US2268550A - Switch and rheostat - Google Patents

Description

Jan. 1942- J. H. LITTLE ETAL 2,253,550

SWITCH AND RHEOSTAT Filed July 16, 1940 4 Sheets-Sheet l INVENTORS JOHN/i LITTLE film/o1. a. A. .51. van:- BY Wax-MM 004 800ml /%Y a ATTQRNEYS Jan. 6, 1942.

J. H. LITTLE ETAL 2,268,550

SWITCH AND RHEOSTAT v Filed July 16, 1940 4 SheetsSheet 5 I Q5 9 0 M? m Jan. 6, 1942. J. H. LITTLE ET' L 2,268,550

SWITCH AND RHEOSTAT Filed July 16, 1940 4 Sheets-Sheet 4 lN ENTORS Joy/v. 074E gamma 6. 51.0014:- B Y Mum/v 04; .BIPOWA my d4; ATTORNEYS Patented Jan. 6, 1942 swrrcn AND nnsos'ra'r John H. Little, Royal Oak, Mich, and Arnold A. Bluemle and William Earl Brown, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application July 16, 1940, Serial No. 345,798

(Cl. 201i8) 7 Claims.

This invention relates to electrical control apparatus and more particularly to a combined electric switch and rheostat.

An object of the present invention is to provide a single operating member which can be re= I ciprocated and rotated to controls. plurality of specific structures of the movable units of aplurality of switches and their connections with a single actuator.

Another object of the present invention is to provide a novel arrangement whereby two switches may be mounted on a single bracket and actuated by the same rod and each switch is operated in a desired manner in response to certain movements of the rod and whereby one switch may be actuated by the rod without effecting the position of the other switch.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings;

Fig. 1 is a front view of the combined switch and rheostat.

Fig. 2 is a sectional view taken on the 2-2-- of Fi 1.

Fig. 3 is a rear view of the combined switch and rheostat.

Fig. 4 is a'sectional view taken on the line 4-4 of Fig.-2. r

Fig. 5 is a sectional view taken on the line 55 of Fig. 1. I

Fig. 6 is an end view of the switch looking in the direction of arrow 6 in' Fig. 1.

line

Fig. 7 is a detail plan view'of the block for Fig. 9- is a sectional view taken on the line 11-4 of Fig. 8.

Fig. 10 is a sectional view taken on the line Ill-10 of Fig. 2.

Fig. 11 is a front sectional view showing parts of the switch actuator and rod shown in Fig. 2 in assembled relation.

Fig. 12 is a wiring diagram of the lighting circuit controls by the combined switch and rheostat shown in Figs. 1 to 11 inclusive.

Fig. 13 is a front plan view of a modified form of a combined switch and rheostat.

Fig. 14 is an end view of the combined switch and rheostat shown in Fig. 13.

Fig. 15 is a sectional view taken on line l5l5 of Fig. 13.

Fig. 16 is an end view of the switch looking in the direction of arrow H6 in Fig. 15.

Fig. 1'7 is a sectional view taken on line ll-ll of Fig. 15.

Fig. 18 is a sectional view taken on line 48-18 of Fig. 15.-

Fig. 19 is a sectional view taken on line 19-49 of Fig. 15.

Fig. 20 is a wiring diagram of the lighting circuits controlled by the combined switch and rheostat shown in Figs. 13 to 19 inclusive.

Referring to the drawings '20 designates a bracket of L-shaped formation comprising arms 2| and 22. The bracket is adapted to be supported from a panel 23. The panel 23 and the arm 22 of the bracket 20 are provided with aligned openings. In the present instance the opening in the arm 22 is formed by forcing a portion of thearm 22 out of its normal plane into a tubular portion 25 which is internally threaded to receive the threaded shank of a flanged bushing 26. The outer face of the flange of the bushing 26 is provided with suitable notches or about the bore of the bushing to receive a key whereby the bushing may be threaded into tubular portion 25 to clamp the arm 22 of L-shaped bracket firmly against the rear face of the panel 23.

The arm 2! of the bracket is provided with a bearing opening 30 and an elongated slot 3|, the marginal walls of the slot'23 are deformed out of the plane of the arm 2| to provide a channel shaped recess 33. A switch casing 34 of cupped formation is attached to the arm 22 in any suitable manner, such as spot welding. The casing 34 is closed by dielectric terminal head or closure 35 carrying stationary terminals 36, 31, 38, 39, 40 and 4|. The bottom wall 42 of the casing 34 is provided with a bearing aperture 43 and an elongated slot 44. When the casing is secured to the arm 22, the opening 44 and the slot 43 will be in alignment with the opening 30 and slot 3| respectively; The channel shaped recesses 33 and bottom wall of the casing 34 form channels 45 between the casing and the bracket.

Before the casing 42 is attached to the arm 22 an actuator unit 50 is assembled with the elements. The actuator unit 50 comprises a U- shaped member having arms and 52 connected by a yoke 53. Each arm of the .U-shaped member is provided with an aperture, the arm 5| has a bearing aperture 54 while the arm 52 is provided with an enlarged aperture 55 through which a shaft 60 may loosely pass. The yoke 53 carries a pin or post 6| having a collar portion 62 and a shank portion 6241.. The collar 02 projects into the channels 45 formed by the arm and housing, said collar having a sliding fit with in the channels and assists in guiding the actuator longitudinally in the slots. The collar also prevents the actuator unit 50 from being disassembled from the arm 22. A flat spring of L- shaped formation has one of its arms 54 thereof attached to the yoke 53. This is accomplished in the present instance by riveting over one end of the pin 6| against the upper face of the spring. The other arm 65 of the spring is biased upwarolly as viewed in Fig. 2. The arm 55 is provided with an opening 55 through which the rod 60 may loosely pass. The lower end of the opening 66 is reduced as at 65a, see Fig. 11. A portion of the arm 64 of the spring is struck out to form a lug 67. This lug Bl extends into a slot 53 in the arm 52 of the U-shaped member to prevent the spring from rotating relative to the arm. The yoke 53 is also struck out to provide an ex tension 68 which projects into the elongated slot of arm 2| to prevent the actuator fromtuming relative to the arm 2|.

The shank portion 62a of the post 51 projects through the elongated slots 3| and d6 of the arm I and a shank I02 is disposed between the arm ll and bracket respectively and extends into a radial slot ll provided on one side of a dielectric rotor 32.. The radial slot H is adjacent the inside surface of the bottom wall 52 of the casing. The

other side of the rotor is provided with a recess to receive a compression spring 13 which urges a movable contact l4v drivingly supported on the rotor 12 against the stationary terminals carried by the closure 35. The spring 13 also operates to maintain a boss 15 carried by rotor within the. bearing openings 30 and 43 provided in the arm 2| and the bottom wall of the casing and also to maintain the shank portion 62a in the radial slot l l The arm 22 supports a U-bracket 80 having arms BI and 82 provided with aligned apertures through which the shaft 60 may loosely pass. The arm 82 carries an insulating block 83 having a counterbored opening 83a. in alignment with the opening in the arm 82. Within the counterbored opening is housed a coil spring 84 and an insulating washer 85, the spring 84 having one end resting on a shoulder formed in the opening 83a and the other end engaging the washer 85 to urge the washer 85 against the end ofa tubular portion 86 formed on a disc portion 81 provided at one end of a conducting strip 88. The conducting strip 80 is attached to the insulating block 83 by a tubular rivet 89 see Fig. 8.

The block 03 is provided with an arcuate recess 90 about the opening 83a. A resistance element 9| is supported within the recess 90. The resistance element comprises a helically wound wire and has one end bearing against a shoulder 90a and the other end of the wire unit extends its own resiliency, into the annular groove ||-l.

fiat sides on its exterior surface and the interior of the shank is non-circular. A movable contact N13 is supported on the shank. This contact comprises a disc portion I04 having an opening cone forming in outline to the exterior surface of the shank so as to be, driven thereby. I The contact |03 is provided with two arms I05 and Mia. Each arm is provided with a boss. The boss of arm I05 is urged into frictional contact with the resistance unit 9| while the boss of arm I051: is urged into electrical engagement with the flat surface of the disc portion Bl of the strip 58 by a spring I06 about the shank M1. The spring is disposed between the flange |0| of the bushing 90 and the disc portion I04 of the movable contact. The other end of the strip 88 is electrically connected to the terminal 40 carried by the closure 35.

The contour of the rod 50 conforms with the non-rounded interior of the bushing I00 so as to drive same. The inner end of the shaft 50 is provided with a conical or cam surface M8 and a shaft portion |09 with the shaft portion supported in the maring opening 54 in the arm 52. The outer end of the rod carries a knob M0.

The bushing 26 forms the other bearing for the rod. The rod-58 is provided with an annular groove intermediate its ends and said groove is so positioned on the rod 80 that when the rod is in its assembled relation the groove ill will be just inside the arm 5! of the bracket '50.

When the rod is assembled with its associated elements, the rod is first passed through the bearing bushing 25 and then the rod is rotated until the non-rounded contour of the shaft registers with the inside bore of the bushing I09. When that registration occurs further inward movement of the rod will cause the shaft portion N6 of the rod to pass through the/openings in the arms 59 and the arm-63 of the spring member.

At this point the enlarged portion of the opening portion 56a of the opening 66, consequently when.

the rod is moved further the arm 53 will be moved against the bias of the spring so that the rod can pass through the opening until the shaft portion |09 engages the bearing in the arm 5|. When the shaft portion I09 fltsjinto the bearing opening 54 the spring will snap, due to When this occurs the rod will be interlocked which projects into the radial slot ll of the rotor 12 will cause the rotor to rotate in the bearing openings 30 and 43 in the arm 2| and the bottom 42 respectively. It is to be stated here that so long as the rod 60 is not rotated the movable contact I03 will remain stationary. When the knob I01 is rotated, the rod 60 will drive the insulating bushing I which in turn will drive the movable contact I03 causing the arms II05 and I05a'to slide frictionally over the resistance coil SI and disc 81, respectively.

Referring to Figs. 13 to 20, inclusive, a modifled form of the present invention is shown. In the modified form of the invention the L-shaped bracket I has arms I2I and I22. The arm IZI is provided with an opening formed by forcing a portion of the arm I2i inwardly to provide a tubular portion I24 which is internally threaded,

to receive a flanged bushing I25. The flanged bushing in this instance forms a bearing for an actuating rod I26.

The arm I22 of the bracket is provided with. an elongated guide slot I21 intermediate its length and supports a switch 528. The switch comprises a rectangular casing I29 provided with marginal tongues I30 on its side walls which are bent over against a closure I3I of insulating material to complete the switch assembly. The closure I3I carries a plurality of stationary terminals the arrangement of which will be set out later. The stationary terminals have their inner ends thereof flush with the inner face of the closure I3I.

The movable contact mechanism -for the switch comprises a metal plate or slide I32 fitted for reciprocation within the switch casing I29. This slide comprises a metal plate having a rectangular head portion I33 with the side edges thereof adjacent the side walls so as to be guided by the side walls of the casing I29 and a long arm I34 which extends through an opening I35 in an end wall I36 of the casing I29. Thefree end of the arm is bent downwardly and is provided with a reduced portion projecting into and having a sliding fit with the slot I21 to assist in guiding the plate in its longitudinal movements.

The central section of the head portion I33 of the plate I32 is apertured to receive a reduced .portion of a counterbored sleeve I36. The sleeve is attached to the head portion I33 by spinning over the sleeve against the bottom faced the slide. The smaller bore dimension of the sleeve houses a ball I31 which normally restsin one or the other of depressions I38 formed in the bottom wall of the casing. The corners of the head portion I33 of the plate I32 are partially severed therefrom and the severed portions are bent upwardly to provide four prongs I39. These prongs are adapted to guide a block I of insulating material which has notched corners to receive the prongs I39. The lower side of the block has a recess I'4I the bottom of which forms a seat for one end of a spring 2. The other I38 are formed in the bottom wall of the switch casing I29 in straight alignment and are in the longitudinal path of the ball I 31 which moves with the slide I32. The depressions indicate the various positions of the slide.

A flat spring I50 is attached to the plate I32 by the sleeve I36. This is accomplished by having the reduced portion of the sleeve passing through a suitable opening in the spring and spun over the lower face of the plate M2. The spring 359 is so formed and arranged with respect to the plate 32 that the free end oi the spring is biased upwardly. The free end of the spring I50 carries an L-shaped brasket which has one arm icI attached to the spring by rivets. The other arm 1152 of the bracket extends Toe= yond the free end of the spring and projects downwardly. The arm 552 is provided with a end of the spring I42 rests on a shoulder provided by the counterbore in the sleeve 136. The spring I42 operates in one direction to urge a contact plate I43 carried on the upper surface of the block into contact engagement with the inner surface of the closure I3I and in the otherv washer I61.

direction to urge the plate I32 against the bottom wall of the switch casing. A small compression spring I44 is confined within the spring I. The spring I44 has one end seated against the bottom of the recess HI and the other end engaging the ball. I31 to urge the ball against the bottom wall of the casing. Three depressions consuming devices.

grooyes partially overlie the coils, see Fig. 19,.

.the coils out of the grooves.

slot having a portion larger than the diameter of a rod I26 and'having a narrow portion equal to the diameter of reduced portion of the rod which is formed by cutting an annular groove I54 at the inner end of the red.

A resistance unit I60 is supported on the arm I22. This unit comprises a U-shaped bracket I6I having arms 162 and I63. Each arm is provided with an aperture through which the rod I26 may loosely pass. The arm 162 carries an insulating block I64 having a counterbored opening I65 in alignment with the openings of the arms I62 and I63. Within the counterbored opening of the block I64 is housed a coil spring I66 and an insulating washer I61, the spring has one end engaging a shoulder provided by the counterbored opening and the other end engaging the washer I61 to urge same against the end of a tubular portion 168 formed in a metallic disc I69.

The inner face of the block I64 is provided with a pair of segmental grooves HI and I12 arranged concentrically with respect to the counterbore I65. A pair of resistance elements I13 and I14 comprising helically wound wire is formed to lie in the bottom surface of the grooves HI and I12 respectively and are adapted to be retained in the grooves by one end of conducting members I15 and I16 which are electrically connected to one end of the coils I13 and I14, respectively, by tubular rivets I11 and I18 respectively. The other end of the conducting members I15 and I16, respectively are connected to suitable lead wires to lamp or other It will be noted that the thereby ensuring against upward movement of By this arrangement the free ends of the coils need not be fixed to the block.

A bridging contact I punched and stamped from sheet metal is provided with a non-circular opening I8I formed in a central portion I82. The bridging contact has two diametrically opposed arms I86 and I86. The bridging contact I80 is drivingly supported upon an insulating bushing I81 having a flange I88 anda shank I89. The bushing. is disposed between the arm I63 of the U-bracket I6I and the insulating The contact arms I85 and I86 are urged into frictional contact against .the inner face of the block I64 by a coiled spring I about the shank I89 and having one end bearing the rod I26 supports an insulating knob I93. Adjacent the conical end 593 of the rod there is provided an annular groove I94. To assemble the rod MS with the plate I32 the conicalend I03 of the rod is first passed througha bushing 26 and then through the aligned openings provided by the resistance unit. It is to be understood that the fiat side of the rod registers with the interior contour of the bushing I81. In case the contours'of the bushing I37 and the rod i26 do not register the rod is rotated until the registration occurs. The rod then is pushed inwardly until the conical end I93 projects through the opening of the bracket. As soon as the annular groove I94 is in the same vertical plane of the arm, thespring I50 will snap the bracket upwardly into the groove which interlocks the operating rod I26 with the spring I50. Longitudinal movement of the rod M6 on the front side of the panel 23 then serves to shift the plate from one position to another, the plate being held in its selected position by the action of the spring I44 forcing the ball I31 downwardly to seat in one of the depressions.

If it is desired to rotate the contact 580 so that the arms' I85 and I86 will engage the coils I73 and I14 the knob is rotated. The contacts are adapted to rotate. 180. A stop 200 formed integral with the block controls the limit of rotary movement of the contact arms.

- The stationary terminals carried by the closure I3I and which have been referred to as having their inner ends flush with the inner face of the closure will now be described. The closure I3I supports a conducting bracket 224 outside the closure. The bracket which supports at one end thereof a plurality of terminal screws 226. The bracket is attached to the closure I3! by rivets 221. The other end of the bracket 225 supports an adjustable contact 228 normally engaged by a movable contact 229 carried on the free end of a thermostatic strip 230. The other end of the thermostatic strip 230 is electrically connected to an elongated conducting plate 23I, shown diagrammatically in Fig. 20. Paralleling the conducting plate 23I are three stationary terminals, a dimmer switch terminal 232, a tail lamp terminal 233, and a park light terminal 234. The terminal 232 is electrically connected by a lead 235 to the common terminal of a dimmer switch, 236. The terminal 233 is connected by a lead. 237 to the conducting member I175. The terminal 234 is connected by a lead 238 to the park" lamps 240. The conducting strip 23I is connected to a terminal 24I supported on the block H64. The tail lamp 242 is connected to the conducting member I35 by a lead 243. It is to be understood that the tail lamp could be connected to the lead 243 to the terminal 233.

The switch structure shown in detail in Figs. 1 to 12, inclusive, is useful in controlling the various lighting circuits of an automotive vehicle. The circuits adapted to be controlled in this instance is shown diagrammatically in Fig. 13. It is to be stated here that the stationary contact terminals 36, 31, 38, 39, 40 and 4| are supported on the closure I35 are arranged in a circular row and that the terminal 36, 31 and 40 and 4| are connected together by conducting plates 2M and 202, respectively, and that the plates 20I and 202 are only shown in the diagram. In the diagram 203 designates a storage battery having one terminal grounded at 204. The other terminal of the battery is connected to the plate 20I by a lead 205 througha fuse 206. The head lamps 201 having dim" filaments 208 and bright filaments 209-. are adapted to be alternately connected in a circuit by a dimmer switch 2w having a live terminal 2 connected by a lead 2I2 to terminal 33. The terminal 39 is connected tothe parking" lamps 2E3 by a lead 2M. The plate 202 is connected to the contact by the strap 88. The resistance coil is connected to the conducting plate which is in turn connected by a lead 2I5 to the various instrument board lamps 2I6. All'of the lamps are grounded by the usual ground connections.

Referring to the wiring diagram .the movable contact 2 is shown in dotted lines in the ofif position of the lighting switch. When the control knob is moved away from the panel the movable contact 2H will be moved in the direction of the arrow 2I0. In the first on position of the switch the movable contact will bridge plate 20I, terminal 30'and plate 202 causing current from the battery 203, lead 205, fuse 206, plate 20!, movable contact 2I'I from whence it is divided; a portion of the current will flow from contact 2, through terminal 39, lead 2&4, parking lamp 2I3 and back to battery through the ground connections. Another portion of the current will flow from the movable contact 2, terminal plate 202, lead 2I0, tail lamp 220 and back to battery through the ground connection.

Should the operator turn the rod a certain angular distance the contact arm I05 of contact I03 will engage the resistance coil 0| causing current to also flow from the plate 202 through plate 83, movable contact I03, resistance coil 9i, plate 35, lead 2I5, through the instrument lights 228 and back to battery through ground connections. The instrument lights in this instance will burn dimly when the movable contact arm I05 is rotated to engage the conducting strip 35 the instrument light will burn brightly.

When the rod is pulled out further from the panel the movable contact will be moved to the second on position of the switch causing the movable contact to bridge terminals 205, 30 and 202 causing current to flow from the battery 23,

lead 205, fuse 206 contact 20I and movable con-.

tact 2|! from whence it will be divided; a portion of the current will flow from the movable contact 2|? to the head lamps 209 through lead M2 to the live terminal fill of dimmer switch 2"]. The dimmer switch is manually operated and is adapted to connect-alternately the dim and bright filaments of the head lamps in a circuit. Since one or the other of the dim or bright lamps are connected in the circuit, the return flow of the current to the battery is through the ground connections. The other portion of the current will flow from the movable contact 2I'I through terminal 202, lead 2I9 tail lamp 220 and back to battery through the ground connection.

' The switch structure shown in detail in Figs. 13 to 19 inclusive is useful in'controlling the various lighting circuits shown diagrammatically in Fig. 20. Referring to the diagram the storage battery 203 has one terminal grounded at 204 and having the other terminal electrically connected to the conducting member 226. Both switches position the triangularshaped contact I43 will bridge stationary contacts 234, 233 and 23I, caus- 228, movable contact 223 conducting plate 23I,

bridging contacts I43, from whence it is divided; 8. portion of the current will flow from the movable contact through stationary terminal 234,1ead.

238 through stationary terminal 234, lead 238 through parking lamps 240 and back to battery through the ground connections. Another portion of the current will flow from the movable contact 243, terminal 233, lead 231 tail light 242 and back to battery through ground connections. In the second on position ,of the switch I28 the movable contact 243 will bridge terminals 23 l, 233 and 232, and disconnect the terminal 234 from the circuit. In this position the current will flow from the batmry 203m the same manner as in the first on position with this exception that a portion of the current will flow from the movable contact 243 to the terminal 232 and thence through the lead 235 to the common terminal 238 of the dimmer switch. The dimmer switch is adapted to connect alternately the bright filament 245 and the dim filament 246 of the head lamp 241 the circuit only when the switch I28 is in the second on position.

When the operator desires to have the instrument lamp mounted on the dash board burning the knob I 93 is rotated a certain angular distance in the direction of the arrow 250 see Fig. '20, to drive the movable contact I80, when the movable contact I80 is rotateduntil the arms I88 and I85 bridge stationary contacts 250 and 25I supported on the block I64. The contact 250 is electrically connected to a plate 252 while contact 25I is electrically connected to plate 253. The plate 252 is connected to the contact 23! of switch I28 by a lead 254 while the plate 253 is connected by a lead 255 to a lamp 258.

-An instrument lamp 280 is connected to the plate I18 by a lead 251. It, is to be understood that more than one lamp may be connected in parallel or series to the terminal plate I16. When the operator turns the knob I83 until the arms I85 and I88 of contact I80 engage the resistance coils I13 and I14, the instrument lamp 258 will burn dimly. When the arms engage the rivets or contacts I11 and I18 the resistance .coils I13 and I14 will be short circuited andthe lamp 258 will burn brightly. It will be observed that the instrument lamp 258 can be connected in a circuit only when the switch I28 is moved to one of its on positions while the lamp 258, suitable for reading road maps. can be connected in a circuit in any position of the switch I28.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows;

1. A combined variable resistance and switch unit comprising a panel having an opening; a frame member attached to, the panel; a resistance unit of substantially arcuate shape; a support for the resistance unit carried by the frame; a switch carried by the frame; a member slidably supported on the frame including means for actuating a movable part of the switch upon sliding movements of the member; a common removable shaft adapted for rotary and longitudinal movements adapted to be inserted through the opening from the front of the panel said shaft being provided with anannular groove; means provided by the slidable member and the frame for supporting the shaft centrally of the resistance elements; 'a contact arm slidably engaging the resistance unit and rotatable with the shaft; and resilient means fixed at one end to the slidable member and having its free end biased toward the shaft, said free end being provided with opening through which the shaft passes, said opening in the resilient means being reduced to fit snugly in the groove of the shaft for interlocking the resilient means with the shaft whereby said shaft is capable of imparting longitudinal movements to the member in the assembled relation of the parts.

2. A mounting comprising; an L-shaped bracket of whichthe one arm is provided with an aperture to provide a bearing for a shaft while the other arm is provided with an elongated slot; a cup-shaped housing having its bottom wall fixed to the second mentioned arm and having an elongated slot in alignment with the slot in said arm; a U-shaped member having each arm provided with apertures with one aperture being larger than the other the larger opening permitting a shaft to pass loosely therethrough while the other opening provides a bearing for a shaft; means carried by the U- shaped members extending through the elongated slots of the housing and the bracket and adapted to actuate movable means within the wardly, a portion of the free end being cut out to form a slot of a size to allow the shaft to pass therethrough, said slot having a narrow portion to fit into the groove of the shaft whereby said shaft is adapted to impart longitudinal movements to the U-member in the assembled relation of the elements. a

3. A combined variable resistance and switch unit comprising; a frame; a resistance unit of substantial arcuate shape; a support for the resistance unit carried by the frame; a switch carried by the frame; a bracket slidably sup ported upon the frame including means for actuating the switch upon sliding movements of the bracket; a removable shaft adapted for rotary and longitudinal movements, said shaft being provided. with an annular groove; spaced apertured arms provided by the frame and bracket to provide bearings for the shaft and to support the shaft centrally of the resistance unit; a contact arm slidably engaging the resistance unit and rotatable with the shaft; and a resilient member fixed at one end to the bracket and provided with an opening at its free end through which the shaft passes, said opening being reduced to fit snugly between shoulders formed by the groove, said resilient member being sufficiently strong to maintain the reduced portion between the shoulders of the groove whereby said shaft is adapted to impart movements to the bracket when the shaft is moved longitudinally in the assembled. relation of the parts.

4.. A combined variable resistance and switch unit comprising; a frame; a resistance unit substantially arcuate in shape; a support for the resistance unit carried by the frame; a switch carried by the frame; a bracket slidably supported upon the frame including means for actuating the switch upon sliding movements of the bracket; a removable shaft adapted for rotary and longitudinal movements, said shaft being provided with an annular groove; spaced apertured arms provided by the frame and bracket to provide bearings for the shaft and to support the shaft centrally of the resistance unit; an insulating bushing supported relative to the resistance unit through which the shaft extends; a contact arm supported on the bushing whereby upon rotation of the shaft said bushing and contact will be rotated therewith, said arm being in frictional contact with the resistance unit; and a resilient member secured at one end to the bracket with the free end inclined upwardly with a portion of the free end being cut out to form a slot of a size to allow the shaft to pass through, said slot having a narrow portion to register with the groove whereby said shaft is capable of imparting sliding movements to the bracket in the assembled relation of the parts.

5. A switching mechanism comprising a plurality of circuit controllers adapted to be mounted on the one side of a support and including a plurality of movable elements and a frame adapted to be mounted over a bearing aperture in the support; a non-rounded rod adapted to be inserted through the bearing aperture in the support and through a non-rounded aperture in a part of one of the movable elements, the inner end of the rod having a reduced portion adapted to extend into a bearing aperture in another movable element and having a perimetrical groove; and a yieldable member carried by the second mentioned movable element, said yieldable element having an opening through which the rod passes, the opening being reduced at one side to fit into the perimetrical groove of the rod so as to interlock the yieldable element with the rod whereby the rod is capable of imparting longitudinal movements to the second mentioned movable element and rotary movements to the first mentioned movable element in the assembled relation of the parts.

1 6. A switching mechanism comprising a comrounded rod adapted to pass through a nonrounded opening provided by the rotatable carrier, said rod being provided with an annular groove intermediate its end; and a resilient member fixedat one end to the longitudinal movable member and having its free end biased toward the axis of the non-round opening of the contact carrier, said free end having an opening of such size to permit the inner end of the rod to pass therethrough, said opening also having a narrow portion adapted to fit into the annular groove to interlock yieldingly the langitudinal movable member with the rod and to permit rotation of the rod in the assembled relation to drive the rotatable carrier.

7. An electrical control device including a plurality of circuit controllers adapted to be mounted on one side of a panel, comprising a the variable resistance; a common removable operating shaft for operating the actuating means, said shaft adapted to be inserted from the other side of the panel through the openings of the panel and bracket arm and having a rotatable driving association with the actuating means for the resistance, the inner end of the shaft being rotatably supported on the actuating means for the switch; a yieldable element fixed to the actuating means for the switch; and cooperating provisions provided by the shaft and the yieldable element for interlocking the element with the shaft whereby the shaft is capable of longitudinal movement to operate the switch actuating means without effecting the position of the resistance actuating means, said cooperating means also permitting rotational movements for the shaft so as to drive the actuating means for the resistance without changing the position of the switch actuating means in bined switch unit and a resistance unit; a longithe assembled relation of the parts.

tudinally movable member for actuating a contact carrier of the switch unit; a rotatable contact carrier for the resistance unit; a non-

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