US2247165A

US2247165A - Indexing apparatus

Info

Publication number: US2247165A
Application number: US277115A
Authority: US
Inventors: George W Crise
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-06-02
Filing date: 1939-06-02
Publication date: 1941-06-24
Anticipated expiration: 1958-06-24

Description

Patented June 24, 1941 UNITED STATES PATENT oFFicE l ENDEXING APETUS George W'. Grise, Maronti/Yemen, @hic Application Ltune 2, i939, Serial No. 277,115 "J Ciairns. (Cl. F12-239) This invention relates to an indexing method and apparatus by which a movable member can be indexed or set at any desired vone of a number of possible positions or settings. My indexing method and apparatus are particularly well suited for adaptation to radio tuning and for that reason are herein disclosed as being used for Athat purpose, but it should be understood that they are also adaptable to various other kinds of apparatus and uses.

With particular reference to the need for a satisfactory indexing method and apparatus in the neld of radio tuning, it might be pointed out that heretofore it has been necessary to provide indexing devices for radio tuning with two commutator segments mounted with sufficient separation such that a position-selecting brush or Contact riding thereon could rest upon an insulated section betweenthe segments to obtain a stationary position. lin these devices'the commutatorvis driven by a motor to bring the insulated section under the brush or contact to thereby select the desired position or setting and the circuits are such that a tendency to cause such rotation occurs whenever the brush touches either segment` A certain tolerance has been necessary in devices of this kind to insure the driving motor being disconnected from both segments when they commutator arrives at the desired setting and this tolerance must be great enough to accommodate and isolate the largest brush or contact of a group containing a number of such position-selecting brushes or contacts. Because of this required tolerance moreor less variation occurs in the tuning operation and this disadvantage has made it necessary for radio manufacturers to more or less standardize on the use of automatic frequency control to compensate for this variation. The use of automatic frequency control is undesirlems and also causes a tendency for the radio to shift from one station to another if fading .occurs in the signals or program being received.

segments to become burned and worn with the result that the above mentioned tolerance was further increased with a corresponding increase able because it increases cost and servicerprob-l in the variation occurring in the indexing ione tion.

My indexing method and apparatus overcome these disadvantageous and provide for accurate indexing and precision radio tuning without the need' of automatic frequency control. It may, therefore, be said to be an object of my invention to provide a novel indexing method and apparatus for radio tuning andv other purposes by which a commutator or other member to be indexed or set can be accurately stopped and held at the desired position. y

Another object of my'invention is to provide a novel method and apparatus for indexing a movable member having spaced contact ele? ments or segments; in which the. rotative forces o an electric power device are unbalanced for moving said member toward a desiredsetting whereupon a position-selecting contact or brush connects such contact elements to cause balancing of the rotativeiorces of the power device for stopping the movable member at the desired setting.

Still another object of my invention is to provide a novel indexing method and apparatus, as just referred to, in which the electric power device is a shaded-pole type of motor and the engagement of the position-selecting contact or brush with the contact elementsr or segments of the movable memberl controls the circuits for the shading coils for determining the direction of rotation and. the stopping of said movable member.

Other objects and advantages of my invention will be apparent from the following description when taken in conjunction with the accompanying sheets of drawings in which Fig. 1 is a diagrammatic view showing index-v ing apparatus arranged according to my invention and withv which my indexing method can be carried out;

Fig. 2 is a partial edge view of a part of the apparatus' looking in the direction indicated by the line 2 2 of Fig. Y1;

Fig. 3 is a partial perspective view of the manually operable switch device of my indexing apparatus; l

Fig. 4 is a diagrammatic view showing aV modied arrangement of indexing apparatus embodying my invention;

Fig. 5 is another diagrammatic view showing*V indexing apparatus embodying my invention;

Fig. 6 is'another diagrammatic View showing Fig. 'I is a partial elevational view of a rotate able commutator of an indexing apparatus; and

Fig. 8 is a partial transverse sectional view v thereof taken on line 8- 8 of Fig. 7.

More detailed reference will now be made to\ the accompanying drawings for the purpose of describing my novel indexing method and apparatus. Before proceeding with the detailed description it should be understood, however, that my invention may be embodied in various other forms of indexing apparatus and' steps ofv procedure than those herein specifically disclosed.

In Fig. 1 of the drawings I show indexing apparatus with which my indexing method may be carriedout and which may be applied to radio tuning or to various other uses where an oscillatable member is required to be indexed or set at any desired one of a number of available different positions. The apparatus here shown comprises a rotary contact device I0, an electric power device or motor I I having a drive connection with'the rotary contact device, and al The `commutator I] may comprise a disk I8' formed of electrically insulating material and a pair of segment-shaped contact elements I9 and 20 which are mounted on such disk with spaces or gaps 2l and 22 between their adJacent edges. The insulating disk I B may have a groove in its outer edge in which a driving belt 23 engages for imparting rotation or oscillation to the commutator Ill. although the commutator may be driven from vthernotor II in any suitable manner.

For cooperation with the commutator I1, I provide a plurality of position-selecting contacts or brushes 2d which maybe mounted Von one of the walls I of the frame. As many of these contacts may be provided as can be accommodated l aamfiea y nated frame 25 and an armature 26 operable therein. The armature may also be of laminated construction and has short-circuited inductor bars 26a. The frame 25 is constructed with two poles thereon each of which 'carries or is-divided into two pole pieces, thereby providing the motor with two pairs of opposed pole piecesor sections. One such pair consists of pole sections 21 and 28 and the other pair consists of pole sections 29 and 30. The frame may also be constructed with arm portions 3| and 32 which` connect the pole sections with a common leg 33.

The windings of the motor II consist of a primary winding 34 on the leg 33 and pairs of shading coils mounted on the respective pairs of opposed pole sections. The primary winding 34 has its ends connected respectively with current supply conductors 35 and 38 whereby this winding can be continuously energized by closing the switch 31 Wherever the indexing device is to be put into operation. `The shading coils of the pairs of opposed pole sections consist of coils 39 and mounted respectively on the opposed pole .sections 21 and 28 and coils 4I and 42 mounted respectively on the opposed pole sections 29 and 30. The shading coils 38'and 40 are connected in series with each other andlikewise the coils 4I and 42 are also connected in series with each other. but in a separate circuit from that of the' coils 39 and t0. l

The characteristics of this shaded pole motor l are such that itthe primary winding 34 is en-v ergized and one set of shading coils, for example the set of coils 39 and t9, A-is energized by being short-circuited, While the other set of shading coils is deenergized by being open-circuited, the armature 26 will rotate in a counterclockwise direction. On the other hand if the set of shading on the wall I5 or as may be desired, one such the latter is at a given position or setting. The

nger 24a may be mounted on the wall I5 so as l to bef insulated-therefrom and so that each nger is carriedby, or connected with, a rotatable knob 24e. 4By rotation of these knobs the various ,contacts or brushes 24 can @be manually set at positions corresponding with the various stations to which the'commutator I1 may be moved. For reasons hereinafter explained, the motor II which drives the commutator I'I is preferably an induction motor of the shaded-pole type whose rotation `can be 'controlled by variation of the shading effect. This 'motor may have a lamicoils dI and H2 is energized, as by short-circuiting thereof, while the coils 39 and ttil are opencircuited the armature 26 rotates in a clockwise direction. The sets of shading coils are so wound that the shading eect of one set is vsubstantially equal to and opposes the shading effect of the otherv set'whenever both sets are enersized simultaneously.

For the purpose of establishing the desired circuits through the pairs of shadingicoils of the motor Il, as will be explained hereinafter, -I connect the leads at one end of the shading coils as indicated by the junction point 45. At the other end of the shading coils, the leads 46 and @l are brought outside the motor.

The switch device I2 by which the indexing apparatus is controlled comprises a single jack type switch d@ and a `push button 5I, the latter being one of a group or series consisting of a number of such push buttons. The number of such push buttons occurring in the group will depend upon the number of different settings or stations to which the apparatus is capable of being set or indexed. Usually the number of such push buttons in a given apparatus will correspond with the number of position-selecting contacts or brushes o the rotary contact device Il). YFor the sake of clarity I show, in Fig. 1, only the push button 5I which corresponds with the position-selecting contact or brush 62 of the rotary contact device.

The switch device I2 may, as here shown, include an insulating support l61| in which the stem 55 of the push button 5I is slidable. A spring 56 disposed around the stem 55 normally holds thepush button 5I in its extended position with accrues the contact head 57 of the stem engaging the underside of the support B. The jack switch et comprises a pair of normally closed contacts B, 59 and a pair of normally open contacts 60, 6l. The

contacts

58 and 59 are carried respectively by a pair of spring lingers 62 and 63 and the contacts 5U and ti are carried respectively by spring ngers G4 and 65, Both pairs of spring fingers are mounted between layers of aninsulating block 66 which is connected to the insulating support 54 by suitable screws El. The spring ngers 63 and E@ may have extensions 6d and le thereon which carry a pusher or thrust member 'il formed ci insulating material. An insulating spacer l2 disposed between the extensions 69 and iii always holds the hhgers t3 and iid andthe contacts 5t and t@ thereof in spaced-apart relam tion.

.At a point between the push button 5l and the jack switch Sii I provide a pivoted latch l@ which cooperates with the contact head 5l and also with the insulatingthrust member 'l l 'lihis latch may be of a length to extend beneath all of the push buttons of the above mentioned series. As

shown in Figs. l and 3, the latch il@ may have a rounded enlargement lf3 pivotally retained in a socket of the support M and may lalso have a substantially hoolr-shaped arm portion entending from such enlargement. A compression spring ld acts on the latch 'lil to normally hold the same in the path of downward movement of the Contact head di oi the push button 5i. When the push button is depressed, the contact head El engages the inclined section 'it of the latch and travels along the same until it passes the corner` or shoulder point 'il whereupon it enters the hook portion of the arm and remains therein to hold the push button in its depressed position. While traveling along the inclined section "it the contact head 5l exerts lateral pressure on the latch causing the same to swing about the axis of the rounded portion l'l thereby depressing .the thrust member 'l l and deecting the spring fingers i353 and @Il downwardly. rlhis downward deflection oi the spring ilngers S3 and @il causes opening of the contacts 58 and 5t, followed by a .closing or" the contacts il@ and di. When the contact head El! passes the shoulder point il the latch lil swings hack toward the right permitting contacts 58 and di) to be reclosed and contacts t@ and Si to be reopened.

The push button t, or any other individual push button or the series which has been depressed, can be reset by manually lifting the sameto disengage the contact head 5l from the hoolr portion oi' the arm. Such manual lifting is usually unnecessary, however, because the depress-V l cuit connections must flrst be pointed out. -As

will be seen from the diagrammatic view of Fig. 1, one end of the pairs of shading coils 39, 4o and 4i, 42 is connected with a terminal screw 19 of the switch device |2 by a conductor 8U. A

flexible lead 8| connects the terminal screw 19 with the pivoted latch 13. The spring iinger B4 ing or any button of the series will swing the I is also connected to the terminal screw it by a conductor 82. The other end of the set of shading coils di and t2 is connected with the spring nger 62 by the lead 46. The push button 5i is connected with its position-selecting contact or brush 52 by means oi conductor St. The segments I9 and 2U of the commutator il are connected respectively with the spring ngers 65 and 83, the segment i9 being connected with nger 6E through conductor t5 and :dexible conductor Bt and the segment 2li being connected with iin ger 63 through iiexible conductor di. The other end of the set of shading coils 39 and itil is also connected with the :finger 55 through lead 4l and conductor Bt. From the circuit connections just referred to, it will be seen that one end of the set of shading coils Si@ and iii is .permanently connected with the segment i9 of the commutator through lead all and exible conductor tit, and that the corresponding end of the set of shading coils (il and l2 is connected with the segment d@ of the commutator through lead 135, normally closed switch contacts :dexible conductor Let it be assumed that the present position of the commutator il is a setting to which this member has been previously indexed hy the de pressing of a push button (not shown) corresponding with the position-selecting contact or hrush 89. For this setting of the commutator it will be noted that the contact bridges the gap 2i and electrically connects segments lil and Ztl with each other. At this time the two sets of shading coils are contained in energizing circuits which are parallel to each other and the energizing of the two sets of shading coils through these parallel circuits causes a substantial halancing of the rotative forces of the motor .'l i with the result that the commutator il is held stationary.

Let it be assumed also that it is desirable to index the commutator to bring the gap 2l under the position-selecting contact or in other words, to a setting corresponding with the position of this position-selecting contact. To do this the operator depresses the push button 5l which corresponds with the position-selecting contact 52. As explained above, the depressing or the button 5i causes. swinging of the latch 713 and this, in turn, causes vcontacts iii and t@ to he opened and contacts il@ and 5l to be closed. The separating of contacts 5i? and Si? opens the cir cuit for shading coils Si and i2 and the closing of contacts @il and tl causes short-circuitlng oi shading coils 39 and till. This produces an uribalanced shading effect which causes an initial rotation o1" the armature 2t and the commutator il in a countercloclrwise direction. This initial countercloclrwise rotation of the armature causes the gap 2l to move out from under the previously chosen position-selecting contact @Si to produce what may be conveniently referred to as unlocking. The result of this initial counterclockwise rotation of the armature or unlocking is to cause the previously chosen contact 89 to ride only on segment 2li and to thereby break the electrical connection between the segments. i

The movement of the contact head 5l of the push button 5i past the shoulder point H and into the hooked portion of the latch 13 permits the

contacts

58 and 59 to reclose and the contacts 60 and 6l to be reopened, as explained above. The reopening of the contacts B0 and 6l causes deenergization of shading coils 39 and 40 and the reclosing of

contacts

58 and 59 causes closing it and and through of an energizing circuit for the shading coils 4| and 42. This energizing circuit may be traced from Junction point 45 through conductor 80, flexible conductor 8|, to latch 13, through push button and flexible conductor 04 to segment 20, then through iiexible conductor 81,

jack 4switch contacts

59 and 58, and then through lead 49 and shading coils 42 and 4|, back to junction point 45.

energizing of shading coils 4| and 42 while sh'a i coils 39 and 40 are deenergized results in an balanced condition for the rotativel forces of the motor Ii causing clockwise rotation of the commutator l1. During this clockwise rotation, the gap 2| passes under position-selecting contact 89 and other similar contacts 24 and at each' such point the segments of the commutator are electricallyl connected witheach other to cause momentary energization of both sets of shading coils in parallel with each other. Although the energization of both sets of shading coils at these points tends to slow down the rotation of the armature, the effect is only momentary and the momentum of the armature causes the gap to glide past the contacts. However, when the gap 2i reaches the position-selecting contact 52, the `felement 24h of this contact bridges the /gap and for an interval of time, electrically connects thesegments i9 and 20. During this interval the previously deenergized shading coils 39 and 40 ywill beenergized in Vparallel circuit With the shading coils 4| and 42 and the tendency will -be for the motor to-come to a stop as the result of the friction 'of the moving parts.

The momentum of the commutator I1 may be suilcient to carry the gap 2| beyond the positionselecting contact 52, and this will result in this contact being shifted from the segment 20 on to other purposes.

tact 52 alternately in opposite directions, pro,

` duces an oscillation of the commutator which will decrease in amplitude by reason of the friction .on the moving parts. The commutator presently comes to rest with thegap 2i beneath mutator to a different setting, the operator first releases the push button 5| and then depresses the push button corresponding with whatever different setting he desires for the commutator. The operation above explained is repeated with thecommutator first rotating in a counterclockwise direction to unlock the gap 2| from the previously chosen contact 52, after which the rotation of the commutator reverses or continues,

as the case may be, to bring the gap under the newly chosen position-selecting contact.

If the operator desires to change the setting for one of the position-selecting'contacts, for e'xample, the contact 52, he presses the corresponding push button to cause the commutator to -be buttons.

shifted to bring the gap 2| under the chosen contact. He then grasps the knob 24o which is frictionally mounted in the frame wall I5 and rotates y the knob to shift the contact in the desired direction. During this shifting of the contact the gap 2| will follow the contact to any position Within the range to which theV nger 24a can be swung. In this way the position-selecting contacts can be initially set, or subsequently reset, at positions corresponding with the desired stations or frequencies. The position-selectingcontacts will remain at these settings until a future manual change is made. v

In Fig. 4 of the drawings I have shown another arrangement of indexing apparatus which can be used for precisionr radio tuning or for various This indexing apparatus comprises a rotary contact device 9|, a driving motor 92 and a manually operable switch device 93 for controlling the indexing operation.

The rotary contact device 9| may besimilar inconstruction to the device I0 of Fig. 1, that is to say, it may include a commutator 94 comprising an insulating disk 95 having a pair of segmentshaped contacts 96 and 91 mounted thereon with their adjacent ends spaced apart by gaps 98 and 99. The commutator 9d may be connected to and carried by-a shaft |00 which is journaled in a suitable frame i0! and may be connected with the., actuating shaft ofa main tuning condenser of a radio set. The insulating disk 95 may have This rotary contact device 9| also includes av plurality of position-selecting contacts |03 corresponding in number with the number of stations to which the commutator may be indexed or set. In this instance lI show only positionselecting contacts |03 and |04, but several may be provided. These contacts may be similar to the contacts 20 of Fig. 1, that is to say, they may be frictionally mounted on the frame |0| and each may have a resilient conducting finger or varm and a round-nosed contact element |05 which rides on the segments 96 and 91.

The motor 92 may be a single-direction motor adapted to be driven by either alternating or direct current and arranged so that, when ener? gized, it will rotate in a clockwise direction. The belt |02 may have one end thereof wrapped around the pulley |01 of the motor and anchored thereto as indicated at |08. The opposite end of the belt may extend beyond the commutator 94 and may have a weight |09 suspended thereon. This weight has a mass such that the force of gravity will rotate the commutator and the motor in a counterclockwise direction whenever the motor is deenergized. On the other hand, the mass of the weight |09 and the character'- istics of the motor 92 are such, that when the motor is fully energized its power will be sufficient to rotate the commutator clockwise and to lift the weight against the action of gravity, and when the energization of the'motor is reduced, as by inserting a resistance in the motor circuit, the power lof the motorwill be reduced suiciently to merely balance the weight |09 whereby the commutator can be held -in a desired position as long as such balanced condition obtains. l

The switch device 93 may he of the Jpushbutton type having a plurality of pairs of push and |I2 constituting one oi such pairs and which are connected with a switch lever ||3 at In this instance I show push buttons opposite sides of the pivot H4 thereof. The contacts associated with the push buttons Hi and ||2 include contacts ||5 and HB which are connected respectively with position-selecting contacts |03 and |04 by conductors ill and H8. These contacts also include three arcuately arranged stationary contacts |20, |2| and $22 and a movable contact |23 adapted to sweep across these arcuately arranged contacts. The contact |23 may be carried by the lever H3 but is insulated therefrom by the interposed body |25. Suitably located stops i26 and l2? may be provided so as to be engaged by the lever it when the latter is swung to one or the other oi its positions by the depressing of the push buttons l il or H2.

Current for operating the motor 92 may be supplied through line conductors 629 and i3@ and through a switch` iti which is closed when the indexing apparatus is to be put into operation. The power conductor '29 is interrupted at a point iip at which the switch formed by the cooperating contacts litt-i123 is inserted. The contact i211 is connected with the outer section of the power conductor i2@ and the contacts l2@ and lit are connected with the inner section ila. The movable contact U23 is of a length such that it will bridge the pair of contacts i2i and iti? or thepalr of contacts itil and l2l, depending upon the position oi the lever dit, but will cause opening oi the power circuit during the shifting oi the lever 'from one of its extreme positions to the other. This interruption of the power circuit is desirable at the beginning of each indexing operation for deenergizing the motor so that the commutator iid can be rotated by the weight itil in a counteri clockwise direction to shift the gap Sd out troni under the position-selecting contact to 'which the apparatus was previously indexed. This interruption of the power circuit and resulting counterclockwise rotation of the commutatcr may be referred to as an unlocking operation.

The commutator segments @t and are connected respectively with the power conductors, the segment being connected with the conductor section itlc through flexible conductor it@ and resistance and the segment Sill being connected with the line conductor through flexible conductor itt and resistance itl. Une of the terminals of the motor Q52 is also connected with 'power conductor i3@ by conductor itt and the other motor terminal is connected with the switch lever il@ by conductor 1139. The resistance i535 may or may not be needed, depending upon the voltage ci the power circuit. The rnotor @2 is so designed as to be fully or normally energized when operating with .the normal voltage and current supply. and this may be with or without the resistance it in the motor circuit as conditions reduire.

From the circuit connections and switch arrangement just explained. it will be seen that hv depressing either of the push buttons iii or M2. an energizing circuit for the motor-.92 can be established.' When the push button iii has been depressed` as shown in the drawing. the lever I3 is swung to a position in which it engages'contact ||5 and the contact i23 overlies and connects contacts |20 and |2|. By` movement of the lever H3 to this position an energizing circuit for the motor has been completed which may be traced from power conductor |30 through conductor |38 to the motor and then back through conductor |39 to switch lever l I3,

section |29a. From this point the motor circuit continues through contacts E20, |23 and |2l back to power conductor |29. The resistance i3d is of such value that when a motor energizing circuit has been established as just traced, the motor will run in a clockwise direction and will develop sufclent power to rotate the commutator in the same direction and lift the weight |09 against the action of gravity.

The rotation of the commutator QG in a clochwise direction by the motor continues until the gap 98 comes under the contact M33 whereupon this contact electrically connects the segment 96 with the segment Sl. When this occurs it will be seen that a circuit connection is established between the rotary contact device iii and the power conductor i3@ which isvin parallel with the motor Si. This parallel circuit connection may be traced from segment @t through contact H03, which is then engaging in gap 98, to segment Si and thence to power conductor i3@ through exicle conductorl it@ and resistance itl. The value ci the'resistance ll is such that a current flow will taire place through this parallel circuit oi a value to reduce the energizing current flowing through the motor to a point' where the power output ot the motor is only sufficient to balance the gravity pull exerted by the weight its. Because of this balanced condition, the commutator will come to a stop with the gap under the contact it and will remain in this position as long as the button il i remains depressed.

II' the clockwise rotation of the commutator @il should cause the gap t@ to travel beyond the contact itil, it will be seen that this contact will then disengage the segment 95 and will engage only the segment Q'J. This will result in the motor energizing circuit being broken at the commutator il@ and this will permit the weight i339 to rotate the commutator in a counterclockwise direction to return the gap @t to a position 'oeneath the contact thereby reestablishing the motor energizing circuit and producing a locking-in effect, as explained above.

When the operator wishes to index the device to a different setting or station, lor example, that with which the push button iii.3 corresponds, he depresses this button and thereby shifts the switch lever itil to engagement with the contact lit. This same movement of the switch lever lit shifts the contact B23 to the contact i22 and in so doing, interrupts the motor circuit so that the weight it@ can rotate the commutator in a counterclockwise direction and thereby unlock the gap @d from its engagement with the contact 03 to which the apparatus was previously indexed. This counterclockwise rotation will continue until the segment 96 is engaged by the contact iM whereupon` the motor 92 will be energized through the circuit above traced to cause, either a balancing of the rotative forces if the contact illl remains in engagement with both of the segments and 97, or to produce a clockwise rotation of the commutator if the contact |05 overruns the gap 98 and engages only the segment 96. From th'e foregoing explanation it will be readily seen that the oscillation of the commutator 94 under the lnuence of the motor 9,2 and the weight |09 will result in the gap 98 being quickly brought to a stop beneath the chosen position-selecting contact and will be held in this position until a different setting is desired.

A single-direction motor |53 adapted to be operated by direct or alternating current is lolcated adjacent the commutator and has a belt or strand |54 anchored to its pulley |55 and extended over the pulley |81 of the commutator. A weight |56 is suspended on the strand |56 of sucient mass to balance the power output of the motor when it is operated at reduced enrergization or to 'turn the motor and commutator |4| in a counterclockwise direction when the motor is deenergized. Leads or conductors |51 and v|58 extending from the motor are connected respectively with the power conductor |58 and the segment |64 of the commutator.

A brush or position-selecting contact |60 mounted in relatively xed position cooperates with the commutator and rides on the segments thereof. This contact may comprise a holder 6| which is connected with power conductor |62 by a conductor |63 and a contact element |66 in the holder which is adapted to be pressed against the commutator segments by a sprin When a push-button switch or other manu-- tion results and the commutator is held against further rotation in either direction.

If the momentum of the commutator should Vcarry thezsegment |46 in a clockwise direction beyond the contact 60, the Contact will pass J onto the deadsegment 45 and the motor will be completely deenergized. This vwill permit the weight |56 to promptly rotate the commutator in a counterclockwise direction to bring the segment |46 back under the contact |60 and thus produce a locking-in at 'the desired setting or station.

In the operation of the indexing apparatus of Fig. 5, some variation may occur in the setting orindexing of the commutator because of the segment |46 being longer than the width of the contact |60 and, lfor this reason, it may be desirable to employ automatic frequency control in conjunction with this indexing apparatus.

In Fig. 6 ofthe drawings I have shownva commutator |68 and a position-selecting contact |61 which correspond with the commutator and position-selecting contact of the indexing apparatus of Fig. 5, but are constructed in a manner to secure certain.. important advantages. The commutator |66 has live and dead segments |68 and |68 and also has van intermediate segment or part corresponding with the segment |46 o! Fig, 5. This latter segment or part comprises a screw |10 mounted in a substantially radial position von the insulating disk |1| of the commutator with its outer end extending into a' gap |12 between the adjacent ends oi the segments |66 and |69. A recess or opening |13-.formed in the insulating disk |1| affords access tothe screw |10 for adjustment thereof. This screw` through the resistance |14 whereupon the commutator |66 is held at an accurately indexed setting. 'I'he use of the screwv |10 as the intermediate segment permits the gap width to be reduced and also afords a means for readily making adjustments and taking up wear.

Instead of mounting a screw in the insulating disk of the commutator, as shown in Fig. 6, Ir may construct the insulating disk with aslot |11 therein and mount a contact member |18 on the disk with a radially extending rib |19 thereof disposed in such a slot, as shown in Figs. I and 8. The member |16 may be con-` nected with -the insulating disk by means of |82 whereby the position of contact rib |19 in the slt |11 and relative to the faces of contact segments |83 and |86 can be' varied. An advantage for this form of commutator segment or contact is that it extends radially of the commutator and permits a large number of position-selecting contacts to `be arranged at desired points and all of which can operate onthe same commutator.

From the foregoing description and the accompanying drawings, it will now be readily seen that I have provided a novel indexing method and apparatus whereby the tuning condenser of a radio apparatus, or 'other memberto be indexed or set, can be moved to a desired position in lresponse to actuation of a push-button control switch located either adjacent the apparatus or remote therefrom. It will be seen furthermore that in the use of my novel indexing method and apparatus the member to be indexed is rst rotated by unbalancing the rotativeV forces of the power device and is then brought to a stop at the desired setting or index position vby balancing the rotativeforces of the power device.' The,

Having'thus described my invention, I claimz` with said segments, and a selectorcontact riding said segments and having circuit connections with said shading coils for short-circuiting one I I coil while riding one segment and short-circuiting the other coil while riding the other segment and short-circuiting both coils when in engagement with both segments said selector contact comprising an arm having pivotal connection with said frame permitting manual swinging of the arm for adjustment of the conitact to different settings.

2. In combination, a movable member having a pair of spaced segments, an alternating current motor adapted `to drive said member andhaving a pair of opposed shading coils connected respectively with said segments, a selector contact riding said segments and having circuit connections with said shading coils for shortcircuiting one coil while riding one segment and short-circuiting the other coil while riding the other segmentand short-circuiting both coils when in engagement with both segments,

and switch means included in said circuit connections and operable for short-circuiting one of the shading coils and opening the circuit of the other coil.

3. In apparatus of the character described, a rotatable member carrying a pair of adjacently spaced segments, an alternatingcurrent shadedpole motor connected with said member totdrive the same and having opposed shading coils, a position-selecting contact adapted to ride said segments, a switch having a plurality of pairs of contacts and actuating means therefor, and circuit connections for said shading coils including means connecting an end oi one coil with one of said segments and means connecting an end of the other coil with the other of said segments through one pair of the switch contacts and means connecting the remaining ends of both coils with said position-selecting contact through another pair of the switch contacts.

4. In apparatus of. the character described, a

frame and carrying a pair of adjacentlyspaced segments, an alternatingl current shaded-pole motor connected with said memberto drive the same and having opposed shading coils, a plu- Vrality of position-selectingcontacts adapted to ride said segments, switch means comprising a plurality of manually movable position-selecting contacts electrically connected respectively with the rst mentioned position-selecting contacts anda contact common to said manually movable contacts and adapted to be individually engaged thereby, and circuit connections connecting an end of one of said coils with one of said l -on said frame for individual swinging so as to permit manual. adjustment of said contacts to different settings. I

6. In apparatus or vthe character described, a

' rotatable member carrying a pair of adjacently rotatable member' carrying a pair of adjacently spaced segments, an alternating current shadedpole motor connected with said member to drive the same and having opposed shading coils, a position-selecting contact adapted to ride said segments, switch means having pairs of cooperating contacts including at least one pair of normally closed contacts and one pair ofvnormally open contacts and manually operable actuating means for causing closing of the open contacts followed by opening or the closed contacts and a reclosing of said closed contacts, 'and circuit connectionsdor said shading coils including means connecting one coil with one of said segments and means connecting the other coil with the other segment through said pair of normally closed contacts and meansl connecting both Vcoils with said position-selecting contact through said normally open contacts.

spaced segments, an alternating current shadedpole motor connected with said member to drive the same and having opposed shading coils, a plurality of position-selecting contacts adapted to ride said segments, switch means comprising a plurality of manually movable position-selecting contacts electrically connected respectivelywith the first mentioned position-selecting con' tacts and a contact common to said manually movable contacts and adapted to be individually engaged thereby, and circait connections connecting an end of one of said coils with one of said segments and an end o the other coil with the other segment and the remaining ends of both coils with said common switch contact, said switch means also including apair of normally closed contacts located in the circuit connections for one of said coils and adapted to be opened by actuation of one of said manually mov-able contacts.

'7. In apparatus of the character described, a rotatable member carryinga pair of adjacently spaced segments, an alternating current shadedpole motor connected with said member to drive the same and having opposed shadingA coils, a

plurality of position-selecting contacts adapted to ride said segments, switch means comprising a plurality of manually movable position-selectmovable contacts and adapted to be individually engaged thereby, circuit connections connecting an end of one of said coils with one of said .segments and an end of the other coil with the other segment and the remaining ends of both for one of said-coils and adapted to be opened by actuation of one of said manually movable contacts and a pair -of normally open contacts 5. In apparatus or the character described, a

frame, a member rotatably supported by said,

vother or said'ecoil's.

adapted to be closed by sid one manually movable contact, andmeans connecting the contacts of said normally open. pair with the ends of the GEORGE w. cares.