US3493696A

US3493696A - Modular selector switch assembly

Info

Publication number: US3493696A
Application number: US722483A
Authority: US
Inventors: Richard C Rothweiler
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1968-04-18
Filing date: 1968-04-18
Publication date: 1970-02-03
Anticipated expiration: 1987-02-03

Description

Feb. 3, 1970 R. c. RoTHwElLER MODULAR SELECTOR SWITCH ASSEMBLY FIG 5 BY RICHARD C. ROTHWEILER Filed April 18, 1968 United States Patent O 3,493,696 MODULAR SELECTOR SWITCH ASSEMBLY Richard C. Rothweiler, Wauwatosa, Wis., assignor to Square D Company, Park Ridge, Ill., a corporation of Michigan Filed Apr..18, 1968, Ser. No. 722,483 Int. Cl. H01h 9/00, 21 78 U.S. CL 200-4 9 Claims ABSTRACT OF THE DISCLOSURE A selector switch which may be assembled of modular components including a plurality of cam operated rotary switches, an indexing module, a spring return module wherein each of the modules has an individual cam which is telescopically connected with the cam in an adjacent module and each of the cams has a bore extending therethrough for transmitting a control function through the telescopically connected cams.

This invention relates to electric switches and more particularly, to a rotary type selector switch that is assembled of modular components to provide the required switching functions.

Rotary type selector switches have long been used to control the operation of electrically powered material handling vehicles, such as fork lift trucks and the like, wherein switches having large rugged components were used because they were frequently subjected to abusive operation. Because of their rugged construction, operating switches for industrial vehicles were designed as a single switching assembly having a xed rotary cam and contact arrangement designed to satisfy the particular requirements of the vehicle to which they were yapplied and therefore modification of their sequence or mode of operation could be achieved only with great difficulty. Additionally, while rotary selector switches having less rugged components have "been furnished for use in industrial type control panels along with push buttons, pilot lights and the like, to control industrial processes and machines, because of their constructional limitations they were not particularly suited for industrial vehicle applications. In contrast, the modular selector switch as hereinafter disclosed can be readily modied or assembled to provide a large variety of different modes of operation and switching combinations and can be used either in industrial vehicles or control panels.

It is an object of the present invention to provide a modular selector switch assembly that includes fa stack of individual corresponding rotary carn type switch modules, at least one module for indexing the cams of the switch stack to at least one rotary position and a switch operator 'and to provide and to arrange the cams of the switches so they can be telescopically connected together and with a rotatable member of the indexing module and provide the cams of the switches and the rotatable members with bores so a switching function can be transmitted through the bores of the indexing module and switches from the operator to the end of the switch assembly that is remote from `the operator.

An additional object is to provide a modular selector switch assembly that includes a stack of individual corresponding rotary cam operated type switch modules, an indexing module having a member for resiliently positioning the cams of the switch modules in any one of a plurality of radial positions, a spring return module for constantly resisting rotative movement from a selected position, and an operator for rotating members in the indexing module and a spring return module as well yas the switch module cams, and to arrange the cams of the switches so they can 3,493,696 Patented Feb. 3, 1970 ICC be telescopically connected together and with a rotatable member of the indexing module or the spring return module and provide the cams of the switches and the rotatable members of the indexing module and the spring return module with bores so a switching function can be transmitted through the bores from the operator to the end of the switch assembly that is remote from the operator.

Another object is to provide a rotary selector switch with a plurality of individual modules which are `assembled in juxtaposed facial engagement with each other with their operating members telescopically connected to each other to provide selected switching functions and modes of operation in response to both linear and rotary movements of a switch operator.

A further object is to provide a modular rotary selector switch that includes a switch stack that is formed of a lplurality of corresponding switch modules which are assembled with their ends in facial juxtaposition and with the rotary cam members telescopically connected with each other and to removably secure one end of the switch stack to a module which provides an indexing function for the assembly and to provide the telescoped cam members @and a member in the indexing module which rotates the tcam members with bores which are aligned to provide a continuous bore through the assembly whereby a separate lswitch having a linearly movable actuator that is positioned at an end of the assembly remote from the indexing :module may be operated by a linear element extending through the bores from an operator that is located at the indexing module end of the assembly.

Further objects and features of the invention will be readily apparent to those skilled in the art from the specilication and appended drawing illustrating certain preferred embodiments in which:

FIG. 1 is a side plan view of a modular selector switch incorporating the features of the present invention with a portion of an operating handle broken away illustrating the position of wires as may be included in the switch assembly.

FIG. 2 is =a cross sectional view of a modified form of the switch assembly in FIG. 1.

FIG. 3 is a view taken generally along line 3-3 in FIG. 2 with a cover removed.

FIG. 4 is a view taken generally along line 4-4 in FIG. 2, adjacent switch removed.

FIG. 5 is a view taken generally along line 5 5 in FIG. 2 with a cover removed.

FIG. 6 is a plan view illustrating several telescoped cams as used in the switch modules in the switch assemiblies in FIGS. l and 2.

In the drawings, and particularly in FIG. l, a modular selector switch assembly 10 includes an operating handle 12, a mounting bracket 14, a spring return module 16, an indexing module 18, a pair of covers 20 and 22, a plurality of rotary switch modules designated as 24, 26 and 28, a terminal module 30 and a shaft 32. The spring return module 16, the indexing module 18, the covers 20 and 22, the

switches

24, 26 and 28 as shown in FIG. 2 are identical to the correspondingly designated modules in FIG. l. The terminal module 30 in FIGA 1 is replaced by an additional switch module 34 in FIG. 2. The modular selector switch assembly 10 in FIG. 2 additionally includes an adapter 36, a switch 38 having a linearly movable contact `operator 40, an operating rod 42, a switch operator 44, an operating button 46, a return spring 48 and means including a pair of threaded rods 50 for maintaining the modules assembled.

Each of the switch modules 24, 26, 28- and 34, as well as the terminal module 30, have identical housings and therefore, referring to FIGS. 2 and 4, a description of the switch module 26 will apply to the remaining switch modules and terminal module. The switch module 26 has a housing 52 formed as a unitary molded part, preferably of transparent plastic material, to have a substantially flat, square-shaped closed rear wall 54 and side walls 56 extending to an open front face 58, dening an internal cavity 60. At each of the corners of the square-shaped rear walls 54 the side walls 56 extend inwardly into the cavity 60 to provide indentations 62 at the external four corners of the switch housing with the rear wall 54 ex tending to provide a barrier wall at one side of each indentation 62. Positioned in each of the indentations 62, as by suitable slots in the material of the housing 52, is a wire connecting terminal member 64. The terminal members 64 are -substantially identical and each includes a portion that exposes a wire clamp 66 and a screw 68 in an indentation 62 so as to be accessible from the exterior of the housing 52 and a portion 70 within the cavity 60. As shown, the terminals 64 are arranged in pairs at the corners of top and bottom of the housing 52 with one of the terminals of each pair having a stationary contact portion 72 thereon and the other terminal of each pair having an end of an arm 74 for a movable contact 76 secured thereon. The arms 74, which are formed of a resilient metal, such as beryllium copper, have a iixed end secured to the portion 70 and a free end carrying the movable contact 76 positioned to engage the stationary contact portion 72 when a cam sur-face on a rotatable cam member moves into engagement with an apex of a V-shaped portion. The V-shaped portion is formed in a central portion of the arm 74 between the fixed end and the free end which carries the contact portion 76. The indentations 62 and the notches which position the terminals 64 and the arms 74 in the housing 52 are arranged to provide a switch unit 77 at the top portion of the cavity 60 and a switch unit 79 at the bottom portion of the cavity 60 with an apex designated as 80 in the arm 74 at the upper portion of the cavity 60 positioned adjacent the rear wall 54 portion of the cavity 60 while an apex designated as 82 in the arm 74 at the lower portion of the cavity 60 is positioned forwardly of the rear wall 54. Thus the apexes 80 and 82 of the switch units 77 and 79 are axially displaced relative to each other with the apex 80 being located and movable along the inside rear wall 54 and the apex 82 being located and movable along the open face 58. The rear wall 54 has a centrally located opening 84 which provides a bearing for a journal portion 86 on a cam 88.

Each of the

switch modules

24, 26, 28 and 34 has an individual cam 88 and each of the cams 88 has a body which provides a cylindrical portion 98 positioned within the cavity 60 between the apexes 80 and 82 when the journal portion 86 of the cam body is in the opening 84. The apexes 80 and 82 are located on the arms 74 t0 engage the periphery of the cylindrical portion 90. The cylindrical portion 90 has a diameter which permits the movable contacts 76 to be separated from the stationary contacts when the apexes 80` and 82 are in engagement with the periphery of the cylindrical portion 90. Extending inwardly into the cylindrical portion 90 from the open face 58 into the cylindrical portion 90 is a socket 92 and projecting outwardly of the journal portion 86 of the cam body and external of the rear wall 54 is a projection 94. The journal portion 86, the cylindrical portion 90, the socket 92 and the projection 94 are axially aligned along a common axia and the socket 92 and projection 94 have a square shaped cross section ysized so the projections 94 and sockets 92 of adjacent switch modules have a tight non-rotatable telescopic connection when the

switch modules

24, 26, 28 and 34 are in axial Ifacial juxtaposition with each other to form a switch stack as shown in FIGS. 1 and 2.

To aid in making the telescopic connection between the projections 94 and the sockets 92 of adjacent switch modules, slots 96 as shown in FIGS. 3 and 6 are included in the projections 94. Each of the cam bodies 88 has a bore 98 extending completely therethrough and one or more raised cam surfaces extending outwardly of the cylindrical portion 90. For the purpose of assembling the switch modules and their associated cams in proper oriented positions relative to each other when the

switch modules

24, 26, 28 and 34 are assembled to provide a switch stack, the rear wall 54 facing the cavity 60 of each module is provided with a groove 102 and an indexing mark 104. Similarly, the front end of the cylindrical portion 90 surrounding the socket 92 is provided with an indexing notch 106. Each of the cams 88 may have a plurality of raised cam surfaces thereon which are both radially and axially displaced relative to each other and to the indexing notch 106. As shown in FIGS. 3 and 6, the cam 88 includes a pair of raised cam surfaces 100e and 10011 which are radially spaced relative to each other as shown in FIG. 4, and axially spaced as shown in FIG. 6. When required, other cam configurations and spacings may be used as illustrated by the cam surfaces 100C and 100d in FIG. 6, as well as arrangements wherein more than two cam surfaces may be present on any individual cam 88.

If desired, the top and the bottom surfaces of the housings 52 may be provided with dovetail slots 108 which will position a marking strip, not shown, which is inserted in the aligned dovetail slots in the switch stack to identify the functions provided by the individual switch modules forming the switch stack.

When the cam 88, shown in FIG. 4, is rotated clockwise in the cavity 60, the cam surface 100a will engage the apex and cause the movable contact 76 to engage the stationary contact 72 of the switch mechanism 77 in the ripper portion of the housing 52 while the apex 82 moves over the cylindrical portion of the cam 88 so that the

contacts

76 and 72 of the switch mechanism 79 in the lower portion of the housing remain separated. When the cam 88 is rotated in a counter-clockwise direction, the cam surface b will engage the apex 82 and cause the movable contact 76 to engage the stationary contact 72 of the switch mechanism 79 in the lower p0rtion of the housing 52 while the apex 80 moves over the cylindrical portion 90 of the cam 88 so that the

contacts

76 and 72 of the switch mechanism 77 in the upper portion of the housing remain separated.

As previously stated, the housing 52 has a rear wall 54 and an open face 58. When the switch modules are assembled to form a switch stack, the switch modules are arranged to face in the same direction with the rear walls 54 and the open faces S8 of adjacent switch modules juxtaposed in facial engagement with each other. Thus the switch stack will have a closed end provided by the rear wall 54 at one end of the switch stack and an open face 58 provided by the switch module at the other end of the switch stack. The open face of the switch stack is closed by the cover 22 that has an opening 110 axially aligned with the opening 84 in the rear walls 54 of the assembled

modules

24, 26, 28 and 30 in FIG. l, or 24, 26, 28 and 34 in FIG. 2. The opening 110 preferably has a larger diameter than the openings 84 and provides a bearing for a journal portion 112 of an indexing cam 114 included in the indexing module 18 shown in FIG. 3.

The indexing module 18 includes a housing 116 having a square shaped rear wall 118 and side walls 120 extending to an open front face 122 defining an open cavity I124 with the open front face oriented to face toward the switch stack and closed by the cover 22. The housing 116, including the rear wall 118 and the side walls 120, is sized so the indexing module 18 and the switch modules have the same overall external dimensions as illustrated by FIGS. 3 and 4. The rear wall 116 is provided with a central opening 126 which provides a bearing for a journal portion 128 on the indexing cam 114. The opening 126 is partly counterbored as at 130 to receive and provide a stop for a ring-like member 132 nonrotatably carried on the journal portion 128. Located between the journal portions 112 and `128, the indexing cam 114 is provided with a cylindrical indexing portion 134 having a plurality of sawtooth-like notches 138 in its outer periphery. The notches 138 provide a detent action with a pair of rollers 140 each of which has one end received in one of the pair of grooves 142 formed in the rear wall 118 and their other end, not shown, received in suitably located grooves in the face of the cover 22 which closes the cavity 124. The rollers 140 are resiliently urged into the notches 138 by a pair of leaf springs 144 that have their opposite ends positioned in notches in the walls 120. Extending outwardly of the journal portion 112 into the cavity 60 of the switch 24 is a projection 146 that is integrally formed on the body of the cam 114 and has the same size as the projections 94 of the switch modules. The projection 146 is received in the socket 92 in the switch module 24. Extending inwardly in the portion of the body of the cam member 114 which provides the support for the ring-like member 132 and the cylindrical portion 136 is a square shaped opening or socket 148 which is axially aligned with the projection 146. The socket 148 has a square lshaped cross section which is considerably larger than the cross sectional size of the sockets 92. Extending from a bottom wall of the socket 148 through the remainder of the body of the cam including the projection 146 is a bore 150 which is axially aligned with the bores 98 in the cams 88 of the switch module.

The spring return module 16 includes a housing 152 having a square shaped rear wall 154 and side walls 156 extending to an open front face 158 defining an open cavity 160 with the open front face oriented to face toward the switch stack and closed by the cover 20. The housing 152, including the rear wall 154 and the side walls 156, is sized so the spring return module 16 and the switch modules have the same overall external dimensions as illustrated by FIGS. 4 and 5. The rear wall 154 is provided with a central opening 162. The opening 162 is provided with a counterbore 164. The covers 22 and 20 are identical with the cover 20 providing an opening 166 identical to the opening 110. Extending inwardly into the cavity 160 from a portion of a side wall 156 is a projection 168. Positioned within the cavity 160 is a torsion spring return mechanism including a spool member 170, a pair of bearing members 172 and 174 and a torsion spring 176. The spool member 170 may be formed of one or more parts and includes a cylindrical body portion

y178 having flanges

180 and 182 at its opposite ends. The

flanges

180 and 182 have

fingers

184 and 186 pointing toward each other. The torsion spring 176 has convolutions 188 surrounding the body portion 178 and opposite ends 190 and l192 pressing against the

fingers

184 and 186 in a direction to stress the convolutions 188. The bearing members 172 and 174 are identical and each respectively includes a journal portion which is received in the

openings

110 and 166 to position the spring return mechanism in the cavity 160. The bearing members '172 and 174 as well as members forming the spool member 170 have a square shaped bore 198 extending therethrough. The bore 198 has the same cross-sectional shape as the bore 150 and is axially aligned with the bore 150 of the detent module 18 as well as the `bores in the switch modules providing the switch stack.

The mounting bracket 14 has a main body portion 200 from which a mounting portion 202 extends. The main body portion 200 has a central opening 204 therein which has substantially the same diameter as the opening 162 and other openings, not shown, which receive screws for mounting the body portion 200 on the rear wall 154. As shown in FIG. l, the mounting portion 202 is spaced from the remainder of the switch assembly so the assembly 10 may be mounted on a support. If desired, in FIG. 2 the mounting portion 202 may be eliminated if the mounting portion is secured to a suitable panel 206 which has an opening 208 aligned with the opening 204.

The assembly in FIG. 2 also includes the adapter 36 and the switch 38. While the switch 38 may be of any suitable type having a linearly movable contact operator, the switch 38 shown preferably is of the type shown in the United States Patent No. 3,336,455, issued Aug. 15, 1967, to Merlin Y. Turnbull et al. As disclosed in the Turnbull et al. patent, the operator 40 is normally biased outwardly of the housing for the switch 38 and is arranged to open or close circuits between the terminals 210 of the switch 38 when the operator 40 is moved inwardly in the housing for the switch 38. The adapter 36 is provided in the assembly to provide a means for mounting the switch 38 on the rear wall 54 of the switch 34 and includes suitable openings for the rods 50 and a bore 212 and a counterbore 214. The bore 212 is aligned with the bore 98 in the cam 88 of the switch 38 and the counterbore 214 provides a stop surface 216.

The components of the assemblies shown in FIGS. 1 and 2 are maintained in juxtaposed facial engagement with each other by the rods 50` and, if desired, suitable projections on the front faces of the modules may be received in recesses in the rear faces of the modules to prevent relative rotation of the modules independently of the rods 50. When the modules are assembled, the bores 9-8 in the telescopically connected cams 88 of the assembled

switch modules

24, 26, 28 and 34 will provide a continuous bore which is aligned with the bore 212 in the adapter 36 and the bores 150 in the indexing cam 114 and bore 198 in the spring return module 16. The shaft 32 has a square shape cross section to be tightly received in the square shaped socket 148 in the indexing module 18 and the bore 198 in the spring return module to provide a nonrotative connection with the spool member and the indexing cam 114. The shaft 32 has an end 218 extending external of the mounting bracket 14. The indexing cam 114 has a nonrotative connection with the cam -88 in the switch module 24. Thus rotation of the shaft 32 will cause the cams 88 of the

switch modules

24, 26, 28 and 34 to rotate to operate the switch contacts of the switch modules in a sequence dependent upon the disposition of the cam surfaces on the cams 88 of the respective switch modules.

The shaft 32 has a bore 220 axially extending therethrough which has the same diameter as the bores 98 in the cams 88 and the bore 150 in the indexing cam 114 to provide a passage extending through the assembly 10 for the rod 42. The rod 42 has an enlarged end 222 engaging the operator 40 to switch 38 and has a button 46 on its opposite end. The button 46 is biased by the spring 48 so that the enlarged end normally engages the stop surface 216. When the button 46 is depressed inwardly in a recess in the operator 44, the switch 38 will be actuated to close circuits between its terminals 210. Normally the switch shown in FIG. 2 is furnished without the spring return module 16 so that the rear wall 118 of the indexing module 18 is positioned adjacent the panel 206. When this arrangement is employed, the operator 44 which has a nonrotatable connection with the shaft 32 may be rotated to any one of a selected number of positions to actuate and program the switch contacts of

switch modules

24, 26, 28 and 34 to provide a selected program which program is executed when the button 46 is depressed to operate the switch 38 in a manner well known to those skilled in the art. The detent module 18 is provided in the assembly 10 to maintain the switch modules in a position required by program preselected by the operator 44 and may contain the required number of notches to provide a selective number of operations. For example: the switch assembly 10 may be used to provide a decade control if five switch modules are included in the switch stack and the cam 818 has suitable cam surfaces thereon to cause the paths of the switch contacts within the switch modules to be actuated to ten different positions in response to the movement of the handle 44 to 10 positions. When this arrangement is employed the indexing portion of the indexing cam 114 will include at least 10 notches to indicate lO different switching positions.

The assembly shown in FIG. l is particularly suited for use as a master control switch for an electric vehicle and accordingly, the operating handle 12 includes a suitable button 224 which when depressed will actuate a switch, not shown, within the handle that is connected to wires 226. The wires 226 extend through the bore 220 in the shaft 32 as well as the bores 98 in the indexing cams 88 to the module 30. The module 30 has a housing identical to the switch modules. However, in module 30 the indexing cam 88 as well as the switch units 77 and 79 are eliminated, so that the module 30 acts as a terminal block. The wires 226 are connected to the terminals 64 of the module 30 so that the terminals may be connected in circuit with a horn, not shown, so that the actuation of the switch 224 will operate the horn of the vehicle. When the spring return module 16 is employed, the handle 12 will Ebe constantly urged to a neutral position by the torsion spring 176. When the handle 12 is moved in either direction from the neutral position, the torsion spring 176 will resist the movement while the components of the detent module 18 will require movement of the handle 12 to successive positions wherein the contacts of the

switch modules

24, 26 and 28 will be positively closed and thereby prevent movement of the switch contacts to positions wherein the movable contacts lightly engage the stationary contacts with a contact kiss which would cause burning of the contacts.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art.

What is claimed is:

1. A modular selector switch assembly comprising: a switch stack comprising a plurality of individual corresponding switch modules removably secured together in axial facial juxtaposition, each of the switch modules including a housing having a pair of spaced ends defining a cavity, a rotatable cam and a set of cooperating contacts actuated upon rotation of the cam within the cavity, the rotatable cam of each switch module including a body having a projection extending outwardly through an opening in one of the pair of ends, a socket inwardly extending into the housing from the end other than the said one end in axial alignment with the projection, the projection and socket each having a square shaped cross section and sized to provide a tight telescopic connection with a complementary cam of an adjacent switch module in the switch stack and a bore extending completely through the cam body in axial alignment `with the socket and projection providing a continuous bore extending axially through the cams of the switch modules in the switch stack, a switch indexing module removably secured in axial facial juxtaposition to a switch module at one end of the switch stack, said indexing module including a rotatable member having a nonrotatable telescopic connection with the cam body in the switch module at the said one end of the switch stack for rotating the cams of the switch modules in the switch stack, a bore extending through the rotatable member axially aligned with the continuous bore, and a torsion spring for resiliently maintaining the rotatable member and the cams in the switch modules against rotation from one rotative indexing position and for resiliently urging the rotatable member and the cams in the switches to the indexed position when the control means is operated in either of two opposite directions of rotation from the indexed position, means securing the switch modules and indexing module together, and a control means including a member having a nonrotative connection with the rotatable member for rotating the rotatable member and a member extending through the bore in the rotatable member and the continuous bore for transmitting a control function from the control means to an end of the switch stack that is remote from the said one end.

2. The modular `selector switch assembly in accordance with claim 1 wherein the indexing means includes a detent mechanism for resiliently maintaining the cams of the switch modules in the switch stack in any one of a plurality of indexed positions and a spring return module secured in axial facial juxtaposition with the indexing module between the control means rotatable member and the indexing module, said spring return module including a rotatable member having a square shaped central opening axially aligned with the cams of the switch modules and a torsion spring for resiliently urging the rotatable member of the spring return module toward said one indexed position.

3. The modular selector switch assembly in accordance with claim 1 wherein the cam body in each switch module includes a pair of axially spaced cam surfaces on the portion of the cam body with the cavity for actuating two sets of contacts within the cavity.

4. The modular selector switch assembly in accordance with claim 3 wherein the cam surfaces are radially spaced on the cam body.

5. The modular selector switch assembly in accordance with claim 1 including a separate switch mounted on the remote end of the switch stack, said separate switch having a linearly movable contact actuator and wherein the member for transmitting a control function includes a rod extending through all of the bores in the switch stack and the indexing module and having an end engaging the switch actuator and an end externally exposed at the control means end of the switch assembly for moving the actuator in response to movements imparted to the exposed end of the rod.

6. The modular selector switch assembly in accordance with claim 2 wherein the control means includes a rod having a square shaped cross section extending in the square shaped openings of the indexing module and the spring return module, said rod having a bore axially extending therethrough and a handle having a square shaped socket receiving a portion of the rod extending external of the spring return module, and the means for transmitting a control function includes a pair of wires for completing a circuit between a switch carried by the handle to the remote end of the switch assembly.

7. The modular selector switch assembly in accordance with claim 1 wherein one of the spaced ends of each switch module presents an open face which is oriented to face toward the indexing module and a cover closing the open face of a switch module at an end of the switch stack adjacent the indexing module is removably secured in axial facial engagement between the end switch module and the indexing module.

8. The modular selector switch in accordance with claim 7 wherein the cover has an open'mg axially aligned with the continuous bore which provides a bearing support for the rotatable member of the indexing module.

9. A modular selector switch assembly comprising: a switch stack comprising a plurality of individual corresponding switch modules removably secured together in axial facial juxtaposition, each of the switch modules including a housing having a pair of spaced ends dening a cavity, a rotatable cam and a set of cooperating contacts actuated upon rotation of the cam within the cavity, the rotatable cam of each switch module including a body having a projection extending outwardly through an opening in one of the pair of ends, a socket inwardly extending into the housing from the end other than the said one end in axial alignment with the projection, the projection and socket each having a square shaped cross section and sized to provide a tight telescopic connection with a complementary cam of an adjacent switch module in the -switch stack and a l`bore extending completely through the cam body in axial alignment with the socket and projection providing a continuous bore extending axially through the cams of the switch modules in the switch stack, a switch indexing module removably secured in axial facial juxtaposition to a switch module at one end of the switch stack, said indexing module including a rotatable member having a nonrotatable telescopic connection with the cam body in the switch module at the said one end of the switch stack for rotating the cams of the switch modules in the Switch stack, a bore extending through the rotatable member axially aligned with the continuous bore, and an indexing means including a detent mechanism for resiliently maintaining the cams of the switch modules in the switch stack in any one of a plurality of indexed positions, means securing the switch modules and indexing module together, and a control means including a member having a nonrotative connection with the rotatable member for rotating the rotatable member and a member extending through the bore in the rotatable member and the continuous bore for transmitting a control function from the control means to an end of the switch stack that is remote the said one end.

References Cited ROBERT K. SCHAEFER, Primary Examiner I. R. SCOTT, Assistant Examiner U.S. Cl. X.R. ZOO- 6, 14, 166