Chain – staple – and horseshoe making – Chains – Links
Reexamination Certificate
2000-08-01
2001-09-04
Jones, David (Department: 3725)
Chain, staple, and horseshoe making
Chains
Links
C059S093000
Reexamination Certificate
active
06282879
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a shackle structure to be secured to the link of a chain.
BACKGROUND OF THE INVENTION
A shackle, commonly also referred to as a clevis or shank, is composed, as known, of a half-ring usually in steel with a U or horseshoe shape, wherein the ends of the legs are widened and perforated to allow the passage of a bolt for closure which can be threaded to screw into one of the holes, also threaded, or which alternatively can be locked to the relative leg by means of a split pin. In nautical applications a shackle is widely used for example for connecting two chain sections one to the other, for securing a chain to a fixed eye or to the anchor, or to a buoy.
As is known, a shackle is attached by linking the bolt to the chain link to be hooked, and this, for standard chains wherein the span in the link theoretically extends axially for a section equal to three times the diameter of the link, means in practice that the diameter of the bolt of the shackle has to be smaller than that of the chain link.
The span actually available for hooking the bolt, having subtracted the overall dimension of the arch of the links chained to the link to be hooked, is slightly smaller than the diameter of the link, due both to the curve of the arches of the links which are chained and to the thickness of additional zinc-plating of these same links. This leads to the need to use a smaller shackle. Naturally the presence of a smaller shackle causes a weakening of the hooking to the link of the chain, and the relevant bolt becomes the most fragile point of breakage from tensile stress.
SUMMARY OF THE INVENTION
The object the present invention is therefore that of providing a shackle which remedies the disadvantages suffered by a traditional shackle and in particular one object is that of providing a shackle for a chain which provides solid hooking to the link of a chain and namely hooking with resistance to breakage from tensile stress no less than the intrinsic resistance of each link of the chain.
Another object of the present invention is that of providing a shackle for a chain which has a simple structure and principle of operation and for this reason is also inexpensive.
Yet another object of the present invention is that of providing a shackle for a chain which can also be adapted with versatility to links of chains of different sizes.
These and other objects are achieved with a shackle for a chain in accordance with the present invention, of the type comprising:
an external support half-ring formed by an arch of the half-ring and by two legs of the half-ring which originate from the opposite ends of said arch, each of the two legs having the terminal end widened and provided with a transverse hole which, in the position of closure of the shackle, is aligned with the transverse hole of the other one; and a bolt, possibly unlosable, slidingly supported in the hole of one leg to insert in the hole of the other leg with means for locking closure of the shackle. The shackle is characterised by the fact of providing, inside the support half-ring, a fork shared element which can be inserted on a diameter of the two straight sides of the chain link to be hooked and can be damped between the chained links to said chain link to be hooked, said fork having each leg integral with and parallel to a corresponding leg of the support half-ring and mouth lying on the side of the bolt.
The shackle of the present invention advantageously offers a point of hooking to the chain which has a resistance to breakage from tensile stress equal at least to the intrinsic resistance of a link of the chain, given that the shackle can embrace externally the entire link with a bolt of diameter even greater than that of the link itself.
The sliding on the chain of the shackle of the present invention is locked in that, while the link is inserted in the fork and restrained therein by the bolt brought into the position of closure, the upper and respectively lower wall of the fork hit against the arch of the chain link above the hooked link and respectively on the arch of the chain link below the hooked link and the fork remains restrained there.
REFERENCES:
patent: 285962 (1883-10-01), Bracken
patent: 1222997 (1917-04-01), Rottmer
patent: 2259217 (1941-10-01), Stevenson
patent: 3224185 (1965-12-01), Grim et al.
patent: 3583751 (1971-06-01), White
patent: 3817028 (1974-06-01), Blackwood
patent: 3962755 (1976-06-01), Buschini et al.
patent: 4020630 (1977-05-01), DeShetler
patent: 4134255 (1979-01-01), McBain et al.
patent: 5647198 (1997-07-01), Mihailovic
patent: 2672358A1 (1992-08-01), None
patent: 112796 (1918-01-01), None
patent: 1452358 (1976-10-01), None
Bonaiti Marco
Servadei Sauro
Jones David
Kong S.p.A.
Young & Thompson
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