US558252A - Rheostat-plate - Google Patents

Description

(No Model.)

J. 1?. BALL.

RHEOSTAT PLATE.

No. 558,252. Patented A r. 14,1896.

Witnesses.

aBrA W Attorney.

UNITED STATES PATENT OFFICE.

JOSEPH P. BALL, OF PHILADELPHIA, PENNSYLVANIA.

RH EOSTAT-PLATE.

SPECIFICATION forming part of Letters Patent No. 558,252, dated April 14:, 1896.

Application filed January 27, 1896. Serial No. 576,947- (No model.)

To all whom it may concern:

Be it known that I, JOSEPH P. BALL, a citizen of the United States, residing at Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented a new and use ful Improvement in Rheostat-Plates, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, which form a part of this specification.

My invention relates to rheostatplates or resistance-plates, and particularly to those wherein a high-resistance wire, connected at one end with one pole of an electric circuit, is secured to a plate and is in electrical c011- nection at several points along its length with terminals, with each of which an operatinglever is designed to make contact, whereby a greater or less length of wire, and consequently a greater or less resistance, is thrown into the circuit.

My invention consists, generally speaking, in a plate of non-conducting material having grooves in its lower surface, within which, bent upon itself to form a convolute, is the resistance-wire, the grooves being vertically disposed and of substantially the width of the thickness of the wire, so thatthe wires will be held within the grooves by frictional eontactthat is, by binding against the walls of the grooves.

My invention also consists in details of construction particularly described hereinafter.

The objects attained by the above construction are: to simplify and cheapen the manufacture of resistance-plates; to obviate the necessity of holding the wire in place by enamel or other material commonly adapted for that purpose and thereby provide for free expansion and contraction of the resistance; to facilitate the repair of the wire or the insertion of a new coil when for any reason it breaks or burns out, and, also, if desired, to place a long length of wire, with or without a great number of terminals, in a plate of comparatively small area. The usual construction, which consists in placing the wire on a plate and surrounding the wire with enamel which adheres to the plate and holds the wire in place, is objectionable for the reason that the unequal contraction and expansion of the enamel and resistance-wire cause the wire to break. The enamel is also liable to cleave and crack, and minute particles of dust, &c., settle in the fissures, which interferes still more with the free expansion and contraction of the resistance. Repair is troublesome and expensive. I find that I can dispense with an insulator for this resistance, as the supposed disintegration from oxidation is of small importance in comparison with the advantages above enumerated.

In the drawings, Figure 1 is an inverted plan view of my improved rheostat-plate, and Fig. 2 a section through line :10 00 of Fig. 1. Fig. 3 is a Vertical transverse section through the slots L M in the plate A.

A is a plate of slate or other non-conducting material; B B, the binding-posts; O, the hand-lever pivoted to the bolt D, which passes through the plate into a recess I on the opposite side thereof and engages the nut E, which binds against the bottom of the recess a wire I), connected at its other end to the bindingpost B. By this means the binding-post B is permanently connected with the pivot end of lever G. The drawings show three other recesses F F F in the bottom of the plate, into each of which projects a bolt G, secured to a contact-plate or terminal H on the face of the plate. The free end of the hand-lever is adapted to pass over and make contact with these terminals.

Grooves of a depth equal to about half the thickness of plate A are formed in the under surface of the plate in the following manner:-

Groove K extends from one side of the plate to recess F, grooves L and M from recess I to recess F, groove N from one side of the plate to recess F and groove 0 from one end of the plate to groove K, intersecting the other grooves. The resistance R, bent or convoluted, as shown, extends from recess F through grooves K, O, and L to recess F, the resistance R from recess F through grooves M, O, and N to recess F The ends of the resistances are secured to plates or washers P, held in place against the bottom of the recesses by nuts Q. The resistances R R are preferably a continuous wire, and are so shown, B and R representing merely sections thereof. The resistance-wire is thus in electrical connection with all the terminals. To

the plate P in recess F is secured the end of a wire I), connected at its other end to the binding-post B. I have shown two other grooves extending, respectively, from binding-post B to recess I and from binding-post B to recess F for the ieception of the connecting-wires, although it will be understood that these grooves are unnecessary, as these wires are not resistance-wires and may extend over the under face or around the edge of the plate.

When the hand-lever is in contact with the terminal connected directly with bindingpost B, the current will pass through wire I), lever C, and out by wire Z). hen the handlever is brought over the central terminal, the current will pass through resistance-section R, and when the lever is in contact with the third terminal the current will pass through both sections. (See arrows, Fig. 1.)

The resistance B being convoluted, as shown, and of the same thickness as the width of the grooves, is held securely in place by binding against the walls thereof, yet it can be readily removed for repair or for replacing the old wire with a new one. The width of the convo'lutes is preferably somewhat less than the depth of the groove.

It will be understood that the number of grooves and the number of resistance-sections may be increased indefinitely without departing from my invention. The grooves for the resistances occupy so little space in superficial area that a great number of resistance-sections may be secured in a plate of small size.

Having now fully described my invention, what I claim, and desire to protect by Letters Patent, is-

1. A rheostat or resistance plate, having grooves, in combination with a resistancewire bent upon itself to form a convolute and held in place within the grooves by compres sion against the walls thereof, substantially as described.

2. In a rheostat or resistance, the combination with a plate, of binding-posts and terminals secured thereto, said plate having vertical grooves connecting the terminals, a lever adapted to be brought in contact with said terminals, electrical connection between one binding-post and one of the terminals, and between the other binding-post and the lever, and a convoluted resistance held in place within the grooves by compression against the walls thereof and connecting the terminals one with the other, substantially as described.

3. Arheostat or resistance plate having terminals on its upper face, grooves on its under face extending from the edge of the plate to points opposite said terminals, one of said grooves extending at an angle to and opening into the others, in combination with resistance-sections connecting adjacent terminals, each of which extends through two of said grooves, and through a portion of the length of the common intersecting groove, said resistance-sections being held in place within the grooves by compression against the walls thereof, substantially as described.

4. A rheostat or resistance plate having a series of terminals on its upper face,and grooves on its under side terminating at points opposite said terminals, there being one groove for the end terminals of the series, and two grooves for each central terminal, the plate having another groove common to all the grooves leading to the terminals, resistancesections connecting adjacent terminals, each of which extends through two of said grooves, and through a portion of the length of the common intersecting groove, said resistancesections being held in place within the grooves by compression against the walls thereof, substantially as described.

In testimony of which invention I have hereunto set my hand.

JOSEPH P. BALL. \Vitnesses:

FRANK S. BUssnR, CAROL. H. DESHONG.

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