Coupling piece for connecting containers

The coupling piece for connecting two container corner fittings has a housing (10) with an upper and a lower middle piece (21/22), a locking bolt (15) and two crossbars (16 and 17) fastened to its free ends projecting from the housing (10). The lower middle piece (22) only partially matches the contour of an orifice in a container corner fitting, so that the lower crossbar (17) projects laterally beyond it. In the released position, the upper and lower crossbars (16 and 17) are rotated through an angle relative to one another, so that the lower crossbar (17) has to be introduced into the container corner fitting first and then the entire housing has to be rotated through this angle, before the upper crossbar (16) is correctly aligned opposite the orifice in the container corner fitting of the upper container.

BACKGROUND OF THE INVENTION 
The invention relates to a coupling piece for connecting containers. More 
particularly, the present invention concerns a coupling device for 
connecting containers which includes a locking bolt which is rotatable 
between a locking position and a release position. 
By means of such a coupling piece, containers of standardized design can be 
connected together vertically on top of one another. For this purpose, the 
containers have corner fittings which conform to international standards 
and which have orifices in their horizontal surface. Coupling pieces of 
the type mentioned in the introduction, which are in general also referred 
to by the term "twistlock", are known, and in these the connecting force 
(anchoring force) is transmitted solely via the crossbars and the locking 
bolt. 
Another type of known twist lock is referred to as a "permanent-base 
twistlock" in the specialized jargon. Its housing is equipped, at one end, 
with a foot which is anchored in the corner fitting of a (lower) container 
as a result of the rotation of the housing. Here, a crossbar is provided 
only at the top end of the locking bolt. The bottom end of the bolt is 
anchored rotatably in the housing or by means of small crossbars or 
flanges on the lower outer face of the housing. Here, the force is 
transmitted with the assistance of the housing. The disadvantage of the 
last-mentioned "permanent-base" type of twistlock is that it has a lower 
load-bearing capacity. This is because the rotary anchoring of the locking 
bolt in or on the housing is critical. On the other hand, however, this 
type also has considerable advantages which is one reason for the increase 
in use of this type. It must be assumed, here, that very great care is 
exercised when containers are loaded in harbour. There is no guarantee 
that the twistlocks are always attached to the corner fittings in one and 
the same relative position. However, this is a prerequisite for making it 
possible, by means of the position of the actuating lever (hand lever) for 
the locking bolt, to ascertain from outside whether the twistlock between 
the containers is in the locking position or the release position. The 
twistlocks are designed so that, when assembled properly the right way up, 
the hand lever always points to the left in the locking position. In a 
cargo inspection, it is consequently possible to ascertain visually, by 
checking the relative position of the hand lever, whether the twistlock is 
locked or not. This inspection is necessarily deficient if the twistlocks 
are fitted upside-down. This only applies to the type of twistlock 
mentioned first in the introduction. 
This risk does not arise in a twistlock of the "permanent-base" type, 
because it is only possible to assemble it when the "anchoring foot" of 
the housing is directed downwards. In particular, for assembly, it is 
necessary for the housing to be rotated in the orifice in the corner 
fitting so that the lateral flanges of the foot can engage. In other 
words, the housing is inserted into the corner fitting and then rotated. 
Only after this rotation is the upper, still free crossbar aligned 
correctly, so that it can engage into the corner fitting of the upper 
container. 
If such a twistlock is used the wrong way round by mistake, that is to say 
with the pivotable crossbar towards the bottom, the upward-directed 
anchoring foot of the housing would assume a position unsuitable for 
attaching the upper container. It would then be impossible for the corner 
fitting to be slipped over the twisted or skew anchoring foot. 
Consequently, errors are not possible with twistlocks of this type when 
containers are being loaded. 
However, there still remains the above-described disadvantage of the 
relatively low load-bearing capacity. 
OBJECTS AND SUMMARY OF THE INVENTION 
The object of the invention is to improve the coupling piece mentioned in 
the introduction, in such a way that the advantages of the "permanent-base 
twistlock" are preserved, but the disadvantage of relatively low 
load-bearing capacity is avoided. 
This object is achieved by means of the features indicated in the 
characterizing clause of patent claim 1. 
The basic idea of the invention is that an "imitation" permanent-base 
twistlock, in which locking is also effected at the bottom via a pivotable 
crossbar, is provided. Here, in the released position, the lower crossbar 
assumes a relative position in relation to the housing or to the cone or 
middle part of the housing, where handling in the same way as with a 
permanent-base twistlock is required. In this position, the lower crossbar 
projects laterally beyond the cone or middle part by means of edge or 
corner regions. As a result of this, it can only be introduced into the 
corner fitting of the container when the housing has first been inserted 
in the rotated position and then rotated after insertion. After that, the 
lower crossbar is then moved into an essentially transverse locking 
position as a result of the actuation of the hand lever or the rotation of 
the locking bolt. The invention thus makes use of the construction 
principle of a "locking bolt" with two crossbars. On the other hand, 
however, the property of a permanent-base twistlock is also put into 
effect, specifically because of the appropriate initial position of the 
lower bar in the released position. 
In the released position, the relative position of the crossbar is 
determined by stops or catches on the housing, in particular at the 
corners of the middle part. 
Furthermore, when the twistlock is assembled incorrectly, that is to say 
upside-down, the function of the stops or catches is to prevent the 
possibility of a container nonetheless being placed on the container 
underneath it. This would be possible if there were no stops or catches, 
because the crossbar then wrongly located at the top could, under certain 
circumstances, be (forcibly) shifted by the weight of the container placed 
on it, until it could be forced through the corresponding orifice in the 
corner fitting. Moreover, the flat design of the (lower) crossbar also 
contributes to preventing the crossbar from being forcibly twisted when 
the twistlock is assembled the wrong way round.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The coupling piece has a housing 10 which, here, is designed as a two-part 
housing with the housing parts 10 and 11. However, a one-part housing can 
also be used. The two housing parts 11 and 12 are connected to one another 
by means of screws 13 and 14 which are partially countersunk in the 
housing. Mounted in a bore extending through the housing is a rotatable 
locking bolt 15 which, at its two ends projecting from the housing 10, 
carries an upper (conical) crossbar 16 of conventional design and a lower, 
but flattened crossbar 17. Because of the flattening of the lower crossbar 
17, the outwardly facing surface is generally planar, in contrast to the 
outwardly facing surface of the upper crossbar 14 which is generally 
conical. The locking bolt 15 and consequently the crossbars 16 and 17 
connected firmly to it can be rotated jointly about the axis of the 
locking bolt 15, specifically via an actuating lever 19 projecting from a 
housing orifice 18 located approximately in the centre of the housing 10. 
In the centre, the housing 10 has a widened portion 20, of which the 
surfaces directed upwards and downwards serve as abutments fo the 
containers or their corner fittings. On both sides of this widened portion 
20, the housing has two middle parts 21 and 22 or cones which engage 
through the orifice in the container corner fitting and which match its 
contour. 
According to the invention, the lower middle piece 22 and the lower 
crossbar 17 are of novel design. This emerges most clearly from FIG. 2. 
The orifice in the container corner fitting is represented there by the 
broken line, the coupling piece already being inserted and rotated through 
an angle 24. The middle piece 22 is represented by a broken line, its 
longitudinal axis 25 coinciding with the longitudinal axis of the orifice 
23 in the container corner fitting. However, the middle piece 22 is cut 
off at two diagonally opposite corners in the regions 26 and 27, so that 
there its side wall does not rest against the inward-pointing wall of the 
orifice 23 of the container corner fitting. 
Furthemore, the middle piece 22 has, adjacent to the cut-off regions 26 and 
27, stops or catches 28 and 29 which project perpendicularly downwards and 
which are located diagonally opposite one another. In the opening position 
of the coupling piece shown in FIG. 2, the crossbar 17 is rotated through 
the angle 24 relative to the longitudinal axis 25 of the middle piece 22. 
It consequently projects laterally beyond the middle piece 22 by means of 
side portions 30 and 31 located opposite the catches 28 and 29. 
Furthermore, the crossbar 17 has recesses adjacent to the catches 28 and 
29, so that, as seen in a plan view or in the sectional view of FIG. 2, 
the crossbar 17 and the two catches 28 and 29 form a complete contour 
which corresponds to the contour of the orifice 23 of the container corner 
fitting. The height of the catches 28 and 29 is somewhat less than the 
height of the lower crossbar 17. It can be seen from this that the housing 
can be introduced into the orifice 23 by means of the lower crossbar 17 in 
the opening position and can then be rotated as a whole through the angle 
24, until the appropriate side walls of the middle piece 22 come to rest 
against the inner wall of the orifice 23 of the container corner fitting. 
This angle is, for example, 20.degree.. During this rotation of the 
housing, the lower crossbar 17 is rotated with it at the same time, 
specifically likewise through the angle 24. The portions 30 and 31 thereby 
engage behind the container corner fitting (orifice 23), so that the 
coupling piece is temporarily fixed to the container corner fitting of the 
lower container. As a result of this rotation, in which the upper crossbar 
16 also participates, the latter is adjusted in such a way that it is now 
aligned opposite the orifice in the container corner fitting of an upper 
container. Only then can the upper container be placed on top. In other 
words, the main axis 32 of the upper crossbar 16 is likewise rotated 
through the angle 24 relative to the main axis 33 of the lower crossbar. 
After the upper container has been placed on top, the locking bolt 15 is 
rotated (in the counter-clockwise direction in FIG. 2) by means of the 
actuating lever 19, with the result that the two crossbars 16 and 17 are 
rotated further and locking is completed. 
The rotating or pivoting range of the locking bolt 16 by means of the 
pivoting of the actuating lever 19 can be seen even more clearly in FIGS. 
3 and 5. Here, the actuating lever 19 can be pivoted from the position 
shown into the position according to the line 34. 
FIG. 4 shows a section along the line 4--4 of FIG. 1 and consequently a 
section through the upper middle piece 21. This also shows the mounting of 
the locking bolt 15 and the counter-sunk arrangement of the screw 14 and 
screwnut 14'. 
FIG. 5 illustrates a section along the line 5--5 of FIG. 1. The actuating 
lever 19 is connected firmly to the locking bolt 15 which has, in the 
middle region of the widened portion 20, two engaging notches 35 and 36, 
into which a ball 40 prestressed by a spring 37 engages in the two 
limiting positions of the actuating lever 19. The housing orifice 18, from 
which the actuating lever 91 projects, can also be seen. In principle, 
this orifice is funnel-shaped, but at least has bevelled edges 38 and 39 
which serve as stops for the actuating lever. The engagement device with 
the engaging notches 35 and 36 and the ball 40 serves primarily to prevent 
the actuating lever from being pivoted inadvertently. 
FIG. 6 shows a section along the line 6--6 of FIG. 1, that is to say a 
section through the lower middle piece 22. This again shows more clearly 
the shape of this middle piece and its alignment relative to the lower 
crossbar 17. It can be seen particularly how the crossbar projects 
laterally beyond the middle piece 22 by means of its regions 30 and 31 and 
how the main axes 25 and 33 of the middle piece and of the crossbar 17 
respectively are offset relative to one another by the angle 24. 
The side view of FIG. 7, as seen in the direction of the arrow III of FIG. 
1, shows a view of the housing orifice 18 in more detail. Here, the upper 
crossbar 16 shows its narrow side whilst the lower cross bar 17 appears 
wider because it is rotated through the angle 24. Once again, it becomes 
very clear from this that, in the position according to FIG. 7, the two 
crossbars 16 and 17 cannot be introduced simultaneously into aligned 
orifices in container corner fittings. On the contrary, for this purpose, 
it is necessary for the lower crossbar 17 to be introduced first, then the 
housing rotated and then the upper crossbar 16 introduced into the 
corresponding container corner fitting.