US2133858A - Snap switch - Google Patents

Description

Oct. 18, 1938. c. HATHORN 2,133,858

SNAP SWITCH Filed Nov. 24, 1934 4 Sheets-Sheet l INVENTOR C.J.HATH0RN ATTERNEY Oct. 18, 1938. C, T QR 2,133,858

SNAP SWITCH Filed Nov. 24, 1934 4 Sheets-Sheet 2 274 Insu/mor :27

INVENTOR C.J.HATHQRN BY W ATTZRNEY Oct. 18, 1938. c. J. HATHORN 2,133,858

SNAP SWITCH' Filed Nov. 24, 1954 4 Sheets-Sheet 5 [Mil/07 msuwr/am 6160457704- //////////2 ill A -IIIIIIIIIIH u.v 5 .125 13 F7914.

INVENTOR CJHAT oRN av W ATTOZNEY llKSULRf/O/V Oct. 18, 1938. c. J HATHORN SNAP SWITCH Filed Nov. 24, 1934 4 Sheets-Sheet 4 THORN firm/1.0770 i .2 5.

, INVENTOR CJHA BY W ATT NEY Patentecl Oct. 18, 1938 UNITED STATES SNAP SWITCH Clarence J. Hathorn, St. Marys, Pa., assignor to The Stackpole Carbon Company, a corporation of Pennsylvania Application November 24, 1934, Serial No. 754,587 In Canada January 30, 1934 10 Claims.

My invention relates to switches and relates particularly to snap switches that are combined with adjustable resistance devices.

This application is a continuation in part of my prior patent application, Serial No. 701,802,

filed December 11, 1933.

In my earlier filed patent application, I disclose a combined adjustable resistance device, also termed a volume control, combined with a snap switch, wherein one shaft operates both the switch and the volume control.

It is an object of my invention to combine a new and novel snap switch and volume control unit wherein the thickness of the combined unit is reduced to a minimum value.

Another object of my invention is to construct a switch that will simultaneously close or open an electrical circuit at two or more difierent places.

Another object of my invention is to construct a snap switch wherein the same spring which moves the bridging terminal to open or closed circuit position, also maintains the bridging terminal in contact with the circuit terminals.

4 A still further object of my invention is to provide a simple and sturdy snap-switch trigger mechanism.

Another object of my invention is to provide a snap-switch composed of a minimum number of parts which may be readily and quicklyassembled.

Another object of my invention is to construct a snap switch having a bridging member that has an equalizing pivot whereby the contact pres sure on each of the fixed terminals will be equal.

Another object is to adapt a snap-switch for use with a rheostat utilizing an extremely shallow housing or base.

Another object of my invention is to construct an insulating base to interchangeably receive different types of movable contactors to provide switches adapted for different forms of wiring.

Other objects of my invention are to provide an improved device of the character described, which is easily and economically produced, that is sturdy in construction, and which has a maxi-'- mum efliciency and accuracy in operation.

With the above and related objects in view, my invention consists in the following details of construction and combination of parts, as will be more fully understood from the following description, when read in conjunction with the accompanying drawings, in which: I

Fig. 1 is a perspective view of a combined volume control and snapswltch unit embodying my invention. I

Fig. 2 is a fragmentary sectional View of the combined volume control and switch unit as shown in Fig. 1.

Fig. 3 is a plan view of the snap switch embodying my invention.

Fig. 4 is an exploded view of the trigger, the torsional spring, the throw arm, and the bridging member of the snap-switch.

Fig. 5 is an assembled plan view of a snapswitch embodying a modified construction of my invention.

Fig. 6 is an exploded view of the snap-switch shown in Fig. 5.

Fig. '7 is a diagrammatic plan view showing the path of the snap-switch operating pin and its complementary snap-switch trigger in both opencircuit and closed-circuit positions.

Fig. 8 is a schematic view of the terminal connections and the terminal bridging members of the switch shown in Figs. 12 and 14.

Fig. 9 is a schematic view of a modified arrangement of the terminal connections of the switch 7 shown in Figs. 12 and 14.

Fig. 10 is a schematic view of the terminal connections and the terminal bridging members of the two-pole single-throw bridging element shown in Figs. 17 and 18.

Fig. 11 is a fragmentary sectional view taken on the line H-H of Fig. 12, showing the bridging element in open circuit position.

Fig. 12 is plan view of a disc-like type of snapswitch in open circuit position.

Fig. 13 is a fragmentary sectional view taken on the line l3--l3 of Fig. 14,-showing the bridging element in closed circuit position.

Fig. 14 is a plan view of the snap-switch shown in Fig. 12 in closed circuit position.

'Fig. 15 is an exploded view of the important elements comprising the snap-switch shown in Figs. 12 and 14.

Fig. 16 is a sectional view taken on the line |6l6 of Fig. 12.

Fig. 17 is a plan view of a modified construction of a two-pole single-throw bridging member.

Fig. 18 is 'a side elevational view of the bridging element shown in Fig. 17.

Fig. 19 is a rear elevational view of a combined volume-control and snap-switch unit wherein the snap-switch and the volume-control are in the same vertical plane.

Fig. 20 is a rear view of the combined volumecontrol and snap-switch unit with the rear casing removed.

Fig. 21 is a sectional view taken on the line 2l-2I of Fig. 20.

Fig. 22 is a sectional view taken on the line 22-22 of Fig. 20.

Fig. 23 is a perspective view of the snap-switch trigger member.

Fig. 24 is a perspective view of the bridging element embodied in the snap-switch shown in Figs.

20 and 21.

Fig. 25 is a perspective view of the U-shaped bridging element carrier for the snap-switch shown in Figs. 20 and 21; and

Fig. 26 is a perspective view of the carrier of the U-shaped and trigger members shown in Figs.

, moving an insulating member 36, that is fastened to one end of the control shaft 36, and a pressure arm 38, the latter is the connecting medium between the insulating member 36 and the contact member 32. A snap-switch actuating pin 39, projecting from theinsulating member 36, has one end securely retaining an end of the pressure arm 38 together with the insulating member 36 after that particular end is upset, see Fig. 2. However, for a more specific description of the volume control or rheostat A reference is made to my copending patent application Serial No. 701,802, filed December 11, 1933. A base, generally designated as C, for the snapswitch B is comprised of insulating material. The body portion 46 of the base is substantially flat and from its periphery extends an annular flange 42. The flange is widened at the portions designated 44 and 46, and a hole is in each widened portion. The base is held to a casing or I An apertureis provided through the shell of the rheostat so a switch-trigger operating mechanism, generally designated as D, on the switch may protrude therethrough. The aperture on the shell for the trigger is sufficiently large so that the trigger does not, at any time, contact the shell.

The metallic rheostat casing, upon which the snap-switch is mounted, when grounded acts as an electro-magnetic and/ or an electrostatic shield to prevent any feedback noises from the power circuit.

The switch mechanism is mounted within the insulated base C preferably comprised of a molded phenol condensation product. A pivot 56 is located adjacent the peripheral flange 42 of the switch-base C, and one end of a contact carrying throw arm, generally designated as E, of insulating material is loosely mounted upon the pivot. The arm E is substantially fiat and the free end 52 of the arm E, having limited oscillatory movement carries a contact or bridging member, generally designated as F. The bridging member F comprising, a substantially rectangular low-resistance metallic bar 53 is pivotally mounted as at 54 and lies in the same horizontal plane as the main body portion of the contact carrying arm E.

A bridging member support 56, illustrated in Figs. 3 and 4, carries at one end the pivot or stud 54 about which pivot the bridging bar 53 is mounted and the other end 58.0f the bridging member support 56 is securely attached to the contact carrying arm by a suitable holding means as, for example, an eyelet or rivet 66. The pivotal connection between the bridging member 53 and the bridging member support 56 comprises an interfitting opening and stud; and the purpose of the above construction is to allow the bridging member to adjust itself with stationary contact terminals and 82, particularly where such terminals are not in their predetermined location.

Adjacent the throw arm E and loosely mounted on the same pivot 50, as shown in Fig. 3, is the switch-throw trigger which has laterally extending wings or members 62 and 64 for limiting the movement of the trigger D by engaging the flange 42 of the switch base. A member 66 integrally formed with the wing members 62 and 64 extends perpendicular to a line joining the members 62 and 64 and also extends in the same plane as the wing members. One leg 61 of a torsional compression spring, generally designated as G, is attached to the member 66 by passing through aperture 69. A pair of lugs or arms 68 and 10 are integrally formed with themember 66 by a stamping operation. The lugs 68 and I6 project perpendicular to the member 66 of the trigger, and are adapted to be transiently engaged by the circular end of the actuating pin 39 on the member 36 that is rotatable by the control shaft 36; the pin 39 moves the trigger from one extreme position to its opposite extreme position, but the pin 39 only engages one of the lugs for a brief portion of the complete movement of the trigger D.

The helical torsional spring has the tip of its leg 61 terminating in the aperture 69 in the member 66 of the switch-throw trigger D, and its other leg 14 connected to the contact carrying arm E by a tip I5 of the leg I4 protruding into an aperture 16 ofthe arm E.

Movement of the trigger D does not actuatethe contact carrying member until themedial axis of the closed or helical end of the spring passes slightly beyond dead center as the trigger compresses the spring-arms of the torsion spring G together. The energy stored in the spring rapidly turns the contact-carrying member, either closing the electrical circuit when the terminals are bridged or breaking the circuit when the bridging contact is moved away from the terminals. However, as the rheostat control shaft also actuates the snap switch it is essential that the control shaft be rotated through a small fraction of the entire angle that it may be rotated before the switch is actuated, such arrangement allows the major movement of the control shaft to control the position of the contact shoe on the resistance element.

The torsional spring G is adapted not only to throw the contact carrying member with great velocity, but, also to press the contact carrying member E inwardly against the switch base C, so

that in circuit-closing position a lower horizonbridging member F for closing the circuit, and, also, are positioned to limit the movement of the contact carrying member E at the circuit closing end of its oscillation.

Each of the stationary terminals 88, 82 are I similarly constructed, therefore, only terminal 88 will be described. Terminal 88 is comprised of a hollow cylindrical base 81 which passes through the snap-switch base A and rigidly holds itself, the snap-switch base A, and an outside circuit terminal 89 after its end is peened over. From the inner end of the terminal base 81,

see Fig; 4, one surface of the flange '18 sharply circuit, passes through the eye and is soldered to the conducting strip in order to make a low resistance connection. The terminal 82 has a terminal 8| connected thereto and the terminal 9| is similar to the terminal 88 both in structure and in function.

It is to be recalled, at this time, that the breaking of an electrical circuit creates an are which tends to pit and destroy the contacts. Obviously the faster the separation of the electrical contacts then the less the amount of pitting or vaporizing .of the terminals. The rapid break is accomplished by the use of the torsional spring. To further reduce the arcing and so to prolong the life of the switch, a double break in the circuit is simultaneously effected by the snap switch.

As the torsional spring G tends to press or urge the contact carrying arm against the base C, a side H of the bridging bar F and the tapered flange I8 of each terminal are the first and the last portions to make an electrical contact. Thus, a wiping action, which tends to keep the contacts clean, and a bump-type of contact is employed, maintaining a low contact resistance when in operation. Since the arcing will primarily take place between the flange and the side of the contact bar, the useful service of the switch is prolonged.

The switch base flange is extended, as at 46, see Fig. 3, adjacent the upper portion of the contact carrying member E to limit the backward movement of the contact carrying member E. An arcuate formed groove 88 in the interior portion of the base is formed in the path of the swing or arcuate movement of the arm E in order to permit the bridging member support 58 to slide freely therein; and another arcuate groove 88 in the path of the movement of the tip 15 of the torsional spring G prevents any frictional engagement between that tip of the spring and the base.

Referring now to Figs. and 6 I disclose a modified structure of a snap-switch embodying my invention.

A snap-switch base, generally designated as H, is of the general type as the base C shown in Figs. 1 and 4. However, the base H has a pro- ,iecting stud or pivot I88 molded or formed integrally therewith. The stud I88 is located adjacent an opening I82, through which openinga A helical torsional spring similar in details of construction to the helical compression spring G, shown in Figs. 3 and 4, and therefore, designated in the drawings by the same letter G, has one of its legs attached to the switch trigger and its other leg attached to a throw arm, generally designated as J. The legs of the torsional spring when compressed together tend to shift the coiled portion of the spring and when the dead center position is past, the stored-up energy rapidly moves the throw arm J.

The throw arm J, see Fig. 6, is comprised of a fiat body portion I86, and a circular wall I88 forming a journal adjacent one end thereof is complementary to the stud or: pivot I88. A small aperture H8, for receiving one tip of the helical spring, is adjacent the journal I88 of the throw arm. A substantially enlarged rectangular slot H2 is cut through the body portion and the slot is substantially in the path of a line joining the center of the apertures I88 and H8. A side wall II4 of the throw arm is substantially parallel to the longitudinal axis of the slot I I2, and is sharply turned towards the opening H8. The side wall continues to recede from its line of approach towards the opening I I8 and thus a substantially V-shaped niche H6 is formed in the throw arm. 7 Movable by the throw arm J is a contact or bridging member, generally designated as K. The bridging member K, of good electrical con ducting material, rides within a recess H8 in the body portion of the base H and is adapted to engage the stationary terminal contacts I28, I22 that are similar -in structural details and function to the terminals 88, 82 of Fig. 3. The terminals I28, I22 are located at one end of the recess H8.

The bridging member K is stamped of a single fiat piece of conducting material. From the body portion I24 of the bridging member is an offset I26. The horizontal lower surface I28 and the vertical side wall I38 actually make electrical engagement with the terminals I28, I22 when the bridging member is in circuit-closed position. Pressed out from the body portion I24 is a vertically extending tongue member I 32. member opening H2 of the throw-arm J, and the vertically extending longitudinal walls of the opening H2 engage the tongue member I32 when the bridging element is thrown either to circuitopening or circuit-closing position.

The throw arm J is limited in its movement to circuit-opening position by one of its Walls I34 engaging an extension I36 of the peripheral flange of the base H. It will be seen in Fig. 6 that the Junction of edges I38 and I48 of the offset I26 of the bridging member nest within the V-shaped niche H6 of the throw arm, so that the throw arm and the bridging member are unobstructed in movement.

A small recess I42 in the base H permits the unobstructed movement of the tip of one leg of the torsional spring which tip projects into the opening I I8 of the throw arm.

The manner of operating the snap-switch disclosed in Figs. 3 and 5 is clearly illustrated in Fig. '7. The pin 38is movable in the path of an are that may extend close to 360 and when the pin moves in a clockwise direction from one extreme position it engages only the arm I8 and moves the switch trigger, provided the switch is in its circuit closing position. The spring G is compressed by the movement of the switch trigger and rapidly turns the throw arm to circuit-open position after the spring has passed its dead center position. To open the circuit the pin 39 is moved in a counterclockwise position until the arm 68 is engaged and the spring G is compressed, until the spring is moved past its dead center, this results in the rapid movement of the throw arm to open-circuit position.

The operation of the snap switchis effected by a relatively small movement of the operating pin as compared to its entire arcuate movement.

In Figs. 11 to 15 I disclose another modification of my snap-switch invention which is adapted to be used as the snap-switch in the combined volume control and snap-switch unit of Fig. 1;

- a circular substantially fiat base, generally designated as L, and comprised of an insulating material, such as a molded phenolic condensation product, has a peripheral flange 200 thereon. The flange is widened at the portions designated 2M, 202 and holes 203, 264 respectively, also are therein. Holding bolts or rivets pass through the holes 203, 204 to retain the base against a rheostat casing. Eccentrically positioned in the base and integrally formed therewith is an abutment 205 whose vertically extending wall is circular and whose horizontally extending surface is fiat.

Mounted within the base L- but in the center of the abutment 205 is a pivot, generally designated as M, upon which the actuating switch trigger, generally designated as N, is adapted to be mounted. The pivot or axis M is hollow at one end 201 and abruptly increases in diameter at the portion 208, the abrupt change in diameter creates a flange which is adapted to rest upon the flat surface of the abutment 205. The other end 2) of the pivot M is peened over to a diameter which is sufiicient to limit the movement of the switch trigger N in a direction along the longitudinal axis of the pivot but not to restrain the switch trigger from moving in a rotary direction about the pivot.

The switch trigger N is comprised preferably of insulating material and its main body portion 212 is substantially fiat. A continuous circular wall 2M, through the inner body portion 2B2 serves as a journal. An annular hub 2M, see Fig. 16, whose internal diameter is of the same diameter as the opening defined by the circular wall 2M serves as an additional journal support to prevent wobbling and, also, serves as a member for positioning the body portion 2l2 of the switch trigger a predetermined distance from the base abutment 205.

The side bounding surface of the trigger N is irregular in formation and hereinafter will be described in detail. Radially extending spaced side walls 216 and 2|8 limit the movement of the switch trigger N and the walls are joined at their inner edges by an arcuate wall 220. Closely adjacent the side wall 2I6 of the switch trigger is a wall 222 which is substantially radially extending for a portion of its outer length. The inner portion side wall 222 curves away from the center of the circular wall 2I4 until it joins one end of a straight wall 224. The straight wall 224 at its other end is joined by an arcuate wall 226 which is concentric to the interiorly located circular wall 2M, and the wall 226 continues to join the edge ofthe wall 2l8. Thus, an irregular bound switch trigger N is defined.

Adjacent to the junction of the wall 2|8 and the arcuate wall 226, but located in the body portion of the switch trigger N, is a small aperture 228. The aperture 228 extends substantially parallel to the aperture defined by the circular wall 2|4 and is for the purpose of retaining one end of a torsional spring, generally designated as Q.

The wall 222 is adapted to be engaged by a protruding operating pin 229 on a rotatable member of the rheostat, to move the switch trigger in one direction, and the short arcuate wall as at 223, adjacent the junction of the walls 222 and 226 is adapted to be engaged by the operating pin 229 to move the switch trigger in the reverse direction.

A pin 230 is fixed in the switch base and functions to limit the movement of both the switch trigger N and a contact or terminal bridging disc-like member, generally designated as P, and hereinafter further described.

The coiled torsional compression spring Q, adapted to rapidly move the contact disc P from one extreme position to-its other extreme position, has one leg 232 passing into the opening 228 of the switch trigger N and its other leg 234 connected to a suitable bearing 235 in the bridging member P.

The contact disc-like or bridging member P has a body portion which is substantially fiat and circular. The bridging member P is of good electrical conducting material, such as copper alloy coated with silver, and has a central aperture' 236 therethrough which is virtually closed when placed through the switch trigger pin M. However, there is suificient play of the bridging member P so that it is freely rotatable about the pin M. A'large aperture 238 is ofiset to one side of the central aperture 236 for the purpose of having the stop pin 230 engaged by a portion of the circumferential wall defining. the aperture 238. The aperture 238 through the bridging member is of a larger diameter than the diameter of the stop pin 230 in order to permit the bridging member P- to move a distance sufiicient to make and break the electrical circuit.

Adjacent to and parallel to the periphery of the bridging member are short equi-spaced arcuate slits 240, 241, 242, 243. One end of each slit is joined by a radially extending slit which projects radially inwardly from the outside circumference. Thus,four slits 244, 245, 246, and 241 are used to form bridging contact members 248, 249, 250 and 25L The end of each contact member is slightly bowed and the intermediate portion is inclined in a direction towards the switch base thus making the contact member resilient. The purpose of bowing the end of each contact member is to provide a freely sliding action of the contact member over the head of terminal rivets or contacts 252, 253, 254, 255 at circuit making and breaking positions. The

sliding action between each contact member and the head of the terminal keeps the contacting area free from dust, grit, or moisture; and so the value of the contact resistance is kept low.

Although four contact members on the bridging member have been disclosed it is apparent that two bridging members may be used, and the number of contact members used is to be determined by the particular use for the device.

Connected to the outside of two of the terminal rivets is a strip of metal 258 comprised of good electrical conducting material, see Fig. 8. Each terminal has an upturned end 262, and the latsoldered to the conducting strip.

It is apparent that with the use of four contact units, two of which are electrically joined together, that each side of the electrical circuit will be broken at four places, thus the amount of arcing when the circuit is broken will be diminished.

In Figs. 8 and 9 is shown diagrammatically the connection of the snap switch in an electrical circuit. The circuit on one side of the line is broken at four distinct places. Since it is virtuallyimpossible to build a bridging element so that all contacts are absolutely identical, one contact at each side of the line will first take the are, thus, that contact will become pitted and the other contact on the same side of the line will be clean. For the purpose of more clearly explaining the reaction which occurs, the contacts designated 248 and 250, represent the contacts or bridging members which remain free from pitting and the contacts designated 249a and 25la represent the bridging members which are pitted by the arc.

In Figs. 17 and 18 I disclose a single-throw, double-pole double-break oscillatory bridging member embodying a structure similar to the single throw single pole snap switch shown in Figs. 11 to 16.

Since the bridging disc'is changed it will also be necessary to employ four external terminals. Each external terminal has an eye therein which is connected to an end of each rivet.

The double-break, double-contact disc-like member generally designated as R, is comprised of two complementary bridging sections 210, 212. The complementary sections prior to assembly are similar in structure to the bridging member P in Figs. 12 and 14. However, the section 210 is severed along one diameter and a semicircular central portion is cut therefrom, the cut out portion is of a diameter larger than the diameter of a shaft on which a switch trigger is pivoted. The second section 212 of the disc-like member is similarly constructed so that when the two portions of the disc-like member are mounted on a circular fiber disc 214, of insulating material, no electrical connection will exist between the two sections. Of course, the bridging section 210 closes one line of the electrical circuit by engaging the rivets 214 and 215, see Fig. 10, and the bridging section closes the other line Y of the circuit by engaging the rivets 216 and 211.

Through the bridging section 210 and the insulating disc 214 is a continuous circular wall 218 complementary to a stop pin. The wall 218 is of sufliciently large diameter to permit the disc R to oscillate to open or to closed circuit position. The contact members of the disc-like bridging member R are similar to the contact members of the disc-like bridging member P both in structural details and in function.

Referring now to Figs. 19 to 26, I disclose a combined snap-switch S and rheostat T unit, wherein a single control shaft-300 actuates both devices and wherein the snap-switch is located in the same plane as the rheostat.

The switch and the rheostat are mounted on a common base 302 of insulating material. A resistance element 304 is mounted on the upper portion of the base and has a contact shoe 306 which is adapted to move in contact with differ ent parts of the resistance element. A pressure arm 308 is connected at its ends to the contact shoe 306 and to an insulating member 3| 0. The

disc contact 350.

rotatable control shaft 300 supports the insulating member 3l0.

integrally formed with the insulating member 3| 0 is a snap-switch actuating lever M2. The actuator 3l2 is positioned towards the rear portion of the combined unit and is thin so that it may freely pass over the upper surface of the resistance element, when it is rotated.

The actuator 3l2 is adapted to cooperate with a forked tumbler or switch trigger, generally designated as U. The tumbler U has substantially forked ends 3l4, 3l6 whose diametrically opposed edges are adapted to be engaged by a curved tip 318 of the actuator 3l2, in order to operate the snap-switch from off to on, or vice-versa, position. Integrally formed with the formed end of the tumbler is an arcuate segmental portion 3| 9 that has a slot 320 therethrough. The arcuate segmental portion 321 functions as a journal in a complementary bearing of an insulating back cover member 358.

A carrier, generally designated as V, has diametrically opposed ears 322, 324 extending outwardly which cooperate with suitably positioned bearings 326, 328 in the front and back portions of the casing. A horizontally extending yoke 330 of the carrier has a small central aperture 332 therethrough for retaining one end of a helical tension spring 334. Integrally formed with the carrier V and at the left side thereof, as viewed in Fig. 26, are a series of steps 335, 33 6, 331 defining the lower horizontal edges, and steps 335a, 336a, and 331a on the upper horizontal edges, the two series of steps diverge as the vertical center is approached.

Central steps, designated as 331 and 338, act as bearings for the substantially V-shaped notches 340, 34! of a U-shaped contact carrier, generally designated as X. A yoke 342 joining the parallel legs 344, 345 has a rectangular slot 346 therein through which passes a tongue 348 of a The disc 350, of good electrical conducting material, has a tongue 348 projecting therefrom, in which there is a small aperture 352 at the tongues upwardly extending end. The tongueis formed from the'disc body portion 350 by a punch-press operation.

The helical tension spring 334 has its other end A 352 attached to the tongue by virtue of the end of the spring passing through the aperture 352. Thus, as best illustrated in Figs. 20 and 21, when the spring 334 is in position, the carrier V, the U-shaped member X, and the tongue 348 are resiliently drawn together.

Mounted interiorly of the switch casing are the heads of rivets 354,355 which are diametrically opposed. Each rivet is placed so that its end is upset over an opening in a terminal 358 to which a circuit wire may be soldered or otherwise suitably attached. It is obvious that the metallic contact disc 350 is adapted in one extreme position of the carrier to bridge the diametrically opposed rivets and in the other extreme position of the carrier to disengage the rivets. The bridging member 350 engages the heads of the rivets 354, 355 with a wiping action, thus, corrosion is prevented, and dust, grit and dirt removed.

Since the rheostat control shaft also actuates the snap switch, to either open or 'closed circuit positions, it is essential that the control shaft actuate the snap switch at a predetermined part of its cycle, and that the arcuate movement of the control shaft should be comparatively small as compared tothe control shafts .entire movement.

The casing is partially comprised of a molded insulating material 358 and a metallic material In the above arrangement of the combined volume-control and snap switch unit it is particularly to be noted that the over all thickness of the unit is substantially the thickness of a rheostat alone.

Although the embodiments of my invention have been described in considerable detail, such description is intended to be illustrative rather than limiting, as the invention may be variously embodied, and the scope of the invention is to be determined as claimed.

I claim as my invention:-

-1. In a snap-switch, a plurality of terminals adapted to be connected to an outside circuit, each of said terminals comprising a holding rivet, a flange and a main shank integrally formed together, a short-circuiting bar comprising a side wall and a front wall whereby the side wall will wipe the flange before and after the engagement of the front wall of the bar with the shank of the terminal so that the arcing will take place between the side wall of the bar and the flange.

2. In a snap-switch, a plurality of terminals adapted to be connected to an outside circuit, each of said terminals comprising a flange and a main shank of electrical conducting material, a shortcircuiting bar comprising a side wall and a front wall whereby the side wall will wipe the flange before and after the engagement of the front wall of the bar with the shank of the terminal so that the arcing will take place between the side wall of the bar and the flange, a throw arm carrying said short-circuiting bar, a snap-switch trigger arm, and a spring between said throw arm and said trigger arm for actuating said throw arm and for maintaining the short-circuiting bar in elec trical contact engagement with said terminals.

3. A snap switch comprising a snap switch base having a pivot mounted therein, a snap switch trigger including two spaced arms mounted upon said pivot, an insulated throw arm mounted upon the same pivot as that upon which the trigger is mounted, said throw arm being located between said trigger and said base, a spring connected to said trigger and to said throw arm and said spring being adapted to impart rapid movement to the throw arm and also being adapted to press said throw arm towards said base, a bridging member having a substantially flat lower wall and a front wall substantially perpendicular to the bottom wall, said bridging member being pivotally mounted to said throw arm, a plurality of terminals adapted to be connected to an out- "Side circuit, each of said terminals including a flange and a main shank of electrical conducting material extending from said flange, said terminals adapted to be bridged by said pivoted bridging member whereby an electrical circuit will be closed, said front wall of the bridging bar being adapted to engage'the shank, and the side wall being adapted to wipe the flange before and after the engagement. of the front wall of the to limit movement of the contact member in one direction and the outside end of said rivet member expanded to hold the stationary contact member in position, another surface of said flange being conically shaped and terminating in a main contact shank, said main shank having its axis extend in the same line as the axis of the rivet, said rivet, flange and main shank being integrally formed, and means to bridge said stationary contact members, said means being adapted to engage said flange prior to engaging said main shank.

5. A snap switch comprising a base having a pintle mounted therein, a snap switch trigger including two spaced arms mounted upon said pintle, an insulated throw arm mounted upon the same pintle as that upon which the trigger is mounted, said throw arm being located between said trigger and said base, a spring connected to said trigger and to said throw arm and said spring being adapted to impart rapid movement to the throw arm and also being adapted to press said throw arm towards said base, an electrical bridging member having a substantially flat lower wall and a front wall substantially perpendicular to the bottom wall, said bridging member being pivotally mounted to said throw arm, a plurality of terminals adapted tobe connected to an outside circuit, each of said terminals comprising an integrally formed rivet, a flange and main shank, said terminals adapted to be bridged by said bridging member when the switch is in closed circuit position, said front wall of the bridging bar being adapted to engage the main shank of each terminal, andthe side wall of the bridging member being adapted to wipe the flange before and after the engagement of the front wall of the bridging member with the shank of the terminal so that arcing will take place on the side wall of the bridging member and the flange;

6. In a snap-switch, a plurality of terminals adapted to be connected to an outside circuit,'

each of said terminals comprising a flange and a main shank of electrical conducting material, a short-circuiting bar comprising a side wall and a front wall whereby the side wall will wipe the flange before and after the engagement of the front wall of the bar with the shank of the terminal so that the arcing will take place between the side wall of the bar and the flange, a throw arm, said short-circuiting bar pivotally mounted with respect to said throw arm and movable by said throw arm, a snap-switch trigger arm, and

a spring between said throw arm and said trigger arm for actuating said throw arm and-for maintaining the short-circuiting bar in electrical contact engagement with said terminals.

'7. In a snap switch adapted to be actuated by a pin during a relatively small portion of its full angular movement; a base; a plurality of fixed terminals mounted on said base; a pintle mounted on said base; a switch throw trigger pivotally mounted on said pintle; an insulating throw arm pivotally mounted on said pintle between the trigger and the base; a torsional spring having one leg connected to the trigger and one leg connected to the throw arm for rendering quick movement to the throw arm after the spring has been turned past dead center by the trigger and said spring pressing said throw arm towards said arm being of substantially the same thickness and the bridging member and throw arm lying in the same plane, said plane being substantially parallel to the plane of the base, and said bridging member being adapted to bump against said terminals to close the circuit or to move away from said terminals to break the circuit, said fixed terminals limiting the movement of said throw arm in one direction.

8. A snap switch comprising an insulated base having a pivot mounted therein, a trigger including two spaced arms, a throw arm, said trigger and said throw arm being mounted on said pivot, said throw arm being located between said trigger and said base, a spring connected to said trigger and to said throw arm and said spring being adapted to impart rapid movement to the throw arm and also being adapted to press said throw arm towards said base, an electrical bridging member having a substantially flat bottom wall and front contact wall portions substantially perpendicular to the bottom wall, said bridging member being pivotally mounted to said throw arm, a plurality of electrical terminals adapted to be connected to an outside circuit, each of said terminals including a flange and a main shank extending from said flange, said terminals adapted to be bridged by said pivoted bridging member whereby the electrical circuit will be closed, one of said front wall portions of the bridging member being adapted to engage the terminal shank, and the side wall being adapted to wipe the flange before and after the engagement of the front wall of the bridging member with the shank of the terminal so that arcing will take place on the side wall of the bar and the flange.

9. A switch comprising a pivotally mounted throw arm, means for actuating said arm, a plurality oi terminals spaced from one side of the arm, a bridging member disposed between the arm and terminals and provided on the side ad- Jacent the arm with an arcuate lateral extension, said arm being provided with a cooperating arcuate recess for receiving said extension and a link connected at one end to said arm and pivotally connected at the opposite end to said bridging member.

10.1 switch comprising a pivotally mounted throw arm, means for actuating said arm, a plurality of terminals spaced from the arm, a bridging member adapted to engage said termi nals, and a link connected at one end to said arm and pivotally connected at the opposite end to said bridging member, each of said terminals comprising a shank surrounded by an outwardly and downwardly inclined flange which is engaged by said bridging member before it strikes the shank.

CLARENCE J. HATHORN.

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