US3528139A - Pivoted cable clamps - Google Patents

Description

A. E. E. DESPLATS PIVOTED CABLE CLAMP Filed Oct. 20, 1957 SepL 15, 1970 United States Patent O Int. CI. F16g 1 1/00; B66f 3/00 U.S. Cl. 24-134 1 Claim ABSTRACT OF THE DISCLOSURE The present clamp is for acting on a cable passing therethrough with a self-gripping effect and includes plate springs which ensure the pre-clamping of the jaws thereof to permit a permanent contact of the jaws on the cable and separation of lateral extensions of the jaws and the opening of control links particularly in the event of small movements of the control links.

Traction and hoisting clamping apparatus of the nipper type are already known which act upon a cable of which the feed movement is obtained by Operating a pair of levers actuated separately according to the direction in which it is desired to move the cable.

This invention is applicable more particularly to apparatus of this character which comprise two clamping units through which the cable is passed, these clamping units being reciprocable in opposite directions, each unit comprising pairs of jaws of which the cable clamping or release movements are controlled automatically by actuating each lever controlling in turn the pivotal movements of links mounted in the clamping device, so as to produce the movement of the traction or hoisting cable extending through the apparatus and having one end attached to the load to be transferred.

The aforesaid clamping units are designed with a view to produce a self-clamping action; in other words, due to the traction exerted by the cable supporting the load, their jaws grip the cable with a force increasing with the cable tension. Of course, this action exerted by the cable on the jaws makes it necessary to keep the jaws in contact with the cable surface and this contact is obtained in known apparatus of this character by spring means constantly urging the aforesaid links in the clamping direction, thus creating a pre-clamping force providing the desired self-clamping feature. Briefly, said spring means actuate the jaws through the medium of control links.

Under these conditions it is clear that this indirect preclamping action requiring the use of intermediate links introduces a certain time lag likely to involve failures in the pre-clamping action, and besides, in case of seizing or fouling of the mechanism the springs may become inoperative.

It is the essential object of the present invention to obtain a constantly and permanently reliable self-clamping action in apparatus of the type disclosed hereinabove, by using to this end spring means acting directly upon the clamp jaws, with the complementary advantage of reducing considerably the Stress applied to the contact surfaces through which said links act upon the jaws, while improving the lubrication of these surfaces. The springs acting directly upon the jaws of this invention may either be substituted for the hitherto known springs acting upon the links, or complete the action exerted by these known springs.

The chief difficulty encountered in a practical application of the principle on which the present invention is based was that producing the above-described self-clamp- 3,528,l39 Patented Sept. 15, 1970 ing effect required a movement of the jaws not only transversely to the cable within the clamps but also longitudinally in order to be responsive to the cable traction, this twofold motion involving serious technical problems for properly mounting the springs in the clamp bodies.

According to this invention, it was found that the direct pre-clamping action could be applied to the jaws without any difiiculty by using spring blades urging the jaws against the cable from opposite sides.

Moreover, according to another feature of this invention, these spring blades are advantageously mounted on the links following the longitudinal movements of the jaws within, and relative to, the clamp, thus reducing the movements of said jaws in relation to said springs.

Although the above preamble refers essentially to the application of this invention to an apparatus comprisng two movable clamps, it will be readily understood by anybody conversant with the art that this invention should not be construed as being limited by this specific form of embodiment and that it is also applicable to any other clamping apparatus incorporating self-clamping jaws.

More particularly, it is obvious that the direct preclamping action constituting the essential object of this invention can be obtained by resorting to one of the means broadly set forth hereinabove, even if the apparatus does not comprise two movable clamps, for instance in the case of an apparatus having a fixed clamp and a movable clamp mounted tandemwise, in which case the pre-clamping action would be obtained by using springs reacting against a fixed jaw in order to act upon a movable jaw.

In order to aiford a clearer Understanding of this invention and of the manner in which the same may be carried out in practice, reference will now be made to the accompanying drawing of which FIG. 1 illustrates diagrammatically by way of example and in fragmentary sectional view a typical form of embodiment of a traction and hoisting apparatus provided with the pre-clamping spring mounting constituting the subject-matter of this invention. FIG. 2 is a cross-section taken on line 2-2 of FIG. 1.

The apparatus illustrated in the drawing comprises a hollow body 1 constituting a case having opposite holes 2 and 3 provided with guide bushings permitting the longitudinal passage of a traction and hoisting cable 4, and also with an anchor member in the form of a hook 5.

Within the case 1 the cable 4 extends in succession through a pair of tandem clamps 6, 7 comprising each a pair of jaws 8, 10 and 9, 11. The jaws of each clamp are each adapted to be actuated by two pairs of lateral control links, ile. 12, 14 for clamp '6, and 13, 15 for clamp 7. These links are fulcrumed on the side walls 16, 17 of the clamp bodies, at 18, 20 and 19, 21 respectively. The links 12, 13 have extensions 22, 23 at their ends opposite to their ends fulcrumed on said pivot pins 18 and 19.

The bodies of clamps 6, 7 are connected via actuating or coupling rods 24, 25 to a double crankpin or two-armed lever 26 rigid with a shaft 27 carrying a control lever (not shown) disposed externally of the case 1. Another control lever 28 extends through a slot 29 formed in the case wall, and has its inner end pivoted on the one hand at 30 to the extensions 22 of links 12 and on the other hand at 31 to an arm 32 pivoted in turn at 33 to the extension 23 of links 13. A release control lever 34 fulcrumed at 35 on lever 28 is adapted to pull the links of both clamps smultaneously in the direction to eliminate the self-clamping action when it is desired to allow the cable to move manually through the device.

The links control the jaws by means of cam faces of which the structure and function are well known and therefore need not be described in detail herein. It is only necessary to point out that the movement of the link extensions 22 or 23 to the right in relation to a corresponding clamp body (as seen in the figure) is attended by a gradual clamping of the jaws of this clamp body.

The general known structure broadly disclosed hereinabove is completed in known constructions by springs acting upon the links in the direction to clamp the cable by means of the jaws associated therewith; in other words, these springs urge the links for rotation in the clamp bodies in the clockwise direction as seen in the drawing, so as to produce the desired self-clamping action.

It is clear that when the tensioned cable moves towards the load with respect to a clamp body, it carries along the pre-clamped jaws of this clamping unit, so as to pivot the links in the direction to cause the jaws to exert an additional clamping eifort and therefore produce the desired self-clamping efect.

According to this invention, instead of, or in addition to, the springs acting upon the links, other springs acting 'upon at least one jaw of each clamping unit by hearing against the outer surface of the jaw, which is opposite the cable, for producing the jaw preclamping action, are provided.

In the example illustrated in the drawing a spring of this type is associated with each jaw and the springs of jaws 8 to 11 are designated by the reference numerals 36, 37, 38 and 39. These springs may consist for example of a blade anchored at one end to a pin 40 to 43 carred by one of the links or interconnecting the two links of a same pair.

In the drawing only one lateral link of each pair is illustrated, i.e. the one located behind the jaws, but it is clear that each lateral link illustrated is associated with another identical lateral link disposed symmetrically in relaton to the plane of the figure. The links of each clamping unit are disposed against the inne-r faces of the lateral walls 16, 17 of clamping units 6 and 7, respectively.

Although no spring acting on the links themselves has been shown in the drawing, it will be readily understood that conventional springs, if provided, may be left in 4 position, so that the springs acting directly upon the jaws according to the arrangement of this invention may complete the action exerted by said existing springs acting upon the links in the known fashion, instead of being substituted therefor.

Besides, various modifications and variations may be brought to the specific form of embodinent illustrated and described herein, without inasmuch departing from the spirit and scope of the invention as set forth in the appended claim.

What I claim is:

1. Clamp for acting on a cable with a self-gripping eifect, comprising a pair of superposed jaws between which the cable is housed, cam shaped extensions disposed on the lateral faces of said jaws, a lever, control links co- Operating with said jaw extensions by means of openings of a corresponding shape and adapted to pivot under the control of said lever to cause the opening or the closing of said jaws, and at least one plate spring fixed at one end to said control links and exerting with its other end a pushing force on the outer face, opposed to the cable, of one jaw in a direction practically perpendicular to the cable.

References Cited UNITED STATES PATENTS 1,117,874 11/1914 Main.

l,320,600 11/1919 Bush.

l,520,716 12/1924 Judd.

2,7`78,084 1/ 1957 Imparato.

3,222,742 12/ 1965 Persiaux 24-134 2,58S,l01 2/1952 Faure 254-76 1,59l,525 7/1926 Gardner.

BERNARD A. GELAK, Primary Examiner U.S. Cl. X.R. 254-76

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