US2594181A - Selector switch - Google Patents

Description

April 22, 1952 H. A. KLIEGL ETAL 2,594,181

SELECTOR SWITCH Filed July 29) 1950 2 SHEETS-SHEET 1 FIG. I I, W" 48 FIG. 2

FIG. 3

A; M M M W ATTORNEYS April 22, H A ETAL SELECTOR SWITCH Filed July 29, 1950 2 SHEETS-SHEET 2 FIG. 4

FIG. 5

@ 6) ca 9 9 31 (3 (1D 63 G9 Q) (9 QL nuuuunnnnu UMP-i 14/- 2 8 41 I vl 43 (s: H i? 5 2 6 I 1 In or\,o W W 2W 44 41 1\ x PflWf/Y 42 LINE ATTORNEYS Patented Apr. 22, 1952 Forest Hills, and. JoseplLKliegl,

Queens. Villagc, N; Y., assignors to; Kliegl': Bros. Universal Electric Stage Lighting Co.,,Inc.,.NeW York, N. Y.,. a. corporationof." New York.

Application July 29, 1950, ScrialN'o. 1763.652

11$: Claims.

1 Thisinvention relates. to: electric control. systems and: more, particularly to selector switches for: controlling. multiple electric circuits in: such systems. Theinventionrisadvantageouslyadapted to the. control of. lighting. circuits.- in. theatres, television studios, au'ditoriums, and other. places where-complex lighting or comparable circuits arcremployedl Especially in lighting systems it isof ten d'esired' to provide. several lighti circuits grouped through theasameieeder sourcewandlcontrolmeans soxthat they. maybe: controlled as a: unit.- It is' 3180.116- sirableto: be able to. select any one of; a: number of control means and connecta particular light circuittoeiti.

The application.- of ordinary multi-contact switches: in this: specialized fieldlhas evidenced numerous. disadvantages; vantages are: the arcingrwhenetheswitch is opened or moved from one contactto another; resulting inpoor connections and short life from-burning, disturbance of intermediate circuits: while moving the switch through intermediate contact points, overloading af'eeder circuittemporarily and;blowing its fuse or: circuit breaker when additional. load. is connected to the corresponding contact: point. momentarily in selecting a new switch position, inability. topreset light circuits without an identical duplicate set of' switches, and the vast multiplicity of switches of ordinary type required. toyield the desired flexibility of control:

The present invention. overcomesthese disad'vantagesbya novel selective switching device and control system: which eliminates arcing and curning of the contacts, permits light or other load circuit-std be preset while the switch contacts are automatically de-energized, and afiords superior flexibility, speed and facility of control. For example, the invention permits-any selection of light circuit'stoform'a-group comprising a-load suitable-fol! a f'eedercircuit which includes a dimmer of" certain wattage; Thus, the number of feeder. circuitsxrequired to operate a given number. of' light circuits properly may-be considerably reduced. with: resultant: economy and simplicity in installation. and operation. These, as well as other advantageawillbe evident from the follow'- ing description-of a preferred. embodiment of. the invention, as illustrated: by the accompanying drawings; inwhich:

Eigarisa front orelevational view of. a; selector switch. inpaccordanceawitlr the invention;

Fig'LZ is a cross-sectional'view takenalong the line: Z -ZrOf Fig; 1;

Among: thesedisad- 2 Fig. 3: is atopor plan view of the switch of Fig; 1;. v

Fig; 4. illustratesa control board of a type use.- ful in theatres, and the like, whichincludes severalselector switches and other controls in accordance withthe'invention;

Fig. 5 is awcircuit diagram illustratin the electrical. connection:of.- a. single; selector: switch in a lighting circuit controlsystem such aswould includes; control board asshown in Fig. 4.

Briefly, the: switching, :deviceof the invention includes twoswitches connected in series, the firstof. these being of the selective type and the second" being: of. the circuit breaker type, the first being soconstructed that it can be closed only zit-contact positions, and. .When it is closed ata given position its contacts are positively locked in: contact at -that position, both switches being so constructed and interrelated that the first cannot move from one contactpositionto another without first. automatically opening the second switch The. selector switchisadapted to connect to: a; load circuit: such: asa. light circuit, for example, any. one, of. a number of, feeder circuits which may in: themselves include any desired equipment such as dimmers, or other circuitn'lodifyingl apparatus. For this-- purpose the. sclector switch is arranged to make contact selectivelywith; any one ofa plurality of contacts, each connected to a. feeder circuit. The second switch .may\ be. manuallyv opened and closed, but only,- when thecontacts of. the. first are positively locked ztogether; The-invention wilhbebetter undcrstoo'd from the, following, detailed descrip- U011.

Referring toFigssL, 2-.and' 3, the selector switch in accordance with theinventioncomprises aiface plateor'front-panel. I4; preferably of metal, and a rear panel l Dreferably of'insulating material. Through these panels. which: are rigidly secured togetheri and. spaced:- apart, passes. a metal shaft preferably-of? two sections;- l,6, [51,, separated by an insulatingportion. This separation. is efifected by;drilling;two holes on the sameaxis from opposite? sides of: a; block: l8. of: insulating material, leaving. an: insulating. portion. I 9'; to: separate the shaft" sections,- thus making; the: front;- section of the: shaft; electrically: "dead;"; shaft: secdons; in; efiectiiorming; asingleshaft, are. journall'edi in... the: panels; so: as fltojbe rotatable, and movable; axially therein: at all? position of rotation;

Secured to the insulating.- rear panei [5 are a pluralityofifixedi contacts .23. arranged in a circle.

These are: connectibleto; thexvarious. branch or another screw 23.

feeder circuits through suitable terminal studs 36 on the rear face of panel iii. If adjacent contacts are spaced from each other by a distance less than the width of block it, the movable contact element which cooperates with the contacts can be turned from any one to another in either direction, no stop beingrequired. The contacts, are, as illustrated, formed as expansible collars into which a cylindrical contact pin 2i frictionally engages by axial movement.

Contact pin 2! is secured in insulating block l8, as illustrated, a portion of the block being drilled to form a recess 22 around the periphery of the pin to accommodate fixed contact 23 when block i8 is moved toward rear panel 15. The tip of the pin is positioned below the surface of the insulating block. Pin 24 is secured in block l8 and in turn is connected to the rear section ll of the shaft by screw ll. The block, in turn, is secured to the front section iii of the shaft by Both screws are threaded into the shaft. On the extended end of shaft section It a suitable manipulating knob 24 is secured in front of panel I43.

By means of knob 24 the shaft may be rotated or moved axially, as desired. To rotate the shaft for purposes of selecting a desired fixed contact and its feeder circuit, knob "2 3 is pulled out-from panel i l to disengage pin 21 from the fixed contact. It may then be rotated until index 32 (Fig.

"-1) is adjacent a-desired oneof the indicia 33 indicating that the indicated "contacts are in alignment; Those contacts are-thenengaged by pushing knob 25 inwardly toward panel l4, moving the shaft axially and similarly "moving contact pint i into engagement with the newly selected contact to which the desired feeder circuit is connected. This operation is interlinked with the operation of the second switching means in a manner later to be described.

Forms of locking means other than that illustrated may be employed. For example, a posiwould also serve the purpose of preventing wiping connection between contact pin 2| and'any of the fixed contacts while the switch is being rotated for selected alignment. When this type of positioning pin isemployed, the contacts need not be of the type shown, but may be of any acceptable design, preferably spring'pressed, to

secure positive electrical contact.

In order to assure adequate electrical contact at all angular and axial positions of shaft [1, two connection means to the shaft are provided. First, shaft IT is journalled in insulating panel l5 by means of a metallic bearing 34. Secondly, a metallic spring wiper contact 35 wipes at all times against shaft 1? assuring a clean contact. against shaft l'i urges shaft H against one side of bearing 34 tending to maintain 'better'electrical contact between bearing 34 and shaft 11. The combined current-carrying. capacity of the shaft I! with wiper contact. 35 and with bearing 34 is ample to assure reliable and cool operation. Terminal so is electrically connected to both wiper contact 35 and bearing 34.

The second switching The resulting pressure of spring 35 means. above mentioned may here be assumedto comprise a switch 4 26 of the circuit breaker type which is manually operable from the front of the panel, as by knob 25, to open and close the circuit in which it is connected. The particular type of switch here termed circuit breaker is immaterial provided it be of sufficient current-carrying capacity. The circuit breaker as illustrated is of the springbiased toggle type, being closed or on in the upper position of the knob 25 (Figs. 1 and 2), and open or off in the lower position (Fig. 3). This circuit breaker preferably includes the usual overload release device which will automatically open the breaker when the load current exceeds a predetermined value. Two terminals 21, 28 of circuit breaker 26 permit its external connection. Terminal 2! is connected through jumper 29 to wiper terminal 39, and terminal 228 permits connection to a load circuit such as light circuit 3| (Fig. 5).

So called toggle switches, mercury pool switches, or other suitable switches may be substituted for. circuit breaker 2t. If a mercury switch of .the toggle type be substituted, substantially no other modification would be required. Other types of mercury switches could also be employed by obvious modification of the linkage mechanism by which axial movement of the shaft [6-1 1 tends to rock the'mercury pool of the switch.

A pilot light 48, shown in Fig. 1, may be connected from the power line to output terminal 28 of the circuit breaker so that the pilot is illuminated only when the circuit is completely closed and current is flowing to the bank of lights or other load to be controlled. This pilot thus not only indicates whether that particular circuit is on or ofi, but it also indicates to some extent the adjusted condition of the circuit, viz., the change of adjustment of a dimmer will affect the brilliancy of the pilot light.

An important feature of the invention resides in the yinterlocking action between the two switching devices. As previously mentioned, the invention includes means automatically act ated by movement of the selector switch to main.-

tain the circuit through that switch open while the movable contact is not in complete engage ment with a fixed contact. To this end a stop 31 is provided on the front of panel it to prevent the closing of the circuit breaker, if it is initially in the "open position, or to release or trip the circuit breaker, if it is initially'in the closed position. To move stop 3?, a link arm 38 having a follower piece 39 is provided. As can be'seen from Figs. 2 and 3, a straight portion of link arm (is-passes through a hole in panel it permitting stop 3'! to be either in the position illustrated in Fig. 2 where it is in contact with the face of panel 14, or to be extended therefrom, as illustrated in Fig. 3. When stop 3? is in the extended position of Fig. 3, the circuit breaker cannot be closed. If stop 31 is in the position of Fig. 2 and the circuit breaker is closed, the circuit breaker will be tripped and opened if link arm 38 is moved so that the stop 31 assumes the position of Fig. 3.

To control the movement of link arm 38, and hence the position of stop 37, a link disc to is secured to the front surface of insulating plate is so as to move with it. Since disc til is flat and normal to the axis of shaft it, its position with respect to follower 39 is unchanged by rrotation of shaft 16.. Howevenlthe relative positions of disc 50 and follower 39 do change in accordance with axial .movement of shaft is. The relative positioning and dimensions of these components aresuchithat when .knob. 24. assumes the: i'nposition;.. at which time. the movable con-tact.anda-fixedcontact are completely engaged, stop"31 will assume the position shownln Fig. 2,,permitting closure of the circuit breaker. When knob 24 is pulled out, withdrawing the movable contact from a stationary contact, as shown in Fig. 3, disc 40 contacts follower 39, urging. stop 31 outwardly and tripping the circuit breaker; as illustrated. Thus it is impossible to. rotate'shaft l6'unless the circuit breaker 2B is open, and'conversely it is impossible to close the circuit. breaker unless knob 24 is in, at which position the movable contact pin is engage'd with a fixed contact. Because of the'fact that insulating block I8 is wider than the'space between any two adjacent contacts it is imposslbleto push knob 24 inwardly unless the movable contact pin .is' in. alignment with one of the fixed contacts. When this alignment occurs, index 32 (Fig. 1 willcoincide with a corresponding one ofithe. indicia' 3 3.

Erom. the-foregoing it. will be understood that knobi24 not rotatable except when pulled out. asshownini Fig. 3. When it is in this position theselector switch is not energizecLso that while selection? of. the desired feeder circuit is being made by rotating the movable switch arm, no other'circuit or feederis contacted crsaifected in any. way. When the knob has. been rotated to the'desired position it is pushed in to complete the connection between contact pin 2i and a fixed contact beneath it. However, the circuit is not then energized because the circuit breaker is still open, being manually closable only. The circuit breaker may'then be closed to complete. the circult, providing contact pin 2| has been fully ins'erte'd in the fixed contact collar. In this manner the desiredfeeder. can be'selected and the switch preset, tube-later energized byclcsing the circuit breaker. If one'or more positionsofithe selector switch are not to be used, the'hole within the collar' may be temporarily filled with a plug so that the switching knob 24 cannot be pushed in at that position, or suitable. stops maybe. employed to prevent the switch from being rotated into such unused positions. It is preferable,v however,. to have the-selector switch arranged so. that it may be turned continuously clockwise.. or counterclockwise to facilitate rapid selection of the desired" positions.

A typicalswitchboard. or control panel which incorporates 28 selector switches in accordance with the invention, is illustrated in Fig. i, showin'g' the manner in which these switching devices maybe-employed in theatres, for example. This panel in'cludesla main switch 4!, a row oi feeder line switches 42- and a number of dimmers or other circuit-modifying devices 231 Each of the selector switches would be connected to a group or bank of lights; and as below explained, current must pass from thepower line through. the feeder circuit which is selected by a selector switch in order to pass. through the appropriate bank of lights.

The schematic diagram of Fig; 5v illustrates the control system in accordance with the invention and shows one manner in which the selector switch may be connected'in such a system. For example, in a control panel such shown in Fig. 4', each selector switch mounted on panel I may be connected as shown in Fig. 5. in such panel there would actually be 28 connections fromeachfeederline, one from eachfeeder to its respectively numbered contact on each of the other selector switches; Figs. 1, 2 and 3, there'would be 12 feeder lines (in:- stead of 8 as shown in Fig. 5) connected'toeach selector switch. The omissions in the drawing are for thepurposeof clarifying it. The actual number offee'der circuits and selector switches will, of course; vary. withthe relative complexity of the lighting system, as wellias in accordance with the nature of the different lighting effects desired.

In 5 one side of a. single-phase power system is shown, the: other side being grounded. With a three-phase source of supply the system can be wired in difierent ways depending upon whether the lightingsystem operates at220tvolts orrat 115 volts. For. example, in a 220-volt system two of the three-phases would supply the feeders by each of the. two being connected to alternate feeders with the third of. the three phases connected.as'groundtoall of the feeders, thus imposing a 220'-volt potential across each of. the feeders (line-to-line). In a 1l5'-volt'system each of the three-phase lines. would beconnected to every thirdfeeder, consecutively, and the other. side" of the feeder would be connected to ground (line-to-ground).

Power line 44 is connected: through main switch 4! to a bus feeding the feeder line switches 42. In feeder lines [-5, dimmers 43 are shown to be connected for controlling. the degree of illuminationtof:thelights; These dimmers are representedas comprising rheostats or potentiometers, but in accordance with modern practice they would usually be of the autotransformer type or of the reactor type. In an actual installation, some feeders would include noncurrent-modifying equipment asshown in. feed.- ers 6 and 1 of Fig. 5. However, any desired circuitor current modifying apparatus may, of

- c'ourse,.be' connected in any desired feeder; and

such apparatus is'generally' represented by box 45 in' feeder line 8. Each of' the feeder lines is connected to its terminal, respectively numbered, on' all of the selector switches mounted on the control panel, and in' turn, the movable switch member of each selector switch: is connected (through its circuit breaker) to its par.- ticular branch of the system. As is customary in theart, thevarious circuits are fused'with fuses of appropriate capacity.

, controlled throughthemain switch 45. With the main switch and selector." switches closed, each feeder. and its connected selector switches can be controlled. as a group,.viz., either"on and off control through the feederv witch or variable 1 control through the dimmer, or other apparatus connected in. the feeder. When the feeder switch and the main switch are closed the selector' switch can be preset at any desired position and. will draw current from the selected feederby closure of the circuit breaker of that selector switch to complete the circuit.

Itis to be understood that theembodiment of the invention herein described and illustrated comprisesbut one example of the many applications of the present invention and that the To be consistent with.

scope of the invention is to be limited only as defined in the appended claims.

We claim:

1. A selector switch including a face plate, selective switching means supported on said face plate and being movable in two directions in each of two degrees of freedom with respect to said face plate, a plurality of current-carrying contacts supported in fixed relation to said face plate, said switching means being movable in either direction of the first degree of freedom for selective alignment with any one of said contacts, and being movable in one direction of the second degree of freedom to effect mechanical engagement with a selected contact thereby preventing further movement in the first degree of freedom, and to eifect electrical engagement with said selected contact thereby completing electrical continuity from the selected contact through said switching means, said switching means being also movable in the opposite direction of said second degree of freedom to effect mechanical and electrical disengagement thereof from said selected contact, a terminal, a circuit breaker of the spring-actuated snap-opening type adapted to break heavy current, and being connected in series between said selective switching meansand said terminal, said circuit breaker being operable independently of said switching means to assume a fixed open circuit position, and means actuated in response to initial movement of said switching means in said opposite direction of said second degree of freedom to free said spring to open said circuit breaker so as to disconnect said switching means from said terminal.

2. A selector switch in accordance with claim 1, which includes a movable element on said circuit breaker, and linkage means linking said switching means to said movable element and disposed so as to release said spring and open said circuit breaker to disconnect said switching means from said terminal prior to the disengagement of the switching means from said selected contact.

3. A selector switch in accordance with claim 1, which includes stop means associated with said circuit breaker, said stop means being mechanically linked to said selective switching means and being actuated by movement of said selective switching means in said second direction of said second degree of freedom, said circuit breaker having a movable element, and said stop means coacting with said movable element to prevent closure of the circuit breaker when the selective switching means are disengaged.

4. A selector switch including a face plate, selective switching means supported on said'face plate and being movable in two directions in each of two degrees of freedom with respect to said face plate, manual means for moving said switching means, a plurality of contacts supported in fixed relation to said face plate, said switching means being movable by said manual means in either direction of the first degree of freedom for selective alignment with any one of said contacts, and being movable in one direction; of the second degree of freedom to effect electrical connection with the selected contact thereby completing electrical contact through said switching means, locking means so disposed as to coact with said switching means in said movement of second degree of freedom to lock said switching means and prevent movement in said first degree of freedom, said switching means being also movable in the opposite direction of said second degree of freedom to ef- 8. feet electrical disconnection thereof from said selected contact and to unlock said locking means and thereby allow selective alignment by movement in the first degree of freedom, a terminal, a circuit breaker connected in series between said selective switching means and said terminal, means foroperating said circuit breaker independently of said manual means, means independent of said manual means automati cally actuated in response to movement of said switching means in said opposite direction of said second degree of freedom to open said circuit breaker so as to disconnect said switching means from said terminal, and means actuating said locking means when said circuit breaker is closed.

5. In a selector switch, a movable switching member, a plurality of spaced electrical contacts cooperating therewith a terminal for external connection to said switching member, a circuit breaker connected in series between said switching member and said terminal, said circuit breaker having a movable member adapted to assume open and closed positions, locking means for locking said movable member against moving to closed position, and linkage means connecting said switching member to said locking means, said locking means being operable in response to operation of said linkage means,.said linkage means and said locking means? being disposed and arranged to lock said circuit breaker against closure except when said switching means is electrically connected to one of said contacts.

6. In a selector switch, a movable switching member, a plurality of fixed spaced electrical contacts cooperating therewith, a terminal for external connection to said switching member, a circuit breaker connected in series between said switching member and said terminal, said circuit breaker including a movable element operable to open and close said circuit breaker, said element being operable to open said circuit breaker independently of the switching member, and linkage means interconnecting said switching member and said circuit breaker, said linkage means being operable in response to movement of said switching member in a direction to eifect disconnection of said switching member from a contact and being disposed so as to actuate said movable element and open said circuit breaker coincident with said movement of said switching -member prior to disconnection thereof from a contact.

7. In a selector switch, a movable switching member; a plurality of fixed spaced electrical contacts cooperating therewith; a terminal for external connection to said switching means; a circuit breaker connected in series between said switching member and said terminal; said circuit breaker including a movable element .operable to open and close said circuit breaker; first locking means for locking said switching member in contact position; second locking means for looking said movable element in open circuit position; and linkage means coacting with both said locking means; said element, said member, said locking means and said linkage means being operatively associated to comprise interlocking means operative to lock said switching member in contact position except when said element is in open circuit position and to lock said element in open circuit position except when said switching member is in contact position,

8. In a selector switch, a movable switching member andashait for moving the-same, a-plu: rality of fixed spaced electrical contacts velec-v trically cooperating therewith, said member be.- ing adapted to assume contact and out-ofecon-r tact positions, a terminal for external connec tion to said switching member, acircuit breaker electrically connected in series between said switching member and said terminal, said circuit breaker including a movable element operable to open and closesaid circuit breaker, means independent of said circuit breaker for moving said shaft, linkage means actuated by movement of said switching member, and stop means actuated by said linkage means, saidstop means being disposed so as to coact with said movable element to lock said circuit breaker open when said switching member assumes an out-of-contact position.

9. In a selector switch, a movable switchingimemher, a plurality of spaced fixed'electrical-contacts cooperating therewith, each said contact comprising an area permitting limited movement of said member while maintaining connection therewith, a terminal for external connection to said switch, a circuit breaker connected in series between said switching member and said terminal and having a movable element, linkage means connecting said switching member to said movable element and disposed so that the movement of said switching member which disconc nects said switching member from one of said contacts actuates the movable element of the circuit breaker, disconnecting said terminal from said switching member during said limited movement and prior to disconnection of said switching member from said contact.

10. A selector switch including, two switching means, the first of said switching means having selective contacting means and a plurality of fixed contacts cooperating therewith, said contacts being spaced apart in the same plane, said contacting means being movable parallel to said plane for selective electrical connection with said contacts, said contacting means being also movable toward and away from said plane, a

terminal for external connection to said contacting means, second switching means connected in series between said selective contacting means and said terminal such that the opening of said second switching means disconnects said contacting means from said terminal, a movable element on said second switching means operable to open the same, mechanical linkage means connecting said selective contacting means to said movable element and operable in response to movement of said selective contacting means away from said plane to move said movable element of said second switching means and thereby open said second switching means.

11. A selector switch including, a shaft, selective switching means mounted thereon, a support in which said shaft is journalled for axial and rotary movement with respect thereto, a plurality of contacts supported in fixed relation to said switching means for electrical cooperation therewith, said switching means being rotatable for selective alignment with any one of said contacts only when disconnected therefrom, and being movable axially to sheet electrical connection of the switching means to a selected contact, a terminal, a circuit breaker connected in series between said terminal and said switching means, said circuit breaker having a movable element by which said circuit breaker is opened and closed and which is movable independently of said shaft, linkage means me chanically linking said switching means to said movable element and disposed so as to actuate said movable element and open the circuit breaker in response to and coincident with axial movement of said shaft and said switching means in a direction to effect disconnection from said contact, and stop means on said circuit breaker actuated by said linkage means, said stop means coacting with said movable element to prevent closure of said circuit breaker while said selective switching means is disconnected from said' contact.

12. A selector switch including a shaft, selective switching means movable therewith, a support in which said shaft is journalled for axial and rotary movement with respect thereto, said shaft comprising two sections, an insulating block interposed between said two sections so as to mechanically link and electrically insulate said sections, means connecting said switching means to one of said sections, a plurality of fixed contacts arranged in a closed circle on a single plane to provide uninterrupted rotation of said switching means in both clockwise and counterclockwise directions for selective alignment thereof with any one of said contacts, said shaft being movable axially in said support to effect electrical connection of said switching means to a selected contact, a spring contact in connection with said section of said shaft disposed so as to wipe said section of the shaft in both its axial and rotary movement, a terminal, a circuit breaker having a movable member and being connected through said spring contact in series between said terminal and said switching means, linkage means mechanically linking said switching means to said circuit breaker and disposed so as to actuate said movable member and open said circuit breaker in response to and coincident with axial movement of said switching means in a direction away from said plane to effect disconnection from said contact, and stop means on said circuit breaker actuated by said linkage means, said stop means coacting with said movable member to prevent closure of said circuit breaker while said selective switching means is disconnected from said contact.

13. An electrical control system including a load to be controlled, a source of electric power, a plurality of feeder circuits having various electrical characteristics, means connected in said feeder circuits for controlling said characteristics, said feeder circuits being connected in common to said power source, selective switching means for connecting said load to said power source through any one of said feeder circuits, said switching means comprising, a plurality of contacts each of which is con nected to one feeder circuit, selective contacting means disposed for rotary movement to permit selection of any one of a plurality of contacts, and disposed for axial movement in one direction to connect the selected contact with said contacting means, locking means including extensions or said contacting means and said contacts coacting in said axial movement so as to lock said contacting means against rotary movement while said selective contacting means is electrically connected to a selected contact, a terminal connectible to said load, a circuit breaker connected in series between said terminal and said selective contacting means, and linkage means mechanically connecting said selective'contacting means to said circuit breaker positioned and arranged so as to open said circuit breaker and thereby tie-energize said contacting means in response to axial movement of said contacting means in a direction opposite to said first-named direction, whereby said contacting means and contacts are de-energized when said contacting means are axially positioned for rotary selective movement.

14. An electrical control system including an electric power source, control devices of various electrical characteristics connected on one side in common to said source, a plurality of selector switches, a. plurality of fixed contacts on each of said selector switches, the other side of each of said devices being connected to a diiferent one of the contacts on each switch, the corresponding one of said contacts of each switch being connected to and identified with the same one of the said control devices, a movable contac- 12 tor on each switch disposed for selective connec tion to any one of the fixed contacts thereon, a.

' circuit breaker on each switch connected on one REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,563,160 Catlin Nov. 24, 1925 2,426,306 Houck et a1 Aug. 26, 1947

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