US789651A - Electrical conductor. - Google Patents

Description

.No.'789,651.' I PATENTED MAY 9, 1905. o. L. BURLINGHAM & w. J. BURTON.

ELECTRICAL CONDUCTOR.

APPLICATION FILED FEB. 16. 1903.

* Lzitlfoz'l 08,06.

No. 789,651. I Patented May 9, 1905.

UNITED STATES PATENT OFFICE.

CHARLES L. BURLINGHAM AND WILLIAM. J. BURTON, OF CHICAGO, ILLI- NOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO SAID BURTON AND JUANITA M. BURLINGHAM.

ELECTRICAL CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 789,651, dated May 9, 1905.

Application filed February 16,1903. Serial No. 143,509.

T 107107711 it y 200271: of greater resistance than the interior copper Be it known that we, CHARLES L. BURLING- conductor unbalances the circuit. HAM and WILLIAM J. BURTON, citizens of the The primary ob ect of our invention Is to United States, residing at Chicago, county of provide a flexible electrical connector which 5 Cook, State-of Illinois, have invented a cerwill avoid the objections above pointed out tain new and useful Improvement in Electrical and which will possess the requisite conduc- Connectors; and we declare the following to be tivity and at the same time be resilient and a full, clear, and exact description of the indurable. vention, such as will enable others skilled in A further object of our invention is to pro- 10 the art to which it pertains to makeand use vide a flexible electrical cord comprising a the same, reference being had to the accomplurality of insulated conductors so arranged panying drawing, which forms a part of this as to render the cord thoroughly flexible and specification. at the same time of small diameter.

Our invention relates generally to electrical A still further object of our invention is to 15 connectors, and more particularly to flexible provide a flexible connector which Wlll be cordssuch, for instance, as are used for coneflicient and durable in use. necting subscribers at a telephone switch Our invention generally described consists board. in an electricial cord comprising one or more It is essential that flexible electrical conspirally-disposed conductors, each consisting 20 nectors which are subjected to frequent use in acentral wire possessing structural strength in completing circuits should possess the reqand resiliency surrounded by a material pos uisite electrical conductivity and at the same sessing high electrical conductivity. time be sufliciently strong and resilient struc- Our invention further consists in an elec- 7 turally to stand constant bending without trical connector comprising a plurality of in- 5 breaking or destroying the conductivity. sulated conductors coiled in a single spiral.

Owing to the lack of resiliency and strength Our invention will be more fully described of copper, considerable difliculty has been exhereinafter with reference to the accompanyperienced heretofore in constructing flexible ing drawing, in which the same is illustrated connectorssuch, for instance, as switch as embodied in a convenient and practical 3 board-cordswhich will stand constant usage form.

without wearing out or short-circuiting in a The figure in the drawing illustrates a cord comparatively short while, especially when constructed in accordance with our invention the diameter of the connector is necessarily and united to a plug. of limited size. A conductor commonly used I/Ve have shown the cord as comprising two .35 in making switchboard-cords is composed of a conductors; but it is evident that one or more number of strands of tinsel-that is, a fibrous than two of such conductors may be wound thread and a filament of copper twisted tospirally together to constitute the cord. Each gether. The constant flexure of tinsel, howconductor consists in a wire A, of a metal pos- 5 ever, soon breaks the filaments of copper and sessing strength and resiliencysuch, for in- 4 results in a short circuit when the cord constance, as brass, aluminium, or steel. In sists in more than one conductor. It has practice a steel wire, such as is commonly been proposed to avoid the objection to tinsel known as a piano-wire, has been found by constructing cords of an interior conductor preferable.

i of copper and an exterior surrounding con- B indicates a fine copper wire, which is 45 ductor of a metal possessing greater strength wound around the wire A to impart to the and resiliency; but such cords are open to the conductor the necessary electrical conducobjection that the exterior conductor being tivity.

G designates an insulating-covering around each conductor, which may conveniently consist in silk wound around the same.

D indicates a covering for retaining the silk insulation in place around each conductor and may conveniently consist in braided thread.

The conductors are wound together in the form of a spiral the diameter of which is approximately that of the thickness desired for the cord. The spiral is surrounded by an outer covering E, which may conveniently consist in braided cotton thread. A second covering F, surrounding the first covering E, is also preferably provided,which is composed of braided linen thread.

When the connector is to be used as a switch board-cord, its opposite ends are secured within a plug Gr, comprising conducting portions G and G insulated from each other and to which the ends of the conductors are separately connected.

It is evident that by winding a plurality of conductors which are to constitute a cord in the-form of a spiral a number of conductors may be employed without increasing the diameter of the cord. It is also evident that by arranging the conductors in the form of a spiral the cord is rendered thoroughly flexible and capable of continued usage Without breaking or short-circuiting. Byconstructing each conductor of an interior wire possessing structural strength and resiliency and of a surrounding material possessing high electrical conductivity a conductor results which possesses the requisite conductivity and at the same time possesses sufiicient structural strength to render the cord durable and capable of hard usage without breaking or short-circuiting.

\Vhile we have described more or less precisely the details of construction, we do not wish to be understood as limiting ourselves thereto, as we contemplate the changes in form, the proportion of parts, and the substitution of equivalents as circumstances may suggest or render expedient without departing from the spirit of our invention.

Having now fully described our invention, what we claim as new, and desire to secure by Letters Patent, is

1. A switchboard-cord consisting of a flexible conductor wound in parallel convolutions and composed of a strong resilient wire around which is wound a copper wire.

2. In a switchboard-cord, the combination with a plug, of a spiral flexible conductor connected to the plug and composed of a strong resilient wire surrounded by a good conducting material.

3. In a switchboard-cord, the combination with a plug, of a plurality of insulated conductors wound in parallel convolutions to form a single continuous spiral, each conductor being composed of a strong resilient wire around which is wound a copper wire.

In testimony whereof we sign this specification in the presence of two witnesses.

CHARLES L. BURLINGHAM. WVILLIAM J. BURTON.

WVitnesses:

E. H. BELL, GEO. L. TILKINSON.

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