US498799A - Rheostat - Google Patents

Description

(No Model.) 2 Sheets-Sheet 1. E. R. KNOWLES.

RHEOSTAT.

No. 498,799. I Patented June 6,1893.

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in series.

U TED STATES PATENT QFFICE.

EDWARD R. KNOWLES, OF MIDDLETOVVN, CONNECTICUT, ASSIGNOR TO THE SCHUYLER ELECTRIC COMPANY, OF CONNECTICUT.

R H EO'STAT.

SPECIFICATION forming part of Letters Patent N 0. 498,799, dated June 6, 1893.

Application filed January 9, 1893. fierial No. 457,817- (No model.

new and useful Improvements in Rheostats;

and I do hereby declare the following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings,-and to the letters-of reference marked thereon,which form a part'of this specification.

My invention relates to rheostats, and its object is. to provide a compact and easily regulated apparatus, designed more especially for use with constant potential electric lamps.

The invention consists in a plurality of cylinders of slate or other non-conducting, heatresisting material, each having a coil of Wire wrapped around it, the coils being connected One or more movable contact plates or switches enable more or less of the coils to be shunted, to vary the resistance. These and other details of construction are hereinafter set forth and particularly pointed out in the claims.

In the drawings,-Figure l is a side elevation, showing the cover in section. Fig. 2 is a top plan View, with the cover removed. Fig.

- 3 is a section of a binding screw. Fig. 4 is a cross section of one of the cylinders; and Fig. 5 is an elevation partly in section, showing a switch.

A number of cylinders A, of non-conducting, heat-resisting material, preferably slate,

are grouped together, preferably in a circle,

and are secured at equal distances apart to a metal frame, such as the ring B, B, by means of screws a. Each cylinder preferably has an annular groove a near each end, and a transverse hole a 'termina ting in said groove. In the surface of the cylinder between the grooves a is a helical groove a of small pitch.

7 A helical wire coil C of high resistance, such as German silver wire, is wound in the groove a and its ends are secured by being passed through the holes (L The adjacent ends of the several coils are connected, so that the coils are all in series. The bottom ring B,

has ears Z2, through. which pass screws 1), fastening it to a suitable base, D, preferably the shelf of a wall bracket, as shown. The bracket contains a number of holes corresponding with the cylinders A, in order to give access to the screws 0. in the bottom ring B, and also to assist in ventilating the apparatus.

Near the centerof the bracket, or at any other. convenient points, are two holes in which are placed insulating bushings E, preferably of lava. The bushing has a flange e to rest against one surface of the bracket, and a washer e of lava is laid upon theother side of the bracket concentric with the bushing. A screw F passes through the Washer and bushing, which insulate it from the bracket, into the base of a binding post G, provided with a set screw g. The terminals insulating bushings'd, preferably of fiber, in-

serted in holes in the base D, and are each carried to the nearest binding post, and securely clamped between the base of said post and the flange of the bushing E.

In ordervto enable a portion of the coils to be cut out, one or more movable switches or bridges are provided, each composed of two metallic pieces H, H, provided with oppositely arranged arms h, h curved to conform to 'the surfaces of the coils. A clamping screw I passes, through a hole in the piece H and is tapped into the piece H. By backing out the screw, the bridge is loosened and may be slipped up or down along the coils to vary the efiective length of the same, and thereby vary the resistance of the rheostat. The coils are protected by a removable sheet metal cover K, which rests upon the base D,'and may be fastened byascrew-bolt 7c tapped into a boss at in the center of the base.

Having thus described my invention, what I claim is- 1. A rheostat comprising a plurality of insulating, heat-resisting cylinders, a helical coil of-wire encircling each cylinder, said coils being connected in series, and one or more movable bridges to connect adjacent coils between their ends, substantially as described.

2. A rheostat comprising a plurality of slate cylinders, two rigid frames to which said cylinders are attached attheir ends, helical coils of wire encircling the cylinders and connected in series, and one or more movable bridges to connect adjacent coils between their ends, substantially as described.

3. In a rheostat, a slate cylinder for supporting a coil of wire, said cylinder having near each end a transverse hole terminating in an annular groove, and a helical groove of small pitch encircling the cylinder between the annular grooves, substantially as described.

4. 111a rheostat, comprising parallel coils of wire, a bridge for connecting two adjacent coils, composed of two metallic pieces having arms to fit the coils, and a screw for clamping said pieces upon the coils, substantially as described.

5. In a rheostat, the combination with two 20 parallel coils, of the metallic pieces H H,

having the curved arms h, h, and the screw I passing through the piece H and tapped into the piece l-I, substantially as described.

6. A rheostat, comprising a plurality of grooved slate cylinders, metallic frames to which said cylinders are attached at their ends, a base to which one of said frames is secured, coils of wire on said cylinders, connected in series, binding posts secured to the base and connected with the terminals of the coils, one or more movable bridges, to connect adjacent coils, and a sheet metal cover inclosing the entire apparatus, substantially as described.

In testimony whereof I affix my signature in 35 presence of two witnesses.

EDWARD R. KNOWLES.

WVitnesses:

MAX LOEWENTHAL, J. A. KENIsToN;

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