The present invention relates to a mechanism for hinged mounting of a cargo ship hatch cover to the ship's hull structure, the mechanism comprising, in addition to the pivotal mechanism connecting the hatch cover to the hull struc- ture, at least one actuator adapted between the hatch cover and the hull structure, such as a hydraulic cylinder by means of which the hatch cover is rotatable from a substantially vertical open position into a substantially horizon- tal closed position and vice versa, said closed position being secured by means of support brackets arranged to support the hatch cover from below.

The invention is particularly (but not exclusively) related to hinged mounting of the hatch cover of an intermediate cargo-carrying deck. In cargo ships, the intermediate deck is a hatch cover which is located below the weather deck in the payload cargo hold and adapted to carry the weight of cargo placed thereon. Conventionally, the hatch covers of the intermediate cargo-carrying deck are either stowed (lifted off and on) by means of a lift or, alternatively, are cylinder-operated hatch cover panels generally adapted to rotate about one hinged edge. Lift-operated hatch covers may be arranged to rest on support brackets settable at different heights in the cargo hold, thus allowing the hatch cover to be adjusted by its height position. During the time the lift-operated hatch cover panels of the intermediate cargo-carrying deck are not in use, they are stowed away onto the weather deck or into the cargo hold or they may even be removed from the ship. In contrast, a hinged hatch cover cannot be adjusted by its height position.

Moving intermediate cargo-carrying decks by a lift is time-consuming and clumsy. As cargo-carrying intermediate deck structures generally are large and heavy, the hoisting capacity of cranes used in harbors may be insufficient for

handling the deck panels. Hinged structures are placed upright in their stowing position (that is, when they are not supporting overlying cargo), whereby they steal the valuable payload cargo hold. Furthermore, panels stowed in their storage position may become damaged when cargo is being handled.

It is an object of the present invention to provide a novel type of mechanism with greater flexibility and user-friendliness for a hinged hatch cover construc- tion aboard a cargo ship. Such mechanism according to the invention is charac- terized in that the hinged connection of the hatch cover to the ship's hull structure is implemented using a mechanism that facilitates a limited movement of the hinged end of the hatch cover in the vertical direction so that the hatch cover can be adjusted to a desired height.

A preferred embodiment of the invention is characterized in that said mecha- nism comprises an articulated link arm having its one end hingedly connected to said hull structure and the other end to the hatch cover, respectively, and that the support brackets serving to support the hatch cover in its closed position are placed at least at two different height levels.

Another preferred embodiment of the invention is characterized in that at least the upper set of the support brackets is settable either into an operative position wherein they support the hatch cover and, respectively, into a home position wherein the upper support brackets facilitate the rotation of the hatch cover onto the lower set of the support brackets or away therefrom.

A still another preferred embodiment of the invention is characterized in that the operation of the upper set of the support brackets between their operative posi- tion and their home position is arranged to take place manually, hydraulically or other similar manner.

Among other benefits, the invention offers fast and easy operation without the

use of a lift. Furthermore, no usable cargo hold is reserved for the stowing of the hatch cover panels. The mechanism is simple and reliable in use. Opening, closing, elevation into its top position and respective lowering of the hatch cover into its horizontal deployed position can be performed by means of a single actuator. The mechanism according to the invention facilitates both opening and closing as well as elevating the cargo-carrying deck hatch cover into its top position and respectively lowering the same into different height positions within the confines of the cargo hold.

In the following, the invention is examined in greater detail with reference to the appended drawings, in which: FIG. 1 shows a cargo ship and its hatch covers; FIG. 2 shows a hatch cover system equipped with a mechanism according to the invention in a position where the hatch cover of a cargo-carrying inter- mediate deck is in its operative position resting on the lowermost set of the support brackets and the weather deck hatch cover is deployed into its closed position; FIG. 3 shows the same view as FIG. 2 but now with the weather deck hatch cover operated into its open position; FIG. 4 shows the same view as FIG. 3 but now with the intermediate deck hatch cover, too, operated into its open position; FIG. 5 shows the same view as FIG. 4 but now with the upper set of the support brackets actuated operative and the intermediate deck hatch cover simulta- neously beginning to rotate onto this upper set of the support brackets; FIG. 6 shows the same view as FIG. 5 but now with the intermediate deck

hatch cover already rotated onto this upper set of the support brackets, where it rests in its stowed position; and FIG. 7 shows the same view as FIG. 6 but now with the weather deck hatch cover already rotated into its closed position.

As shown in FIG. 1, above a cargo hold 1 is situated an intermediate cargo- carrying deck whose hatches 2 are shown in the diagram operated into both their open and closed positions. The trajectory of the hatch cover panels of the cargo-carrying deck is denoted by hatched lines. Above the hatch covers 2 of the cargo-carrying intermediate deck are placed the weather deck hatch covers 3 that respectively are shown in their open and closed positions. Cargo such as sheet steel rolls 4 can be carried on top of the hatch covers 2 of the cargo- carrying deck.

In FIG. 2 is shown a more detailed diagram of the hinged mechanism according to the invention. The mechanism comprises an actuator such as a hydraulic cylinder 6, which is at its one end pivotally connected to the hinged edge of the hatch cover 2 and, also pivotally, at its other end to the ship's hull structure 5.

Between the hatch cover 2 and the hull structure 5 is also adapted a link arm 7 having its one end pivotally connected to the hatch cover 2 and the other end to the hull structure 5. By virtue of its two pivotal ends, the link arm 7 facilitates a vertical movement of the hinged edge of the hatch cover 2 within a given range.

In the situation illustrated in FIG. 2, the hatch cover 2 of the cargo-carrying deck is shown in its deployed operative position supported by the lower set 8 of the support brackets. In this position, the hatch cover of the cargo-carrying deck is capable of receiving cargo 4 to be loaded thereon. Further above this hatch cover is located the hatch cover of the weather deck that also is placed into its closed position. As is obvious from the diagram, the entire volume of the actual cargo hold 1 is thus usable for the payload cargo.

In the situation shown in FIG. 3, the weather deck hatch cover 3 has been stowed aside by means of its own actuator not shown in the diagrams. Then, the cargo 4 can be unloaded from above the hatch covers 2 of the cargo- carrying intermediate deck. In FIG. 4, the hydraulic cylinder 6 has been actuated to rotate the hatch cover 2 of the cargo-carrying deck into its vertical open position. In the situation shown in FIG. 5, the upper set 9 of the support brackets has been deployed, that is, the brackets are rotated or pulled, e. g., manually or hydraulically into their supporting position. In the situation shown in FIGS. 2 and 3, however, the upper set of the support brackets were not deployed in order to permit the passage of the hatch cover onto the lower set of the support brackets and off therefrom. With the upper set of the support brackets deployed into the operative position, downward lowering of the cargo- carrying deck hatch cover 2 by rotation thereof causes the cover to meet first the support bracket 9 located closest to the hinged edge of the cover 2, whereby this bracket becomes the dynamic center of rotation. Subsequently, the link arm 7 makes it possible for the hinged-edge side of the hatch cover 2 to rise upwards, whereupon the hatch cover can finally attain the position shown in FIG. 6. Herein the hatch cover 2 of the cargo-carrying deck remains resting on the upper set of brackets 9. This position of the cargo-carrying deck hatch cover is its stowed position, wherein it steals the minimum volume from the payload space of the actual cargo hold, while no cargo is capable of being loaded thereon. In FIG. 7 also the weather deck hatch cover 3 is illustrated deployed into its closed position.

The actual rotational movements of the cargo-carrying deck hatch cover are actuated with the help of a hydraulic cylinder 6, while the changes in the height position of the hatch cover 2 are implemented by means of the link arm 7 and the support bracket sets 8,9. In this fashion, the mechanism described above makes it possible to both open/close of the cargo-carrying deck hatch cover 2 and to elevate/lower the same into different height positions in the cargo hold 1.

In short, the function of the mechanism is based on a link mechanism based on

two pivotal points. Complementarily, the pair of support brackets located closest to the link mechanism at support bracket levels above the lowermost support bracket level act as a dynamic center of rotation for the hatch cover 2. The support brackets 8,9 are typically placed at the sides of the cargo hold.

To those skilled in the art it is obvious that the invention is not limited to the exemplifying embodiments described above, but rather, can be varied within the scope and spirit of the appended claims. Accordingly, if a greater number of deck height positions is required between the upper and lower levels recited above, a greater number of bracket sets can be installed to provide, e. g., one deck level for cargo of a very low height, while simultaneously a cargo hold of a maximally high volume is made available below the cargo-carrying deck.

It is obviously possible to implement equivalent hinged trajectories by means of more complicated link arm mechanisms using a greater number of pivotal points. Furthermore, guide rails and slide surfaces may be used to implement the geometric trajectories described above.