COUPLER FOR COUPLING TWO CONTAINERS STACKED ON TOP OF ONE ANOTHER, ESPECIALLY ABOARD A SHIP

Abstract

The invention relates to a coupler for coupling two containers stacked on top of one another, especially aboard a ship, which has an upper coupling projection (10) engaging in a bottom corner fitting of the upper container and a lower coupling projection (11) engaging in a top corner fitting of the lower container, which coupling projection has in longitudinal direction of the containers a lateral coupling lug (22) and a vertical back wall (21), which is mounted on the side of the lower coupling projection (11) facing away from the coupling lug (22) in such a way that the space (b) between a free edge (25) of the coupling lug (22) and the back wall (21) is smaller than or equal to the width of an upper slotted hole in the top corner fitting. To securely couple two containers stacked on top of one another even when outrightly exposed to tractive forces, the invention-based coupler is characterized in that the lower coupling projection (11) in the back wall (21) has a recess (26) which extends in slot-like manner across the entire length of the lower coupling projection (11).

Description

The invention relates to a coupler for coupling two containers stacked on top of one another, especially aboard a ship, which has an upper coupling projection engaging in a bottom corner fitting of the upper container and a lower coupling projection engaging in a top corner fitting of the lower container, which coupling projection has in longitudinal direction of the containers a lateral coupling lug and a vertical back wall, which is mounted on the side of the lower coupling projection facing away from the coupling lug in such a way that the space between a free edge of the coupling lug and the back wall is smaller than or equal to the width of an upper slotted hole in the top corner fitting.

Such a coupler has been disclosed in DE 102 38 895 A1.

Because of the fact that containers allow for rapid cargo handling, they have gained great acceptance for transporting goods. Therefore, constant efforts are made to improve the rigging process of the containers aboard a ship. In addition to safety issues, it has also been attempted to accelerate the handling of the containers in the ports, in order to reduce the waiting times of the ships. In particular, this applies to the containers transported on deck of ships. At first, they were secured manually using twistlocks, which had to be manually applied when loading the ship with containers, as well as unloading the containers. This was not only very time-consuming, but required also the presence of stevedores on deck while loading the containers, forcing them to work under suspended loads. Moreover, in unfavorable weather conditions, the surface of the containers on which the stevedores have to walk is very slippery. This involved considerable dangers for the stevedores, resulting in the fact that in the 1990s it was prohibited during the period of loading a ship that stevedores stayed in the bay area that was loaded with containers.

A first step toward increasing the safety of the stevedores and accelerating container handling was the use of semiautomatic twistlocks (SAT). Semiautomatic twistlocks couple automatically when the upper container is placed on the lower container, so that the containers stacked on top of one another are permanently coupled together. However, to unload the containers, the semiautomatic twistlocks have to be manually opened by the stevedores. This process is safe for the stevedores because they can open all twistlocks of the containers to be unloaded as soon as the ship is in the port, and they can leave the ship before the containers are lifted from the ship. Consequently, the stevedores no longer have to stay under suspended loads. However, the manual process of uncoupling the twistlocks remains very time-consuming.

The above-mentioned DE 102 38 895 A1 introduces a fully automatic twistlock (FAT), which fully automatically couples the containers when an upper container is placed on a lower container and fully automatically decouples the containers when they are unloaded. The stowage personnel is only required to insert at the dock the fully automatic twistlocks into the bottom corner fittings of the upper container before the container is lifted aboard the ship, or to remove at the dock the twistlocks after the container is lifted off the ship.

A lateral coupling lug makes sure that the fully automatic twistlock according to DE 102 38 895 A1 securely couples the containers stacked on top of one another during the maritime transport. This fully automatic twistlock is based on the knowledge that pitching motions of the ship hardly result in any vertical acceleration of the containers, which exposes the containers to hardly any or no lift-off forces. It is true that considerable vertical acceleration occurs when the ship is rolling. However, in this case, compressive forces on the one lateral side (pressure side) occur between two containers stacked on top of one another while on the other lateral side tractive forces (tensile side) occur. Because of the design of the fully automatic twistlock, the twistlocks mounted on the pressure side prevent the two containers stacked on top of one another from shifting horizontally against each other. This ensures that the coupling lugs of the twistlocks mounted on the tensile side are prevented from uncoupling. However, when at the port the upper container is lifted by a crane, tractive forces are applied to all four twistlocks, making it possible that they are uncoupled.

However, it is still feared that under certain conditions in specific stowage spaces, for example, in a front or rear bay, tractive forces could occur on all four twistlocks and result in undesired uncoupling. To prevent this from happening, it has been proposed using fully automatic twistlocks which have two coupling lugs situated opposite from one another (DE 20 2004 017 252 U1). FIG. 3 of this document shows such a fully automatic twistlock, in which both coupling lugs are arranged on different levels. This results in a “Z-motion” both during the coupling, as well as the uncoupling process, which is considered to be of disadvantage, because the containers could be jammed or caught during the loading or unloading process.

Based on these facts, the invention proposes to further develop the above-mentioned coupler in such a way that it securely couples two containers stacked on top of one another even when outrightly exposed to tractive forces and that it prevents “Z-motions” from occurring during the coupling and uncoupling process.

To solve this problem, the invention-based coupler is characterized in that the lower coupling projection in the back wall has a recess which extends in slot-like manner across the entire length of the lower coupling projection.

Therefore, the invention-based coupler is basically designed in the form of a fully automatic twistlock according to DE 102 38 895 A1. However, a slot-like recess is provided in the back wall of the twistlock. As a result, the “Z-motion” which occurred during the coupling and uncoupling process is eliminated. If, despite all provisions, the coupling lug on the tensile side should slide out of the associated corner fitting, i.e., be released behind the edge of the slotted hole of said corner fitting, the upper container would slip on the lower container horizontally in a direction that is opposite to the direction in which the coupling lug points, i.e., in the direction of the recess. As a result, the edge of the upper slotted hole that is opposite of the coupling lug engages with the recess, so that the coupler is not completely uncoupled. The upper container remains coupled with the lower container. In addition, the invention-based coupler has specific emergency operating features.

By means of the recess an additional lug is formed on the side facing away from the coupling lug. This lug should have a shoulder that is inclined to the outside. In this way, it can be prevented that the lower coupling projection gets caught at the slotted hole of the corner fitting, if the edge of the slotted hole should accidentally engage in the recess during the process of unloading the container. For this purpose, the inclined collar does not have to be as flat as the shoulder of the coupling lug. As a result, the angle of the shoulder to a back wall of the lower coupling lug can be larger than the angle of the shoulder of the coupling lug to a front wall. For manufacturing reasons, it is especially preferred when the shoulder of the lug is aligned with an inside surface of a grip recess in the lower coupling projection. Usually, couplers are made of steel casting and the aligned shoulder would make it easier to produce the casting mold.

According to a further development of the invention, on a side that is opposite of the lug, i.e., on a side facing the upper coupling projection, the recess is restricted by an inclined insertion surface. If the recess is applied in the above-mentioned manner or, during the process of coupling the coupler with the top edge fitting of the lower container, the edge of the slotted hole would accidentally get into the recess (which could happen because of wind pressure or because the container starts swinging on the crane), the inclined insertion surface would ensure that the coupler attains (again) its coupled position.

Subsequently, the invention is described in more detail by means of an embodiment depicted in the drawing. It is shown:

FIG. 1 a front view of the coupler having the characteristics of the invention, and

FIG. 2 a lateral view of the coupler shown in FIG. 1.

The depicted coupler has an upper coupling projection 10 and a lower coupling projection 11. A lock 12 has been arranged between the coupling projections 10, 11, which also forms a parting plane between two containers stacked on top of one another (not shown). The bottom side of the lock 12 is attached to the upper side of the top corner fitting of the lower container, while the bottom side of the of the bottom corner fitting of the upper container is standing on the top side of the lock 12. However, according to the invention, provision has also been made to design in well-known manner the lock 12 merely in the form of a protruding wedge-like bulge, which then engages in a groove formed by bevels at the slotted holes of the corner fittings. As a result, the corner fittings of the containers are standing directly on top of one another.

Above the lock 12, the upper coupling projection 10 has a shaft 13, which has a head 14 on the side facing away from the lock 12. FIG. 1 clearly shows that the head 14 protrudes on both sides beyond the shaft 13, thus forming locking projections 15 and 16.

The lower coupling projection 11 also connects to the lock 12 by means of a shaft 17. On the one side, the shaft 17 has a front wall 18 which extends vertically to the lock 12. On the side that is located opposite of the front wall 18 the shaft 17 has an inclined insertion surface 19 which crosses over to a bevel 20 on the end facing the lock 12. This bevel 20 correspond with a bevel at the slotted hole of the corner fitting and is attached to the bevel when the coupler is coupled. Therefore, the bevel 20 could also be considered to be part of the lock 12, especially when the lock 12 is designed in the form of a bulge, as described above.

At the end facing away from the lock 12, the inclined insertion surface 19 crosses over in arch-like manner to a back wall 21, which is also arranged vertically to the lock 12.

Furthermore, the lower coupling projection 11 has a coupling lug 22, which is located opposite of the back wall 21. The coupling lug 22 is arranged laterally in relation to a longitudinal axis of the two containers to be coupled. On its upper surface, the coupling lug 22 has a shoulder 23 that is inclined to the outside. Furthermore, an insertion pin 24 has been arranged on the lower side of the coupling lug 22 ist an der Unterseite der Kupplungsnase 22. The width b of the coupling luggsnase 22, i.e., a space between a free edge 25 of the coupling lug 22 and the back wall 21, is maximally as wide as the width of the slotted hole into which the lower coupling projection 11 engages.

In this respect, at least the lower coupling projection 11 corresponds basically to the fully automatic twistlock according to DE 102 38 895 A1. In contrast to the fully automatic twistlock according to DE 102 38 895 A1, the coupler according to the present embodiment has a slot-like recess 26 in the back wall 21. The recess 26 extends across the entire length of the lower coupling projection 11 or the back wall 21 and has a base 27 extending parallel to the back wall 21. On the side facing the upper coupling projection 10 or lock 12, the groove 26 is restricted by an inclined insertion surface 28, and on the side located opposite of the inclined insertion surface 28, i.e., the side facing away from the upper coupling projection 10 or lock 12, it is restricted by an inclined shoulder 29. Therefore, the groove 26 has a trapezoid shape, wherein the angle of the inclined insertion surface 28 and the angle of the inclined shoulder 29 do not have to be equal in relation to the back wall 21. Instead, FIG. 1 clearly shows that the inclined insertion surface 28 is steeper than the inclined shoulder 29, with an angle of approximately 135°, while the inclined shoulder 29 has an angle α₂₉ of approximately 110° in relation to the back wall 21.

Furthermore, the inclined shoulder 29 is not as steep as the inclined shoulder 23 of the coupling lug 22. In the present embodiment, the inclined shoulder 29 restricting the recess 26 is aligned with a lower inside surface 30 of a grip recess 31, which is shown in FIG. 1 as a covered edge with a dotted line. In general it can be stated that an angle α₂₃ of the inclined shoulder 23 of the coupling lug 22 in relation to the vertical line, i.e., to the front wall 18, is larger than or equal to the angle α₂₉ of the inclined shoulder 29 restricting the recess 26 in relation to the back wall 21.

By means of the recess 26 in the lower coupling projection 11 a further lug 32 is formed, the upper side of which forms the inclined shoulder 29 restricting the recess 29. If required, with this further lug 32, the coupler can hook behind the edge at the upper slotted hole of the associated corner fitting.

The locking projections 15, 16 of the head 14 of the upper coupling projection 10 have lower supporting surfaces 33 or 34 facing the lock 12. At the same time, the supporting surface 34 of locking projection 16, which is located above locking lug 22, is arranged closer to the upper side of the lock 12 (parting plane between containers stacked on top of one another), and thus lower than the supporting surface 33 of the opposite locking projection 15.

BEZUGSZEICHENLIST

• 10 upper coupling projection
• 11 lower coupling projection
• 12 lock
• 13 shaft
• 14 head
• 15 locking projection
• 16 locking projection
• 17 shaft
• 18 front wall
• 19 inclined insertion surface
• 20 bevel
• 21 back wall
• 22 coupling lug
• 23 bevel (the locking lug 22)
• 24 insertion pin
• 25 edge
• 26 recess
• 27 Grund
• 28 base
• 29 bevel (the recess 26)
• 30 inside surface
• 31 grip recess
• 32 further lug
• 33 supporting surface
• 34 supporting surface

Claims

1. A coupler for coupling two containers stacked on top of one another, especially aboard a ship, which has an upper coupling projection (10) engaging in a bottom corner fitting of the upper container and a lower coupling projection (11) engaging in a top corner fitting of the lower container, which coupling projection has a shaft (17) with a front wall (18), a lateral coupling lug (22) arranged in longitudinal direction of the containers, and a vertical back wall (21), which is mounted on the side of the lower coupling projection (11) facing away from the coupling lug (22) in such a way that the space (b) between a free edge (25) of the coupling lug (22) and the back wall (21) is smaller than or equal to the width of an upper slotted hole in the top corner fitting, wherein the shaft (17) on the side opposite of the front wall (18) has an inclined insertion surface (19), characterized in that the lower coupling projection (11) in the back wall (21) has a recess (26) which extends in slot-like manner across the entire length of the lower coupling projection (11).

2. A coupler according to claim 1, characterized in that a further lug (32) has been arranged on a side of the recess (26) facing away from the upper coupling projection (10), which further lug has an upper shoulder (29) that is inclined to the outside.

3. A coupling projection according to claim 2, characterized in that the angle (α29) of the shoulder (29) of the lug (32) in relation to the back wall (21) is larger than or equal to an angle (α23) of an inclined upper shoulder (23) of the coupling lug (22) in relation to a front wall (18) of the lower coupling projection (11).

4. A coupler according to claim 2, characterized in that the shoulder (29) of the lug (32) is aligned with an inside surface (30) of a grip recess (31) in the lower coupling projection (11).

5. A coupler according to claim 1, characterized in that the recess (26) on a side facing the upper coupling projection (11) is restricted by an inclined insertion surface (28).

6. A coupler according to claim 3, characterized in that the shoulder (29) of the lug (32) is aligned with an inside surface (30) of a grip recess (31) in the lower coupling projection (11).

7. A coupler according to claim 2, characterized in that the recess (26) on a side facing the upper coupling projection (11) is restricted by an inclined insertion surface (28).

8. A coupler according to claim 3, characterized in that the recess (26) on a side facing the upper coupling projection (11) is restricted by an inclined insertion surface (28).

9. A coupler according to claim 4, characterized in that the recess (26) on a side facing the upper coupling projection (11) is restricted by an inclined insertion surface (28).

10. A coupler according to claim 6, characterized in that the recess (26) on a side facing the upper coupling projection (11) is restricted by an inclined insertion surface (28).