the danger of impact.

The sighting means in the positioning member may be optical means, such as a monitor or a telescope.

The positioning member is advantageously formed by a driver's cabin adapted to travel over the girder. In this instance the driver positions the cabin, and thus the stopping position of the carriage, with the help of an image of the upper portion of the vessel shown on the monitor in the cabin by means of a Television camera, while the holes of the catches of the containers or of the container guide ways in the vessel may form the points of orientation.

In employing two carriages, the girder may consist of two parts extending in parallel spaced apart relationship, the lower carriage, seen in front view having the shape of a box or trough which, at the end portions of the vertical sides, is supported by the girder, whereas the upper carriage, seen in front view, has the form of a gate which, at the ends of both legs, is supported by the girder. Thus, in the upper carriage a container suspended from the hoisting cables will be situated between the legs of the gate structure in the upmost position. Advantageously the upper carriage may be provided with hoisting means mounted for a rotational movement about a vertical axis, so that a container suspended from the hoisting ropes can be rotated through 90.degree. and be positioned with its largest dimension extending in the longitudinal direction of the girder and the distance between both parts of the girder need only be constructed for accomodating the width of a container.

The invention will now be explained in more detail with reference to the annexed drawing.

FIG. 1 is a side view of a load handling crane according to the invention with one carriage.

FIG. 2 is a side view of a load handling crane according to the invention with two carriages.

FIG. 3 is a back view of the load handling crane of FIG. 2 on an enlarged scale.

In FIG. 1 the crane comprises supporting structures 1 and 2 which are provided with wheels 3 with which the entire crane can travel over dock 4. These supporting structures 1 and 2 support a girder 5 over which a carriage 6 can travel to and fro with the aid of the wheels 7. The carriage 6 is provided with a hoisting device 8 by which the container 10 and/or the yoke 11 can be raised or lowered through the hoisting ropes 9.

Furthermore, a positioning member 12 is provided, which consists of a driver's cabin adapted to travel over the girder. The member 12 is provided with sighting means in the form of a Television camera positioned at the end of one or more brackets 13 connected with the member 12. Through said camera the driver receives a picture of the upper portion of the vessel 14, so that the driver in the cabin 12 can accurately direct and position the cabin 12 with respect to the openings of the catches of the containers on the vessel. Moreover, the positioning member 12 has an arm 15 which is adapted to cooperate with a switch on the carriage 6, so that as soon as the switch comes into contact with the arm 15 the carriage will stop. Thus the carriage will always stop at a distance determined by the arm 15 of the positioning member 12, and as the positioning member 12 is accurately located with respect to the vessel, the carriage will also be accurately positioned with respect to the vessel. When the carriage has stopped, the driver in the cabin 12 has only to actuate the hoisting device on the carriage 6.

The load handling crane shown in FIGS. 2 and 3 comprises supporting structures 21 and 22 which, at their bottom ends, are provided with wheels 23 by which the entire crane can travel over dock 24. These supporting structures 21 and 22 support girder 25 which consists of two parts 26, 27 (see FIG. 3). An upper carriage 28 and a lower carriage 29 are adapted to travel over the parts 26 and 27 of the girder. The upper carriage 28 has a gate-shaped structure which, at the end of its legs is provided with wheels 30, by which the carriage is adapted to travel over the parts of the girder 26 and 27. The carriage 28 is moreover provided with a hoisting device comprising hoisting drums 31 which are mounted on a platform 32 which is mounted for a rotary movement about a shaft 33 mounted on the carriage 28.

In this manner the container 35 suspended from the hoisting ropes 34 can be rotated through 90.degree. such that the container can be positioned with its largest dimension in the longitudinal direction of the parts of the girder 26 and 27, so that the distance between the girder parts 26 and 27 need only be constructed to accommodate the width of the container 35.

The lower carriage 29 consists of, as seen from the front, a box-like shaped structure which, at the end of the vertical parts, is provided with wheels 36 by which the carriage 29 can travel over the girder parts 26 and 27. The carriage 29 is provided with a hoisting device comprising two hoisting drums 37 by which the container 39 can be raised and lowered through the hoisting ropes 38.

Furthermore, there is a positioning member 40 which comprises a driver's cabin, and which is adapted to travel over the girder parts 26 and 27. The member 40 is provided with sighting means comprising one or more Television cameras at the end of an arm 41 connected with the member 40. Moreover the member 40 has arms 42 and 43 which can cooperate with a switch or a similar member on the carriages 28 and 29 respectively.

The driver in the cabin 40 receives through the Television camera a view of the upper portion of the vessel 44 and can thus position the mobile cabin 40 with respect to the vessel 44 with the aid of said picture, his bearings being formed by the openings of the catches of the containers on and in the vessel, or the container guide ways in the vessel. In this manner, the driver's cabin 40 is thus positioned in respect to these orienting points, the projecting arms 42 and 43 having such a length that on engaging the switch on the carriage, whereby said carriage comes to a stop, the carriage is also positioned accurately in respect of said orientating points, so that the driver in the cabin has only to actuate the hoisting device on the carriage, whereupon a container is automatically picked up in the correct manner, or a container is placed in the vessel in the correct manner.

Claims

What we claim is:

1. A bridge crane for loading and unloading containers or packing crates into and from a vessel, said crane comprising a support structure including a horizontal girder, at least one carriage supported for movement along said girder, hoisting means on said carriage for raising and lowering a load from and into a vessel therebelow, propelling means for advancing the carriage along said girder, a positioning member supported for movement along said girder independently of said carriage and including optical sighting means on said positioning member for determining the position of the positioning member along the girder with respect to the vessel therebelow, and means operatively associated with said carriage and said positioning member for halting the carriage at a predetermined distance from said positioning member.

2. A crane as claimed in claim 1 comprising a second said carriage supported on said girder for travel therealong in the same vertical plane as the first carriage, one carriage being disposed above the other such that the lowermost point of said one carriage with a load suspended therefrom in an upmost position is at a higher elevation than the topmost point of the other said carriage so that the carriages are permitted to pass each other in superimposed relationship.

3. A crane as claimed in claim 2 wherein said means for halting said carriage comprises a distance counting means on said carriage and a distance counting means on the positioning member by which the respective positions of the carriages and the positioning member on the girder can be determined, and a computer connected to said counting means to produce a control signal for stopping the carriage at a predetermined distance from the positioning member.

4. A crane as claimed in claim 3 wherein said counting means are also connected with the hoisting means of at least the upper carriage.

5. A crane as claimed in claim 2 wherein said girder comprises two parts extending in parallel spaced relationship, the lower carriage, as seen in front view, having vertical sides, at the end portions of which the carriage is supported by said girder, whereas the upper carriage, as seen in front view, has transversely spaced legs with lower ends which are supported by the girder.

6. A crane as claimed in claim 5 wherein the hoisting means on the upper carriage is rotatable about a vertical axis.

7. A crane as claimed in claim 5 wherein said parts of said girder include two parallel superposed surfaces on the upper of which said upper carriage travels and on the lower of which said lower carriage travels, said upper carriage being of inverted U-shape and the lower carriage being of upright U-shape.

8. A crane as claimed in claim 1 wherein said means for halting said carriage comprises an arm on said positioning member and a switch means on the carriage which is operated by said arm when said carriage is at said predetermined position with respect to said positioning member.

9. A crane as claimed in claim 1 wherein said optical sighting means comprises a television camera.

10. A crane as claimed in claim 1 wherein said positioning member includes a driver's cabin.