US3657496A

US3657496A - Permutation switches

Info

Publication number: US3657496A
Authority: US
Inventors: William J Davidson
Original assignee: ECC Corp (FORMERLY ELECTRONIC CONTROL CORPORATION)
Current assignee: Teccor Electronics Inc
Priority date: 1970-10-09
Filing date: 1970-10-09
Publication date: 1972-04-18
Anticipated expiration: 1989-04-18

Abstract

A plurality of tumblers located behind a wall are rotated by selective movements of a combination dial to place conductive or dielectric peripheral portions of the tumblers in circuit making or breaking contact with spring contact fingers. The combination dial includes a shaft which is insertable through an opening in the wall into a socket formed in a member forming part of means for rotating the tumblers. A plurality of such permutation switches are disclosed coupled together in axial alignment so that a single dial operates the tumblers of all switches. The spring contact fingers are mounted on semi-cylindrical carriers which plug into each switch from the rear of the switch. Each switch unit may include two separate sets of spring contact fingers. All switches of a plural switch circuit are disclosed wired in parallel, with each switch performing the same control function and each also operating its own recorder device, so that a record is made with respect to which combination is used as any given period of time.

Description

nite States Patent [151 3,6 avitlson [45] Apr.18,1972

[541 PERMUTATION SWITCHES Primary Examiner-Robert K. Schaefer [72} Inventor. William J. Davidson, Scio, Oreg. AssistantExaminer wimam Smith [73] Assignee: Electronic Controls Corporation, Scio, yG y e ,C arnard Oreg. 22 Filed: Oct.9, 1970 [57] ABSTRACT [52] 0.8. CI. ..200/43, 70/278, 70/DIG. 71, 200/168 K, 200/172 A [51] Int. Cl ..H01h 27/06,l-I01h 27/10 [58] Field of Search ..200/43,45, 168 K, 172 A, 172, 200/166 CT; 70/320, 329, 445, DIG. 71, 278; 338/115, 132, 184, 199, 201

[56] References Cited UNITED STATES PATENTS 3,192,331 6/1965 Davidson ..200/43 3,267,749 8/1966 Tanner ....338/132 X 2,723,329 11/1955 Baird ..200/172 3,245,022 4/1966 Goerg ..338/132 3,165,614 1/1965 Carissimi.. .....200/166 CT 3,214,531 10/1965 Dux ..200/43 A plurality of tumblers located behind a wall are rotated by selective movements of a combination dial to place conductive or dielectric peripheral portions of the tumblers in circuit making or breaking contact with spring contact fingers. The combination dial includes a shaft which is insertable through an opening in the wall into a socket formed in a member forming part of means for rotating the tumblers.

A plurality of such permutation switches are disclosed coupled together in axial alignment so that a single dial operates the tumblers of all switches. The spring contact fingers are mounted on semi-cylindrical carriers which plug into each switch from the rear of the switch. Each switch unit may include two separate sets of spring contact fingers. All switches of a plural switch circuit are disclosed wired in parallel, with each switch performing the same control function and each also operating its own recorder device, so that a record is made with respect to which combination is used as any given period of time.

13 Claims, 10 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improvements in permutation switches of the general type shown and described in: US. Pat. No. 2,797,271, granted June 25, 1957 to Arthur L. Augustine; US. Pat. No. 2,984,717, granted May 16, 1961 to Raymond W. Davidson; and U.S. Pat. No. 3,192,331, granted June 29, 1965 to Raymond W. Davidson.

2. Description of the Prior Art Each of the aforementioned US. Pat. Nos. 2,797,271; 2,984,717 and 3,192,331 shows a permutation switch of the general type to which the present invention relates. In a switch of such type a plurality of disc-like tumblers are arranged for free selective rotation about a support shaft mounted in a case. The tumbler peripheries have conductor insulator regions. Contact fingers are mounted on the inside of a lateral wall of the case and project radially inwardly into contact with the peripheries of the tumblers. A combination dial is secured to one end of the shaft in a radial arm secured to the opposite end. This radial arm and some rotary motion transmitting abutments on the tumblers function upon selective movements of the dial to temporarily couple the tumblers to the shaft, so that further shaft movement causes tumbler movement.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide a maximum security switch which is housed inside of a cabinet or other closed housing and is operated by a dial which includes a shaft insertable through an opening in a wall of the cabinet into a socket of a control member for the switch. The invention also relates to a plurality of switches and mechanism coupling them together for joint operation by a single control dial, to improvements in mounting means for contact finger portions of a permutation switch, and to circuits involving a plurality of permutation switches controlled by a single operating dial.

BRIEF DESCRIPTION OF THE DRAWING I FIG. I is a view in side elevation, with some parts in axial section, of a permutation switch installation embodying features of the present invention;

FIG. 2 is a side elevational view of a preferred form of control dial, showing the key shaft thereof in its folded or inoperative position;

FIG. 3 is a side elevational view of another permutation switch installation involving a plurality of switch assemblies coupled together in axial alignment, and showing the operating dial in spaced relationship to a mounting panel opening leading into a key socket in a control member connected to the first switch assembly;

FIG. 4 is an exploded isometric view of one of the switch assemblies, showing one of its two contact finger assemblies spaced axially rearwardly of its housing;

FIG. 5 is an end elevational view looking towards the rear end of an assembled switch assembly;

FIG. 6 is a side elevational view looking into one of the contact finger housings, with the end panel and an electrical connector being shown in section;

FIG. 7 is a cross-sectional view taken through a switch assembly, with the rotatable internal parts of such assembly being omitted;

FIG. 8 is an axial sectional view of one of the intermediate switch assemblies, showing a control shaft which projects both forwardly and rearwardly from the housing of such assembly, and a coupler secured to each end of the shaft;

FIG. 9 is a cross-sectional view taken substantially along line 99 of FIG. 8, with a major portion of the back cover removed to expose some of the internal parts of the switch assembly; and

FIG. 10 is a schematic diagram of a typical lock control circuit involving three two circuit switches and six independently controlled locks.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to both normally open and normally closed switches. By way of typical and therefore nonlimitive example, the invention is illustrated and will be described in connection with normally open switches.

Referring first to FIGS. 1 and 8, each switch assembly 10 is shown to comprise a casing having a cylindrical lateral wall 12 and a front wall 14. Wall 14 is formed to include a central tubular portion 16 which receives the forward end portion 18 of a tubular journal 20. A control shaft 22 extends through the journal 20 and projects both forwardly and rearwardly of the

casing

12, 14.

A plurality of tumblers T1, T2, T3, T4 are rotatably supported on the journal 20. In the illustrated embodiment the tumblers T1, T2, T3, T4 are made of dielectric plastic or some other dielectric material, but are provided with a conductor segment 24 in the form of an insert at the periphery of the tumblers T1, T2, T3, T4 (FIG. 9). The tumblers T1, T2, T3, T4 may be of the individually adjustable type forming the subject matter of my copending United States application Ser. No. 29,528, filed Apr. 17, 1970, and entitled Permutation Switch. However, in the illustrated embodiment the tumblers T1, T2, T3, T4 are shown by way of typical and therefore nonlimitive example to be of the same general type as disclosed in US. Pat. No. 2,797,271, granted June 25, 1957 to Arthur L. Augustine.

Each tumbler T1, T2, T3, T4 is shown to be generally in the form of a circular disk or wheel having an axial opening therein for receiving the bushing 20 and a forwardly directed annular recess 26. A driving peg 28 extends from the radial wall portion of each tumbler T1, T2, T3, T4 forwardly into the annular space 26. On the opposite or rearward side of each tumbler T1, T2, T3, T4 a driving pin 30 extends rearwardly into the annular recess 26 of the tumblers T1, T2, T3, T4 immediately behind it. The pin 30 on the rearmost tumbler T1, T2, T3, T4 is in the circular path of travel of a radial control arm 32 which is secured to the shaft 22, such as by a set screw 34.

A substantially semi-annular mounting member 36 of dielectric material, such as synthetic resin plastic, having a chordal inner face 38, is injection molded or otherwise formed to fit snugly within each of the arcuate spaces defined on opposite sides of the two circumferentially spaced apart mounting bolt bosses 40 (FIG. 9). A plurality of

spring contact fingers

42, 44 are secured to the chordal surface 38. As shown by FIG. 8, a single prong 44 rides on the forward tumbler T1 and a single prong 42 rides on the periphery of the rear tumbler T4. The prong 42 which rides on the forward tumbler T1 is a part of a U-shaped connector which includes a prong 44 which rides on the periphery of the second tumbler T2. Similarly, other two

prong contacts

42, 44 bridge between tumblers T2 and T3, and T3 and T4. A lead wire 46 extends from the forward single prong contact 44 back to a control circuit (not shown) and a second lead wire 48 extends from the rear single prong contact 42 to the control circuit. As will be evident, when the tumblers T1, T2, T3, T4 are aligned to place all of the conductive inserts 24 in contact with the

fingers

42, 44, an electrical current path will be established from the lead wire 46 through the

fingers

42, 44 and the contacts 24 to the lead wire 48.

The

contact fingers

42, 44 are spring members containing stored energy tending to urge them radially inwardly into tight contact with the periphery of the tumblers T1, T2, T3, T4. As disclosed in US. Pat. No. 2,984,717, granted May 16, 1961, to Raymond W. Davidson, and entitled Permutation Switch, the peripheries of the tumblers T1, T2, T3, T4 may be axially serrated and the contacting portion of the

fingers

42, 44 shaped to in effect lock in the valley regions of the serrations.

From the foregoing it will be readily apparent that an electric circuit through the switch will remain open as long as the dielectric portion of any one tumbler T1, T2, T3, T4 remains in contact with the

contact fingers

42, 44 which are in contact with such tumbler. The circuit can be made only when all

contact fingers

42, 44 are in contact with the conductive segments 24 of all tumblers T1, T2, T3, T4. Making and breaking of the electrical circuit can only be accomplished by rotating the tumblers T1, T2, T3, T4 relative to each other about their supporting bushings 20 by means of the operating shaft 22, and then only by an authorized person who has knowledge of the number of turns of the shaft 22 to the right and to the left which are necessary to bring the contact 24 into contacting alignment with the

fingers

42,44.

Initially, the shaft 22 and the actuation arm 32 carried thereby are rotated several revolutions, so as to cause the driving pins 30 of the tumblers T1, T2, T3, T4, beginning with the rear tumbler T4, to be moved into engagement with the pegs 28 so that the successive tumblers T3, T2, T1 are in turn picked up" and rotated along with the control arm 32. The first stop of the combination will result in the conductive segment 24 of the front tumbler T1 being brought into engagement with its

respective contact fingers

42, 44, thus initially making a circuit path only through these two

contact fingers

42, 44. With the front or first tumbler T1, now held against rotation by the frictional contact of the

spring fingers

42, 44 which are in engagement with the conductive segment 24 at the periphery of the tumbler T1, the shaft 22 is rotated in the opposite direction, one less turn than previously. This causes actuator arm to first disengage from one side of the driving pin 30 of the rear tumbler T4 and to then rotate around into engagement with the other side of said pin 30, causing driving peg 28 of the rear or fourth tumbler T4 to pick up the pin 30 of the third tumbler T3 immediately forwardly thereof, to rotate the same in said opposite direction. Peg 28 of the third tumbler T3 will pick up the pin 30 of the second tumbler T2, to rotate the same until its contact segment 24 is engaged by the tips of its

respective contact fingers

42,44, and frictionally held against further rotation thereby. With the first and second tumblers T1, T2 now in the positions just mentioned, a circuit path has been successfully established through the first two tumblers T1, T2. Additional rotation of the shaft 22 and the actuator arm 32 in the opposite direction will similarly impart rotation to the third tumbler T3 to position its contact 24 and

respective contact fingers

42, 44 in circuit-making position. Further rotation of shaft 22 and actuator arm 32 in the reverse direction will finally position the contact segment 24 of the rear tumbler T4 in circuit-making engagement with its

respective contact fingers

42, 44 and thus completely make the circuit through the switch, from conductor 46 to conductor 48.

Referring to FIG. 1, in the installation illustrated a single switch assembly is mounted rearwardly of a panel 50 by upper and lower

U-shaped brackets

52, 54. By way ofexample only, panel 50 may be a front, back or side panel on a vending machine which includes a lock controlled by the switch assembly 10. Panel 50 includes a relatively small diameter opening 56 which receives the control shaft 58 secured to a control knob 60. A member 62 is secured to the forwardly projecting end portion of shaft 22 such as by a set screw 64. Member 62 includes a conical entrance portion 66 having sloping walls which guide the inner end portion 68 of shaft 58 into a noncircular socket 70 formed at the base of the cone 66. The end portion 68 of shaft 58 is also non-circular and is sized to snugly fit within the socket 70. As will be evident, the control shaft 58 is inserted through opening 56 and is guided by the sloping walls of passageway 66 into the socket 70. Numbered indicia on the flange portion 72 of dialing knob 60 are positioned in reference to a fixed indicator mark or reference point 74 on panel 50 to establish the circuit-making combination.

The operating shaft 58 may be pivotally connected to the dialing knob 60, such as by a pivot pin 76. This enables the shaft 58 to be swung into a relatively compact position against the inner face of dial 60 when it is not being used.

The just described removable dial feature permits the operator to leave behind only a small hole. There is no chance for an unauthorized person to operate the switch by manipulation of a dial. However, the dial, or another one like it, can be easily reinserted by an authorized person and used for dialing the operating combination.

In FIG. 3 a plurality of switch mechanisms 10 are shown coupled together end-to-end with their control shafts 22 in axial alignment. A member 62 which includes a conical entrance passageway 66 is secured to the forwardly projected end portion of the shaft 22 of the forward mechanism 10. Couplers 78 of the type shown in detail by FIG. 8 are used to couple together the shafts 22 of the forward and intermediate mechanisms 10 and the intermediate rearward mechanisms 10.

One advantage of a plurality switch mechanism installation of this type is that each of the switch mechanisms 10 can be arranged in parallel in a single circuit and each arranged to make or break the circuit. Each mechanism 10 may be operable by a different combination. Then, different operators, each knowing only one of the combinations would be able to open or close the circuit.

Referring now to FIGS. 4-7, each switch mechanism 10 may be provided with two sets of

contact fingers

42, 44. Each set of

contact fingers

42, 44 are secured to a separate carrier 36 which is generally semi-cylindrical and, as earlier described, is made of a dielectric material. A rear panel part 80 is secured to each mounting member 36. Each back part 80 includes a portion 82 which overlaps one of the internally threaded bores 84 formed in the bosses 40. A stud 86 may be threaded into each bore 84. The outwardly projecting portion of the stud 86 extends through an aperture 88 formed in back part 80. A nut 90 is screwed onto such portion of the stud 86 and used for securing the back part 80 to the housing l2, 14. The inner edges of the parts 80 are cut so that they come together when the parts 80 are secured to the

housing

12, 14, as shown by FIG. 5.

Referring to FIG. 6, the

lead wires

46, 48, and an extra lead wire 48' are all shown extending from points of connection with the contact finger members over to separate pins 92 of a plug in type connector 94. The connector 94 includes a socket 96 in which the pins 92 are generally axially disposed and are spaced laterally apart. A complementary connector member 98 including a plurality of pin receiving sockets 100 is sized to plug into the socket 96, with each of the pins 92 entering into each of the sockets 100. The sockets 100 are each connected to an individual metallic wire 102 which extends through an insulative sheath 104 with the other wires 102.

The presence of the extra lead wire 48' makes two switches out of the single set of tumblers T1, T2, T3, T4. A first flow path is established from lead wire 46 through the first three tumblers T1, T2, T3 and the contact fingers in contact therewith to the supplemental lead wire 48'. A second flow path is established through lead wire 48 when the conductor portion 24 of the fourth or rearmost tumbler T4 is in contact with its

fingers

44, 42.

FIG. 9 is a schematic diagram of a simple circuit involving a series of three switch mechanisms 10, each of which is arranged to be two switches, by use of either the auxiliary lead wire 48 or the use of a second set of

contact fingers

42, 44. In the diagram the circuit makes are designated M1, M2, M3, M4, M5, M6. By way of typical and therefore non-limitive example, the first makes M1, M3, MS of each switch mechanism 10 may be established by the tumblers T1, T2, T3 of the switches and the second makes M2, M4, M6 of the switch mechanisms 10 are established by the tumbler T4 and the

contact fingers

42, 44 in contact therewith. Also by way of typical and therefore non-limitive example, the circuit illustrated by FIG. 10 may represent six different solenoid lock controls and time recording means. Each of the six controls C1, C2, C3, C4, C5, C6 are controlled by a separate one of the six switches represented by the three dual switch mechanisms 10. Each switch is operated by its own combination. When it makes a closure in the circuit of which it is a part it both actuates a solenoid lock control and energizes a timing device which records which combination opened the lock and the time of opening.

What is claimed is:

1. In combination:

a wall of an enclosure having a relatively small keyhole opening therein;

a permutation switch mounted in said enclosure, behind said wall, said switch comprising a plurality of coaxial, independently rotatable, generally cylindrical tumblers, each of which has conductive and dielectric peripheral regions, conductor elements resting on the periphery of each tumbler; a tumbler control member having a control portion substantially coaxially aligned with the keyhole opening in said panel, and means associated with said tumblers and operable upon selective rotation of said tumbler control member for rotating said tumblers into positions wherein the conductive regions are in circuitmaking contact with the conductor elements or the dielectric region are in circuit-breaking contact with the conductor elements; and

a control dial with angular position indicia thereon, including a key shaft which is insertable through the opening in said wall and is removably engageable with the control portion of the control member, such that upon rotation of said dial the key shaft imparts a rotational force on said control member.

2. The combination of claim 1, wherein said switch includes a housing for said tumblers and said conductor elements, said housing having a front wall, and bracket means interconnected between the enclosure wall and said switch housing, and holding the front wall of the switch housing in spaced relationship from the enclosure wall, wherein said permutation switch includes control shaft means projecting forwardly from within the switch housing, through an opening in the front wall of said housing, and wherein said control member is secured to said control shaft and occupies a position between the enclosure wall and the front wall of the switch housing.

3. The combination of claim 1, wherein said control portion of the control member is a key socket in the control member for receiving the key shaft, and said key shaft and said socket have cooperating cross-sectional shapes such that upon rotation of said dial the key shaft imparts a rotational force on said control member.

4. The combination of claim 2, wherein said control portion of the control member is a socket in the control member for receiving the key shaft, and said key shaft and said socket have cooperating cross-sectional shapes such that upon rotation of said dial the key shaft imparts a rotational force on said control member.

5. The combination of claim 1, wherein said key shaft includes means pivotally connecting it to the control dial at a location closely adjacent the dial, so that the key shaft can be folded into an inactive position relatively against the dial.

6. in combination, a plurality of permutation switches, each of which comprises a control shaft, means mounting a plurality of disc-like tumblers mounted for free selective rotation about said control shaft, each said tumbler having conductor and insulator regions at its periphery, contact fingers in contact with the peripheries of the tumblers, and means including a radial arm secured to the support shaft and some rotary motion transmitting abutments on the tumblers, all together functioning upon selective movements of the control shaft to temporarily couple the tumblers to the shaft, so that further shaft movement causes tumbler movement and the conductive and dielectric peripheral portions of the tumblers can be dialed into circuit making and circuit breaking contact with the contact fingers;

means coupling the control shafts of said switches together for conjoint rotation; and

a dial having angular position indicia thereon and a control shaft connectible with the control shaft of one of said switches, so that said dial may be used to rotate the control shafts of all switches.

7. The combination of claim 6, wherein each switch includes a housing for its tumblers and its contact fingers, and said combination includes bracket means securing the respective housings together in a substantially coaxial spaced relationship, wherein the control shafts of each switch includes a first end portion projecting endwise outwardly from one end of the housing and a second end portion projecting endwise outwardly from the opposite end of the separate housing, and said combination includes coupler means between each adjoining pair of switches for coupling together the projecting end portions of the two switches.

8. The combination of claim 7, further comprising an enclosure for all of the switches, including an enclosure wall, and bracket means connecting the switches to the enclosure wall, with the switch to which the control dial is coupled being closest to said wall.

9. The combination of claim 8, wherein said enclosure wall includes a relatively small opening therein which is substantially coaxially aligned with the control shafts of the switches, and wherein the switch closest to the enclosure wall includes a projecting end portion of its control shaft which is directed towards said opening, and wherein a control member, located wholly within said enclosure, is connected to such projecting end portion, and wherein the control dial includes a control shaft which is insertable through the opening in said wall and is engageable with the control member, such that upon rotation of said dial the control shaft imparts a rotational force on said control member, and in turn on all of the control shafts of the switches which are coupled thereto.

10. A control system comprising load means to be activated by an electrical signal, and control circuitry for providing the electrical signal, said circuitry comprising a plurality of permutation switches, each of which comprises rotary tumbler controlled circuit-making means arranged to complete an electrical energy flow path to the load means independently on the other switches, a rotary control means; means coupling together the rotary control means for the tumblers of all switches; and a single control dial for all switches connected to said rotary control means.

11. For use in combination with an enclosure including a wall having a relatively small keyhole opening therein, a permutation switch comprising:

means for mounting the switch in said enclosure, behind said wall, said switch comprising a plurality of coaxial, independently rotatable, generally cylindrical tumblers, each of which has conductive and dielectric peripheral regions, conductor elements resting on the periphery of each tumbler, a tumbler control member having a control portion in the nature of a socket opening in said control member, said socket opening having a relatively wide entrance portion which is larger in diameter than the opening in the enclosure wall, said entrance portion tapering inwardly to a non-circular base portion of the socket, said socket opening being substantially coaxially aligned with the keyhole opening in the panel when the switch is mounted in said enclosure, and means associated with said tumblers and operable upon selective rotation of said tumbler control member for rotating said tumblers into positions wherein the conductive regions are in circuitmaking contact with the conductor elements or the dielectric region are in circuit-breaking contact with the conductor elements; and

a control dial with angular position indicia thereon, including a key shaft which is insertable through the opening in said wall and which includes an inner end portion having a non-circular cross-section sized to snugly fit within the base portion of the socket, such that upon rotation of said dial the key shaft imparts a rotational force on said control member, with the inwardly tapering side walls of the socket opening serving to direct the inner end portion of the key shaft into a position of alignment and engagement with the base portion of the socket.

12. A permutation switch according to claim 11, wherein said switch includes a housing for said tumblers and said conbetween the enclosure wall and the front wall of the switch housing.

13. A permutation switch according to claim 11, wherein said key shaft includes means pivotally connecting it to the control dial at a location closely adjacent the dial, so that the key shaft can be folded into an inactive position relatively against the dial.

Claims

1. In combination: a wall of an enclosure having a relatively small keyhole opening therein; a permutation switch mounted in said enclosure, behind said wall, said switch comprising a plurality of coaxial, independently rotatable, generally cylindrical tumblers, each of which has conductive and dielectric peripheral regions, conductor elements resting on the periphery of each tumbler; a tumbler control member having a control portion substantially coaxially aligned with the keyhole opening in said panel, and means associated with said tumblers and operable upon selective rotation of said tumbler control member for rotating said tumblers into positions wherein the conductive regions are in circuit-making contact with the conductor elements or the dielectric region are in circuit-breaking contact with the conductor elements; and a control dial with angular position indicia thereon, including a key shaft which is insertable through the opening in said wall and is removably engageable with the control portion of the control member, such that upon rotation of said dial the key shaft imparts a rotational force on said control member.

6. In combination, a plurality of permutation switches, each of which comprises a control shaft, means mounting a plurality of disc-like tumblers mounted for free selective rotation about said control shaft, each said tumbler having conductor and insulator regions at its periphery, contact fingers in contact with the peripheries of the tumblers, and means including a radial arm secured to the support shaft and some rotary motion transmitting abutments on the tumblers, all together functioning upon selective movements of the control shaft to temporarily couple the tumblers to the shaft, so that further shaft movement causes tumbler movement and the conductive and dielectric peripheral portions of the tumblers can be dialed into circuit making and circuit breaking contact with the contact fingers; means coupling the control shafts of said switches together for conjoint rotation; and a dial having angular position indicia thereon and a control shaft connectible with the control shaft of one of said switches, so that said dial may be used to rotate the control shafts of all switches.

11. For use in combination with an enclosure including a wall having a relatively small keyhole opening therein, a permutation switch comprising: means for mounting the switch in said enclosure, behind said wall, said switch comprising a plurality of coaxial, independently rotatable, generally cylindrical tumblers, each of which has conductive and dielectric peripheral regions, conductor elements resting on the periphery of each tumbler, a tumbler control member having a control portion in the nature of a socket opening in said control member, said socket opening having a relatively wide entrance portion which is larger in diameter than the opening in the enclosure wall, said entrance portion tapering inwardly to a non-circular base portion of the socket, said socket opening being substantially coaxially aligned with the keyhole opening in the panel when the switch is mounted in said enclosure, and means associated with said tumblers and operable upon selective rotation of said tumbler control member for rotating said tumblers into positions wherein the conductive regions are in circuit-making contact with the conductor elements or the dielectric region are in circuit-breaking contact with the conductor elements; and a control dial with angular position indicia thereon, including a key shaft which is insertable through the opening in said wall and which includes an inner end portion having a non-circular cross-section sized to snugly fit within the base portion of the socket, such that upon rotation of said dial the key shaft imparts a rotational force on said control member, with the inwardly tapering side walls of the socket opening serving to direct the inner end portion of the key shaft into a position of alignment and engagement with the base portion of the socket.

12. A permutation switch according to claim 11, wherein said switch includes a housing for said tumblers and said conductor elements, said housing having a front wall, and bracket means for connecting the switch housing to the enclosure wall and holding the front wall of the switch housing in spaced relationship from the enclosure wall, wherein said permutation switch includes control shaft means projecting forwardly from within the switch housing, through an opening in the front wall of said housing, and wherein said control member is secured to said control shaft and during use occupies a position between the enclosure wall and the front wall of the switch housing.