Field of the invention

The present invention relates to a chain coupling assembly com¬ prising a closed ring member adapted to be coupled to a hoisting means, such as a crane hook, and at least one chain coupling member having a shank portion adapted to be securely connected to the closed ring member and a chain coupling portion adapted to be coupled to at least one hoisting chain.

Prior art

Chain coupling assemblies of this general kind, m particular including shortening clutches, shortening hooks or grab hooks, are known m many configurations and embodiments. See, e.g., WO83/03649. However, the chain coupling or shortening member is normally connected to the closed ring member (often denoted master link) by means of a separate shackle or a similar detachable member, so that the total assembly is rather complicated, elongated and costly since it consists of at least three different members, viz. the closed ring member, a separate connection member and a shortening or coupling member. Frequently, two, three or even four hoisting chain slings or branches are coupled to one master link. Then, the number of coupling components becomes very large.

Summary of the invention

The object of the invention is to provide a simpler, more compact and less expensive chain coupling assembly. This object is achieved m that at least one portion of the closed ring member has a flattened, non-circular cross-section and m that the shank portion of said at least one chain coupling member comprises a hook part for securely engaging the closed ring member directly, said hook part having an insertion opening facing generally towards said chain coupling portion and being dimensioned to snugly receive said one portion of said closed ring member when the latter is inserted into said hook portion.

Thus, the chain coupling member can be securely connected directly to the closed ring member, i.e. without any inter¬ mediary connection member such as a shackle. The assembly is therefore relatively short and is rather simple and mexpen- sive.

Further suitable features are stated in the claims 2-8 and will appear from the detailed description below. As appears from claim 8, the invention also concerns a chain coupling member as such, for use together with a closed ring member.

The invention will now be explained more fully with reference to the appended drawings illustrating some preferred embodi¬ ments.

Brief description of the drawings

Fig. 1 shows, in a side view, a chain coupling assembly according to the invention including a closed ring member and a chain coupling member securely connected to the ring member;

Fig. 2 is a sectional view along the line II-II m fig. 1;

Fig. 3 shows, in a side view, a second embodiment of the chain coupling member;

Fig. 4 is a sectional view along the line IV-IV m fig. 3;

Fig. 5 shows, m a side view, a third embodiment of the chain coupling member;

Fig. 6 is a sectional view along the line VI-VI in fig. 5, including a portion of a chain;

Fig. 7 shows, in a side view, a fourth embodiment of the chain coupling member; and

Fig. 8 is a sectional view along the line VIII-VIII m fig. 7.

Detailed description of the drawings

The assembly shown m fig. 1 includes an upper, closed ring member or link 1 and a lower, chain coupling member 2. The closed link 1 has the form of an oval ring with two longer side portions la, lb and two curved end portions lc, Id. The link 1 is made of an elongated iron blank which is forged into an oval configuration and welded at the ends so as to join the latter into a closed ring. At the middle of the longer side la, the material is flattened by forging. Hereby, a narrow portion le with a flat, elongated, non-circular cross-section is formed.

The cross-sectional area is substantially the same at the narrow portion le as at the other portions. Consequently, the strength of the material is substantially the same at both longer sides la, lb of the closed link 1.

The chain coupling member 2 in figure 1 comprises an upper hook portion 3, a middle portion 4 and a lower chain grabbing portion 5 serving as a shortening device. The hook portion 3 is formed as an arcuate loop having a free end 3a located opposite to the middle portion 4 and defining an insertion opening 6 therebetween. The insertion opening 6 leads into the interior opening 7 of the hook portion 3 and is dimensioned to snugly receive the flattened portion le of the closed link 1. Thus, the link 1 can be laid down with its longer side la and the flattened portion le adjacent to the insertion opening 6, whereupon it can be entered into the interior opening 7. To do this, a spring-biassed locking pin 8 is retracted so as to provide a free passage along the insertion opening 6. Finally, the link 1 is swung into the upright position shown m fig. 1, where the curved position Id is securely held m place m the interior opening 7 of the hook portion 3.

The lower, chain grabbing portion 5 of the member 2 includes a slot 9, which accommodates and supports a central chain link 21, and adjoining recess surfaces 10 with which the adjoining links 22 and 23 engage so as to hold the chain link 21 m a well-defined central position.

In the second embodiment of the chain coupling member 2', shown in figs. 3 and 4, the upper hook portion 3' is similar to the one shown m fig. 1, although there is no locking pin m the insertion opening 6'. Thus, the latter faces generally towards the chain grabbing portion 5'. The member 2' serves as a shortening device m this case as well.

The chain grabbing portion 5' is slightly different m that the centrally located chain link 21' is accommodated m a flat, almost horizontal position (when the member 2' is upright as shown) m a cradle or pocket-like recess 9'. At one side thereof, to the left m fig. 4, there is a central slot 11' for accommodating an adjoining link 22' standing upright and at the other side, to the right m fig. 4, there is a minor recess for supporting the other adjoining link 23'.

Another example, viz. a third embodiment of the chain coupling member 2'' is shown figs. 5 and 6. In this case as well, the upper hook portion 3'' is basically similar to the one shown in fig. 1, although the insertion opening 6'' faces obliquely sideways (to the left in fig. 5). A locking pin 8'' is mounted at the free end portion 3' 'a of the hook portion 3''.

The chain grabbing portion 5'' consists of a fork-like structure with two parallel legs 12' 'a, 12' 'b defining a cradle or pocket-like recess 13'' shaped so as to accommodate a central chain link 21'' and adjoining links 22'', 23'' m well- defined positions as shown m fig. 6. At a front end 14'' of the fork like structure with the legs 12' 'a, 12' 'b, there is a transverse, detachable anchoring pin 15''. The latter extends between the legs 12' 'a, 12' 'b through an end link 24'' of the chain. Hereby the end link 24'' is securely connected to the chain grabbing portion 5''. A chain loop is formed between the links 23'' and 24'' and can easily be shortened or lengthened as desired.

The chain coupling member 32 shown m figs. 7 and 8 has a shank or hook portion 33, which is quite similar to the one (3'')

shown m fig. 5. The lower, chain coupling portion 34, on the other hand, is different in that it is provided with two anchoring means for anchoring the respective end links 44a, 45a of two separate chain branches 44 and 45, respectively.

The lower portion 34 includes two downwardly extending projections 35 and 36, each such projection 35, 36 being formed as a fork with two parallel legs 35a, 35b and 36a, 36b, respectively. An anchoring pin 35c, 36c is detachably mounted between the respective legs so as to securely hold the respective end link 44a, 45a in place therebetween.

The illustrated embodiments may be modified within the scope defined by the appended claims. For example, the closed link or ring member may have several portions with a flattened cross- section. Alternatively, the ring member may have a non- circular, flat cross-section all around it, i.e. at all portions thereof. Such a cross-section may be rectangular, with slightly bevelled corners, ellipsoidal or elongated m some other way. Preferably, the hook portion of the chain coupling member is formed with an internal curvature adapted to the cross-sectional dimensions of the closed ring member. The chain coupling or grabbing portion of the chain coupling member may be provided with two recesses or pockets instead of or in addition to the two anchoring means shown in figure 7, whereby two shortenable chain branches may be coupled to the same coupling member. Furthermore the assembly may include two, three or even more chain coupling members, so that the ring member is securely connected to a corresponding number of chain slings, loops or branches.