US2331191A - Circuit interrupting means - Google Patents

Description

Oct. 5, 1943.

c. H. HODGKINS CIRCUIT INTERRUPTING MEWS Filed Nov.- 29, 1939 2 Sheets-Sheet l INVENTOR WITNESSES:

Oct. 5, 1943- c. H. HODGKINS CIRCUIT INTERRUPTING MEANS Filed Nov. 29, 1939 2 Sheets-Sheet 2 INVENTOR Q 464, ja

BY j ATTORNE WITNESSES:

Patented Oct. 5, 1943 CIRCUIT INTERRUPTING MEANS Charles H. Hodgkins, Fairiield, Conn., asslgnor to The Bryant Electric Company,

Bridgeport,

Conn., a corporation of Connecticut Application November 29, 1939, Serial No. 306,655

23 Claims.

My invention relates to circuit interrupters in general, and more particularly to an electric switch which is capable of controlling a, plurality of circuits.-

My novel switch will be disclosed for controlling a plurality of heating elements, such for example as are found in an electric range. However, the switch, as will appear to be obvious, may be used for controlling a plurality of electric circuits containing any desired type of electrical equipment, and my switch is particularly designed for controlling such circuits, where the equipment served by the circuits draws appreciable load currents.

Switches used for this type of control, have in the past been made relatively large and cumbersome, and have embodied a set of arcing contacts for each circuit to be energized. These switches have been usually in the form of cam-operated switches, with a cam operating a set of contacts for each circuit to be controlled, and with all of the cams mounted on a common operating shaft. It is obvious that space limitations may limit the number of positions obtainable with such a switch, inasmuch as each position required a separate set of contacts and an additional cam or operator therefor.

It is therefore, an object of my invention to provide a novel switch which is capable of controlling or establishing a relatively great number of different circuits, but which employs relatively few arcing contacts.

It is a further object of my invention to provide a novel type of switch for controlling a plurality of circuits, which embodies two sets of contacts, one of which establishes connections for the desired circuits, and the other of which makes and breaks the circuit established.

As is well-known in the art, arcing contacts are usually made of large size and of a noble metal such as silver, or an alloy thereof, to obtain long life and eflicient operation. These contacts are, therefore, relatively expensive, and require considerable mounting space.

Another object of my invention is to provide a 2 switch for controlling a plurality of circuits, in-

cluding two sets of contacts, one of which functions to set up or select a circuit, while the other set acts to energize or deenergize the circuit.

Another object of my invention is to provide a switch capable of controlling a plurality of circuits, which includes relatively few arcing contacts, compared to the number of circuits controlled. In line with the desirability of obtaining control by a single switch of a relatively large number of circuits, space limitations are often a lim-' iting factor as to the number of circuits which can be controlled. This was especially true when it was found to be desirable to mount electric range switches on the splash board which projects upwardly at the back of certain types of ranges. These splash boards in practice, are made of sheet metal with a short rearwardly projecting peripheral flange designed to engage a building wall at the back of the range and providing only a shallow space in which switches may be mounted.

Hence, another object of my invention is to provide a switch capable of controlling a plurality of circuits, the parts of which are so constructed and arranged as to take up a minimum of space.

Another object of my invention is to provide an electric switch for controlling a plurality of load circuits, which shall be relatively simple of construction and eflicient in'operation.

These and other objects of my invention will become more apparent when considered in connection with the following detailed description of a preferred embodiment of my invention, taken in connection with the attached drawings, in which:

Figure 1 is a perspective view illustrating a preferred embodiment of my invention;

Fig. 2 is a plan view of the switch shown in Fig. 1 with the handle and cover plate removed, and a portion of the arcing shield broken away;

Fig. 3 is a bottom plan view of the switch shown in Fig. 1;

Fig. 4 is a plan view of the interior of the switch similar to Fig. 2 but with the contact operating member and its indexing means removed;

Fig. 5 is a central longitudinal cross sectional view of the switch shown in Fig. l to 4; and

Fig. 6 is a schematic view illustrating one circuit for which my switch is particularly adapted and showing six different positions of the switch.

The particular apparatus and circuits shown in Fig. 6 are claimed in my copending applica- 171011. Serial Nofiled November 29, 1939, now Patent No. 2,303,460, issued December 1, 1942, and assigned to the Westinghouse Electric 8: Manufacturing Company.

My novel switch, generally, is of the multiposition type and two methods of making contact are employed; (1) in which movable, normally spring closed contacts are operated by cams to cause these contacts to engage or disengage from stationary contacts, and (2) in which pairs of stationary segmental contacts are bridged by a sliding shoe carried by the cam which operates the spring contacts.

The connection relation of this switch with respect to one circuit which it may control is such that the circuit is always made or interrupted by the cam. operated spring contacts engaging with or separating from. their cooperating stationary contacts. Therefore, arcing occurs at these contacts only.

The relation of the segmental contacts and the sliding shoe to the cams which operate the spring contacts is such that there is a definite timing in the functioning of all contacts. When switching from one position to another, the sequence is as follows: The spring contacts are first opened by the cam, the sliding shoe moves from one set of segmental contacts to another set and the spring contacts are then closed, thereby completing the circuit. The sliding shoe and segmental contacts can, therefore, be considered as set-up contacts or circuit selecting contacts, and no arcing can occur at this point.

Referring to the drawings, I have illustrated a switch which is mounted in an insulating casing 2, which may be of any desired heat resistant insulating material such, for example, as a moulded insulating material such as Bakelite. The insulating casing 2 includes a bottom wall it, opposed side walls 6, and end walls 8. The bottom wall 6 of the casing is provided with a central aperture it for receiving a reduced end portion E2 of the switch operating shaft. Concentric with the aperture it in the bottom wall of the casing, there is provided concentric annular grooves id and it. In the outer groove N there are mounted spaced arcuate contact segments it, 23 and 22 maintained in spaced relation by the arcuate insulating segments 28. These segments may be maintained in the groove It in any desired manner, preferably by friction. The contact segments may be of any desired conducting material such for example, as copper or the like. The inner groove N is likewise provided with spaced arcuate contact segments 2d and 26 maintained in spaced relation by the arcuate insulating segments 28. The segments are preferably slightly raised above the adjacent surface of the bottom wall 4 of the switch casing 2 as shown in Fig. 5.

The operating shaft is provided with an enlarged cylindrical portion 30 adjacent the reduced portion I2 and forming a shoulder 32 which is adapted to abut against the bottom wall of the switch casing to limit movement of the operating shaft into the switch casing. The operating shaft is also provided with an intermediate hexagonal portion 34, forming a shoulder 36 at its juncture with the portion 30, and an outer reducedportion 38 forming a shoulder 40 at its juncture with the hexagonal portion 34. The outer end of the operating shaft is reduced as at 42 to receive an operating handle I48.

A contact operating member 44 of any desired insulating material such, for example, as a moulded insulating material such as Bakelite, is slipped over the reduced end of the operating shaft [2 until the shoulder provided in the aperture through the operating member 44, engages the shoulder 36 on the operating shaft. The enlarged portion of the aperture through the operating member 44 is made hexagonal in shape to correspond with the hexagonal portion 34 of the operating shaft, to lock the operating member 44 for movement with the operating shaft. The contact operating member 44 is formed on its lower side with integral annular concentric projections 55 positioned to be received in spaced annular depressions d5 provided in the bottom wall 4! of the switch casing. These projections 36 are provided between the sets of contact segments, and between the operating shaft and the inner set of contact segments respectively, to increase the creepage distance between these parts. The contact operating member at is provided with an opening 50 which opens toward the bottom wall 41 of the switch casing, and has an enlarged open end portion 52 in which is received the contact segment bridging contact 56, which is elongated in shape and has an outwardly extending integral projecting portion 56, extending into the inner portion of the aperture 50 and telescoping into one end of a coil compression spring 58, which bears against the bridging contact 56 at one end thereof and engages the closed end of the aperture 50 at its other end. The coil spring 58 acts to continuously urge the bridging contact 5% into engagement with the contact segments.

Mounted in the two corners of the switch casing at one end thereof, are the fixed contact supports 86 and i l carrying the contact portions 62 andflfi, respectively. The contact supports may be made of any suitable conducting material such as brass, copper, or the like, but the contacting portions thereof are preferably made of a metal capable of withstanding repeated arcing, such as silver or a silver alloy. Cooperating with the contacting portions 62 and 16 are the resilient contact carrying arms 64 and i3, respectively, secured in the opposite corners of the switch casing, on conducting supporting members 65 and 80, respectively. The resilient contact carrying arms carry at their free ends contacting portions l0 and 84 for cooperation with the contact portions 52 and 16 respectively, and are formed of a like material. The resilient contact carrying arms 64 and 78 are stressed so as to normally engage their contacting portions with the fixed contacts 62 and 16. Each of the resilient contact carrying arms 64 and i8 is provided at substantially its mid-portion with a struck-out part 12 and 86, respectively.

As viewed in Figs. 2 and 4, the struck-out portion 88 of the resilient contact carrying arm 18 is struck-out of the upper edge of this contact carrying arm, whereas, the struck-out portion 72 of the other arm 64 is struck out adjacent the lower edge of that contact carrying arm, all for a purpose hereinafter to be described. The contact carrying arms 6d and '18 are secured to the supports 66 and 80, respectively, by any suitable means, such for example, as by the rivets 68 and 82, respectively. Also secured to the support 66 by the rivets 68 is a fixed contact strip 88, having an angularly extending contact portion 90. A substantially U-shaped resilient conducting member 92 integral with a supporting member 94 secured in the switch casing in any desired manner has one leg 96 thereof extended for cooperation with the fixed contact 90. An intermediate portion of the leg 96 is struck out as at 98 for a purpose to be hereinafter described.

The contact operating member 44 is provided with peripheral cam surfaces, as shown especially in Fig. 2. These cam surfaces are provided for cooperation with the struck-out portions 12, 86 and 98 of the three resilient contact bearing arms. As shown in Fig. 2, the periphery of the contact operating member is provided with outer indented portions I00, NH and I02 for cooperation only with the outer struck-out portion 66 of the resilient contact carrying arm I6. These indented portions I00, IM and I62 are provided only in the outer portion of the peripheral surface of the contact operating member 44 as is apparent from Fig. 2. The contact operating member 44 is also provided with indentations I04 and I06 which extend throughout the width of the periphery of the contact operating member 44, so as to operate, or engage with both of the indented portions 66 and I2 of the resilient contact carrying arms. The contact operating member 44 is further provided with an outwardly oilset protuberance I06 for engagement only with the resilient contact arm 66.

As is shown in Figs. 2 and 4, I have provided an insulating barrier I64 integral with the switch casing and positionedbetween the fixed contacts 62 and 16. The insulating barrier I64 is provided with arcuate extensions I66 to substantially isolate the contacts 62 and I6 from the contact segments. A cover I50 is suitably secured to the open side 01' the switch casing, for example, as by the machine screws I6I Secured between the cover and the casing is an arcing shield I52 of insulating material such, for example, as fiber or the like, which, together with the switch casing and the insulating barrier I64, I66, completes the substantial enclosure or segregation of the contacts 62 and I6 from each other and from the contact operating member, and contact segments provided in the bottom of the switch casing.

For indexing the contact operating member in the desired operating positions, I have provided resilient rod elements I54 and I56 on opposite sides of the hexagonal portion 34 of the operating shaft with corresponding ends of the resilient rods received in notches I56 provided in one side wall of the switch casing, and with the opposite ends of the resilient rods received in notches I60 provided in the opposite side wall of the insulating casing, which latter notches are elongated to receive the coil compression springs I62 engaging between the resilient rods I54 and I56,

respectively, and the outer ends of the notches I60. The springs I62 act to maintain the resilient rods I64 in engagement with the opposed fiat sides of the hexagonal portion 34 of the switch operating shaft. Thus, in turning the shaft, it is necessary to slightly separate the resilient rods I54 and I56 by a cam action of the hexagonal portion 34 of the switch operating shaft, until another set of opposite fiat surfaces on the shaft are brought into flush engagement with the resilient rods. This will clearly indicate to the manipulator when an operating position of the switch is arrived at, and the resilient rods I54 and I 56 under the influence of the springs I62 will tend to maintain the switch in its operative positions. A handle I46 is frictionally fitted on the outer end of the switch operating shaft and is provided with suitable iridicia, which will be hereinafter referred to.

The various switch connections which I have provided in this embodiment of my invention may be used by way of example in the circuit shown in Fig. 6. The switch proper is provided with a terminal IIO which has portions extending through the casing bottom wall and connected with the contact segment I6 and the conducting support 66, respectively, which in turn connects this terminal with the resilient contact arm 64 and its contact portion 10 and with the fixed contact 86 and its contacting portion 60. The terminal II2 of the switch is electrically con- I or lowest heat position, labeled the nected through the bottom wall of the switch casing with the support 60, thus connecting this terminal with the resilient contact arm 16 and its contacting ftion 64. A terminal H4 is provided on the back of the switch and, as shown on Fig. 5, includes an inner angular portion II6 extending through the bottom wall of the casing and connected with one leg 01 the U-shaped resilient contact 92 shown in the upper end or the switch casing in Fig. 4. The terminal 6, also provided on the back of the switch casing on one side thereof, is provided with an integral extension I20 extending through the bottom wall of the switch casin s shown in Fig. 5, which is in turn, integral with the contact segment 24. The switch terminal I22 at the back of the switch casing is connected through the bottom wall of the casing to the fixed contact support I4, and has an extension tion extending through the bottom wall of the switch casing for connection with the contact segment 22. The switch terminal I26 also mounted on the back of the switch casing is connected to the fixed contact support 60 through thebottom wall of the casing, and is provided with an extension I21 for connection through the bottom wall of the casing with the contact segment 26. The terminal I24 of the switch casing is provided with a connection through the bottom wall of the casing to the contact segment 20. These connections of the switch terminals with the corresponding contacts or contact segments are readily apparent from an inspection of Figs. 5 and 6. All the switch terminals are provided with screws I26 for attaching lead wires thereto. Referring now particularly to Fig. 6 wherein I have illustrated in schematic form, the incorporation of my novel switch in a circuit for controlling a heater element composed of two identical resistance sections I38 and I40 and supplied with current from a three-wire source of supply giving, for example, 250 volts between the positive and negative conductors of the supply circuit and one-half that value, or volts between either the positive or negative conductors and the grounded neutral conductor. As shown in Fig. 6, the switch terminal H2 is connected by conductor I30 to the positive terminal conductor of the supply circuit. A conductor I 32 connects the neutral conductor ofthe supply circuit with the switch terminal I24, and a conductor I34 connects the switch terminal IIO with the negative conductor of the supply source. The terminal I I4 of the switch is connected to the neutral con ductor of the supply circuit through a pilot lamp I36. One end of the resistance heater element I36 is connected by conductor I 42 to the switch terminal I22. One end of the resistance heater element I40 is connected by the conductor I46 to the switch terminal I I8, and a conductor I 44 connects the switch terminal I26 to the other tlariais of the resistance heater elements I 36 and I have illustrated in Fig. 6 the six positions of my switch when used with this particular circuit, which is capable of providing five different degrees of heat from the heating elements I36 and I 40. At the extreme right in Fig. 6, I have illustrated the off position of my switch wherein all contacts'are open and the circuit through the pilot lamp I36 is broken.

To the left of this, I have illustrated the first simmer position, wherein the circuit through the switch extends from the positive conductor of the supply I23 for connection with a porsource through conductor I88, terminal II2, resilient contact arm 18, fixed contact I4, terminal I22, conductor I42, resistance elements I88 and I48, conductor I46, switch terminal II8, contact segment 24, bridging contact 54, contact segment 28, switch terminal I24, and conductor I32 to the neutral conductor of the supply circuit. This provides 125 volts across the two resistance elements I38 and I48 connected in series, thus providing, for example, with a resistance of approximately 62.5 ohms, and assuming unity power factor, substantially 125 watts of heating eflort.

The other four heating positions of my switch are illustrated to the left of the simmer" position with progressively higher heating eflects provided by successive positions of the switch. Thus, in the position marked low, the heating element I38 alone is subjected to 125 volts, and at the low medium position the heating elements in series are connected across 250 volts. In the medium position, the heating element I38 alone is connected across 250 volts, and in high' position, each of the heating elements I88 and I48 i individually connected, or connected in parallel across 250 volts. The voltage and wattage are marked for each of the positions shown in Fig. 6.

The sequence of operation of the contacts of the switch is as follows. The switch, as shown in Figs. 1 to 5, is in the off position, correassure:

sponding to the off position shown in Fig. 6. It

will be noted that in this position, referring particularly to Figs. 2, 4 and 6, the resilient contact arms 64 and I8 are maintained by the contact operating member 44 out of engagement with their cooperating fixed contacts 62 and I6, respectively. Also, the switch operating member 44 is in a position such that the segment bridging member 54 engages only the segment 24. Also, the projection I88 on the contact operating member is in engagement with the struck-out portion 88 on the leg 98 of the U-shaped resilient contact controlling the pilot lamp I38, to maintain the resilient contact out of engagement with its cooperating fixed contact 88.

Upon movement of theswitching handle fromthe "off position in a counter-clockwise direction, as viewed in Figs. 1, 2 and 4, to the next or simmer position, it is obvious that the resilient contact bearing arms 64 and I8 will remain open until the bridging contact 54 is in a position to bridge the contacts 24 and 28, after which the struckout portion 86 of the resilient contact carrying arm 18 registers with the indentation I84 provided on the switch operating member 44, to permit the contacts 84 and I6 to close to complete the circuit to the heating element I38. It is thus apparent that the circuit is-first set up by the bridging contact 58 and the contact segments, and then the circuit is closed by the arcing contacts l8 and 84.

In moving the switch operating member from the simmer position to the next or low position, it is obvious that the first thing that takes place is engagement of the struck-out portion 86 of the resilient contact carrying arm I8 with the protuberance I88 on the contact operating member 44 to open the contacts I6 and 84 prior to disengagement of the bridging contact 54 with the contact segments 28 and 24. The bridging contact 54 then moves from engagement with the contact segments 28 and 24 into engagement with the contact segments 28 and 26, and thereafter, the indentation I86 on the contact operating member 44 registers with the struck-out portion 88 on the resilient contact carrying arm 18, to permit the contacts I8 and 84 to close.

This same sequence of operation of the switch contacts takes place upon movement of the switch to all of its six positions. In other words, the arcing contacts I8 and 84, or 82 and 18 are first opened upon movement of the switch from one position to another before the bridging contact I54 leaves one set of contact segments to engage with another set of contact segments. These arcing contacts remain open until the bridging contact 54 has engaged with the next set of contact segments, whereupon one or both of the arcing contacts may be closed depending upon whether the resistance elements are to be connected between one of the live conductors of the supply circuit and the neutral conductor, or whether they are to be connected between the two live conductors of the supply circuit. It is thus obvious that no arcing can occur at the contact segments where the circuits through the switch are selected, and that all arcing is done at one or both of the arcing contacts It, 84 and 82, I8 in specially provided arcing chambers which are substantially insulated from the contact segments and the contact operating member 84.

This type of switching arrangement makes it possible to reduce the number of contacts requiring special arcing metals, and also permits the provision of special arcing chambers to prevent distress due to flash-over from one arcing contact to another. The small space required by the segmental contacts, and sliding bridging contact, lends itself readily to a device of small dimension and permits great flexibility since a variety of arrangements of segmental contacts may be employed for the control of different circuits.

Having described one embodiment of my invention in accordance with the Patent Statutes, I wish it to be understood that my invention is not to be limited to the particular embodiment disclosed herewith since it will be obvious particularly to persons skilled in the art that many changes and modifications may be made in this particular structure without departing from the broad spirit and scope of my invention. Thus, for example, it is believed obvious that my switch is capable of use in circuits or relations other than that for which it has been described herein, and for which it was particularly designed. Also, modifications can be made in the switch structure itself without departing from the broad spirit and scope of my invention. Thus, for example, if it is desired to use only a four position switch to give three degrees of heat corresponding to the simmer, low and low-medium positions shown in Fig. 6, obviously the arcing contacts I8 and 62 may be entirely eliminated since, as shown in Fig. 6, these contacts are maintained open for these three positions. Therefore, I desire that my invention be interpreted as broadly as possible and ,that it be limited only by what is expressly set forth in the following claims. I claim as my invention:

1. In a switch, a base, at least two concentric series of spaced contacts on said base, a contact support of insulating material rotatably mounted on said base, a bridging contact on said support direction, and cooperating means on said base and support for increasing the creepage distance between said series 01 contacts and between said series of contacts and the pivot axis of said rotatable contact support.

2. In a switch, a base of insulating material, an annularly arranged series 01' maced contacts on said base, a contact support of insulating material rotatably mounted on said base, a movable contact carried by said support for successivelyv e ing the contacts on said base upon rotation of said support in one direction, and cooperating means on said support and base for increasing the creepage distance at least between said series of contacts and the pivot axis of said support. 1

3. In a switch, a shallow switch casing of in-' sulating material having an open side, cam means ofinsulating material rotatably mounted in said casing, switch means at one side of said casing having relatively fixed and movable contacts at one end 01 said casing, said movable contact mounted on a resilient supporting membar which extends to and i mounted at the opposite end of said casing, said resilient supporting member having an intermediate portion positioned to be engaged by said cam means so as to be actuated thereby, means integral with said casing forming side wall entirely closely confining said contacts except for a relatively narrow opening to accommodate said resilient supporting member, insulating plate means covering at least the confined space within which said contacts are located to complete the enclosure thereof, and means securing said plate mean in operative position.

4. In a switch, a shallow switch casing of insulating material having an open side, cam means of insulating material rotatably mounted in said casing, switch means at one side of said casing having relatively fixed and movable contacts at one end of said casing, said movable contact mounted on a resilient supporting member which extends to and is mounted at the opposite end of said casing, said resilient supporting member having an intermediate portion positioned to be engaged by said cam means so as to be actuated thereby, means integral with said casing forming side walls entirely closely confining said contacts except for a relatively narrow opening to accommodate said resilient supporting member, insulating plate means covering at least the confined space within which said contacts are located to complete the enclosure thereof, and means securing said plate means in operative position, including a cover for the entire casing.

5. In a switch, a, shallow switch casing of insulating material, cam means of insulating material rotatably mounted in said casing, and spaced from opposite side walls of said casing, substantially parallel, resiliently biased contact supporting arms at said opposite sides of said cam mean and extending substantially the entire length of said casing, each of said contact supporting arms being supported at one end of said casing and carrying a movable contact at the other end of said casing, another resilient contact arm mounted at one end in said casing and extending across said casing at said one end thereof and intermediate said first-mentioned arms, another contact cooperable with the other end of said last-mentioned arm, and an intermediate portion of each arm positioned to engage a peripheral portion of said cam means so as to be actuated thereby.

6. In a switch construction, a shallow switch casing of insulating material, at least one annular series of spaced contacts on the bottom wall of said casing, a generally cylindrical block of insulating material rotatably mounted in said casing on an axis substantially at right angles to said bottom wall, a movable contact carried by the lower end wall of said block to successively engage the contacts of said series of contacts upon rotation of said block in one direction, switch means at one side of said casing having relatively fixed and movable contacts at one end of said casing, said movable contact mounted on a resilient supporting member which extends to and is mounted at the opposite end of said casing, and said resilient supporting member having an intermediate portion positioned to be en gaged by a peripheral cam portion on said block so as to be actuated thereby.

7. In a switch construction, a shallow switch casing of insulating materiahat least one annular series of spaced contacts on the bottom wall of said casing, a generally cylindrical block of insulating material rotatably mounted in said casing on an axis susbtantially at right angles to said bottom wall, a movable contact carried by the lower end wall of said block to successively engage the contacts oi said series of contact upon rotation of said block in one direction, said block spaced from opposite side walls of said casing, substantially parallel, resiliently biased contact supporting arms at opposite sides of said block and extending substantially the entire length of said casing, each of said contact supporting arms being supported from said casing at one end thereof, and carrying a movable contact at the other end thereof, cooperating contacts in said.- casing for each of said movable contacts, and an intermediate portion of each arm positioned to engage a. peripheral portion of said block so as to be actuated thereby.

8. In a switch construction, a shallow switch casing of insulating material, at least one annular series of spaced contacts on the bottom wall of said casing, a generally cylindrical block of insulating material rotatably mounted in said casing on an axis substantially at right angles to said bottom wall, a movable contact carried by the lower end wall of said block to successively engage the contacts of said series of contacts upon rotation 01' said block in one direction, said block spaced from opposite side walls of said casing, substantially parallel, resiliently biased contact supporting arms at opposite sides of said block and extending substantially the entire length of said casing, each of said contact sup-- porting aim being supported at one end of said casing and carrying a movable contact at the other end of said casing, another resilient contact arm mounted at one end in said casing and extending across said casing at said one end thereof and intermediate said first-mentioned arms, anothercontact cooperable with the other end of said last-mentioned arm, and an intermediate portion of each arm positioned to engage a peripheral portion of'said cam means so as to be actuated thereby.

9. In a switch, a shallow casing of insulating material including bottom and side walls and an open top, a cover adapted to be removably secured across said open top, switching means in said casing including separable contacts, operating means for said switching means including an operating shaft rotatably mounted in bearing apertures provided in said bottom wall and cover,

contact operating means of insulating material slidably but non-rotatably mounted on said shaft, said shaft having intermediate enlarged portions forming a plurality of shoulders spaced along said shaft, one of said shoulders positioned to cooperate with the inner side of said cover to prevent movement of said shaft out through said cover aperture, and another of said shoulders cooperating with a complementary shoulder formed on said contact operating means and with said bottom wall to maintain said contact operating means in operative position in said casing.

10. In a' switch, a shallow casing of insulating material including bottom andside walls and an open top, a cover adapted to be removably secured across said open top, switching means in said casing including separable contacts, operating means for said switching means including an operating shaft rotatably mounted in bearing apertures provided in said bottom wall and cover, contact operating means of insulating material slidably but nonrotatably mounted on said shaft, said shaft having intermediate enlarged portions forming a plurality of shoulders spaced along said shaft, one of said shoulders positioned to cooperate with the inner side of said cover to prevent movement of said shaft out through said cover aperture, another of said shoulders cooperating with a complementary shoulder formed on said contact operating means and with said bottom wall to maintain said contact operating means adjacent said bottom wall and spaced from said cover, the portion of said shaft in said space being non-circular in form, and indexing means mounted in said space and cooperating with said non-circular portion of said shaft.

11. In a switch, a shallow casing of insulating material including bottom and side walls and an open top, a cover adapted to be removably secured across said open top, switching mean in said casing including separable contacts, operating means for said switching means including an operating shaft rotatably mounted in bearing apertures provided in said bottom wall and cover, contact operating means of insulating material mounted on said haft so as to be located adjacent said bottom wall and spaced from said cover, the portion of said shaft in said space being non-circular in form, and indexing mean mounted in said space and cooperating with said non-circular portion of said shaft.

12. In a switch, a shallow casing of insulatin material including bottom and side walls and an open top, a cover adapted to be removably secured across said open top, switching means in said casing including separable contacts, operating means for said switching means including an operating shaft rotatably mounted in bearing apertures provided in said bottom wall and cover, contact operating means of insulating material mounted on said shaft so as to be located adjacent said bottom wall and spaced from said cover, the portion of said shaft in said space being non-circular in form, and indexing means mounted in said space and cooperating with said non-circular portion of said shaft, said indexing means including means extending across said casing in said space with an intermediate portion resiliently engaging the non-circular portion of said shaft, and opposite ends thereof seated in notches formed in the top edges of opposite walls of said casing.

13. In-a switch construction, a shallow switch casing of insulating material, at least one annular series of spaced contacts on the bottom wal. of said casing. a generally cylindrical block of insulating material rotatably mounted in said casing on an axis substantially at right angles to said bottom wall, a movable contact carried by the lower end wall of said block to successively engage the contacts of said series of contacts upon rotation of said block in one direction, switch means at one side of said casing havin relatively fixed and movable contacts at one end of said casing, said movable contacts mounted on a resilient supporting member which extends to and is mounted at the opposite end of said casin said resilient supporting member having an intermediate portion positioned to be engaged by a peripheral cam portion on said block so as to be actuated thereby, said cam portion arranged relative to the movable contact on said block so as to actuate the contacts of said switch means only when said movable contact on said block is in engagement with one of' said series of contacts.

14. In a switch, a base, at least two concentric series of spaced contacts on said base, a contact support of insulating material rotatably mounted on said base, a bridging contact on said support for successively bridging adjacent contacts of each series upon rotation of said support in one direction, and interfitting projection and recess means on said base and support for increasing the creepage distance between said series of contacts.

15. In a switch, spaced opposed switch means each including a contact which is movable into and out of engagement with a cooperating contact, operating means rotatably mounted between said movable contacts including a unitary insulating block having integral separate cam surfaces for moving said contacts, respectively, in a, predetermined sequence, and at least another integral angularly related contact supporting surface on said block having a selector switch contact definitely positioned thereon so that said switch means are also actuated relative to said contact in a predetermined sequence.

16. In a switch, spaced opposed arcing switch means each including a contact which is movable into and out of engagement with a cooperating contact, operatingmeans movably mounted between said movable contacts for moving the same in a predetermined sequence, selector switch means mounted between said arcing switch means, and insulating barrier means closely confinin the contacts of each arcing switch means to conflne arcs drawn by either of said arcing switch means to prevent arcing to the other arcin switch means, or to said selector switch means or to ground, and a limited opening in each of said insulating means for movably receiving operating means for said movable contacts.

1'7. A multi-position multi-pole switch comprising an insulating supporting panel, a plurality of pairs of relatively movable contacts mounted on said panel, said pairs of contacts including at least one pair of non-arcing contacts and at least two pairs of arcing contacts, a single movable mounted member for actuating all of said contacts, said member being movable to a switch opening position in which said pairs of contacts are open and to at least one switch closing position in which a pair of non-arcing and a pair of arcing contacts are closed to effect a multipole switching function, said member being constructed so that upon a movement of said member to said switch closing position the arcing contacts are closed subsequent to the non-arcing contacts whereby arcs formed upon the closing of said contacts are dissipated at said arcing contacts.

18. A multi-position multi-pole switch comprising an insulating supporting panel, a plurality of pairs of relatively movable contacts mounted on said panel, said pairs of contacts including at least one pair of non-arcing contacts and at least two pairs of arcing contacts, a single movably mounted member for actuating all of said pairs of contacts, said member being movable to a switch opening position in which said pairs of contacts are open and to at least one switch closing position in which a pair of non-arcing and both pairs of arcing contacts are closed to effect a multi-pole switching function, and said member being constructed so that upon a movement of said member from said switch closing position said arcing contacts are opened prior to said nonarcing contacts whereby arcs formed upon the opening of said contacts are dissipated at said arcing contacts.

19. A multi-position multi-pole switch comprising an insulating supporting panel, a plurality of pairs of relatively movable contacts mounted on said panel, said pairs of contacts including at least one pair of non-arcing contacts and at least one pair of arcing contacts, a single movably mounted member for actuating all of said contacts, said member having cam surfaces for actuating at least said arcing contacts and being movable to a switch opening position in which said pairs of contacts are open and to at least one switch closing position in which a pair of non-arcing and a pair of arcing contacts are closed to effect a multi-pole switching function, said cam surfaces being shaped so that upon a movement of said member to said switch closing position the arcing contacts are closed subsequent to the non-arcing contacts whereby arc formed upon the closing of said contacts are dissipated at said arcin contacts.

20. A multi-position multi-pole switch comprising an insulating supporting panel, a plurality of pairs of relatively movable contacts mounted on said panel, said pairs of contacts including at least one pair of non-arcing contacts and at least one pair of arcing contacts, a single movably mounted member for actuating all of said contacts, said member having cam surfaces for actuating said arcing contacts and carrying at least one non-arcing contact, said member being movable to a switch opening position in which said pairs of contact are open and to at least one switch closing position in which a pair of non-arcing and a pair of arcing contacts are closed to effect a multi-pole switching function, said cam surfaces being shaped so that upon a movement of said member to said switch closing position the arcing contacts are closed subsequent to the non-arcing contacts whereby arcs formed upon the closing of said contacts are dissipated at said arcing contacts.

21. A multi-position multi-pole switch comprising an insulating supporting panel, a plurality of pairs of contacts mounted on said panel, said pairs of contacts comprising pairs of nonarcing contacts and a pair of arcing contacts, and means comprising a single movably mounted member for effecting a closure of said pair of arcing contacts and different pairs of said nonarcing contacts when said member is rotated to a plurality of switch closing positions to effect a different multi-pole switching function in each switch closing position, said member being arranged so that when said member is rotated away from any one of said switch closing positions said arcing contacts are opened prior to said non-arcing contacts whereby arcing occurs only at said arcing contacts.

22. A multi-position multi-pole switch comprising an insulating supporting panel, a plurality of pairs of contacts mounted on said panel, said pairs of contacts comprising pair of nonarcing contacts and a pairof arcin contacts, and means comprising a single movably mounted member for actuating all of said contacts, said member having cam surfaces for actuating at least said arcing contacts for effecting a closure of said pair of arcing contacts and different pairs of said non-arcing contacts when said member is rotated to a plurality of switch closing positions to effect a different multi-pole switching function in each switch closing position, said member being arranged so that when said cam is rotated away from any one of said switch closing positions said arcin contacts are opened prior to said non-arcing contacts whereby arcing occurs only at said arcing ntacta 23. A multi-position multi-pole switch comprising an insulating supporting panel, a, plurality of pairs of contacts mounted on said panel,

said pairs of contacts comprising pairs of nonarcing contacts and a pair of arcing contacts, and means comprising a single movably mounted member for actuating all of said contacts, said member having cam surfaces for actuating at least said arcing contacts and carrying a bridging contact for said pairs of non-arcing contacts for effecting a closure of said pair of arcing contacts and diiferent pairs of said non-arcing contacts when said member is rotated to a p1urality of switch closing positions to effect a different multi-pole switching function in each switch closing position, said member being arranged so that when said member is rotated away from any one of said switch closing positions said arcing contacts are opened prior to said nonarcing contacts whereby arcing occurs only at said arcing contacts.

CHARLES H. HODGKINS.

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