GB2049778A

GB2049778A - A Retractable Hold Ladder

Info

Publication number: GB2049778A
Application number: GB7915816A
Authority: GB
Original assignee: Cheng Naval Architect & Marine
Current assignee: Cheng Naval Architect & Marine
Priority date: 1979-05-08
Filing date: 1979-05-08
Publication date: 1980-12-31
Also published as: GB2049778B; JPS566891A

Abstract

A retractable hold ladder comprises a vertical elongate strut 1 which is attached to a bulk head forming the wall of a ship's hold. The strut is in the form of a ladder and has rungs 2. Upper and lower platform members 3 and 4 are provided with rollers 5, which roll on tracks on opposite sides of the strut 1. An upper flight of steps 6 has one end pivoted to the upper platform member 3 at 8, and the other end pivoted to an intermediate platform 9 at 10. A lower flight of steps 7 has one end pivoted to the lower platform member 4 at 11, and the other end pivoted to the intermediate platform 9 on the same axis 10 as the upper flight 6, but axially spaced therefrom. A hoisting system, comprising a continuous rope 14 fixed at one end at 15 to a block attached to the deck head and passing through various blocks to a deck winch, is provided for hoisting the lower platform member up to the upper platform member, so that the two flights of steps are substantially horizontal. Thus, the position of the lower platform can be altered in dependence on the level of cargo in the hold. <IMAGE>

Description

SPECIFICATION A Retractable Hold Ladder There are a number of regulations governing the design of ladders which extend down into ships holds. In particular, a vertical ladder down a bulk head is not deemed to be sufficient to provide access to the floor of a hold, and an inclined ladder must be provided. Clearly, an inclined ladder will take up space which could otherwise be used for cargo storage, and it is therefore an object of the invention to minimize the space required by an inclined ladder. A fixed, inclined ladder is also susceptible to damage by the cargo, and it is desirable that this should be avoided.

A construction is known, particularly for use with corrugated bulk heads, where a pluraiity of flights of steps are provided in a vertically extending trough of the corrugations. The ladder flights are fixed, and the central portion of the ladder is protected by a vertically extending protective cover, so that the central portion of the ladder is in a vertical tunnel which is open at the top and the bottom. Disadvantages of this construction are the costly construction of the cargo hold bulk head in way of the ladder, the weight of the flights of steps, and the fact that the ladder cannot be used once the floor of the hold has been filled with cargo, because then the bottom opening of the tunnel is blocked off.

According to the present invention, there is provided a retractable hold ladder comprising an elongate strut to be attached to a bulk head in a vertical position, upper and lower platform members arranged to be slidable on the strut, upper and lower flights of steps, the upper flight having one end pivotally connected to the upper platform member and the other end pivotally connected to an intermediate platform, the lower flight having one end pivotally connected to the lower platform member and its other end pivotally connected to the intermediate platform, and hoisting means for hoisting the lower platform member up to the upper platform member so that two flights of steps are substantially horizontal.

The two flights of steps may each be separately pivoted to the intermediate platform member. A linking bar or bars connected to the lower and intermediate platform members and parallel to the lower flight of steps, but spaced therefrom, can be provided to maintain the intermediate platform member parallel to the upper and lower platform members.

The vertical strut is preferably provided with rungs and forms a vertical ladder up the side of the bulk head.

Stopping devices may be arranged adjacent the strut to limit the vertical movement of the upper and lower platform members. The stopping devices will be arranged so as to ensure that the platform members always stop in a position where the flights of steps are inclined to the vertical.

The hoisting means may be arranged with pulleys suspended from the deck head and pulleys attached to each of the platform members so that the whole ladder can be raised and lowered by pulling in on only one rope.

The upper platform member may have a hinged panel adjacent the strut, so that the strut can be used as a ladder over its full height.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a ladder according to the invention, in the lowered position; Figure 2 is a view of the ladder of Figure 1 taken in the direction of arrow A; Figure 3 is a view of the ladder of Figure 1 taken in the direction of arrow B; and Figure 4 is a perspective view similar to Figure 1 but showing the ladder in the retracted position.

The ladder shown in Figure 1 has a vertical strut 1 which will be attached to a bulk head forming the wall of a hold. This strut 1 is in the form of a ladder, and has rungs 2. Upper and lower platform members 3 and 4 are provided with rollers 5 which roll on tracks on opposite sides of the strut 1. Upper and lower flights of steps 6, 7 are pivotally attached to respective platform members. Flight 6 is attached to platform 3 at 8 and to an intermediate platform 9 at 10. Flight 7 is attached to platform 9 on the same axis 10 as flight 6, but axially spaced therefrom, and to platform 4 at 11. Linking bars 1 2 are pivoted to extensions 1 3 of platform 4 and to the outer edges of platform 9, so that the bars 12 lie parallel to flight 7 and ensure that platform 9 always remains parallel to platform 4.

The hoisting system is shown in Figure 1. The system comprises a continuous rope 14 which has one end fixed at 1 5 to a block attached to the deck head (not shown), and then passes, in turn, through blocks a, bc, d, e, f, g, h, i, j, kand /to a winch on the deck. Winding up the rope 14 on the winch raises all the various parts of the ladder.

Initially, platforms 4 and 9 are lifted, but when a position is reached when platform 4 contacts platform 3 from underneath, then platform 3 is lifted as well until the whole ladder is as close as possible to the deck head. This position is shown in Figure 4.

Figures 2 and 3 show the ladder without the hoisting means. Figure 2 shows that the treads 16 of the flights 6 and 7 are curved, so that they will be usable when the flights 6 and 7 are at various angles of inclination. Figure 2 also shows a stopper 17 which is mounted on the bulk head and can be positioned at right angles to the bulk head where it receives the upper surface of platform 3. Figure 1 shows the platform received on the stopper 17, and Figure 4 shows the platform 3 raised above the stopper 1 7 and, in dotted lines, the position of the stopper 1 7 when it is swung back against the bulk head. A similar stopper may be provided for the lower platform 4.

Access is obtained to the upper platform 3 by the top section of the ladder or strut 1. Part of the platform 3 is hinged, so that it can be lifted back as shown in Figure 4 to allow unimpeded access up and down the ladder 1.

Hand rails will also be provided around the platforms 3, 4, 9 and on the sides of the flights of steps 6 and 7. These are however not shown in the drawings to avoid any loss of clarity.

It will be seen that the ladder described occupies very littie space in the retracted position, since it is then housed immediately under the deck head, and does not obstruct any of the loading space below. The weight of the ladder is relatively low because it does not require a large fixed supporting structure.

The stoppers 1 7 are arranged to prevent the inclination of the ladder from exceeding 650.

The upper platform 3 may for example have an area of 75 cm by 75 cm. The platform 9 may have an area of 120 cm by 75 cm, and may include some means of anchoring it to the bulk head, when in the lowered position, to prevent undesirable movement of the ladder. The lower platform 4 may have an area 1 50 cm by 75 cm, and additionally has an opening 1 8 for providing access to the bottom part of the vertical ladder 1.

The ladder 1 may be used as a vertical hold ladder when the retractable ladder is not in use.

By way of example only, for a 60,000 DWT bulk carrier, the length of each flight 6, 7 is about 4 m. The width of each step may be 45 cm.

The upper stopper 1 7 for the upper platform 3 may be 250 cm below the deck head.

The ladder described can easily be incorporated in a newly built vessel, or can be added to an existing vessel without any difficulty.

It also has advantages over known access ladders in that the position of the lower platform 4 can be altered in dependence on the level of cargo in the hold.

It is envisaged that for larger vessels, two intermediate platforms with four flights of steps could be used. It may be possible to dispense with the platforms, and to pivot the flights of steps directly to one another and to carriages running on the vertical strut.

Claims

1. A retractable hold ladder comprising an elongate strut to be attached to a bulk head in a vertical position, upper and lower platform members arranged to be slidable on the strut, upper and lower flights of steps, the upper flight having one end pivotally connected to the upper platform member and the other end pivotally connected to an intermediate platform, the lower flight having one end pivotally connected to the lower platform member and its other end pivotally connected to the intermediate platform, and hoisting means for hoisting the lower platform member up to the upper platform member so that the two flights of steps are substantially horizontal.

2. A retractable hold ladder as claimed in claim 1, wherein the two flights of steps are each separately pivoted to the intermediate platform member.

3. A retractable hold ladder as claimed in any preceding claim, wherein a linking bar or bars connected to the lower and intermediate platform members and parallel to the lower flight of steps, but spaced therefrom, is provided to maintain the intermediate platform member parallel to the upper and lower platform members.

4. A retractable hold ladder as claimed in claim 1, wherein the vertical strut is provided with rungs and forms a vertical ladder up the side of the bulk head.

5. A retractable hold ladder as claimed in claim 4, wherein stopping devices are arranged adjacent the strut to limit the vertical movement of the upper and lower platform members.

6. A retractable hold ladder as claimed in claim 5, wherein the stopping devices are arranged to ensure that the platform members always stop in a position where the flights of steps are inclined to the vertical.

7. A retractable hold ladder as claimed in claim 1, wherein the hoisting means are arranged with pulleys suspended from the deck head and pulleys attached to each of the platform members so that the whole ladder can be raised and lowered by pulling in on only one rope.

8. A retractable hold ladder as claimed in claim 1, wherein the upper platform member has a hinged panel adjacent the strut, so that the strut can be used as a ladder over its full height.

9. A retractable hold ladder substantially as herein described with reference to the accompanying drawings.