US2815586A - Permutational switch - Google Patents

Description

6 Sheets-Sheet 1 G. W. M CHEYNE PERMUTATIONAL SWITCH Dec. 10, 1957 Filed April 25, 1952 w. t 2 m. 2 m. E o. m m h w n v m N u NB K M 2 o irf1 i 0 ow. MWWfi I I I I I I I I i i I i I I I 1 l I I I I O: m0- nw N INVENTOR. GEORGE W. MAC CHEYNE BY]! ATTORNEY Dec. 10, 1957 Filed April 25, 1952 G. W. M CHEYNE PERMUTATIONAL SWITCH lOl 6 Sheets-Sheet 2 INVENTOR. GEORGE W. MAC CHEYNE m'jf ATTORNEY Dec. 10, 1957 G. W. MaccHEYNE PERMUTATIONAL SWITCH 6 Sheets-Sheet 3 Filed April 25, 1952 I I I I I I f I O 6 V 4 IllIII/IllIIIII/IIIIl/IIIIII/I/Im/I/ INVENTOR. GEORGE W. MAC CHEYNE ATTORNEY Dec. 10, 1957 G. w. M CHEYNE 2,815,586

PERMUTATIONAL SWITCH 6 Sheets-Sheet 4 Filed April 25, 1952 FIG. 5

INVENTOR. GEORGE w. MAC CH EYNE Jfd-ww ATTORNEY Dec. 10, 1957 G. w. M CHEYNE 2,815,586

PERMUTATIONAL SWITCH Filed April 25. 1952 e Sheets-Sheet 5 INVENTOR. GEORGE w MAC CHEYNE ATTORNEY Dean 10, 1957 G. W. M CHEYNE 2,815,586

PERMUTATIONAL SWITCH Filed April 25, 1952 e Sheets-Sheet a IIIIIII/MIIIII/I/IIIIIIII/II/I/I/I/I/ INVENTOR. GEORGE MACCHEYNE ATTORNEY PERMUTATIONAL SWITCH George W. MacCheyne, Webster, N. Y., assignor, by mesne assignments, to General Dynamics Corporation, a corporation of Delaware Application April 25, B52, Serial No. 284,408

11 Claims. (Cl. 35-4) My invention relates to electrical switches, and particularly to electrical switches of the permutational type. By a switch of the permutational type, I mean a switch in which each of a plurality of input conductors may be interconnected with any desired ones of a plurality of output conductors.

Switches of the permutational type find special application in cryptographic devices in which electrical circuits are employed. In such devices, it is known that a message may be enciphered by interconnecting the input conductors with the output conductors in an order depending upon the cipher being used. Since ciphers may be broken, it is desirable that the particular cipher employed during one period of time be changed to another cipher for use during another interval of time. In electrical cryptographic devices, this means that it is necessary to change the order of interconnection between input and output conductors in order to produce the new cipher. Such changes have been accomplished by code wheels prior to my invention, but such devices are in general too bulky, handle too small a number of interconnections, or require too much time to change from one cipher to another. In some cases, not all of the permutations of possible interconnections may be obtained by the interconnecting devices.

It is accordingly an object of my invention to provide a permutational switch of a new and advantageous type, in which all permutations of the possible interconnections are available.

It is another object of my invention to provide a permutational switch in which a given order of interconnections between input and output conductors can quickly and easily be changed to a diiierent order of interconnections.

It is another object of my invention to provide a permutational switch capable of handling a large number of input and output conductors, yet which achieves a high degree of space utilization.

It is still another object of my invention to provide a permutational switch which may be mounted behind a control panel with minimum frontal protrusion, yet which may easily be set for a given order of interconnections.

It is yet another object of my invention to provide a permutational switch of compact yet rugged construction which can be locked against accidental alteration of the order of interconnections desired.

Further objects and advantages of my invention will become apparent as the following description proceeds, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is a front-of-panel view of one embodiment of my invention;

Fig. 2 is a top view of the embodiment of Fig. 1;

Fig. 3 is an end view of the embodiment shown in tates Patent Fig. 4 is a sectional view taken along the line 4-4 in Fig. 1;

Fig. 5 is a sectional view taken along the line 5-5 in Fig. 3;

Fig. 6 is a sectional view taken along line 6-6 in Fig. l; and

Fig. 7 is a sectional view taken along line 77 in Fig. 1.

The embodiment shown in the drawings permits eighteen incoming conductors to be connected with eighteen outgoing conductors in any desired order. Those skilled in the art to which my invention appertains can readily appreciate that more or fewer input or output conductors may be accommodated in a permutational switch constructed according to my invention. Furthermore, it is to be noted that in this specification, I employ the words input and output relative to conductors as a convenient designation, and not with an absolute electrical connotation. I have chosen to designate the eighteen incoming conductors by means of Arabic numerals 1-18, and the eighteen outgoing conductors by means of letters AS (omitting letter I). In accordance with my invention, incoming conductor 1 may be connected with any one of outgoing conductors AS, irrespective of the interconnections of any of the other incoming conductors. This independence of other interconnections is true of any single incoming conductor.

To avoid confusion with the conductor designation scheme set forth above, I have chosen to explain my invention by a series of reference symbols starting with 101.

The frontal appearance of a preferred embodiment of my invention is shown in Fig. l. The mechanism is mounted behind a front panel 101, with a portion of each of 18 thumb wheels, such as 102 for example, projecting through a slot 103 in the panel. Adjacent to each thumb wheel is an indicia member with letters AS engraved on its circumference. In the case of thumb wheel 102, the indicia member is represented by symbol 104, and a portion thereof may be viewed through a window 105 formed in panel 101. As may be seen from Fig. 1, thumb wheel 102 is shown in a position such that the letter K may be viewed through window 105. This indicates that thumb wheel 102 has been set such that incoming conductor 10 is interconnected with outgoing conductor K. The arrangement for each of the 18 thumb wheels (there being one thumb wheel for each incoming conductor) may be identical to that provided for thumb wheel 102. In view of this circumstance, the arrangement according to my invention of the present embodiment is described in this specification in detail with respect to thumb wheel 102 and the parts cooperating therewith, it being understood that the construction and operation of the other thumb wheels and their accompanying parts may be substantially identical.

It is a feature of my invention that the particular order panying drawings, with its closed, or protective, position I being indicated in Figs. 1 and 4 by means of dashed lines.

Further in accordance with my invention, I may provide a locking lever 107 which may be moved along a slot 108 to lock all thumb wheels simultaneously against accidental alteration of the order of interconnection.-

Thus when locking lever 107 is at end 109 of the L- shaped slot 108, as shown in Fig. 1, all of the thumb wheels are locked against rotation. To unlock the thumb wheels so that the order of interconnection may be al- I tered, locking lever 107 is moved to end 110 of slot 108.

It is- -a feature ofmy invention -that-door106 cannot-be closed and secured in position unless locking lever 107 is at end 109 of slot 108, thus insuring that all of the thumb-wheels are secure' against rotation whenever-the door is observed to be shut.

' The disposition. of par-tsin "Fig. L-may' be inspected in greater detail in Fig. 2. As shown here, door 106-is mounted on hinges Ill-and 11:2, with mating' hinge 'mem ber 113 being mounted on panel 101. Also vi'sible-in Fig. 2 'are the incomingconductors, that corresponding to incoming conductor being designated by reference symbol114. Incoming wires may be attached to-the incoming conductors by anysconvenientmeans, although I have chosen .to show-a hole. 115v in incoming conductor 114 toassistin securing'a wire tomember 114. Incoming conductor114 may be securedto a mounting member 116 made. .of insulatingmaterial by means of screws 117 or other convenient fastening means. Also shown in Fig. 2' are some of. the outgoing conductors; for example, the outgoing conductor corresponding (in 'the:present embodiment). to letter. K is designated by. reference symbol 118. As with the incoming conductors, each .of the outgoing conductors may. be provided with a wire-receiving hole to assist insecuring an outgoing wire to the outgoing conductor. Inthe case of outgoing conductor 118 the hole is designated by symbol 119. Other. outgoing conductors visible in Fig. 2 are indicated-by reference symbols 120-123.and 124-126,.corresponding respectively(in the present embodiment) to the. outgoing conductors designated by letters 0, N, M, L,.and I, H, G.

In accordance with my invention, the outgoing conductors may be connected to, or preferably formed integrally with, a plurality of segmental bars which form a stationary commutator of generally cylindrical configuration. These segmental bars are made of conducting material, such as copper, and are preferably embedded in a mass of plastic material which secures them against motion relative to each other. I have illustrated the present embodiment of my invention as employing the integral construction of segmental bars and outgoing conductors, and therefore a single reference symbol is used for both. The position ofthe commutator bars, such assegmental bar118, relative to each other and to the mass of plastic material is best seen from the dashed outlines thereof in. Fig. 3. The bars are disposed parallel to the. axis of the cylindrical configuration which forms the stationary commutator. The stationary commutator is designated-by reference symbol 127, and is disposed with i-tsdongitudinal axis. substantially parallel to the plane offront panel 101.

.Figs. 2 and 3 .illustrate how commutator 127 may be secured .in placethrough attachment, as by screws 128, to insulatingendplates 129. Insulating end plates 129 in turn may, be secured, as by means of screws 130, to end frame members-131 :of the switch. Front panel 101 may be attached to end frame members 131 by such convenient means as screws 132'which pass-through the front panel and mate in tapped holes (not shown) in the end frame members. Frame members 131 may be positioned relative to each other by means of longitudinal frame member 133, insulating mounting member 116, and spacing member 134.

Fig. 2 shows that each incoming conductor is provided with a relatively long, forwardly-extending portion, this portion being designated in the case of incoming conductor 114 by reference symbol 135. There is thus formed a contact spring whose contour may be examined in greater detail in the end view, Fig. 3. The spring contacts the outer periphery of a conductive ring, 136 (shown by dashed line). As illustrated in the sectional view, Fig. 4, ring 136, in turn carries bracket 137. Mounted on bracket 137 is a spring.'138 which in turn. maintains brush 139 in position to contact commutator 127. -The particular bar being contacted in the drawingsis bar 118.

pointed "out earlier,- each of the segmental bars' isconnected to (or is preferably formed integrally with) an outgoing conductoroutgoing conductor K in the case shown. Thus the conducting path from an incoming conductor such as 114 to an outgoing conductor such as K (symbol 118) may be understood from Fig. 4 to extend from conductor 114, spring portion 135, conductive ring 136, bracket 137, spring 138 and brush 139 to segmental bar 118.

Conductive ring 136 is secured to an insulating memher 140, as by means of screws (not shown) or other convenient means. Proper location is obtained by fitting the center-hole in ring 136 onto an appropriately-dimensioned hub portion of insulating member 140. Fig. 5 indicates the spatial relationship between conductive ring 136 and insulating member 140. Thumb wheel 102 is positioned concentrically about insulating ring 140 and secured firmly thereto, as by means of key and slot arrangement. All conductive rings of the switch are thus seen to be disposed parallel to each other and coaxially with respect to commutator 127.

Also revealed in Fig. 5 is the longitudinal contour of segmental bar 118. This bar, like the other segmental bars of the stationary commutator 127 is seen to have a series of raised portions 141 and undercut portions 142. This contour of the stationary commutator is readily produced by the preferred method of manufacture, which contemplates holding the segmental bars in position and casting a mass of plastic material around them. Upon hardening of the plastic material, the assembly may be placed in a lathe and turned down to produce the contour shown. In this way, a series of parallel grooves, or undercut portions, may be formed circumferentially around stationary commutator 127, thus exposing portions only of the segmental bars.

Secured to insulating ring 140 is a retaining ring comprising a plurality of arcuate segments. As shown in Fig. 7, I prefer to employ three such segments, 143, 144, and 145, each covering approximately I further prefer that they be attached to insulating ring by means of screws 146. Although other means of fastening may be employed, I prefer that screws be used because assembly or disassembly of the switch may be expedited thereby.

Returning now to Fig. 5, it may be observed that the retaining ring segments are formed with an inwardlyextending portion 149, which forms an annular ridge mating with grooved portion 142. Also shown in Fig. 5 is a separator ring 147 adjacent the retaining ring 143. Ring 147 serves as insulation between the indicia portion 104 of thumb wheel 102, which is preferably made of metal to obtain long-wearing qualities, and contact spring 148 of the next adjacent input conductor. Separator ring 147 is preferably formed of friction-reducing material in order to prevent movement of adjacent parts when a given thumb wheel is manipulated.

A feature of my invention-is the use of a detent means which serves accurately to position brush 139 in the center of the particular segmental bar portion chosen. As shown in Fig. 4, a lever arm 150individual to a particular thumb wheel (in this case wheel 102) is pivoted about a common axle 151. Arm 1'50 supports an idler wheel 152. A spring 153 compressed between spring seats 154 and 155 biases wheel 152 against the outer circumference of thumb wheel 102. This circumference'is contoured with radial undulations, or serrations, with a rounded portion, such as 156, being formed at the valleys between serrations. The serrations, in projecting through slot 103 in front panel 101, provide a convenient means for thumb rotation of wheel 102. The pressure of wheel 152 on these serrations provides an added rotational force in addition to thumb force on the wheel, this added force being present until wheel 152 drops into one of the rounded portions.

'As pointed out earlier, I may'alsoprovide a means for simultaneously locking all of the thumb wheels against rotation. Fig. 4 shows how locking lever 107 is secured to lock bar 156, as by means of a threaded portion 157 of the former mating with a threaded hole 158 in the latter. I may, in addition, prefer to retain locking lever 1m in locking bar 156 by means of a set screw 159.

The longitudinal arrangement of the locking means may be seen in Fig. 6. Lock bar 156 may be moved parallel to the axis of stationary commutator 127 by locking lever 1W7. Lock bar 155 has alternate recessed and unrecessed, or brake, portions, such as 169 and 161, respectively. Thus when locking lever 107 is in the unlocked position (that is, at end 110 of slot 108; see Fig. 1) the recessed portions of lock bar 156 are each opposite a corresponding one of the thumb wheels. Locking bar 156 is preferably biased, as by means of spring 162 (Fig. 6) to move toward the unlocked position.

Upon moving locking lever 107 to the locked position (end 1 99 of slot res; see Fig. 1), an unrecessed portion of lock bar 156 is brought opposite each of the thumb wheels. The unrecessed portions consequently mate with the rounded portions in the valleys between the serrations formed in the thumb wheels. By reason of this feature, it may be seen that look bar 156' cannot be placed in the locked position unless each of the thumb wheels is accurately positioned on a particular one of the segmental bars of the commutator 127. Furthermore, it may be observed from Fig. 4 that door 196' cannot be placed in the closed position indicated by dotted line 163 unless locking lever 1697 is in the locked position (end 109 of slot Hi8, Fig. 1). Conversely, door 106, when shut, prevents locking lever 16'! from moving to end 110 of slot 10%. This feature insures that any time door IE6 is locked shut every thumb wheel is accurately positioned and locked against rotation.

Door 1% is preferably retained in the closed position by means of a conventional snap-slide fastener comprising handle Ill-5 (Pig. 6), support 165, slide 166, and mating stud 167. These parts may be protected by an inner cover 163 held in place by a convenient means, as screws 169. Snap-slide fasteners are well-known and hence are not detailed here.

While I have shown and described my invention as applied to a specific embodiment thereof, other modifications will readily occur to those skilled in the art. I do not, therefore, desire my invention. to be limited to the specific arrangement shown and described, and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim is:

1. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator of generally cylindrical configuration having segmental bars disposed paraL lel to the axis of said cylindrical configuration and embedded in a mass of electrical insulating material such that portions only of said bars are exposed at the circumferential surface of said commutator, each of said bars being connected to individual ones of said output conductors, said commutator having a plurality of circumferential grooves formed therein, each of said grooves being located between adjacent ones of said exposed portions of said bars; a plurality of conductive rings, each of said rings being disposed parallel to each other and coaxial with respect to said commutator, and each of said rings further having attached thereto insulating means including an annular ridge mating with a corresponding one of said grooves, whereby said rings are individually prevented from substantial movement in an axial direction relative to said commutator; each of said rings having a brush mounted thereon, each said brush being positioned for contact with one of said exposed portions of one of said bars at a time; a plurality of stationarilymounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors 6 and being mounted to bear on a corresponding one of said rings, whereby through rotation of said rings any one of said input conductors can be brought into conductive relationship with one of said exposed portions of one of said bars, and hence with one of said output conductors.

2. in a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator of generally cylin-- drical configuration having segmental bars disposed paral-- lel to the axis of said cylindrical configuration and embedded in a mass of electrical insulating material such that portions only of said bars are exposed at the circumferential surface of said commutator, each of said bars being connected to individual ones of said output conductors, said commutator having a plurality of circumferential grooves formed therein, each of said grooves being located between adjacent ones of said exposed portions of said bars; a plurality of conductive rings, each of said rings being disposed parallel to each other and coaxially with respect to said commutator; a plurality of insulating rings, each of said insulating rings being attached to an individual one of said conductive rings and having an annular ridge mating with a corre sponding one of said grooves, each of said insulating rings being made in three arcuate segments, each said arcuate segment being independently attached to the corresponding said conductive ring and proportioned to permit removal of said insulating ring from said groove through removal of only one of said arcuate segments; each of said conductive rings having a brush mounted thereon, each said brush being positioned for contact with one of said exposed portions of one of said bars at a time; a plurality of stationarily-mounted contacts, each of said contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said conductive rings, whereby through rotation of said conductive rings any one of said input conductors can be brought into conductive relationship with one of said exposed portions of one of said bars, and hence with one of said output conductors.

3. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rin-gs having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarily-mounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a front panel having its plane substantiarly parallel to the longitudinal axis of said commutator; a thumb wheel attached to each of said rings, each said thumb wheel being positioned to project for convenient thumb actuation through said panel, whereby through rotation of various ones of said thumb wheels, individual ones of said brushes can be brought into contact with individual ones of said segments and therefore individual ones of said input conductors can be brought into conductive relationship with individual ones of said output conductors.

4. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarily-mounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a generally wheel-shaped member attached to each said ring, each said member having multiple indentations around its circumference, said indentations being spaced apart by the same angular proportion as said segments; detent means operating substantially equally against said indentations of each said wheel independent of the indentations in others of said wheels, whereby any of said brushes can be brought into contact with any one of said segments with enhanced surety by reason of said detent means positioning said brush with precision on a given one of said segments.

5. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarilymounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a front panel having its plane substantially parallel to the longitudinal axis of said commutator; a thumb wheel attached to each of said rings, each said thumb wheel having radial undulations about its circumferential edge and projecting through said panel for convenient thumb actuation, whereby through rotation of various ones of said thumb wheels, individual ones of said brushes can be brought into contact with individual ones of said segments and therefore individual ones of said input conductors can be brought into conductive relationship with individual ones of said output conductors.

6. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; -a plurality of conductive rings supported for rotation independent of each other aboutsaid commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarilymounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a front panel having its plane substantially parallel to the longitudinal axis of said commutator; a thumb wheel attached to each of said rings, each said thumb wheel having radial undulations about its circumferential edge and projecting through sa-idpa nel :for convenient thumb actuation; detent means individual to each said thumb wheel and operative against said undulations to position each individual one of said rings for optimum contact between the brush carried by said one ring and the particular one of said segments ,to be contacted, whereby through rotation of said rings any one of said input conductors can be brought into conductive relationship with any one of said output conductors.

7. In a pcrmutational switch device, the combination of a plurality of input conductors; a plurality of, output conductors; a stationary commutator having a plurality of segments, each of said segments 'beingconnected to indiyidualwones of said outputconductors; aplurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarilymounted contacts, each of said plurality of contact being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a front panel having its plane substantially parallel to the longitudinal axis of said commutator; a thumb wheel attached to each of said rings, each said thumb wheel having radial undulations about its circumferential edge and projecting through said panel for convenient thumb actuation; an indicia member individual to each said ring arranged adjacent to said thumb wheel and mounted for integral rotation therewith; indicia individual to each said ring marked around the circumference of the particular indicia member associated with said each ring; a plurality of openings in said panel, each said opening being individual to one of said indicia members and positioned to permit a view of a portion of said indicia marked on said individual ones of said indicia members, whereby said thumb wheels can be actuated to various angular positions relative to said commutator, thereby to interconnect particular ones of said input conductors with particular ones of said output conductors, and the combination of interconnections chosen can be readily and visually identified from the front of said panel.

8. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarilymounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings, whereby through rotation of said rings any one of said input conductors can be brought into conductive relationship with any one of said output conductors; and means for locking said rings against rotation during use and for unlocking them during setting.

9. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; eachof said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarily-mounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings, whereby through rotation of said rings any one of said input conductors can be brought into conductive relationship with any one of said output conductors; and means for simultaneously locking all of said rings against rotation during use and for simultaneously unlocking all of said rings during setting.

10. In a permutational switch device, the combination a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segmentsv each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact with a portion of one of said segments at a time; a plurality of stationarily-mounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a front panel having its plane substantially parallel to the longitudinal axis of said commutator; a brake portion attached to each of said rings; a locking bar spring biased to engage each of said brake portions and so to prevent rotation of said rings; and a locking lever operable from the front of said panel and having lock and unlock positions, said locking lever being operative in said one lock position to counteract and maintain counteracted said spring bias on said locking bar, thereby freeing said rings for rotation relative to said commutator, said locking lever being further operative in said lock position to remove said counteraction of said spring bias and so to lock all of said rings against rotation.

11. In a permutational switch device, the combination of a plurality of input conductors; a plurality of output conductors; a stationary commutator having a plurality of segments, each of said segments being connected to individual ones of said output conductors; a plurality of conductive rings supported for rotation independent of each other about said commutator, the number of rings being equal to the number of said input conductors; each of said rings having a brush mounted thereon, each said brush being positioned for contact With a portion of one of said segments at a time; a plurality of stationarily-mounted contacts, each of said plurality of contacts being connected to individual ones of said input conductors and being mounted to bear on a corresponding one of said rings; a front panel having its plane substantially parallel to the longitudinal axis of said commutator; a brake portion for each of said rings; a locking bar spring biased to engage each of said brake portions and so to prevent rotation of said rings; a locking lever operable from the front of said panel and having lock and unlock positions, said locking lever being operative in said one look position to counteract and maintain counteracted said spring bias on said locking bar, thereby freeing said rings for rotation relative to said commutator, said locking lever being further operative in said lock position to remove said counteraction of said spring bias and so to lock all of said rings against rotation; and a cover normally mounted against said panel but movable for access to said panel, said cover being positioned and contoured to close against said panel only when said locking lever is in said locked position.

References Cited in the file of this patent UNITED STATES PATENTS 903,786 Rutherford Nov. 10, 1908 1,095,839 Fritz May 5, 1914 1,348,575 Odhner Aug. 3, 1920 1,905,593 Korn Apr. 25, 1933 1,938,028 Korn Dec. 5, 1933 2,055,702 Patton Sept. 29, 1936 2,090,103 Bryce Aug. 17, 1937 2,665,067 Wassef Ian. 5, 1954 FOREIGN PATENTS 380,414 Italy May 12, 1940

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