US1092037A - Plug-switch. - Google Patents

Description

T. E. GAMBRELL.

PLUG SWITCH.

APPLIGATION FILED Nov.1a, 1913.

1,092,037. Patented Mar. 31, 1914,

Finca.

THOMAS EDWARD GAMBRELL, 0F LONDON, ENGLAND.

PLUG-SWITCH.

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To all whom it may concern.'

Be it known that I, THOMAS EDWARD GAMBRELL, a `subject of the King of Great Britain, residing at London, England, have invented new and useful Improvements in 4Plug` witches, of which the following is a specification.

This invention relates to an improved switch of the plug type applicable for use in connection with resistance boxes, `Wheat stone bridges, switchboards, contact makers and breakers and the like.

In the plug switches heretofore generally employed, e. g. on resistance boxes, a conical plug has been forced into a socket formed by the adjacent shaped end surfaces of two blocks mounted on the ebonite top of the resistance box.4 I n this arrangement, the blocks themselves are moved slightly during the insertion of the plug between them, so that there is a liability of the plug contacts at the other end of said blocks being disturbed and the contact resistances altered.

According to the present invention, in order to prevent disturbance of adjacent plug contacts and to reduce the contact resistance between the coacting surfaces of the switch, I make the Xed part of the switch in the form of pieces of metal arranged side by side and insulated from each other, the outer sides of said pieces of metal being shaped to form part of a conical surface adapted to fit a correspondingly shaped1 conducting surface in a cap, sleeve or ring, hereinafter referred to as a cap. The inner sides of said pieces of metal are preferably shaped to form part of a cylindrical surface adapted to fit around a pin, preferably of metal, secured concentrically in said cap. By this arrangement the lateral forces on the xed contact pieces are balanced and much larger contact surfaces can be obtained.

In the accompanying drawings, I have shown how my said invention can be conveniently and advantageously carried into practice.

In these drawings: Figure 1 is a side elevation of partof resistance box having my improved switches applied thereto, one of said switches being shown in elevation and the other in section, and Fig. 2 is a plan thereof, showing one switch with the cap on vand the other'with the cap oft'. Fig. 3 ,is a

vertical central section and Fig. 4 a trans- Speoicaton of Letters Patent. I Pwgmed www, 319 9114,

Application led November 13, 1918.l SerialNo. 800,855.

verse section on the line, m, Fig. 3, showmg a modification.

a is an ebonite or other suitable slab forml ing a top to a resistance-box.

5, c; l), c, are pairs of conductors, the lower parts or bases d, d of which are secured to the slab a. in any suitable known manner, for example by means of steady pins (not shown), screwed pins e, c and nuts f, f and the upper parts of which are shaped to form parts of a cone g to lit the correspondingly-shaped interior of a metal cap k. The juxtaposed` faces of the conductors b, c are shaped to form parts of a cylindrical surface y' adapted to t around a metal pin k secured concentrically in the cap h. The conductors b, c are arranged at a suitable distance apart to provide eiicient air insulation. Similarly a space m is provided between the bases d, d to facilitate cleaning ofthe insulating surface of the slab a.

. It will be seen that when the cap L is placed on the conical surface g of the conductors b, c the said conductors will be supported internally by the pin la and thus lateral movement thereof will be prevented. At the same time the engaging surfacesvg, g may be made of any required size to reduce the contact-resistance to any desired value. Moreover a further reduction of the contact-resistance is obtained by the engagement of the surfaces j, j with the surface ofv the pin la. v

In the modification shown in Figs. 3 and 4t the cap l1. is provided on its exterior, adjacent to its open end, with a pair of diametrically-opposite lugs which are provided with segmental screw-threads n. When the cap lz. is applied the lugs may be passed down the space o between the bases d', al' and when the cap h is turned the threads n will engage with screw-threadsp on said bases d', d in order to hold the cap k tightly on the conductors b, c fol-'example in cases where the switch is subjected to vibration. In some cases moreover the screwthreads n, p can be replaced by Vone or more pins xed to the bases d, d and engaging with a corresponding spiral slot or slots in the cap, so that when the cap is turned in one direction the cap is drawn down tightly on to the conductors 5, c.

If desired a screw-thread can be arranged on the pin 7c and engage with corresponding screw-threads on the adjacent surfaces of the conductors b, o instead of arranging the 'l screw-threads 'as shown in Figs. 3 and 4.'

What I-clairn is 1 A plug switch comprisin fixed conductors arranged at a suita le distance apart and insulated from each other and having their outer surfaces shaped to form parts of a conical surface, and a cap having an interior conducting surface shaped to`iton to said conductors.l

2. A plug-switch comprisin xed conductors arranged at a suita le distance apart and insulated from cach other, said conductors having theirVv outer surfaces shaped to form parts of a conical surface 15 andv their inner surfaces shaped to form parts of a cylindrical surface, la cap havingI an interior conducting surface and a plug mounted concentrically in said cap and adapted to lit the innerv surfaces of said 20 fixed conductors.

n THOMAS EDWARD GAMBRELL.

Witnesses:

JOHN T. KNoWLEs, H. CECIL BLAKE.

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