The invention relates to a coupling device for coupling together containers which are placed on top of one another and are provided near the corners of top and bottom face with corner fittings with a passage slit and a twist lock pocket, comprising:

- a housing

- a rotary shaft extending through the housing - twist locks which are fixed at both ends of said shaft and of which the longitudinal directions form an angle with each other

- a control rod for rotating said shaft, projecting laterally from the housing, and connected or to be connected to said shaft

- and arresting devices for arresting the shaft in two end corner positions, one of the twist locks being in the form of a locating twisting cone with a number of side faces tapering to a tip. Such a coupling device is known from US-A-3.820,47 ⁱ ..

In the case of this known coupling device the other twist lock is not in the form of a locating twisting cone, but is bun- shaped with vertical side walls. In the case of normal use of this coupling the bun-shaped twist lock is inserted in each of the four corner fittings on the underside of a container and turned through a certain angle to the one locked end position, so that locking occurs. The downward projecting, twisting cone-shaped twist lock is in the correct position for insertion into a corner fitting on the top face of a container. Locking between two containers stacked one on top of the other can be achieved by turning the four twisting cones thus inserted into corner fittings on the top face of a container to the other locked end position. When the consignment has reached its destination, the twisting cones are taken into a position in which the coupling device is no longer locked relative to the bottom container and transferred hanging from the bottom face of the top container to the quay or, if a container crane with second travelling crab is used, to a buffer platform of said crane.

These coupling devices will have to be removed there before the container can be placed on a chassis loader or on the buffer platform. This constitutes a practical disadvantage.

The object of the invention is to produce a coupling device of the type mentioned in the preamble without spring mechanism, which can be used both in the so-called European method, in which the coupling device is inserted into the fitting on the top surface of an already loaded container, or in the so-called American method, in which the coupling device is inserted into the fittings on the bottom surface of a container to be loaded.

According to the invention, the coupling device mentioned in the preamble is to this end characterised in that the other locking element is in the form of a locating twisting cone with a number of side faces running towards a tip, in that the angle between the longitudinal directions of the locking elements is essentially 45°. and in that the arresting devices can also arrest the shaft in a position halfway between the end corner positions.

The relatively cheap and sturdy coupling devices can be locked and removed both on the quay (American method) and on the ship (European method) . If the American locking method is used for loading (coupling device fitted on the quay), the European method can be used for unloading (coupling devices remain on board) .

The control rod is preferably provided with an eye on the top side. This eye must always point upwards during use. This gives an indication that the twist lock is not being used in the inverted position.

The invention will now be explained in greater detail with reference to the figures.

Figure 1 shows a perspective view of the coupling device according to the invention.

Figures 2a, 2b and 2c show a top view in three positions of the coupling device when it is being used in the normal method in Europe.

Figures 3a, 3b and 3c show a top view in three positions of the coupling device in the method of use which is normal in America. Figure 4 shows a cross-section through the housing, to illustrate the locking mechanism.

The three-position twist lock shown comprises a cast-iron housing 1, a rotary shaft 2 shown by dashed lines, extending through

the housing, and so-called locating twisting cones 3. ~- provided on each of the ends of the rotary shaft, said conical parts having two opposite-lying slanting faces 5a which together with the two other narrow side faces 5b taper to a common tip 5c. Fitted on the rotary shaft is a control rod 6 which projects laterally through a slit- shaped hole 7 into the housing 1, and by means of which the shaft with the twisting cones can be rotated through a limited angle. An upward projecting eye is formed on the rod 6.

As can be seen from the figures, the longitudinal directions of the two twisting cones form an angle of 4 ° with each other. The top cone 3 has a hole 9 which makes it possible to lift the coupling device using a rod or piece of reinforcing steel, and which is also an identifying mark for the top side of the coupling device. In the European method for interlocking of containers to be stacked one on top of the other, four twist locks are fitted in the four corner fittings in the top face of a container placed on board a ship. The slit of a corner fitting is indicated by 10 in Figures 2a, 2b and 2c. Figure 2a shows the position in which the bottom cone 4 is inserted into the slit 10 of a corner fitting on the top side of a container placed on a ship's deck.

Figure 2b shows the position in which the coupling device is locked by turning the rod 6 to the left. The top cone 3 is then in a position in which a slit 10 of a corner fitting on the underside of a container to be fitted lies in alignment with the top cone 3 of the fitted coupling device, so that on stacking said top cone penetrates through the slit into the corner fitting of the container to be stacked. Figure 2c shows the position in which the containers stacked on one another are interlocked by turning the control rod 4 to the right.

When the American method is used, four coupling devices are placed on the quay on the underside of a container to be placed on a ship.

Figure 3a shows the situation where the top cone 3 of a coupling device, being in a neutral position, is inserted into the slit 10 of a corner fitting in the underside of the container.

Figure 3b shows the position in which, by turning the

control rod 6 to the left, the coupling device is arrested and the bottom cone has gone into a neutral position. In this position the container is taken from the quay onto a container already placed on the deck, in the course of which the stacking causes the bottom cone to penetrate into a slit of a corner fitting in the top face of the bottom container.

Figure 3c shows the position in which the containers stacked on top of each other are interlocked by turning the control rod 6 to the right. Both the eye 8 and the hole 9 n the top cone give an indication that the coupling device is not being used in the inverted position.

In European harbours the coupling devices are moved into the position shown in Figure 2b for unloading, following which the upper container of two containers stacked one on top of the other can be removed, and the coupling devices are left behind on the top side of the container below for subsequent removal and collection.

In American harbours the coupling devices are moved into the position shown in Figure 3b for unloading, and are taken along with the container on its underside to the quay, where they are removed.

Figure 4 shows the locking device with which the shaft can be locked in two end positions and a centre position. This mechanism comprises a leaf spring 1 which is mounted in the housing 1 in such a way that the spring can deflect outwards. The spring is provided with a curved part 12 which is designed to accommodate one of the bulges 13a, 13b or 13c of the shaft 2. It will be clear that in the two end corner positions and the centre position of the shaft 2 the twisting cones assume a stable arrested position because one of the bulges 13a, 13b or 13c has fallen into the curved spring part 12.

The coupling device shown is universally usable. The main advantages of the coupling device are: that it is relatively cheap; that it is not easily damaged; that no delays occur during loading and unloading; that container cranes with a buffer platform and a second crab can be used without any problem; that no additional people are needed on the quay or on platforms of container cranes to remove or fit coupling devices;

that no provisions are needed to distribute the coupling devices on the quay; that production can be considerably increased compared with the use of semi-automatic coupling devices; that where the American loading method is used, the European method can be used for unloading, and vice versa.