EP1507736A2

EP1507736A2 - Gantry crane

Info

Publication number: EP1507736A2
Application number: EP03738780A
Authority: EP
Inventors: Evert Luttekes; Joannes Cornelis Rijsenbrij
Original assignee: Technische Universiteit Delft
Current assignee: Technische Universiteit Delft
Priority date: 2002-05-24
Filing date: 2003-05-26
Publication date: 2005-02-23
Also published as: WO2003099700A2; NL1020675C2; AU2003246181A8; WO2003099700A3; AU2003246181A1

Abstract

Portal crane (1) for loading and/or unloading a ship having a multiplicity of bays for containers (10) comprising a gantry (2) with travelling gear (5) for supporting the gantry on a quay (13), a boom supported by the gantry made up of a horizontal beam (6) and a jib (7) that during loading and/or unloading is an extension of the beam, and at least one crab (9) that can be driven along the jib, with hoisting means (20) for the containers. The gantry, viewed in the horizontal transverse direction of the jib, has a base width at the level of the quay. The hoisting means, viewed in this direction, can move along the crab over a traversing distance and the following relationship applies: 2 x Bbay<Bbase<=2 x Bbay+T, where: T=traversing distance, Bbay=bay width, Bbase=base width. Also disclosed is a combination of two such cranes as well as the use of such a crane.

Description

Portal crane for loading and/or unloading sea containers, combination of two such gantry cranes and use of a portal crane or such a combination.

The present invention relates to a portal crane for loading and/or unloading sea containers onto and, respectively, rom a ship having a multiplicity of adjacent bays for said sea containers, which bays are parallel to one another and run transversely with respect to the longitudinal direction of the ship and, viewed in the horizontal longitudinal direction of the ship, have a bay width, wherein the portal crane comprises: • a gantry having support points provided with travelling gear units for supporting the gantry on a quay, • a boom supported by the gantry and provided some distance above the travelling gear units, which boom is made up of a horizontal beam and a jib that at least during loading and/or unloading is in the extension of the beam, and • at least one crab that can be driven along the jib and is provided with hoisting means for lowering or raising the sea containers, wherein the gantry, viewed in the horizontal transverse direction of the jib, has a base width at the level of the quay.

A portal crane of this type is generally known, for example from WO 01/25131 in the name of the Applicant.

Gantry cranes of the type mentioned in the preamble are becoming ever larger. This is a consequence of the fact that the ships to be loaded and unloaded by means of these cranes are becoming ever larger. The most recent developments in this regard are that the ships are not so much becoming longer but broader and that the load height on said ships is increasing all the time.

When designing gantry cranes a number of factors must be taken into account. An important factor is that gantry cranes must not blow over in the event of a storm; in other words they must be able to withstand storm force winds. It will be clear that this problem plays an ever greater role as gantry cranes become ever higher. On the one hand, because as the cranes become higher the tilting moment starts to play a greater role and on the other hand because the wind force is usually greater the greater the distance above the ground. Furthermore, with many gantry cranes the jib is also sometimes peaked up, including in stormy weather, which causes the height of the portal crane to increase even further. The problem of the ability to withstand storm force winds can be tackled in a number of ways, on their own or in combination.

A first approach is to make the storm crane broader at the base, that is to say on the quay, this way the tilt line can be moved further away from the centre of gravity of the portal crane. As far as the base viewed in a direction parallel to that of the longitudinal direction of the boom is concerned, this can usually be implemented in the sense that in this location there is a great deal of space or space can be made available by widening the quay. However, as far as the base viewed parallel to the longitudinal direction of the ship, i.e. in the direction transverse to the longitudinal direction of the boom, is concerned the situation is completely different. Here the doctrine is, namely, that this width, hereinafter termed the base width, must not be greater than twice the width of the largest bay found in the ships for which the crane is intended/has been designed, hi the present application this width of the largest bay is referred to as the (so-called) bay width. The bays of a ship extend in the transverse direction of said ship and the containers are stacked in a bay to form a stack with the longitudinal axes of the containers parallel to the longitudinal direction of the ship. The width of the bays is directly related to the standard lengths of the sea containers that are transported, hi practice, bays for 20-foot containers and for 40-foot containers can be found on a single ship. The width of a bay for 40-foot containers is usually approximately 13.8 metres, which is somewhat more than 40 feet so that there is still working room alongside the containers for securing the containers. The width of 13.8 metres is still sufficient to allow a 45-foot container to be placed in the bay as top cover load. The 45-foot container is currently the largest, frequently used standard length for sea containers. Since nowadays the large, sea-going transport ships have usually been designed at least with this width for the bays, the base width of the gantry cranes to be designed nowadays is related to this bay width of 13.8 metres, which implies that the maximum base width for a portal crane is approximately 27.6 m. The reason why the maximum base width of a portal crane is taken as twice the bay width is that it is desirable that a ship can be unloaded as quickly as possible. This means that the aim will be to use as many gantry cranes as possible at the same time. The corollary of this is that it is desirable to position the gantry cranes with their sides against one another. So as then to be able to unload as many bays as possible simultaneously, the base width of each portal crane must be at most twice the bay width, so that in each case two, for example even-numbered, bays located alongside one another can be unloaded by means of two cranes, whilst the sides of those two cranes facing one another are in front of the intermediate odd-numbered bay. If the so-called base width of the gantry cranes becomes wider than twice the bay width, there will be two or more bays that cannot be loaded/unloaded at that point in time between every two bays that can be loaded/unloaded at the same time, whereas in the case of a maximum base width of twice the bay width there is only one intermediate bay that cannot be unloaded loaded at this point in time. This first method of approach is therefore not employed.

A second method of approach for withstanding storm force winds, which second method is also employed in practice, is that additional ballast is provided in the portal crane, usually in the legs of the gantry. The disadvantage of this is, however, that this causes a further increase in the load exerted on the quay. Since the maximum load to be exerted on the quay is usually restricted, the consequence of the increase in the load on the quay is usually in turn that the width of the travelling gear units, viewed in the horizontal transverse direction of the boom, again increases. Since the travelling gear units are fixed underneath the portal crane by means of a triangular balance beam system, the consequence of the increase in the width of the travelling gear is in turn that the tilt axis of the portal crane, which tilt axis is parallel to the longitudinal axis of the boom, comes closer to the centre of gravity of the portal crane because the maximum base width of the portal crane is restricted to twice the bay width.

A third method of approach for withstanding storm force winds, which is also employed in practice, is the provision of so-called guy wire constructions, hi this case the crane is anchored to the quay by means of guy wires or guy rods from a specific wind force, usually wind force 7 to 9 on the Beaufort scale. However, such guy wire constructions in turn demand very substantial facilities in the quay; after all the guy wires must be secured very firmly to the quay. The aim of the present invention is, now, to provide a portal crane of the type mentioned in the preamble that is better able to withstand storm force winds without the abovementioned disadvantages arising or at least having to arise.

Said aim is achieved with a portal crane of the type mentioned in the preamble in that the hoisting means, viewed in the horizontal transverse direction of the jib, can move back and forth along the crab over a traversmg distance and in that the following applies in respect of the base width:

2 x B_bay < B _ase <2 x B_bay + T, and, in particular: 2 x B_bay < B_base <2 x B_bay + T/2,

where:

T = traversing distance in m B _ay = bay width in m

B_base = base width in m.

The Applicant has gained the insight that the standard design rule that the base width must be at most twice the bay width can be disregarded if the hoisting means are constructed such that they are able to move back and forth along the crab, in the horizontal transverse direction of the jib. The maximum achievable gain for the base width here is the distance, termed the traversing distance, over which the hoisting means can move back and forth in the horizontal transverse direction of the jib. hi this way a few metres can easily be added to the maximum base width that previously applied. If the width of the travelling gear units of the portal crane is then left unchanged, this is pure gain as far as the resistance to storm force winds is concerned. As a consequence of the portal crane becoming higher, the weight thereof will usually increase, which usually, at least according to the state of the art, will also lead to an increase in the width of the travelling gear units, which, as previously stated, causes the tilt axes parallel to the boom direction to move towards the centre of gravity. Thus, some of the base width gained will be lost, or at least will not amount to a gain in the distance from the tilt axis to the centre of gravity.

The consequence of constructing the hoisting means such that they are able to move back and forth over a traversing distance along the crab is that the portal crane no longer has to be positioned centrally in front of the bay to be loaded/unloaded, as is the case in the state of the art, but that this crane can be positioned to one side of said centre. After all, by moving the hoisting means back and forth along the crab, the hoisting means can, as it were, be positioned centrally above the bay, or at least centrally above the containers. This phenomenon makes it possible that two bays located alongside one another or three bays located alongside one another can be loaded and/or unloaded without moving the portal crane in the interim. It should be clear that it is thus possible to increase the base width of the portal crane by the traversing distance without this giving rise to the conventionally anticipated disadvantages associated with the widening of the base width.

According to a preferred embodiment of the invention, the following applies in respect of the base width: B _ase >2 x B_bay + T/8.

According to a further preferred embodiment, the following will apply in respect of the base width:

B_base >2 x B_bay + T/4. According to an even more preferred embodiment, the following will apply in respect of the base width:

B_base >2 x B_bay + 3 x T/8.

In other words, according to the invention it is preferable if the base width is at least twice the bay width plus 2 m, preferably if the base width is at least twice the bay width plus 4 m and even more preferentially if the base width is at least twice the bay width plus

6 m. The present invention envisages base widths of twice the bay width plus 10 metres or even more than twice the bay width plus 10 metres.

As far as the bay width is concerned, this will preferably be greater than 13 m and in particular will be greater than approximately 13.8 m, which, as explained, is a suitable length for 40-foot containers.

Because in the case of a portal crane according to the invention, as a consequence of the fact that the hoisting means can move back and forth along the crab in the horizontal transverse direction, the portal crane no longer has to be driven along the quay during loading and/or unloading of a bay of the ship in order to compensate for small deviations in the longitudinal direction of the ship between crane and ship, it is possible in accordance with an advantageous embodiment to provide one or more of the travelling gear units, at least the travelling gear units located on the jib side and preferably all travelling gear units, of the portal crane according to the invention with outrigger means for supporting the gantry on the quay during unloading or loading. If the portal crane has to be moved during loading and/or unloading to compensate for small movements of the ship in the longitudinal direction of the ship, outrigger means then constitute a highly delaying factor since these in each case first have to be taken out of the blocked position before the portal crane can be moved. However, as a consequence of the fact that the hoisting means can move back and forth along the crab in the horizontal transverse direction, the portal crane no longer has to be moved, but the hoisting means can be moved in the horizontal transverse direction of the jib (corresponding to the horizontal longitudinal direction of the ship). Such outrigger means afford a large number of advantages. One of the major advantages is that the portal crane, in particular the travelling gear units, can be of much more lightweight construction. Specifically, when outriggers are used the travelling gear units only have to be designed to support an unloaded portal crane, that is to say a portal crane from which no containers are suspended or on which there are no containers, and where the jib is not loaded by the weight of the bascule. A further advantage of this is that the travelling gear can be of much shorter design, which, in turn, has the consequence that the tilt axes parallel to the longitudinal direction of the boom can be moved further away from the centre of gravity of the portal crane. Such outrigger means can be constructed per se in a wide variety of ways that can be found in the state of the art. With a view to the stability of the portal crane, it is particularly preferred in this context if the outrigger means and/or travelling gear units are equipped such that during loading and/or unloading the portal crane is essentially supported on the quay via the outrigger means, the wheels of the travelling gear unit preferably not being loaded or not being loaded above a specific maximum.

According to a particular embodiment of the invention, a portal crane where the jib comprises two jibs parallel to one another and located alongside one another a horizontal distance apart is characterised in that, viewed in the horizontal transverse direction of the jib, the distance between the jib beams is greater than the bay width, such that sea containers can be lifted freely in between them. Such an embodiment offers a number of advantages. On the one hand, by this means the maximum achievable traversing distance is increased, at least compared with conventional gantry cranes where the jib beams are usually a distance apart that is much less than the bay width. A further advantage, that is at least as significant, is that by this means the structural height of the crane can be reduced. After all, because the containers can be brought in between the jib beams or optionally to above the jib beams, the jib beams themselves can be closer to the top of the ship to be loaded and/or unloaded. After all, there is no longer any space required below the jib for moving containers to be loaded or unloaded in the longitudinal direction of the jib. The various features also offer the possibility of providing one or two sets of rails between the jib beams for moving wagons in the longitudinal direction along the jib beams for delivering and removing containers, hi this context reference is also made in particular to WO 01/25131 in the name of the Applicant, which for this purpose provides an auxiliary frame 14, now unnecessary, with an upper set of rails 15 and lower set of rails 16 along which container wagons 20 can be moved back and forth. The same principle can be applied in the case of the portal crane according to the invention, except that the auxiliary frame is then omitted, in the sense that here the jib can assume the function of the auxiliary frame directly. Insofar as the delivery and removal system for container wagons 20 is concerned, WO 01/25131 must be regarded as incorporated in the present application by reference. In order to improve the flexibility of the portal crane according to the invention, or in other words the capacity of the portal crane according to the invention for positioning the hoisting means with respect to the bay or container to be manipulated, it is highly advantageous according to the invention if the hoisting means comprise right-hand and left- hand hoist components that interact to manipulate a single container and are located horizontally alongside one another viewed transversely to the longitudinal direction of the jib and if the right-hand and left-hand hoist components are provided on the crab, in particular are provided at a fixed height with respect to the crab and can each individually, viewed in the horizontal transverse direction of the jib, move back and forth along the crab, preferably independently of one another, such that the distance between the right-hand and left-hand hoist component is adjustable. This also makes it possible to make the telescopic lifting beam to be positioned just above the container to be manipulated, which is conventionally of heavyweight construction because it also has to be able to stand flexural stresses, of much more lightweight construction. Specifically, the engagement points of the lifting blocks on said lifting beam can be situated at the end of the lifting beam, as a result of which the lifting beam only has to fulfil the function of a jib and does not have to be able to withstand flexural stresses, or at least only has to be able to withstand lower flexural stresses.

According to a further aspect, the present invention relates to a combination comprising two gantry cranes according to the invention and to the use of two gantry cranes according to the invention that are positioned with the sides adjoining one another.

According to yet a further aspect, the present invention relates to a combination comprising one or more lifting cranes according to the invention, a quay and a ship with bays moored alongside the quay.

According to yet a further aspect, the present invention very particularly also relates to the use of a portal crane according to the invention or the use of a combination according to the invention for loading and or unloading a ship. Supplementary to this, but also independently thereof, the present invention furthermore also relates to the use of a portal crane according to the invention or of a combination according to the invention where the portal crane is positioned in front of a bay and where the hoisting means are positioned with respect to the bay by moving the hoisting means along the crab, viewed in the horizontal transverse direction of the jib, the various features being such that the hoisting means are approximately centred with respect to the vertical central longitudinal plane of the bay. Supplementary to this, but also completely independently thereof, the present invention also relates to the use of a portal crane according to the invention or of a combination according to the invention where, during loading and/or unloading of containers, the portal crane has been supported on outriggers on the quay, preferably has been supported on outriggers in such a way that the wheels of the travelling gear units are essentially not loaded or are not loaded above a specific maximum.

The present invention will be explained in more detail below with reference to illustrative embodiments shown highly diagrammatically in the drawing, hi the drawing:

Figure 1 shows a diagrammatic, perspective view of a combination according to the invention, comprising portal crane according to the invention, a quay and a ship - partially shown diagrammatically;

Figure 2 shows, as a detail of Figure 1, a diagrammatic and perspective view of part of a jib with a crab thereon;

Figure 3 shows a highly diagrammatic plan view of a ship, part of which is shown, a quay and two gantry cranes;

Figure 4 shows, highly diagrammatically, a support beam with travelling gear units;

Figure 5 shows, highly diagrammatically, a set of wheels according to the invention for the travelling gear of a portal crane according to the invention;

Figure 6 shows a highly diagrammatic front view according to arrow VI in Figure 2 of the jib and crab; and

Figure 7 shows a view corresponding to Figure 6 of an alternative embodiment.

Figure 1 shows part of a ship 11. This part of the ship contains 3 bays each filled with a multiplicity of sea containers 10. The length of this part of the ship 11, viewed in the longitudinal direction L of the ship, is approximately 3 bay widths B_bay, i.e. approximately 42 metres for a bay width B _ay of 13.8 m. The ship is in the water alongside a quay 13. A so-called portal crane 1 has been positioned on the quay for loading and/or unloading the ship. The practice is that in such situations several portal cranes positioned alongside one another on the quay are used in order to be able to load and/or unload a larger number of containers per unit time.

The portal crane 1 comprises a gantry 2, which supports a boom 3 some distance above the quay at a height that is higher than the highest point of the cargo of the ship 11. The boom 3 is sub-divided into a section that essentially is located above the quay, termed the beam 6, and a section that at least during use is located above the ship and is termed the jib 7. h the use position, the jib 7 is essentially in the extension of the beam 6, although some vertical offset is certainly not precluded. So that the ship 11, in particular the wheelhouse protruding above the cargo, is able to move along the quay unhindered without the portal crane being of unnecessarily high construction, the jib can usually be peaked up. For this purpose the jib 7 is pivoted upwards about the hinges 8, the axis of rotation of which is parallel to the longitudinal direction L of the ship. It is also known, and possible according to the invention, to construct the jib such that it can be slid in/out so that it can be retracted to above the quay 13 by a sliding in movement.

At the bottom the gantry 2 is provided with two support beams 27 and 28. These support beams 27 and 28 are provided with travelling gear units 5 at the corner points 4 of the gantry. With reference to Figure 4, each travelling gear 5 is made up of a number of sets of wheels 29, also termed bogies, with a number of balance beams 30, 31 arranged in layers above these. The bogies 29 are fixed to the balance beams 30 by means of joints 32, the balance beams 30 are fixed to the balance beams 31 by means of joints [lacuna] and the balance beams 31 are fixed to the support beam 27 by means of joints 34. The joint axes of the joints 32, 33 and 34 are all perpendicular to the plane of the drawing. If the weight of the portal crane increases and the maximum load on the quay is exceeded, the number of bogies will then be increased, which necessitates an increase in the number of balance beam layers.

With reference to Figure 4, the greatest width of the portal crane in the longitudinal direction L of the ship is determined by the distance between the outsides of the outermost bogies of the travelling gear units. This distance is indicated as B_base. However, as a consequence of the balance beams 30, 31 and joints 32, 33, 34 used in the travelling gear units, it is not the distance B _ase that is decisive for the tilt axes running transversely to the longitudinal direction L and parallel to the boom 3, but the distance Z between the joints 34 by means of which the top balance beams are secured to the support beams 27, 28. These joints 34 are closer to the gravity line 35 - that passes through the centre of gravity of the portal crane - than the outsides of the outermost bogies 29. It will be clear that if the B _ase is kept the same and the number of bogies 29 and number of balance beam layers increases that the stability of the portal crane then decreases because the joint positions 34 move closer to the gravity line 35. The number of bogies 29 will increase if the weight of the portal crane 1 increases to such an extent that the maximum load on the quay is exceeded. Conventionally, the stability problems resulting from this are solved by increasing the weight of the portal crane by means of ballast - which ultimately can again lead to the maximum load on the quay being exceeded - and/or by the use of guy wires by means of which the portal crane is anchored to the quay 13 in the event of a storm.

The reason why the distance B _ase is not increased is that this has already been chosen as the "maximum" of 2 x the bay width B _ay. The reason for this is illustrated on the basis of Figure 3. Figure 3 shows a plan view of part of a ship 11 with bays 12a with a bay 12b between them in each case. The bays 12a and 12b are identical to one another per se and have the same bay width B_bay. With a view to a maximum loading/unloading capacity, the gantry cranes 1 are preferably positioned with their sides adjoining one another. By way of illustration, Figure 3 shows, highly diagrammatically, two of these gantry cranes; in practice it could be more. By now positioning the gantry cranes 1 with the sides against one another, for a base width B_base of 2 x the bay width B_bay, according to the state of the art, on the one hand, the stability of the portal crane is maximised and, on the other hand, the loading/unloading capacity. After all, it is still just possible simultaneously to load/unload two bays 12a (or 12b) in close proximity, whilst in each case there is only one intermediate bay 12b (or 12a, respectively) that cannot be unloaded, or at least cannot be unloaded without moving the gantry cranes. As soon as B_base becomes greater than 2 x B_bay, according to the state of the art the number of intermediate bays that cannot be unloaded without moving the gantry cranes becomes greater than one.

With reference to Figure 1, the boom 3 is provided with two crabs 9 that can be moved along the jib and with a double-width crab 19 that can be moved along the beam 6. What has been described up to now with reference to the figures is, at least in the manner described - thus not taking account of what is shown in more detail in the figures - known from the state of the art. The present invention itself will be discussed in more detail below.

The present invention lies in the fact that, on the one hand, the hoisting means 20 are constructed such that they can move along the crab 9 to the left and the right over a total traversing distance T in the longitudinal direction L of the ship, i.e. in the horizontal transverse direction of the jib and, on the other hand, at the same time the base width B_base of the portal crane is increased by at most half the traversing distance T. In this way the stability of the portal crane is increased and the resistance to storm force winds is increased, but without this giving rise to the disadvantage from the state of the art, i.e. reduced loading/unloadmg capacity.

• With reference to Figure 3 it will be clear that if the right-hand portal crane is moved to the right by, say, 1 metre, this provides the room to increase the base width of both gantry cranes by 1 metre each. However, the right-hand portal crane is then no longer positioned with the boom aligned with the bay 12a, but eccentrically with respect to said bay 12a. According to the invention, however, the right-hand portal crane is still capable of loading/unloading as soon as the hoisting means have been moved to the left over a distance of 1 metre. If, with hoisting means that can move back and forth along the crab, the boom is approximately aligned with the boundary between two bays it becomes possible successively to unload/load a bay 12a and adjoining bay 12b without interim movement of the portal crane - which takes a relatively long time.

Furthermore, movement time for the portal crane is saved - and thus loading/unloadmg capacity is gained - in that it is possible to correct for movements of the ship relative to the quay by moving the hoisting means relative to the crab, which can be carried out very much more rapidly as a consequence of the very much smaller mass to be moved.

Because the portal crane no longer has to be moved in the interim for position corrections when loading/unloading a specific bay - these corrections can, after all, be made according to the invention by moving the hoisting means along the crab - the portal crane according to the invention can be provided with outriggers for support on the quay. These outriggers can, on the one hand, be utilised directly to increase the stability and, on the other hand, make it possible to reduce the number of wheels on the travelling gear units, which, in turn, results in an increase in the distance Z (Figure 4) and thus indirectly in an increase in the stability. With this construction it will be possible for the travelling gear units to be made much more lightweight. If sufficient outriggers are used, the travelling gear units have to be designed only for the weight of the portal crane itself, without having to take account of the weight of containers manipulated by the latter. Furthermore, the use of outriggers provides a simple possibility for distributing the crane weight over a larger surface area and thus for reducing the load on the quay, which can lead to less substantial quay constructions. The outriggers 24 on transverse arms, such as are also used with lorries provided with a cherry picker, can be seen in Figure 1. Figure 5 shows a modified bogie 29 with integral outrigger 25. Here the outrigger 25 is of fixed construction and the wheels 26 are constructed such that they can be raised and lowered by means of lever arms 37 and dual- acting cylinder/piston unit 36. Figure 2 shows, as a detail, in particular a crab 9 with hoisting means 20. Figure 6 shows approximately the same more diagrammatically. The basic principle of the hoisting means does not differ very much per se from that known from the state of the art. The hoisting means 20 have four pulleys 40 supporting the lifting beam, not shown in Figure 2. Eight pulleys 42 are provided on the crab 9. hi accordance with the invention these eight pulleys 42 are on a traversing trolley 43 - optionally on two traversing trolleys 44 - see Figure 7 - that can move back and forth along the crab 9 in the direction L. The crab 9 is furthermore provided with further guide pulleys 45 - see Figure 2 - via which the lines running over the pulleys 40, 42 are guided to the jib beams 21. The lines are secured at one end to the end of the jib 7 facing away from the shore and at the other end to a drum via which the lines used for hoisting can be paid out or hauled in. For moving the traversing trolley 43 back and forth along the crab 9, pulleys 46 for guiding the hoist line are also provided on the traversing trolley. However, it will be clear that the traversing trolley can also be operated and driven electrically, via gear racks or in some other way to provide controlled back and forth movement along the crab 9. Incidentally, instead of being designed in the line crab construction discussed, the crab can also be designed as a mechanical crab, where the gear for the hoisting movement is installed on the crab itself.

The lifting beam 41 is of telescopic construction at both ends so as be able to grip containers of various dimensions by means of the gripper claws 47. As will be clear from Figure 6, the gripper claws 47 can engage underneath the jib beams to beyond the jib. This even makes it possible to load/unload a bay should part of tins not be below the jib.

The embodiment according to Figure 7 differs from that according to Figure 6 in that here the traversing trolley is of divided construction in the form of two traversing trolleys 44 that can move back and forth relative to one another, independently of one another. The advantage of this is that the lifting beam 48 can be made more lightweight. The lifting beam 48 can be of single telescopic construction with the pulleys 40 close to the ends. The lifting beam now no longer has to be able to absorb high flexural stresses and functions mainly only as a spacer. Figures 2, 6 and 7 all show top 51 and bottom 50 sets of rails also provided in the jib beams 21 for circulating the delivery/removal trolleys 53, by means of which the containers can be transferred from crab 9 to crab 19 or vice versa, in a loop, comparable to an endless conveyor belt. For a more detailed description of this system reference is made to WO 01/25131 in the name of the Applicant, which as far as this aspect is concerned must be regarded as incorporated in the present application.

Claims

1. Portal crane (1) for loading and/or unloading sea containers (10) onto and, respectively, from a ship (11) having a multiplicity of adjacent bays (12) for said sea containers, which bays (12) are parallel to one another and run transversely with respect to the longitudinal direction of the ship (11) and, viewed in the horizontal longitudinal direction of the ship (11), have a bay width, wherein the portal crane (1) comprises:

• a gantry (2) having support points (4) provided with travelling gear units (5) for supporting the gantry (2) on a quay (13),

• a boom supported by the gantry (2) and provided some distance above the travelling gear units (5), which boom (3) is made up of a horizontal beam (6) and a jib (7) that at least during loading and/or unloading is in the extension of the beam, and • at least one crab (9) that can be driven along the jib (7) and is provided with hoisting means (20) for lowering or raising the sea containers (10), wherein the gantry (2), viewed in the horizontal transverse direction of the jib (7), has a base width (B_base) at the level of the quay (13), characterised in that, the hoisting means (20), viewed in the horizontal transverse direction (L) of the jib (7), can move back and forth along the crab (9) over a traversing distance (T) and in that the following applies in respect of the base width (B _ase):

2 x B_bay < B _ase <2 x B _ay + T,

where, in particular, the following applies in respect of the base width (B_base):

2 x B_bay < B_base <2 x B_bay + T/2,

where:

T = traversing distance in m B_bay = bay width in m B_base = base width in m.

2. Portal crane (1) according to Claim 1, characterised in that the following applies in respect of the base width (B _ase):

2 x B_bay + T/8 <B_base.

3. Portal crane (1) according to one of the preceding claims, characterised in that the following applies in respect of the base width (B _ase):

2 x B_bay + T/4 <B_base.

4. Portal crane (1) according to one of the preceding claims, characterised in that the following applies in respect of the base width (B _ase): 2 x B_bay + 3 x T/8 <B_base.

5. Portal crane (1) according to one of the preceding claims, characterised in that the following applies in respect of the base width (B_base):

2 x B_bay + 2 ≤-B_base

6. Portal crane (1) according to one of the preceding claims, characterised in that the following applies in respect of the base width (B_baSe)-' 2 B_bay + 4 <B_base

7. Portal crane (1) according to one of the preceding claims, characterised in that the following applies in respect of the base width (B_base):

2 x B_bay + 6 <B_base

8. Portal crane (1) according to one of the preceding claims, characterised in that the following applies in respect of the base width (B_base):

B_base ≥13.5 m, and in particular: B_bay ≥13.8 m.

9. Portal crane (1) according to one of the preceding claims, characterised in that one or more of the travelling gear units (5), at least the travelling gear units (5) located on the jib side and preferably all travelling gear units (5), are provided with outrigger means (24, 25) for supporting the gantry (2) on the quay (13) during loading and/or unloading.

10. Portal crane (1) according to Claim 9, characterised in that the outrigger means (24, 25) and/or travelling gear units (5) are equipped such that during loading and/or unloading the portal crane (1) is essentially supported on the quay (13) via the outrigger means (24, 25), the wheels (26) of the travelling gear units (5) preferably not being loaded.

11. Portal crane (1) according to one of the preceding claims, where the jib (7) comprises two jib beams (21) parallel to one another and located alongside one another a horizontal distance apart, characterised in that, viewed in the horizontal transverse direction (L) of the jib (7), the distance (D) between the jib beams (21) is greater than the bay width (B_bay), such that sea containers (10) can be lifted freely in between them.

12. Portal crane (1) according to one of the preceding claims, wherein the hoisting means (20) comprise right-hand (22) and left-hand (23) hoist components that interact to manipulate a single container and are located horizontally alongside one another viewed transversely to the longitudinal direction of the jib (7), characterised in that the right-hand (22) and left-hand (23) hoist components are provided on the crab (9), and can each individually, viewed in the horizontal transverse direction of the jib (7), move back and forth along the crab (9), preferably independently of one another, such that the distance between the right-hand (22) and left-hand (23) hoist component is adjustable.

13. Combination comprising two gantry cranes (1) according to one of the preceding claims.

14. Use of a portal crane according to one of Claims 1 - 12 or use of a combination according to Claim 13 or 17 for loading and/or unloading a ship.

15. Use of a portal crane according to one of Claims 1 - 12 or of a combination according to Claim 13 or use according to Claim 14, wherein the portal crane is positioned in front of a bay and where the hoisting means are positioned with respect to the bay by moving the hoisting means along the crab, viewed in the horizontal transverse direction of the jib, the various features being such that the hoisting means are approximately centred with respect to the vertical central longitudinal plane of said bay.

16. Use of a portal crane according to one of Claims 1 - 12 or of a combination according to Claim 13 or use according to one of Claims 14 - 15, wherein the portal crane has been supported on outriggers on the quay, preferably has been supported on outriggers in such a way that the wheels of the travelling gear units are essentially not loaded.

17. Combination comprising one or more gantry cranes (1) according to Claims 1 - 12, a quay (13) and a ship (11) with bays (12) moored alongside the quay (13).