US321646A - Maker - Google Patents

Description

(NoMoael.)

E. T. SGHOONMAKER.

ELECTRIC WIRE INSULATOR.

Patented July '7,- 1885.

Unire@ Farnnr Ormea.

EDV/'ARD T. SOHOONMAKER, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO JOHN E. SMITH, OF SAME PLACE.

ELECTREC-WlRE INSULATOR.

SPECIFICATION forming part of Letters Patent No. 321,646, d? ed July '7, 1885.

Application liled December 11, 18H4. (No model.)

To all whom t may concern:

Beit known that I, EDWARD T. Sor-loon- Maxnrz, of the city and county of New York, in the State of New York, have invented a new and useful Improvement in Electric Insulators, of which the following is a specilication, reference being had to the accompanying drawings.

This invention relates to insulators for electric conductors, especially to the insulators ot'- aerial telegraphic and telephonie circuits. Its object is to prevent or reduce the leakage of the electric current over theinsulators during wet weather. Heretot'ore the shank of such insulators has generally been cemented or screwed into the glass shield for a distance of an inch and a halt or twoinches, thus making tive or six square inches of contact between the two. In some other forms of insulator the shield is held on the shank by a single pin or arm entering a groove; but in these also a large portion of the body of the shank touches the inner surface of the shield. So large a contact between shank and shield, when both become damp in rainy or foggy weather, allows enough of the electric current to leave the line to seriously interfere with its operation.

The object of my invention is to diminish the surface-connection between theshank and the shield; and to this end my invention consists, essentially, in the combination, in an insulator7 of a shield having a groove or grooves in its inner surface and a shank with spurs which enter the said groove or grooves and so support and hold the shield that it has no contact whatever with the body of the shank.

In carrying out my invention, the shank and the shield may be of any material or materials of sufticient strength, provided one of them is a good non-conductor; but it will probably be most advantageous to make the shank of iron and the shield of glass, as in the insulators now in common use.

In the accompanying drawings, Figure l is an elevation of an insulator constructed according to my invention, the shield being shown in section. Fig. 2 is a horizontal section in the linear of Fig. 1. Fig. 3 is an elevation, with the shield iu section, of an insn- 5o lator differing in its details from that shown in Figs. l and 2, but illustrating my inven tion. Fig. 4 is a horizontal section on the line x of Fig. 3. Fig. 5 is a central vertical section of the shield shown in Figs. 8 and 4.

Similar letters ot' reference indicate corresponding parts in the several figures.

A is the shank, and B is the shield. The shank may have that end, a, which is to be fastened to the cross-arm or pole of any known 6o or suitable form. I have represented it of a round form suitable to be driven into a hole in a cross-arm. The shield may have any desired form externally. The body ofthe shank or that portion of it which enters the shield is considerably smaller than the bore of the shield, and is constructed or provided with radiating spurs c c, of which l prefer that there should not be less than three.

In the example of my invention shown in 7o Figs. l and 2 the spurs c c are arranged spirally, so that they practically form parts of the thread of a male screw; and in this example the shield has the groove b in its interior or bore in the form of a female screwthread, the bore and screw-thread tapering toward the crown, and being of such size relative to the circle circumscribing the points or extremities of the spurs c c that when the shield is screwed onto the said spurs it will 8o become tight and rigid thereon, without the body ofthe shank touching either the side or the crown of the shield.

In the example shown in Figs. 3, 4, and 5, instead of a single groove in the form of a male screw-thread, there are in the interior o1` the shield several grooves, d d, corresponding in number with the spurs on the shank, each in the form of an inverted "i, one portion being vertical or parallel with the axis of the go shield and the other portion being horizontal or ruiming in a direction circumferential to the shield. rlhese grooves are open at the bottom or toward the mouth of the shield, terminating in a portion of the shield which is wider than the portion in which they are formed. The shield being placed directly on the shank with the grooves opposite the spurs,

and then turned a short distance to bring the lorizontal or circumferential portions of the grooves el d on the spurs, the latter alone will touch the shield and prevent the line-wire or conductor from pulling it otl from the shank. ln all eases I prefer to make the angle of the transverse section oi' the groove or grooves inore obtuse than the Corresponding angle or" the extremities ofthe spurs, as shown in Figs. l and 3, so that only the points ot' the latter will touch the shield, leaving;` the body entirely free freni Contact therewith. The groove e to receive the line wire or conductor should, preferably, be opposite or nearly opposite the spurs ofthe shank, to prevent unnecessary strain on said spurs.

By this invention, while l ain enabled to se curely fasten the shield to its support, l. ani

enabled t-o reduce thc contact between thtin to about one sixty-fourth part ot' a square inch, or about one three-hundredth part o1" itc usual amount, and not only this, but the Contact being higher up in the shield is less liable to beconie wet and the distance which the current inust travel over the inner surl'acc of the shield is greatly increased.

That I elaiin as nry invention, and desire to secure by Letters Patent, is*

l. The combination, in au insulator', ot' a shield having a groored inner surface and a shank having spurs on dii't'erent sides thereof' to engage with the said grooved suri'ace, and

support and hold the shield out ol' contact with the body ot' the shank, substantially as herein described.

2. The combination of the shield having in its interior a groove in the forni of a female screw-thread and the shank having a series of spurs arranged at distances apart thereon,

on diii'erent sides thereof', and in spiral relat tion to each other to t'orni portions ot' a inale screwthread corresponding with the groove or teniale thread in the shield, substantially as herein described.

The combination ofthe shank havingr at enc end ot' its exterior a series oi' spurs arranged to forni sections ot' a screwthread and the shield having in its interior a taper t'eniale screw-thread fitting the said spurs to become tight thereon, while the end ofthe shank docs u

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