US2573432A - Assembling fixture - Google Patents

Description

Oct. 30, 1951 B. P. GIRARD ETAL 2,573,432

ASSEMBLING FIXTURE 3 Sheets-Sheet 2 Filed July 23, 1946 llllllll IHIIHIIIIHH H'lll INVENTORS B. RG/RARD BAR/1E TSCH ATTORNEY Oct. 30'. 1951 B. P. GIRARD ETAL 2,573,432

ASSEMBLIING FIXTURE 7 Filed July 23, 1946 3 sheets-sheet s 44 FIG. 7 43 45 42 [45 ll] illlllli i) A T TORNEY Patented Oct. 30, 1951 P-A l em OIFFIICET AS SEMBLI'NG FIXTURE:

lfieorporatedfNew York;

New York NPYi; arcorporation' of ApplicatiomJilly 23,4946, Serial No,685,728

1 GCliiiihsr (01 This invention relates to. assemblingmitturess and more partieuiarly to fixtures'for assembling? potentiometer, cards an'd"associatefelements in potentiometer housings? This inventionisi"related 'in generalftoassem 5' bling potentiometer. cards, insulezting' gstrips Janet i slip rin'gs in multiple'rgroove type cylindriealpotentiometer'housings; The potentiometer"hous-' ingsmayfhaveioneor more annular grooves pro: vided". therein for receiving: a: fixed number; of elements:- requir'edito make: up a single poten-i' tiometerum'ti Iii'one "partidular type: ofpote'n tiom'etr eachemiul'arfgr'oove. of'iheTpotentidme ter-housinghas "assembled'thereintagroupiot'e1e= ments; comprising an outer insulating ring, at. potentiometer card, tworintermediate insulating: rings," a slip :ring "and"aminsulatefbridge mem ber: Thev potentiometeri cardi'hes its beginning: turna'ntFitsi en'dtturn marked'tand' is positioned" in *the'housing'so thatonepffthe'marked turns is "directly oppositescribemarksprovidedbn the: face .of the'respective partition. whic'hiorms .the. particular-annular'groove'involvedi The "potentiometer card'antl thesl'ipring must? havetheir 'conta'ctihg'surfacesinfthe same'wplaine; which plane *must'be slightly above 'th'eia'ce of .1 the housing: while: thewariou's -insu1atingTriri'gs'" must be positioned? substantially "below thisz'con tacti'ngplanes The 'bridee mustfbepcsitionedjn linewith'ithe 0111761 insulating ring ,1 ain'd'ihave it's 1 topt'face extendingiaboveithe .contactiiig plblne of the "potentiometer: card; so that 'it will" lift the V potentiometer "brush" offltne'-card"wlien" itis moving"fr'om the end'i of"'the"cardto the beginning; thereof orvice vers'a;

One proposed'method ot assembling the various. elementsinto' the annular groove was by ifancLfl in whichtcas'e each" element was partially, positionecl'inithe groovein'itsproper position, andf' thenth'e entirefgroup' Wetsiforced'into thezgroove. Inforcin'gthe group oi"el'e'ments intoitheegroovey. relative movement between theindividiialfielments resuitedjland when'it'was necessary toad just'only 'one'pf the"elements:vsuchladjiistnient usualli disturbed the other "elements.

When any movement ocourredbetween 'the'potentiometer'cardiandfthe various insultttingrings,1 it usually-produced e'series' 'of-1oo'se tiirnsion the: potentiometer "card'twhiehlseriousiy j efiectedftfien electriealcheracteristiesof tiirardor broke or" 50' 2. loosenedi'zthelea'ds 'secure'dtothe beginning and endi'turns':o'fi'the"card: Inedditibn, it"wa's'very difiicult t6 1 position" each' individual element at":- its proper" elevationwithre'spect tfieach other and'to the-face of the potentiometer'housing;

h'andess'em'bly'of'the'intiividual elements" within'ihefammlar grooveproved' to: bee? very tediiiusii'andJtime=c0nsumingoperation: Fiirther more; Many units'w'ere unsatisfactory'becau'se"of above-described. defects prod-needby'sucifassem blyl An obi 'e'ct of""the'inventib'n is'ii'tofprovid'i new: andifimproved' assembling fixtures;

Another object of "the invention is to provide an assemblytfiiiture for-assemblingivariws e1'e-'- ments required' to" make up'a cyl'ihdricatpo tenti'ometer. a. p

In accordance withla specifieiembodiinenfioi the invention-.there.is providedmeansifor effect ingea loose pre-assembl'y offtheivarious elements toberassembledfin the groove. of .a potentiometer housing, means for t clamping: the elments' tightl'i together as a composite unitin theifiiitiire-and meansior transferring-4 vthe unit from v the fiiiture 'to'the potentiometer hbusing dfir'ing.which trans fer no: relative -movement occurs between the. in-i dividualielementsof the-unit;

Awclear. .understandi'ngpf the invention. maybe.

hadv from the. following. detailed? description. of-

formingLaspeei-fic embodiment ofethe invention;

Fig, 2 is a vertical, sectionalview-tal zen along, line 2.-2 of Fig-:- 1; t

Fig: 3 is :an enlarged-,tfragmentary, verticaiwiew ofwa pertion of the :fixture :ShOWn in:Fig.-- 1,: and havingiportions .thereofabroken: away to illu'straite- ,,someiofitheiintemalzstructure;

Fig-.14 is" a fragmentary; verticali'rig hwhend viewof a portion 1 oi theapparatusshown in Fig: 1 2 j Fig? 5- is ai"-fi"agmentaryi front verticaivievv of a. portion of the apparatiisshown*inFig 1 Fig: 6* is a horizontaL seetiiinal view" taken aldngiline BLSbfFii fZi" Fig, 7 is anienlar'ged; iregmentem'veritieaisectionaIifviewioiiaportiowofltne :a'pperatiis:

elements to be assembled together in a potentiometer housing;

Fig. 9 is a fragmentary, vertical sectional view showing the various elements of Fig. 8 positioned in the apparatus shown in Figs. 1 and 2;

Fig. is a fragmentary, vertical sectional view taken along line |6|6 of Fig. 5;

Fig. 11 shows the assembling fixture inverted and positioned on a potentiometer housing, and

Fig. 12 shows the position of the elements in the potentiometer housing after they have been transferred from the fixture.

Referring now to the .drawings, particularly Fig. 2, there is shown a cylindrical support 28 having a bore 2| and a counterbore 22 adjacent and supporting an assembling fixture 23. The support 2|] serves to hold the assembling fixture 23 in a substantially stationary position while a potentiometer card and its associated strip-like elements, hereinafter to be described, are assembled in the fixture 23. prises a ring 24 having a bore 25 adjacent to its upper face, a counterbore 26 adjacent to its lower ring 24 adjacent to the counterbore 26 and is provided with an integral flange 32, the periphery of which is substantially flush with the periphery of the ring 24. The flange 32 is positioned against the bottom face of the annular ring 24 and secured thereto by a plurality of screws 3333, and is provided with four arcuate slots 35-35 spaced equidistantly around the periphery 34 of the body portion 3| (Fig. 6). The inner wall of the slots 3535 is vertically aligned with the periphery 34 and the outer wall of the slots is vertically aligned with the bore 25 of the ring 24.

An ejector ring 36 is slidably positioned around the body portion 3| and is provided with four arouate-shaped legs 3131 slidably positioned in the arcuate slots 3535 provided in the flange 32. The flange 32 is wider than the bottom face of the flange 32 and it extends beyond the counterbore 26 and thereby provides an annular shoulder 38 similar to the shoulder 21 provided in the ring 24. The ring 36 is provided with an annular flange 40, the periphery of which slidably engages the counterbore 26 of the ring 24. Since the flange is free to slide in the counterbore 26 between the shoulder 21 and the shoulder 38, the travel of the ring 36 is fixed by these shoulders. The upper face of the ring 36 is provided with an outer groove 4| and an inner groove 42 which .15 to the upper face of the support for receiving 4 municates with the bottom of a horizontal arcuate slot 54 cut in the periphery of the ring 24 so that a substantially thin wall section exists at the sight hole 53, whereby the surface 45 at the points 46 and 41 may be easily viewed therethrough. An elongated sight hole 55 (Fig. 5) is provided at the bottom of a tapered aperture 56 also provided in the periphery of the annular ring 24 (Fig.2). A thin wall section 51 remains above the elongated sight hole 56 and has an index marked 58 centrally scribed thereon. An index mark 66 (Fig. 12) is scribed across the bottom wall of the sight hole 55 provided in the tapered aperture 56 directly in line with the index mark 58..

A resilient clamping ring 62 (Fig. 2) is positioned on the upper face of the base 3|] and is provided with a plurality of substantially circular apertures 6363 adjacent to its outer peri hery The fixture 23 com:

form an outer annular ring 43 between the periphery of the ring 36 and the groove 4] and an inner annular ring 44 between the grooves 4| and 42 (Fig. '7). The bottoms of the grooves 4| and 42 are in the same plane which plane is indicated by the surface marked 45 (Fig. 7) The annular rings 43 and 44 are cut away at points 46, 41, 48 and 5|), as shown in Fig. l, in which case only the surface 45 is present at these points.

At the point 58 a recess 5| (Fig. 3) is out in the ring 36 and has its bottom 52 substantially below the bottom 45 of the annular grooves 4| and 42.

64. The apertures 63-63 break through the inner periphery 65 of the base of the ring 62 and together with a saw cut 66 provided across the ring 62 serve to make the ring 62 resilient about its outer periphery 64. The ring 62 has a tapered bore 61 which tapers outwardly from the inner base periphery 64 to a point on the top face thereof adjacent to the outer periphery 64 of the ring. A cam 68 is provided with a tapered periphery which slidably engages the tapered surface 66 provided in the clamping ring 62 and is provided with a bore 16 and a large counterbore 1|. A clamping bolt 12 is rotatably positioned in the bore 10 of the cam 61 and has provided on the upper end thereof a large circular head 13 which is positioned in the counterbore I. The head 13 is provided with a hexagonal aperture 14 for receiving a suitable socket wrench (not shown) which may be used to impart a rotary movement to the bolt 12. The lower end of the bolt 12 is threadedly mounted in a tapped bore 15 provided in the body portion 3| of the base member 36. A compression spring 16 is positioned over the bolt 12 between a shoulder 18 formed by a counterbore 11 provided in the body portion 3| and the tapped bore 15 and the under surface of the cam 61 and serves to urge the cam plate upwardly as the bolt 12 is backed out of the tapped bore 15. An annular assembling groove 19 is formed between the bore 25 of the ring 24 and the outer periphery 64 of the resilient ring 62, in which the various potentiometer groove elements shown in Fig. 3 are to be assembled as hereinafter to be described. The groove 19 is variable in width due to the fact that the periphcry 64 of the ring 62 may be expanded by drawing the cam plate 68 downwardly by turning the bolt 12 in a clockwise direction. As the cam plate is drawn downwardly against the action of the spring 16, its tapered periphery serves to expand the ring 62 and decrease the width of the groove 19. When the cam plate 68 is positioned substantially as shown in Fig. 2, the resilient ring is in its retracted position, that is, its periphery 64 is not flush with the periphery 34 of the body portion 3|, whereby the groove 19 is at its maximum width, and the fixture 23 is in its normal element receiving position.

A pin is rigidly secured in a vertical bore 8| provided in the body portion 3| of the base member 30 and slidably engages a vertically aligned bore 82 provided in the cam 68. The pin 88 serves to prevent any rotary movement of the cam 68 when the bolt 12 is being rotated. A pin 83 is rigidlysecured in a bore 84 provided in the base 25, and slidably engages the vertically aligned bore e: provided "in the body portion QI or the hose member 30. The pin 83 serves to maintain the fixture 23 in a stationary position during the assembly operation to be hereinafterjdescribed.

Fig. 1 1 shows a portion *of a potentiometer housing -90 which is provided with a plurality of annular grooves 9-1-9 I, in which are to be assembled a potentiometer card and associated elements shown in Fig. 8. 'Since the same prob lemsarise in-assembling elements similar to those shown in Fig. 8 in each of the annular grooves w en of the potentiometer housing "90, the assembly'of the elements in the outer groove "9| only will 'be discussed. The various elements which are to be assembled "in the 'outer groove SI of the housinggm-as shown in Fig-'8, comprise a metallic slip ring 95 having an offset end 96 which overlaps the oppositeend of the'ring'and a very smooth, contacting surface 9 1, a suitable lead '98 secured to the slip ring adjacent to the dfiset end 96, anin'sulating ring I '0? sufficient length to completely surround the slip ring 95 with the-exception-of the oifsetend 96, asecond insulating ring I01 of-sufiicient l'ength to completely surround the insulating ring I00 and having its open end diametrically opposite the open end-of the ring 1330, a "potentiometer card I02 having -'a contacting surface I03, its beginning turn marked as indicated at -'I-0'4 an'd leads I05-I 05 secured to the beginningand end turns of the card, an outer insulating ring I06 of suffioient length to completely surround the potentiometer card I02 except for that portion of the card between the leads II'. .iI05,-a bridge member I01 having acontacting surface 103 and an insulating envelope H0 in which the bridge member I 0? is placed before being positioned against the potentiometer card I 02 and between the ends of the insulating ring I00.

The width of the annular groove 9] is substantially equal to the accumulated thickness of the various elements shown in Fig. :8 which are'to be assembled in the groove whereby a 'very tight-fit of the elements in the-groove 'is assured. Because of the tight fit required between the elements and the groove 9|, hand assembly of each individual element in the groove is "a very diilicult and time-consuming operation. :Since the potentiometer card I or :comprise's a plurality ofturns of very fine wire and has-secured thereto very delicate leads I-t5I 05,an-y relative mova ment'between the insulatingrings I0'I 'or-I0'6 and the card -I 02 may result in a "serious damage to the windings or leads of the potentiometereard. In order to overcome thesedifiiculties it is necessary to provide a relatively loose preassem'bl-y of the elements in a fixture such as that hereinabove described and transfer the various elements a's-acomposite unit to the groove '91 of the 130- tentiometer housing 90.

The various elements to be assembled in the grooveli are first positioned in the assembling groove 19 of the fixture 23 in-the-followingmanner:

'The bolt I2 is rotated-so as to "allow the spring it to urge the camel upwardly which in turn allows the resilient-clamping'ring B2 to retract to its smallest diameter. When the clamping ring 62 is in this'retracte'd position, the annular groove IS (Fig. 2) between the bore 25 of the ring '2 and the outer periphery of theclamping ring '62 is slightly wider than groove "9| of the potentiometer housing 90. "Ili'eslip 'ring '95 is placed "in the'groove I9 with its -"contact "face 97 abutting the "bottomed-of the inner groove 6 t2 Fig. 9) ,and withthe :o'if-se't :end 96 positioned in the cutout portion 5t! provided on the face of the assembly ring 30 adjacent to thegroove SI. The intermediate insulating ring 1 00 is then positioned'in the groove 19 so that it completely surrounds the s'lipring 95 with exception of the offset end 96 and has its bottom face resting completely on the face of the ring 44. The second intermediate insulating ring IOI is positioned in the groove I9 so that it completely surrounds the insulating ring I00 and covers the offset end of the slip ring 95, in which case its ends are diametrically opposite the ends 50f the "insulating ring I00.

"The potentiometer card I02 is then positioned in the groove 19 with the beginning turn I04 directly line with the scribe mark 60 (Fig. 10) provided on the bo'ttom'wall of the sight hole .55 and 'having its contacting face I-I2 positioned against the bottom '45 of the annular groove 4| (Fig. 9). The insulating ring I06 is'then positioned in the groove 1-9 so that it completely surrounds the potentiometer card I02 'withth'e exception of the ends of the card on which the leads I 05-I05 are secured. The bridge I01 :is placed in the insulating envelope IIO with its contacting surface I08 extending beyond the sides of the envelope, and thisunitiispositioned in the groove 19 against the card and between the ends of the ring I66 so that-its exposed end I-08- engages the recess 5 I provided in the assembly ring opposite the word bridge scribed on the face of the ring 24.

It will be noted that the slip ring and the potentiometer card I52 are positioned on the bottom 45 of the annular-grooves El and 42 and thereby have their contact surfaces 91 and I03, respectively, in thesame :plane, whereas the insulating' -rings I 00, WI and I06 are positioned on the face -of the annular rings 43 and which is substantially above the bottom '45. The bridge I01, however, .is positioned in the recess 51 so'that its face I08 abuts the bottom 52 thereof which places the face of the bridge substantially below thebottom '45 or below the contacting surface of the slip ring and potentiometer card as senibled in the groove 19.

As-ea'ch individual element is positioned'in the groove "I9, in-the order described hereinabove,-its position with respect to the bottom 65 of the grooves 4| and 42 or the face of the .:annular rings and 44' is determined by'the sight .holes 53-5'3 'and55. For example, when the slipring 95 is positioned in the groove I9, its contacting surface 91 must abut the bottomed of .the groove 42. The'sight holes will readilyindic'at whether or not the slip ring is properly seated .in the groove 42 around its entire periphery. Likewise, the sight holes will indicate whetheror not the various elements subsequently assembled .in the fixture groove are-properly positioned on the face of -th ejector ring 36.

-When the various elements have been assembled in the groove I9 as described above, a suitable tool is inserted in the hexagonal aperturei'IZ and'actuated to turn the bolt I2 in a-clockwise direction and draw the cam 68 downwardly against the action of the spring I6. As-the cam 68 1s drawn downwardly, its taperedperiphery engages-thetapered'bore el of the clamping ring 62 'and spreads the periphery of the clamping ring outwardly against the slip ring 95 positioned in the groove 19 andthereby squeezes-theyarious elements positioned therein tightly together to form a--compos'ite unit. When the-various elearrests ments have been clamped tightly together in the groove 19, the fixture 23 is removed from the support 30, inverted and positioned on the face of a potentiometer housing such as the housing 9|] (Fig. 11) so that the bottom of the potentiometer card I02 extends into the outer groove 9|. The fixture 23 is positioned on the housing so that the scribe mark 58 provided above the sight.

hole 55 is aligned with a scribe mark I 13 provided on the potentiometer housing '90. -In this way the beginning turn I04 of the potentiometer card N12 is properly positioned with respect to the potentiometer housing 90.

When the fixture 23 and the potentiometer housing 90 bear this relation to one another, the two pieces are placed as a unit on a base plate H4 of an arbor press (not shown) of standard design and having a reciprocable ram H5. The arbor press is actuated so that the ram H is urged downwardly and engages the legs 3T3'l provided on the ejector ring 36. As the ram H5 moves downwardly, it causes the ejector ring 3 6 to slide within the fixture 23 and eject the composite unit clamped in the groove 19 from the fixture 23 into the groove 9| of the housing 90, during which ejection no relative movement occurs between any of the individual elements of the composite unit being transferred. When the ram H5 has descended to th extent that the flange 40 of the ejector ring 36 has travelled from the shoulder 38 and abuts the shoulder 21, the composite unit has been completely inserted in the groove M (Fig. 12) and the face of the annular rings 43 and 44 is flush with the face of the housing 90. The potentiometer card I02 and the slip ring 95 have their contacting faces in the same plane and are substantially above the top face of the various insulating rings I69, I01 and [06. When the various elements have been completely transferred from the groove 79 of the fixture 23 to the groove 9!, the arbor press is actuated to raise the ram H5 upwardly whereupon the fixture 23 is removed from th face of the potentiometer housing.

It will be noted that the composite unit travels only a relatively short distance from the groove 19 when it enters the groove 9i of the potentiometer housing 91 During the remaining travel of the composite unit it is dually supported by the fixture groove and the groove 9i of the housing 90, whereby the individual elements remain in a tightly clamped condition during the entire travel of the composite unit. It will also be noted that while the composite unit is being ejected from the groove 79 by the ejector ring 36, no relative movement can occur between the individual elements of the composite unit because each individual unit is backed up by the face of the ejector ring. In other words, the force applied to the ejector ring by the ram H5 is distributed equally to each element of the composite unit, whereby there is no tendency for any individual element thereof to move separately of the other elements.

The above-described fixture facilitates a rapid and accurate assembly of a, potentiometer card and its associated elements in an annular groove of a potentiometer housing. The fixture provides for a relatively loose pre-assembly of a potentiometer card and associated elements in a groove provided therein so that the delicate windings of the card are not damaged during the preassembly operation. Since no relative movement occurs between the individual elements of the composit unit during the ejection operation, the

potentiometer card winding is further protected from damage.

The fixture 23 is designed to assemble a potentiometer card audits associated elements in the outer groove 9| of the potentiometer housing 90. In order to assemble a potentiometer card and its associated elements into the remaining annular grooves 9I-9l, an assembling fixture similar to fixture 23 must be used, but of such size that th diameter of the assembling groove formed therein is equal to the diameter of the particular groove of the housing in which the elements are to be assembled. The assembling procedure described hereinabove for fixture 23 is followed for each assembling fixture and its respective groove in the housing 90.

While the above-described invention is particularly well adapted to assemble a potentiometer card and its associated elements into annular grooves provided in potentiometer housings, it may be readily adapted to assemble a plurality of strip-like elements into a groove of any desired shape without departing from the spirit and scope of the invention.

What is claimed is:

1. A fixture for assembling potentiometer cards and associated strip-like elements in potentiometer housings, which comprises a cylindrical body member having a central bore therethrough, a base member having an annular flange secured to the bottom of said body member and a cylindrical body portion extending partially into said central bore, said flange being provided with a plurality of arcuate slots, an annular resilient clamping ring positioned on top of body portion of said base so as to form a groove with the central bore provided in the body member in which a potentiometer card and its associated strip-like elements may be assembled in a relatively loose edge-wise position with respect to each other, said resilient ring having a tapered bore therethrough, a ring slidably positioned in the lower portion of said central bore and having a plurality of integral legs which extend through said arcuate slots provided in the flange of the base member, the face of said ring being positioned to form the bottom of said groove and having a pair of annular grooves and a pair of annular rings against which the potentiometer card and its associated elements are seated when said card and elements are positioned in said groove, a plurality of sight holes provided about the periphery of the body member for viewing the position of the card and elements with respect to the grooves and rings provided on the face of the ring, a cam plate having a tapered periphery in engagement with the tapered bore of said resilient ring, and a stud threadedly mounted in the body portion of the base member and having a flanged head thereon in engagement with said cam plate, whereby when the stud is rotated it draws the tapered cam plate into the tapered bore of the resilient ring and expands said ring so as to decrease the width of the groove and clamp the potentiometer card and associated elements into a composite unit between the central bore and the clamping ring.

2. An apparatus for assembling potentiometer cards and associated elements in an annular groove provided in a potentiometer housing, which comprises a member having an annular groove in which a potentiometer card and its associated insulating elements may be positioned in a relatively loose edge-wise position, said groove having an adjustable inner wall so that means provided on --the --member for *expanding the inner-wall-ofsaid-groove 'so as to clamp the individual elements together 'in the groove to form a-composite -unit,-and means provided on the slidable means-for-effectin'g movement of the slidable means so --as -toe-j ect the composite -unit :from said groove, -whereby'-when said member is placed adjacent to a potentiometer housing movement of the slidable means serves to slide the composite unit from the groove in the member into a groove provided in said potentiometer housing.

3. An apparatus for assembling potentiometer cards and associated strip-like elements in an annular groove provided in a potentiometer housing, which comprises a member having an annular groove in which a potentiometer card and its associated strip-like insulating elements may be assembled in a relatively loose edge-wise position with respect to each other, said groove having an expandable inner wall so that the width of the groove may be decreased after the potentiometer card and the insulating elements are positioned therein, a slidable member positioned in the annular groove so that a face thereof forms a movable bottom for said groove, the face of said slidable member forming the bottom of the groove having means provided thereon for aligning the edges of the potentiometer card and the insulating elements at different elevations with respect to each other, means provided on the member for expanding the inner wall of said groove so as to decrease the width of the groove and clamp the potentiometer card and its insulating elements together in the assembling groove as a composite unit, and means provided on the slidable member and projecting externally of the member whereby the slidable member may be moved so as to completely eject the clamped composite unit from the groove, whereby when said member is placed adjacent to a potentiometer housing movement of the slidable means serves to slide the composite unit from the groove in the member into a groove provided in said potentiometer housing.

4. An apparatus for assembling potentiometer cards and associated strip-like elements in an annular groove provided in a potentiometer housing, which comprises a base having an annular groove therein in which a potentiometer card and its associated strip-like elements may be assembled in a relatively loose edge-wise position with respect to each other, means provided on the base for orientating the potentiometer card in predetermined position with respect to the base, said groove having an expandable inner wall so that the width of the groove may be decreased after the potentiometer card and the associated elements are positioned therein, an annular member slidably positioned in the groove so one face thereof forms a movable bottom for said groove, the face of said slidable member forming the bottom of said groove having means provided thereon for positioning the edges of the potentiometer card and its associated elements at different elevations with respect to each other, means for expanding the inner wall of said groove to clamp the potentiometer card and its associated elements together in the assembling groove as a composite unit, nieans provided on the slidable member and projecting externally and completely eject the composite unit therefrom; and means provided on the a'nnular member for limiting the movement-ofthe annular movement within said gr-oove, 'wher eby when the base is positioned over a potentiometer housing so that the orientating means is properly aligned therewith move'men t of the slidable member serves to slide the composite unit from the groove in the base into a groove provided in the potentiometer housing a predetermined distance.

5. An apparatus for assembling potentiometer cards and associated elements in an annular groove provided in a potentiometer housing, which comprises a base having an annular groove therein in which a potentiometer card and its associated elements may be assembled in a relatively loose edge-wise position with respect to each other, said groove having an expandable inner wall, an annular member slidably positioned in the groove so that one face thereof forms a movable bottom for said groove, the face of said slidable member forming the bottom of said groove having means provided thereon for positioning the edges of the potentiometer card and its associated elements at different elevations with respect to each other, means provided on the base for determining whether the potentiometer card and its associated elements are properly seated on the bottom of the groove, means for expanding the inner wall of said groove so as to decrease the width of the groove and clamp the potentiometer card and its associated elements together in the assembling groove as a composite unit, and means provided on the slidable member and projecting externally of said base so that the slidable member may be moved to the top of the groove and thereby completely eject the composite unit therefrom, whereby when said member is placed adjacent to a potentiometer housing movement of the slidable means serves to slide the composite unit from the groove in the member into a groove provided in said potentiometer housing.

6. An apparatus for assembling potentiometer cards and associated strip-like elements in an annular groove provided in a potentiometer housing, which comprises a base having an annular groove in which a potentiometer card and its associated strip-like elements may be assembled in a relatively loose edge-wise position with respect to each other, means provided on the base for orientating one end of the potentiometer card in a predetermined position in the groove, said groove in the base having an expandable inner wall, an annular member slidably positioned in the groove so that one face thereof forms a movable bottom for said groove, the face of said annular member forming the bottom of the groove having means provided thereon for positioning the edges of the potentiometer card and its associated elements at different elevations with respect to each other, means provided on the base for determining whether the individual elements are properly seated on the bottom of the groove, means for expanding the inner wall of said groove to decrease the width of the groove and clamp the potentiometer card and its associated elements together in the groove as a composite unit, and means associated with the slidable member and projecting externally of said base so that the slidable member may be actuated to move the bottom of the groove to the REFERENCES CITED top of the groove and thereby eject the composite The following references are of record in the unit therefrom, whereby when the base is posifile of this patent:

tioned over a potentiometer housing so that the orientating means of the base is properly aligned 5 UNITED STATES PATENTS with the housing movement of the slidable mem- Number Name Date ber serves to slide the clamped composite unit 1,128,240 Flint Feb. 9, 1915 from the groove in the base into the groove pro- 1,135,983 Bartlett Apr. 20, 1915 vided in the potentiometer housing. 1,661,163 Blomstrom Mar. 6, 1928 10 1,690,322 Baker Nov. 6, 1928 BYRON ,P. GIRARD. 2,304,607 Sleeter Dec. 8, 1942 BRUNO A, RAETSCH. 2,337,383 Franz Dec. 21, 1943 2,353,774 Wagner July 18, 1944:

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