|Publication number||US3201737 A|
|Publication date||Aug 17, 1965|
|Filing date||Nov 13, 1962|
|Priority date||Nov 13, 1962|
|Publication number||US 3201737 A, US 3201737A, US-A-3201737, US3201737 A, US3201737A|
|Inventors||Victor G Mathison|
|Original Assignee||Bourns Inc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (18), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
GEAR-ADJ US TED VARIABLE RES IS TOR Filed NOV. 13, 1962 V, nk
INVENTOR. v l4f Meme 6. MA THISON 30 /4, /4 W United States Patent 3,201,737 GEAR-ADXUSTED VARIABLE RESISTOR Victor G. Mathison, Riverside, (Ialih, 'assignor to Bourns, Inc, a corporation of California Filed Nov. 13, 1962, Ser. No. 237,t122
- 16 Claims. (Cl. 338-174) The invention herein disclosed relates to variable resistors, such as otentiometers, and more particularly to miniature single-turn variable resistors or potentiometers of the wormscrew-adjusted (gear-adjusted) type.
Variable resistors of the class to which the invention is applicable are characterized by an arcuate resistance element of somewhat less than 360 extent, a wiper or contact capable of sweeping over the inter-terminal portion of the resistance element, andm'eans such as a shaft, for rotating the wiper or contact. Such potentiometers are of various dimensions and configurations and are in most cases in excess of one-half inch in minimum dimension in the plane of contact of the resistance element. The present invention makes possible the manufacture of a very small A" it Mr x A instrument of the class described without sacrifice of excellence in operating characteristics and without increasing the cost of ,the instruments. According to the invention a base member for supporting the electrical components of the potentiometer is formed, as by molding, of insulative material and so as to include, in situ and embedded in portions of the support, electrical terminal means. The terminal means are disposed for ready application and support of electrical components in readily accessible locations. The base member comprises a flat bottom portion and a walllike structure angularly disposed relative to the bottom and such that insertion of the base member and its attached components into a strong open-ended box-like member brings into proper juxtaposition the driving componentsfor the instrument and completes an exceptionally strong and versatile housing or casing for the operating parts. The operating mechanism comprises rotary means including a wheel-like member adapted to be rotated by a suitable driver means and arranged to in turn impart rotation to a conductive contact device which includes a combined clutch member or disc, clutch spring, slip ring or brush, and a wiper contact for effecting connection to a selected intermediate part of a resistance element. The clutch disc of the contact device comprises a clutch face that is engaged by the wheel-like member (which is hereinafter called a gear wheel for the sake of convenience) and the gear wheel has a complementary clutch face. The gear wheel has a series of long teeth that are disposed for engagement by the thread of a wormscrew or wormgear that acts as a driver for the rotary means of the resistor.
The box or cover member of the housing has mounted therein the driving wormscrew, the latter being so disposed that the gear wheel is brought into proper engagement therewith when the base member is inserted into the cover. After such insertion, the periphery along which the wall of the base member engages the cover is sealed. Thus provisions for close tolerances in relative positioning of the wormscrew and gear wheel are unnecessary, and the cost of producing the variable resistor is greatly reduced from that obtaining when close tolerances in manufacture are required. It is evident that in making a device as small as that presented by the invention,
closetoleiances are extremely diflicult to attain due to the minuteness of the operating parts. Hence avoidance of parts and structures that require close-tolerance manufacture is of considerable advantage in permitting production of a less expensive device.
The preceding brief description makes it evident that ice a principal object of the invention is to provide improvements resulting in reductions of cost of manufacturing a variable resistor of the class mentioned.
Another object of the invention is to provide an extremeiy small but easily manufactured variable resistor.
Another object of the invention is to provide a variable resistor of the class mentioned, which is immune to jamming and damage to parts when the driver is overdriven.
An additional object of the invention is to provide a contact device for a potentiometer of the class mentioned, which contact device includes a resilient washer-like memher that serves concurrently as a clutch spring, a collector ring brush, and a contact support.
Another object of the invention is to provide a molded base structure with embedded terminal means which greatly simplifies and facilitates construction and provides for excellent contact termination of a variable resistor.
Other objects of the invention will be made evident in the appended claims and the following specification including the accompanying drawing in which:
FIGURE 1 is an isometric view, grossly enlarged, of an exemplary physical embodiment of the invention, with the base at the right of the figure;
FIGURE 2 is a view in array of disassembled components of the variable resistor depicted in FIG. 1, to a still higher degree of enlargement, with sections of a housing component or cover broken away to illustrate details.
FIGURE 3 is a sectional view taken as indicated by line 33 in FIG. 1, with sealant only partially applied;
FIGURES 4 and 5 are sectional views taken as indicated by lines 4-4 and 55, respectively, in FIG. 3;
FIGURE 6 is a side view of a contact device formed by fusion-uniting two of the components depicted in FIG. 2; and
FIGURE 7 is a face view of the bottom of a base member and terminal.
Referring first to FIG. 1, the variable resistor, in the form of a potentiometer, is designated generally by the ordinal 1%. As indicated in FIG. 2, it comprises a boxlike housing means comprising an open-ended box or cover 12 and a specially formed base member 14 which includes a substantially flat bottom portion 1% and an integral upstanding wall portion 14w the outermost portion of which has a beveled interior face for a reason and purpose presently to be explained. The base member 14 is formed of thermosetting synthetic resin or other suitable electrically insulative substance, and has molded integrally in the bottom portion 14b a wire-like terminal member 142. During the formation ofthe base member by injection molding, a die operates to flatten a portion 14: of terminal wire 142 at and adjacent to the center of bottom portion 14b, as indicated in FIGS. 3 and 7. The die causes a circular cavity, 14c (FIG. 7) to be formed in the exterior face of bottom portion 14b, in which cavity the flattened portion of the terminal wire 14! is exposed. The die displaces, slightly, the portion of the wire at and near cavity Me as it flattens the wire against a flat surface of the mold; and thus a flattened face of the wire is exposed at and flush with the interior surface of bottom portion 14b of the base member as indicated in FIG. 2. These exposed surfaces of terminal member 141' are provided for reasons presently to be explained.
Following molding of the base member 14, the latter is drilled at appropriate locations through ledges 1431, 142 formed on wall portion 14w, for insertion of second and third terminal wires 14: and 14-), as indicated in FIG. 2. The latter wires are cemented in place with a suitable adhesive such as self-curing epoxy resin or the like; and are bent over against ledges 14y, 14z, as indicated in FIG. 2. Further, a conductive stub shaft or stud, 15, is fusion united in an accurately determined position, to the flattened inner exposed face of wire terminal 142 (FIG. 3). The union may be effected by resistance welding, or by brazing. thus firmly secured to' base member 14 and in excellent electrical communicationwith terminal wire 14L Stud '15 performs the plural functions of providing an electrical variable tap return conductor for the variable resistor, of providing anaccurate positioning means for a resistance element, and a shaft upon which rotary means of the variable resistor are mounted.
In addition to ledges 14y, 14z, the wall portion MW of base member 14 is also provided with an integral projection 14p which serves the several functions of keying a resistance element in place, of providing a stop abutment for limiting the extent of rotation or traverse of rotary contactfmeans that are mounted on stud 15 as hereinafter described, and of reinforcing the base member.
. A wafer=like resistanc'eielement, denoted generallyby numeralld (FIG. 2), is shaped to fit around the base of stud 15 and flat against the inner face 14b of base member 14. Preferably the resistance element 16 is permanently secured toface 14b by adhesive such as epoxy resin cement. As indicated in the drawings, the resistance The circular base of the stud 15 is. i
element comprises an insulative body or support lab that preferably is of ceramic material, anarcuate resistive means 16s supported on the body, and terminal pads Ileq, 1dr that are electrically in contact with respective end portions of. the arcuate resistive means. The resistive means is preferably but not necessarily a film of resistive metal-glass composition, that may be conveniently applied to the body or wafer and fired in a manner known in the ceramic arts. The terminal pads may be similarly applied, as by, painting on appropriate areas of the Wafer organo-metal compound that is decomposed by heating to leave firmly adherent low-resistance metal films. For example, platinum pads may be produced by applying chloroplatinate solution and heating, as is well known in the ceramic art. Silver pads may be produced using comrnercially available silver paint. In either case, the pad' material is applied so as to overlie or underlie each end portion of. the arcuate resistive means, according to whether the material is applied subsequent to, or prior to, application of the resistive means.
The resistance element 16 is of such configuration as to fit aroundthe base of stud l5, and is provided with an indentation or keyslot 16k. in which the lower part of projection 14p is received as indicated in FIG. 5. A suitable adhesive, such as self-curing resin, is applied to the bottom of element 16 and the latter is pressed into place on the inner surface of base. 14b (FIG. 3). Thus the resistance element is accurately positioned and firmly secured in place. The element terminal pads are electrically connected to respective ones of terminal Wires 14g, 141' by suitable solder or other conductive adhesive, or by welding. As is indicated in FIG. 3, the inner ends of the wires are in close proximity to respective ones of pads 16g and 1dr on the resistive element, and are soldered as at 14x to respective ones of the pads.
Disposed above element 16 and rotatable on stud 15 is a contact device 18 that comprises an integral contactcarrying ring and combined spring washer and collector brush. A contact 180 (1 16.2) is formed on an ear 18c protruding from a contact ring 18; that is integrally con-' nected along part of the inner edge to a resilient wavewasher 18w disposedinside the ring. The wave washer has an elongate central aperture one end of which is positioned adjacent the contact 180 and the other end. of which is near the area of-juncture diametrically opposite ear 180. Thus compression of the washer is permitted. Further the Washer aperture is somewhat larger in minimum diameter than the shaft of stud 15, as indicated in FIG. 5, so precision in assembly with a clutch disc presently to be described) is not necessary. That much of the contactdevice may be formed by punching froma fiat sheet of resilient conductive material such 'as berylliumpriately formed die means. Fusion-united to the upper side of the contact ring at an area diametrically opposite the contact (see FIGS. 4-5) is a combined clutch disc and stop member 18d hereinafter called a clutch disc, which is the upper element of the contact device 18. The clutch disc, as indicated in FIGS. 2, 3 and 4, has a central aperture which receives the upper reduced-diameter or shaft end of stud 15. Thus the contact device, including clutch disc 18d, spring washer 18w, and contact ring 1hr as integrated components, is rotatable on stud T5. The
edgewise outline of the complete assembled contact device in the relaxed state is depicted in FIG. 6. Rotatably mounted on stud 15 above the contactdevic 18 is a wheel means or member 20 which is a combined clutch member and gear formed preferably as a molded article of a self-lubricating material such as that marketed in commerce under the trade name Nylatron. The lower face of the clutch and gear wheel member (hereinafter called gear wheel in the interest of convenience and brevity) is constructed and arranged to frictionally engage and rotate the clutch disc of the contact device in each of opposite directions until such rotation is arrested by engagement of stop projection 14p by the ear 18a provided on disc 13d. To that end, disc 18d is formed with a plurality of generally radial deformation such as 1311 which deformations are received in respective ones of a set of complementary radial trough-like depressions Ztln between radially extending protuberances or ridge elements 20m formed on the lower face of gear wheel 20. The gear wheel is also provided with a series of gear teeth such as Ztlg whereby it may be rotated by an engaging driver such as a wormgear or wormscrew' presently to be described.
As is indicated in FIGS. 2 and 4, there is secured in and on the housing cover member 12, a driving or actuating means in the form of a wormscrew 22 the thread 22 of which is constructed and disposed for driving engagement with the teeth of gear wheel2il. Wormscrew 22 is provided with .a tool-engaging driven end 2211 exposed for access from outside the cover, that end being provided with a formation (a screw-driver slot in the illustrated embodiment) suited for driving engagement by a tool such as a screwdriver or the like. The Wormscrew is journaled at its head end in a stepped bore formed in the wall of cover member 12, and at its inner end 221 in a saddle bearing 12M fonmed integral with the cover at an interior. corner, as indicated in FIGS. 2 and 4. The worrnscrew is provided with an O-ring seal 22d (FIG. 4) seated in a recess provided by .a step in the bore in'which it is journaled, whereby passage of undesired substance through the bore is prevented. The wormscrew is pre vented from accidental or unintentional removal from the housing by a retainer pin 22p (FIG. 4) .a first end of which is disposed in a circumferential groove 22g formed in the screw and the other end of which is cemented in a hole or bore 121/ formed in a protrusion 12g formed to be integral withthe wall of the cover 12.
With the resistance element 16 affixed to surface 14b, and the rotary means comprising contact device 18 and gear wheel Ztldisposed on stud 15, it is necessary to compress or stress to some extent the spring wave washer 18w land the contact ring 181? before cover member 12 can be moved over the subas s'embly, or the subassembly slid into the cover. With the wheel 2% pressed downwardly so that the resilient members are stressed, the base member 'and supported parts are moved into the cover until teeth of wheel 2t properly engage in the groove of the thread of the wormscrew, as illustrated in FIG. 3. Wall portion 14w is so formed (see FIGS. 4 and 5) that the inner portion thereof makes snug-fit engagement with the interior surfaces of the walls of cover 12, and that portion is thick enough that the flange 14] does not contact the walls of the cover. Thus close tolerances in means'controlling the spatial location of stud 15 relative to the axis of wormscrew ZZ-are not necessary The'teeth of gearwheel 20 are sufficiently long that engagement with the wormscrew at any of a plurality of locations therealong is satisfactory; hence close dimensional tolerances on thickness of element 16, contact device 18 and the gearwheel need not be imposed. Similarly, close diametrical tolerances on the rotary structures, and precision fits of rotary elements on stud 15, are unnecessary. Thus cost of manufacture of the parts is greatly lessened, and concurrently the assembly of the parts is greatly facilitated. With the base member 14 disposed within the cover member 12 and proper inter-engagement of the thread 22! of the wormscrew with the toothed upper portion of the wormwheel assured by rotation of the screw, the cover member and base member are clamped together under light clamping force and the peripheral groove 30 (FIGS. 3 and 4) between flange 14f of the base and the edges of the walls of cover 12 is filled with a self-curing adhesive sealant 32, as indicated in FIG. 1 and at the right side only in FIG. 3.
It is to be noted that with the resilient components of the contact device stressed (as depicted in FIG. 3), the contact ring 182 is flexed and contact 180 is stressed into firm wiping contact with the resistive film or means 16s of the resistance element, that spaced-apart areas of the spring wave washer 18w are firmly pressed into good electrical contact with the step surface s of stud 15 thereby providing an excellent electrical connection between the stud and contact 180, and that clutch disc 18d is pressed into firm frictional engagement with the clutch face of wheel 26. Thus, rotation of wormscrew 22 by a suitable tool causes the screw to drive wheel and rotation of wheel 20 results in wiping rotation of contact ring 18r and contact 18c until further rotation is stopped by engagement of clutch disc ear 182 with stop project-ion 14p. Thereafter continued rotation of the screw in the same direction results in harmless slipping of the clutch face of wheel 20 over the clutch disc 18d. During such slippage alternate further compression and expansion of wave washer 18w occurs, with slight concurrent additional flexing of contact ring 1551'. Thereafter, rotation of the worm screw in the opposite direction results in rotation of the Wheel and contact device in the opposite sense. During such slipping of the clutch members in either direction, the alternating increase and decrease of resistance to rotation of the screw furnishes a tactile or sensible signal or indication of the .arrestment of the contact device. Similarly, an audible signal is produced as the deformations ride over the ridges of the worm wheel clutch face. Thus the technician adjusting the instrument is advised of the fact that a limit of adjustment has been reached. Further it should be noted that the inner end of the wormscrew is at all times securely maintained in the saddle bearing 14 by force applied to the screw by wheel 20.
Due to the inherent strength of the integral box-like cover member 12, and the nature or construction of the base member and the close fit and permanent cementing of the inner portion thereof to the cover, the resultant housing is extremely .strong and resistant to mechanical abuse. The external dimensions of the housing of the commercially-produced variable resist-or being no greater than 0.25 x 0.25 x 0.19", it is evident that wall thicknesses must be held to the feasible minimum to leave space for the operating parts, and thus the miniatur device would ordinarily ibe housed in a weak structure if conventional variable resistor housing design practices were followed. As constructed according to the description, the housing is inexpensive but extremely strong.
As is evident to those skilled in the art, the lengths of the terminal wires may be such as to meet the requirements of the trade. As depicted the terminal members are adapted to permit mounting of th variable resistor on socalled printed circuit panels or boards.
The preceding description of a preferred physical embodiment of the invention illustrates how the aforestated objects of the invention are attained. In the light of the description, changes and modifications within the scope and spirit of the invention will occur to others skilled in the art; and accordingly I do not desire that the invention be restricted except as defined by the following claims.
1. A variable resistor comprising:
a base member of molded electrically insulative material, said base member including a flat wall-like portion and an integral outstanding portion disposed at a right angle to said wall-like portion;
a rod-like conductive terminal member mounted in said outstanding portion of said base member and having a portion exposed at the exterior of said outstanding portion;
a conductive stud having a base portion disposed on said outstanding portion of said base and fusionunited to the exposed portion of said terminal member, whereby to support the stud perpendicularly of said terminal member and electrically connect the stud to said terminal member;
rotary means, including a rotary contact device, having a contact, rotatably mounted on said stud and conductively connected therewith;
resistance means, including a resistance element secured to said base member and disposed to be brushed by said contact and having at least one terminal;
means, including cover means cooperating with said base member to enclose said rotary means and resistance element for protection of the latter;
and driver means rotatably supported on said cover means and engaging said rotary means for rotating said rotary means, whereby the resistance exhibited between said terminal and said terminal member is varied between limits incident to rotation of said rotary means by said driver means.
2. A variable resistor according to claim 1, said rotary means including a driving means engaging said contact device and engaged by said driver means to be driven by the latter means. i
3. A variable resistor according to claim 1, said resistance element comprising an apertured insulative plate mounted on said base member and said stud, said plate having affixed thereon a generally arcuate resistive means disposed arcuately around said stud.
4. A variable resistor according to claim 1, said rotary means including a gear wheel member having a set of gear teeth disposed about the axis thereof and a set of clutch elements, and said contact device comprising a clutch disc having complementary clutch elements engag'ed with said set of clutch elements, and said driver means comprising a rotary gear having bidirectional driving engagement with said set of gear teeth.
5. A variable resistor comprising:
a base member of molded insulation, said base member comprising first and second integral portions the first of which is a wall-like portion and the second of which is disposed substantially at a right-angle t0 the first portion, said first portion having a generally flat exterior face and an interior face;
an elongate conductive terminal member fixed in said second portion of said base member;
a conductive stud extending upright from said second portion of said base member adjacent to said interior face and welded to said terminal member;
housing means, cooperable with said base member to provide a protected enclosure around said stud;
a resistance element mounted in said enclosure and having terminal means extending therefrom to the exterior of said enclosure;
rotary means, including rotary contact means rotatably disposed on said stud in electrical communication therewith and brushing on said resistance element;
and means, including driver means rotatably supported on said housing means, for rotating said rotary means to vary the resistance exhibited between said terminal member and said terminal means.
6. A variable resistor comprising: 7
a housing including abase member having an exterior face and an interior face, and a conductive stud upstanding from the interior face of the base member;
means including a resistance element disposed on said base member around said stud;
rotary means on said stud, including a contact device including a spring wave washer portion riding upon and electrically contacting said stud, said contact device including integral with said washer portion a contact ring having a contact, and said contact device I further including a ,clutchdisc secured to said contact ring for rotation therewith, and said wave washer portion serving to stress said clutch disc away from said interior face and to stress said contact toward saidresistance element, said rotary means further including a toothed wheel having a clutch face engaging said clutch disc;
terminal means connected respectively to said stud and said resistance element and extending to the exterior of said housing;
and rotary driving means accessible from the exterior.
of said housing and engaging said toothed wheel to rotate the latter to yieldingly drive said contact device through said clutch disc and clutch face, Whereby incident to proper rotation of said driving means the resistance exhibited between said terminals is varied.
7. A variable resistor according to claim 6, said contactdevice including a stop means and said housing in cluding an abutment means disposed for engagement by said stop means for arresting rotary motion of the contact device, said stop means and abutment means being constructed andarranged to limit rotation of said contact device to lessthan 360 of rotation and said contact device when arrested acting to yield and permit continued driving motion of said driving means and driven movement of said toothed wheel and to provide by alternately increased and decreased resistance to rotation a sensible signal indicative of arrestment of the contact device during further continued rotation of said driving means.
8. A variable resistor according to claim 6, said housing including a wall means having an interior face bearing on said toothed wheel and pressing'the latter into engagement with said clutch disc.
' 9. A variable resistor comprising: I means, including a hollow housing comprising a base member and a cover member, said base member comprising a fiat bottom portion, and a stud having a conductive surface, said stud upstanding from the fiat bottom portion of said base member; resistanceelement means, comprising a flat Wafer encircling said stud and ai'lixed to said base and bearing an insulated arcuate resistance element;
rotary means rotatably mounted upon said stud, in-
cluding a contact ring encircling and integral with a wave washer and having a contact brushing on said resistance element, said rotary means further including a clutch disc secured to said contact ring and a gear wheel having a clutch face engaging said clutch disc, said wave washer pressing on said stud and providing electrical connection between the latter and i said contact ring and serving to press said contact onto said resistance element and said clutch disc against said clutch face, said cover member preventing movement of said clutch face out of contact with said clutch disc;
end portions of said resistance element; and driver means supported by said first named means for rotating said rotary means. 10. A variable resistor according to claim 9, said clutch terminal means connected respectively to said stud and disc comprising radial deformations and said clutch face comprising complementary radial deformations.
11. A variable resistor according to claim 9, said clutch disc and said base member having cooperable stop-andabutment means eifective to limit rotation of said contact ring to less than 360, and said clutch disc and said clutch face comprising cooperating radial deformations, whereby incident to overturning of said driver means following arrestment of said clutch ring, said clutch ring intermittently yields downwardly toward said bottom portion and with said gear wheel produces a tactile signal indicative of such overturning,
12. A variable resistor comprising:
housing means comprising a cover member having a box-like form with four side walls and an end wall and an opposite open end, and comprising a base member having a bottom portion arranged to lie against the interior face of one of said side walls and having an upstanding wall portion adapted to closely fit and close said open end of said cover member;
a wormscrew disposed in and across said cover member closely adjacent to the junction of said end wall and one of said side walls;
operating means, including rotary means, mounted on said base member, said rotary means including a rotatable contact traversable along a prescribed path and means including a gear wheel for rotating the contact;
a resistance element means disposed in said housing means with a resistive element disposed along and adjacent said track for cooperation with said contact,
said gear having teeth complementary to the thread of said wormscrew and said gearwheel being constructed and so disposed relative to said base member that insertion of said base member into cover-closing relationship with said cover member brings said teeth into effective operative relationship with respect to said wormscrew in the absence of accurate disposition of the axis of said wormscrew relative to the centers of the teeth of said gear. 13. Awormscrew-adjusted variable resistor comprising: first means, including a box-like cover member having four sidewalls and an endwall closing one end'and having the other end open; wormscrew 'means mounted in said cover generally 7 parallel to said endwall; second means, including a base member having angularly related first and second portions the first of which is constructed and arranged to fit the open end of said cover member and with the cover member form a closed box-like structure and the second of which portions is constructed and arranged to be disposed against the interior of one of said sidewalls, said second means including rotary variable resistor means mounted on said base member and including a rotary gear wheel for operating saidvariable resistor means, said rotary gear wheel being disposed for engagement with said wormscrew means incident to insertion of said second portion of said base member into said cover member; and means securing said base member to said cover memberwith said gearwheel and said wormscrew in operative interengagement. I 14. A variable resistor according to claim 13,'in which said first portion of said base member includes portions abutting against the interior surfaces of the sidewalls of said cover member and including a flange portion spaced from the edges of said sidewalls to provide a groove for reception of adhesive. sealant means, whereby said gear wheel is maintained in operative relation with said worn1 15. A variable resistor according to claim 13, said second portion of said base member having molded in situ therein a terminal wire, and said terminal wire having 9 it welded thereto a stud upon which said rotary variable redriver member for rotating said wheel member, said sistor means are supported. second means further including terminal means for 16. A wormscrew-adjusted variable resistor comprising: said resistance element and aterminal connected to first assembly means, comprising around a stationary said stud for electrical communication with said conconductive stud and in superposed relationship, a 5 tact. stationary resistance element, a rotary contact device, and a wheel member, said contact device com- References Cited y the Examine! prising in superposed relationship a contact ring en- UNITED STATES PATENTS circling and integral with a wave washer device, and a clutch disc connected to the contact ring to rotate 1O g et a] therewith as a unit and said clutch disc being engaged 2884506 4/59 g by said wave washer and said wave washer contact- 2974299 3/61 Yraus g g' 338 163 ing said stud, said contact ring comprising a contact 3054077 9/62 ec e a 338 175 in brushing relationship with said element, and said 5 10/63 Z e 338 174 Wheel member comprising a clutch face in frictional 15 g 11/63 a 0 5 X contact with said clutch disc and comprising a toothed 3 /64 5 174 portion engaged with a driver member for rotating e or the Wheel member; and RICHARD M. woon, Primary Examiner. second assembly means comprising a housing enclosing and supporting said first means and including a 20 ANTHONY BARTIS, Examiner-
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|U.S. Classification||338/174, 338/DIG.100, 338/202, 338/184|
|Cooperative Classification||H01C10/14, Y10S338/01|