GB2421720A

GB2421720A - Cantilevered, counterweighted loading bridge

Info

Publication number: GB2421720A
Application number: GB0500018A
Authority: GB
Inventors: Stephen Osborn
Original assignee: HASKONING UK Ltd
Current assignee: HASKONING UK Ltd
Priority date: 2005-01-04
Filing date: 2005-01-04
Publication date: 2006-07-05
Anticipated expiration: 2025-01-04
Also published as: WO2006072771A1; GB0500018D0; GB2421720B

Abstract

A cantilevered linkspan (10) for connecting and providing access to and from a quay (4) to a ship (6). The linkspan (10) comprising a linkspan deck (12) projecting from the quay (4) and having a distal end (25), a pivot assembly (18) pivotally mounting the linkspan deck (12) from the quay (4), an actuator arrangement (24) for raising and lowering the distal end (25) of the linkspan (10), and a counterweight (16) counterbalancing and supporting the linkspan deck (12) projecting from the quay (12) about the pivot assembly (18). The counterweight (16) preferably entirely counterbalances and supports all of the weight of the linkspan (10) projecting from the quay (4) and in use loads such that the linkspan (10 is cantilevered from the quay (4). The pivot assemblies (18) are preferably slidably mountable to the quay (4) to allow some sliding movement to accommodate ship (6) impact with the linkspan (10).

Description

CANTILEVER LINKSPAN

The present invention relates to a linkspan, otherwise known in the art as adjustable ship to shore boarding ramp, which provide vehicular or personnel access to a ship or vessel from a port quay side. In particular it relates to large scale linkspan arrangements for providing vehicular access to and from roil-on/roll-off (RORO) ships.

Linkspans, or adjustable ship to shore boarding ramp, are used to connect and provide a flat access to and from a ship and port quay. Such linkspans comprise part of the port facility and are mounted on the quay. They can be contrasted with, and are distinct with ship mounted ramps which may also be used with such linkspans. A particular problem which linkspans address is to accommodate the changing height of the ship access relative to the quay due to changes in sea level due to tides for example, as well for different ships.

In their simplest form linkspans comprise a deck element with one end resting and supported on the quay, and the other end resting and supported upon the ship (or ship ramp) As the tide rises and falls, and/or to accommodate different ship configurations, the linkspan pivots about the quay and ship ends and adopts differing angles maintaining access and a connection with the ship. Such arrangements are not however generally suitable for large loads, are cumbersome to position, and are not generally suitable for RORO operations.

In more sophisticated and conventional arrangements, suitable for RORO operations, a tower or pylon incorporating lifting gear supports the seaward/ship end of the linkspan deck allowing it to be raised and lowered in response to the sea level and/or for different ships. The support towers are generally located in the water adjacent to the quay to support the linkspan deck over the sea, and so are susceptible to sea loading and corrosion as well as possible * ft. * . ft.

* * * ft * * * I I * I * I I* * I III I I I * I I I S * S I.. S IfS S S 2 P352591GB collision damage. With the towers and lifting machinery located away from the shore, access for maintenance is also difficult. In addition if the lifting gear fails the linkspan, and any loads on it, will fall and drop downwards into the water.

In a yet further alternative linkspan arrangement a seaward end of the linkspan may incorporate a float or tank whose buoyancy supports the seaward end of the linkspan and any loads travelling over it. The float, and so end of the linkspan, rises and falls in response to the tide and sea level, whilst the height of the seaward end of the linkspan above the float/sea level may be adjusted by adjusting the buoyancy of the float and/or via other ramps from the linkspan or ship. In a further variation a separate floating pontoon may be provided adjacent the quay with a link bridge between and resting on the quay and pontoon. Ramps from the pontoon or from the ship to the pontoon provide the final connection to and from the vessel. Examples of such pontoon arrangements are described for example in EP 0245227 and GB 1499741. Such floats and flotation chambers of any pontoons require regular inspection and maintenance with the floats and chambers being susceptible to corrosion form the sea water and also wave and/or collision damage. In addition various stability problems arise from such floating arrangements both generally and when loads traverse across the linkspan.

It is therefore desirable to provide an improved linkspan which addresses the above described problems and/or which offers improvements generally.

According to the present invention there is provided a linkspan as described in the accompanying claims.

In an embodiment of the invention there is provided a * I.. * t,*.

* S I IS S S S * I S S S S IS * S III * I S S 3:.. : P3*2'591** linkspan for connecting and providing access to and from a quay to a ship. The linkspan comprises a linkspan deck projecting from the quay and having a distal end, a pivot assembly pivotally mounting the linkspan deck from the quay, an actuator arrangement for raising and lowering the distal end of the linkspan, and a counterweight counterbalancing and supporting the linkspan deck projecting from the quay about the pivot.

Such an arrangement provides a cantilevered linkspan supported from the quay and shore by the counterweight which address a number of the above described problems with conventional arrangements. In particular since none of the linkspan is located in the sea, the linkspan is less susceptible to corrosion, is not subject to wave loading and is easier to inspect.

Preferably the linkspan deck projects from one side of the pivot assembly and the counterweight is disposed on an opposite side of the pivot.

The counterweight preferably normally biases and pivots the linkspan deck and the distal end of the linkspan deck towards a raised position. The actuator arrangement operates in use against the counterweight. Furthermore the actuator arrangement is preferably disposed on the opposite side of pivot to the distal end of the linkspan with the actuator arrangement is adapted to push distal end downwards against the counterbalancing load of the counterweight.

This ensures that the linkspan advantageously fails safe towards a raised position and out of the sea.

The counterweight may preferably entirely counterbalance and support all of the weight of the linkspan projecting from the quay and in use loads. Alternatively the counterweight counterbalances and supports only a proportion of the weight of the linkspan projecting from the quay and in use loads.

The counterweight may be mounted above a plane of the * ,* I I a a I gi I I S I I I S S a a.

* I 551 a I S 4:.. : p3591B linkspan deck.

The pivot assembly is preferably slidably mountable to the quay. Dampers may also be provided to dampen sliding movement of the pivot assembly.

The present invention will now be described by way of example only with reference to the following figures in which: Figure 1 is a schematic illustration of a linkspan in accordance with an embodiment of the invention connecting and providing vehicular access to a ship from a port quay; Figure 2 is a more detailed side view of the linkspan shown in figure 1; Figure 3 is a plan view of the linkspan shown in figure 2.

Referring to figure 1, a linkspan 10 provides a flat roadway for vehicles 1 to drive over the linkspan 10 onto a ship 8 moored in the dock 3 allowing roll-on/roll-off (RORO) operation. The linkspan 10 in accordance with an embodiment of the present invention is mounted on a dock quay 4 and projects from the quay 4 over the sea 2 towards a ship 6 moored in the dock 3 with the distal end of the linkspan 10 disposed adjacent the ship access (not shown) . As will be explained further below, the linkspan 10 is pivotally mounted on the quay 4 such that the height of a distal, seaward/ship, end 25 of the linkspan 10 above the quay 4 and level of the sea 2 can be adjusted and aligned with the ship access to accommodate differing heights of ship access and changes in sea level. A small ship ramp 8, or transition ramp mounted on the distal end of the linkspan 10, may bridge the small final gap between the distal end 25 of the linkspan 10 and ship 6.

The linkspan 10, without the ship 6, is shown in more detail in figures 2 and 3. The linkspan 10 comprises a * II. I * ,..

S S S IS S * S I S S I * I SI * . I.. * S I S 5;. : P3'5'591B pivotally mounted cantilevered arrangement with the projecting linkspan portion and distal seaward/ship end 25 of the linkspan 10 supported by a counterweight 16 located at a quay 4 (shore) end of the linkspan 10 rather than being supported by floats or lifting machinery as is conventional.

Specifically the portion of the linkspan 10 projecting from the quay 4, and seaward distal end 25 of the iinkspan 10 is cantilevered about the pivotal mounting of the link span 10 to the quay 4. Accordingly with none of the linkspan in the sea it is less susceptible to corrosion, is not subject to sea and wave loading, and can more easily be inspected and maintained. In addition there is no need to anchor any guide posts or other assembled below the sea and into the seabed.

The linkspan 10 comprises a structural frame 14 pivotally mounted to the quay 4 about a laterally extending pivot axis A by a pair of laterally spaced pivot assemblies 18 such that the linkspan 10 can pivot about the laterally extending pivot axis A as shown by arrow X in figure 2. The pivot assemblies 18 comprise pivot shafts mounted in corresponding pivot bearing housings. A flat planar linkspan deck 12 is mounted upon the frame 14 projecting from the quay 4 on one side of the pivot assemblies 18 and pivots about axis A with the frame 14. The linkspan deck 12 in use defines the roadway for vehicles 1 to drive over the linkspan 10. A planar flat transition flap or ramp 28 with one end resting or mounted upon the shore end of the linkspan deck 12 bridges the gap between the pivoting linkspan deck 12 and quay surface 30, continuing the linkspan deck roadway, and allowing vehicles 1 to drive from the quay 4 onto the linkspan deck 12.

The counterweight 16 is mounted on the frame 14 on the opposite side of the pivot assemblies 18 to, in use, counterbalance the weight of the linkspan 10 and linkspan deck 12 projecting from the quay 4 on the other side of the pivot assemblies 18. The counterweight 16 is preferably * ,.. * * I,.

* * I * S S t I S S I * I II * S *I* P * I P * , * * e * p S * ** * S S S 6 P352591GB significantly oversized, including a significant safety factor, to counterbalance and support both the weight of the linkspan 10 and linkspan deck 12 projecting from the quay 4 and in use loads (for example vehicle weight of traffic over the linkspan 10 and loads from ship ramps 8 etc.) applied to the projecting linkspan 10. As a result the distal seaward end 25 of the linkspan 10 is normally biassed and pivoted upwards towards a raised position. The oversizing, and relative massive size of the counterweight 16 also reduces movement of the linkspan 10 in use as the vehicles 1 and loads (both static and dynamic loads generated) cross and travel along the length of the linkspan 10.

An actuating arrangement comprising a pair of hydraulic extending rams 24 are connected to the structural frame 14 and are arranged to in use act against the weight of the counterweight 16 to raise and lift the counterweight 16 against gravity (as shown by arrow B), pivoting the linkspan about the pivot axis A and allowing the distal seaward end 25 of the linkspan 10 to be lowered (as shown by arrow X) as required to align with the ship access. As shown in this embodiment the hydraulic rams 24 are arranged vertically directly below the counterweight 16 and are connected to a distal shore end 23 of the frame 14. It will be appreciated however that other hydraulic ram arrangements could be used. For example the hydraulic rams could be provided on the other side of the pivot assemblies 18, and operate in the opposite sense/direction. This is however less preferable since access to the rams 24 is less easy.

Other actuating arrangements could also be used. For example suitably configured winch arrangements connected to the frame 14 could be used. Such winch arrangements if acting on the seaward side of the pivots 18 would pull the seaward side and distal seaward end 25 of the linkspan 10 downward.

Alternatively the winch arrangements could be connected to a support tower to lift the counterweight 16 if acting on I q$ I fI * . . ,, I I I

I I I I I I II

I I *I* I I P * I 0 0 0 I I., I 110 0 7 P352591GB the shore side of the linkspan 10. In a yet further variation the actuating arrangement could comprise rotary motors driving rotary movement of the pivots 18 and linkspan 10.

The actuating arrangement acts against the counterweight and in effect pushes' the distal seaward end of the linkspan 10 down to the required height and angle.

This can be contrasted with conventional linkspan arrangements in which lifting gear raises and directly supports the seaward end of the linkspan such that if the lifting machinery fails the seaward end of such a conventional linkspan will drop and fall towards the sea. In contrast with the linkspan of this embodiment of the invention if the actuating arrangement fails then the seaward distal end 25 of the linkspan is raised and lifts upwards towards a safe position out of the water 2.

Furthermore the linkspan 10 can be parked' in a suitable position and with the distal seaward end 25 of the linkspan at a desired height by simply chocking the shore end and counterweight of the linkspan 10.

The structural frame 14 may be of any suitable configuration to support the linkspan deck 12, counterweight 16 and pivots 18, and resist the forces applied to the linkspan 10 in use. In the embodiment shown the structural frame 14 comprises a pair of deck support arms 11 rigidly connected at their ends and at an angle to a pair of counterweight support arms 15, and a pair of support stay arms 13 rigidly connected at their ends and at an angle to the deck support arms 11 and counterweight support arms 15.

The deck support arms 11 project and extend from the pivots 18 and quay 4 towards the ship 6 along either lateral side of and supporting the linkspan deck 12. The pair of counterweight support arms 15 project from the deck support arms 11 and at a vertical angle to the deck support arms on other side of the pivots 18 and support the counterweight 16 II. I p p, p * it Ii

I I I I I II

I I III I II

8 P3'2'591'* in a vertically elevated position. The counterweight 16 is mounted upon a distal shore end of the counterweight support arms 15 extending between an interconnecting the support arms 15. Of course in other embodiments the counterweight 16 may comprise two separate counterweight elements each attached to a respective support arm 15. In alternative embodiments however the counterweight support arms may simply continue the deck support arms 11, or be angled vertically below the deck support arms 11 such that the counterweight 16 is not elevated or is below the deck support arms 11. In such an arrangement suitable pits may be provided in the quay 4 to receive the distal shore ends 23 of the counterweight arms and the counterweights 16. The pair of support stay arms 13 project vertically from the deck support arms 11 generally above the pivots 18 and pivot axis A. The distal ends of the support stay arms 13 are interconnected by a end frame beam 17. Cable stays 24,26 are attached between the distal ends of the support stay arms 13 and deck support arms 11 and counterweight support arms 15 respectively. The support stay arms 13 and cable stays 24,26 stabilises and strengthen the frame 14 and linkspan 10, and supports the distal end of the deck support arm 11.

To accommodate ship impact with the linkspan 10 the pivot assemblies 18 are preferably slidingly mounted to the quay 4 on sliders 22. This allows the pivot assemblies 18, and so linkspan 10 to slide to some degree longitudinally (as indicated by arrow Y) on its foundations as well as allowing a limited degree of slewing of the linkspan 10 (as indicated by arrow Z) in a generally horizontal plane and about a vertical axis orthogonal to the pivot axis A. Energy absorbing devices 18, such as rubber fenders, are disposed between the pivots 18 and sliders 22 to resist damp and absorb such sliding movement of the pivot assemblies 18 on the sliders 22 and so of the linkspan 10.

Whilst as described above the counterweight 16 is sized a **s I * *I* * I I *t S * S S * S * I IS * * III S I I S * I * * . S S S 9 P352591t and arranged to support and counterbalance both the weight of the linkspan 10 and linkspan deck 12 projecting from the quay 4 and in use loads applied, in alternative embodiments the counterweight 16 may be much lighter and arranged to only substantially counterbalance the weight of the linkspan and linkspan deck 12 projecting from the quay 4. In such cases when the linkspan is in use the distal seaward end 25 of the linkspan either rests on the ship 6, or is otherwise supported to a limited degree from the ship 6 in order to take the in use loads of the vehicles 1 passing over the linkspan 10. Alternatively such loads may be resisted and supported by the actuating arrangement holding the linkspan in the required position. It should be noted however that even in such arrangements the linkspan 10 and distal seaward end 25 of the linkspan 10 are still principally supported by the counterweight 16 with the majority of the loads being off set by the counterweight 16. Whilst less preferred, an advantage of such arrangements is that the counterweight 16 does not need to be so heavy so reducing costs and the strength and size of the structural frame 14 to support the counterweight 16. Also smaller actuating arrangements can be used to operate the linkspan 10.

In a yet further variation the counterweight 16 can have a variable weight (for example comprising a tank that is filled or emptied of water), and/or comprise moveably mounted weights, to alter the counteracting moment provided by the counterweight 16 on the linkspan 10. In such arrangements the counterweight could be adjusted for the particular in use loads and/or to move and pivot the linkspan to the required position either replacing, or reducing the loads on the actuating arrangement.

Other further modifications, variations and alternate embodiments of the cantilevered linkspan arrangement described above and shown in the accompanying figures will be apparent to those skilled in the art.

Claims

* a.. . . I.. * . U eq I S I U * * . I UI * S *S* I S * S * I S S I S S S P35259l CLAIMS

1. A linkspan for connecting and providing access to and from a quay to a ship, the linkspan comprising a linkspan deck projecting from the quay and having a distal end, a pivot assembly pivotally mounting the linkspan deck from the quay, an actuator arrangement for raising and lowering the distal end of the linkspan, and a counterweight counterbalancing and supporting the linkspan deck projecting from the quay about the pivot.

2. A linkspan as claimed in claim 1 wherein linkspan deck projects from one side of the pivot assembly and the counterweight is disposed on an opposite side of the pivot.

3. A linkspan as claimed in claim 1 or 2 wherein the counterweight entirely counterbalances and supports all of the weight of the linkspan projecting from the quay and in use loads.

4. A linkspan as claimed in claim 1 or 2 wherein the counterweight counterbalances and supports only a proportion of the weight of the linkspan projecting from the quay and in use loads.

5. A linkspan as claimed in any one of claims 1 to 3 in which the counterweight normally biases and pivots the linkspan deck and the distal end of the linkspan deck towards a raised position.

6. A linkspan as claimed in any preceding claim in which the counterweight is mounted above a plane of the linkspan deck.

* I.. * ,** * . * I. * * 8 I I S S S * *I * I *** * * * 8 5 5 5. S S 11 5.. P352591

7. A linkspan as claimed in any preceding claim in which the actuator arrangement operates in use against the counterweight.

8. A linkspan as claimed in any preceding claim in which the actuator arrangement is disposed on the opposite side of pivot to the distal end of the linkspan, and in which the actuator arrangement is adapted to push distal end downwards against the counterbalancing load of the counterweight.

9. A linkspan as claimed in any preceding claim in which the actuator arrangement comprises a hydraulic ram.

10. A linkspan as claimed in any one of claims 1 to 8 in which the actuator arrangement comprises a winch arrangement.

11. A linkspan as claimed in any one of claims 1 to 8 in which the actuator arrangement comprises rotary motor rotating the pivot assembly.

12. A linkspan as claimed in any preceding claim in which the pivot assembly is slidably mountable to the quay.

13. A linkspan as claimed in claim 12 further comprising dampers to dampen sliding movement of the pivot assembly.

14. A linkspan as claimed in any preceding claim in which the pivot assembly comprises a pair of pivots.

15. A linkspan substantially as hereinbefore described with reference to, and/or as shown in figures 1 to 3.