US 2180866 A
Description (OCR text may contain errors)
Nov. 21, 1939. J. A. CRYER 2,180,866
CONNECTOR Filed July 20, 1958 ////////w Mmmmmm MIMI! 11 I"!!! H I IIIIIIIIIIIIIIIIIIIIIIIIIIIIIHIII/IM INVENTEI John A. Cryei" Ely His ATTuRNEy Patented Nov. 21, 1939 UNITED STATES CONNECTOR I John A. Cryer, Purling, N. Y. ApplicatiomJuly 20, 1938, Serial No. 220,240
My invention relates to connectors and particularly to devices for connecting the ends of wire cables such, for example, as guide rail cables used along public highways.
5 I am aware that many connectors of the general type described below have been proposed, but none of these, so far as I am aware, are capable of developing the full strength of the cable. In New York State, for example, the present'standard specifications call for guide rail cable having ,an ultimate strength of at least 23,000 pounds and, if the cable is spliced, the splice or connection must be as strong as the cable.
In addition to strength, a connector must be cheap, simple in construction and capable of application by unskilled labor.
The objects of my invention therefore are to provide a connector having the above characteristics and particularly a "connector which will form a splice capable of withstanding substan-' tiially the same ultimate tensile stress as the cable self.
A standard cable widely used as a guide cable comprises three strands each formed of seven separate wires which are laid together and twisted to a comparatively long pitch. The three strands thus formed are also twisted together ith a long pitch.
1 In order to provide a connector which will develop the full strength of such a cable, I find, as a result of my tests, that it is necessary to embody in the design thereof several features which are not present in any connector of which I am aware.
By test, it is found that most cable connectors fail at high stress due to the cutting of one or more of the wire cables in the gripping elements which engage the cable in the connector. This is due partly to the usual design of the teeth or projections which directly engage the cable;
partly to the fact that the wedging or cablegripping elements do not somewhere engage all of the wires in the cable at least once; partly to the fact that the hollow, split, frusto-conical 4 plugs or wedges which engage the cable have sharp edges on the inside thereof formed by the intersection of the generally cylindrical interior surface with the plane of the split; and partly to the fact that the stress transfer from the cable 50 to the wedging or gripping elements takes place largely in the zone of initial contact between the cable and these elements and is thus neither uniformly distributed'along the inner surfaces of the elements nor throughout all of the wires of the 65 'cable.
Having in mind these inherent defects in the present types of connectors, I eliminate them and accomplish the ends which I desire by means of the novel elements and the combinations and arrangements thereof described below and illus- 5 trated in the accompanying drawing in which Fig. 1 is a side elevation view, partially in section, of my connector;
Fig. 2 is an axial section of the frusto-conical wedge or plug taken in a plane at right angles to 10 the zone of split;
Fig. 3 is a perspective view of one of the plug sections;
Fig, 4 is an end view of the frusto-conical plug with a cable therein as viewed from its larger 15 end;
Fig. 5 is a view similar to Fig. 4 except as seen from the smaller end. of a plug; and
Fig. 6 is an elevation view of a half-basket used for connecting a cable end to an anchor. 20
Referring to the drawing, I is a basket which may be made of malleable iron or other suitable At each end, the basket is provided with a tapered bore 2 adapted to permit a cable end 3 to be inserted therein, as shown, and 4 25 and 5 are the two sections of the frusto-conical plugor wedge which engage the surface of the cable. The angle A is preferably about 10 although it may vary from a much smaller angle up'to about 40. The surface of the tapered bore 30 must be smooth and is preferably machined to attain this end.
The plug or wedge is a hollow, conical frustum, formed preferably of steel, and having its outside surface 6 conforming in taper to the taper of the bore 2. The outer surface should be machined or ground to a smooth finish in order that perfect wedging cooperation is attained with the bore. The wedge is split longitudinally, as shown at 1, to form two separate sections and 40 suflicient metal is removed in the splitting operation so that when the sections 4 and 5 lie around the cable and in contact with the surface thereof they are in slightly spaced relation along the zone of split. This is to provide suflicient clearance to permit the wedges to be forced into closer engagement with the cable by the wedging cooperation of the sections 4 and 5 with the bore of the basket. The interior surfaces 8 of the sections 4 and 5 merge smoothly with the zone of split as shown at 9; this'smooth merging being accomplished by chamfering the edges formed by the intersection of the generally, semi-cylindrical interior surfaces of the sections with the plane of the split. The smaller ends of the sections 4 and are also beveled or chamfered as shown at ID to prevent the ends of the plugs or wedges from digging into the bore of the basket.
While it is contemplated that, in quantity production, the sections 4 and 5, as shown, may be separately die-formed, and thereafter hardened, it is possible otherwise to form on the interior surfaces of the sections the V-shaped ridges which grip the cable, as follows:
Assuming that a connector for a cable is to be formed, before the frusto-conical plug is split, it is drilled axially to a diameter of 1%" and the passage therethrough is then tapped with an S. A. E. tap which, due to the larger diameter of drill used, instead of producing a sharp crested V thread produces one in which the crests of the threads are slightly truncated as shown at H. At the smaller end of the plug, and preferably extending for about inwardly therefrom, the crests of the V-shaped threads or ridges are ground off slightly, as shown at I2, so that, in operation, these threads near the smaller end of the plug do not grip nor penetrate as deeply into the wires of the cable as do the threads at the larger end of the plug. This is quite an important feature because it effects a fairly uniform transfer of stress from the cable to the plugs throughout their extent.
If the ridges are formed as true threads in the manner just described, the plug is then split and thereafter hardened.
As pointed out above, it is quite important that the plugs or wedges grip each outside wire of the cable at least once, and hence the length of the fr'usto-conical plug sections should be such as to permit this to occur. This length will, of course, depend upon the pitch to which the wires of the cable are twisted.
In Fig. 6 I have shown a half-basket it, provided at one end with a tapered bore 2 adapted to receive the end of a cable together with plug sections 4 and 5, and, at the other end, with a threaded opening I4 adapted to receive an anchoring rod. A portion l5 of the exterior surface of the half-basket being hexagonal to permit a wrench or spanner to be applied thereto.
From the foregoing it will be apparent that I have incorporated in my design several features which are not present in other connectors and each of which contributes to its very high efliciency. It will also be apparent that no skilled labor is necessary in assembling or disassembling my connector. When the connector is in use and it is desired to disconnect it, it is only necessary to relieve the strain on the cable whereupon sharp hammer blows on the ends of the basket will release the wedges and permit the ends of the cable to be withdrawn.
What I claim is:
A cable connector comprising a basket having a tapered bore in one end thereof adapted to receive a cable end, and a hollow, frusto-conical plug adapted to fit closely within said bore and comprising separate sections adapted to lie about and closely engage said cable when said sections are in slightly spaced relation to each other, whereby to provide clearance for forcing said sections into closer engagement with said cable; the interior surface of said plug being provided with a plurality of closely spaced, circumferentiallyextending, V-shaped ridges having truncated crests to prevent the weakening of said cable by substantial penetration of said ridges therein;
said ridges being truncated at an appreciably .greater depth at the smaller end of said plug than at the other end thereof to provide a gradual transfer of stress from said cable to said connector; and the inner edges of said sections being rounded to eliminate sharp projections therealong in contact with said cable.
JOHN A. CRYER.