US1919979A - Electric switch - Google Patents

Description

July 25, 1933. R. w GOFF 1,919,979

ELECTRIC SWITCH Filed June 8, 1929 Hg. z

ei i Inventor: A

I/ Robert \)V. C:`|off7 Hi s AttoIne g.

Patented July 25, 1933 UNITED STATES PATENT OFFICE ROBERT W. GOFF, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK ELECTRIC SWITCH Application filed June 8,

My invention relates to electric switches, particularly those having electroresponsive operating means and a series of contacts operable thereby in timed sequence, although certain features of the invention may be applied with advantage in other types of switches.

The principal object is to provide an improved switch having the following characteristics.

The switch contact operating member can move a desired amount either before or after operation of a contact.

Only a very slight movement of the operating member is required to operate a contact.

During operation of the contact the movement thereof is proportional to movement of the operating member.

The switch contact is locked in position after operation thereof, without impeding further movement of the operating member and with practically no load imposed on they operating member after the contact is locked in position.

A series of contacts can be operated in timed sequence by a single operating electromagnet or other electroresponsive device and by suitable adjustment the sequence can be varied at will.

The operation of anv Contact in the series does not in any way interfere with the operation of anv other contact.

Special provision is made so that a portion of the series of contacts are both closed and opened before the sequential closing and opening of the remaining contacts.

The load on the operating member gradually decreases throughout the sequential operation of a large number of contacts.

A switch with any required number of scuentially operable contacts can be made up from practically duplicate contact operating parts of inexpensive construction.

In accordance with the present invention I obtained the above characteristics by means of an improved form of toothed switch contact operating arrangement together with an improved connection arrangement with the 0 electro-responsive operating means which 19.29. Serial No. 369,324.

may be best understood from the following description of an electromagnetically operated multiplc contact time element motor starting switch illustrated in the accompanying drawing as a preferred embodiment of the invention.

Fig. 1 is a perspective view of the motor starting switch with the operating electromagnet deenergized and all the contacts in the open position, Fig. 2 is a similar view with the electromagnet energized and the contacts closed, Fig. 3 is a perspective view of the toothed contact operating elements used in the motor starting switch of Figs. 1 and 2 with the elements disposed so as more clearly to reveal the arrangement of the ininter-meshing teeth thereon, Figs. 4 and 5 are end views of the toothed contact operating elements in cooperating relationship, Fig. 6 is a perspective view of a modified form of the toothed contact operating elements, and Fig. 7 is a circuit diagram of a push button motor control system employing the starting switch mechanism shown in Figs. 1 and 2.

The motor starting switch of Fig. 1 has an operating electro-magnet 10 arranged to operate the motor line switch 11 and the 'motor accelerating switches 12 and 13 in timed sequence under the control of the timing device 14. The operating electro-magnet l0 is of the improved type described in Patent 1,696,615 and is mounted on the bracket 15 extending from the base 16 with the auxiliary switch 17 located in the space between the magnet frame and the base.

The plunger 18 of the electro-magnet is connected thru the link 19 and the pin 2O to operate the yoke arm 21 which is rotatably mounted upon the shaft 22 with the latter supported in spaced relation with the base by suitable brackets 23. The yoke arm 21 is connected to operate the line contact 11 directly by means of the bent member 24. This bent member is secured at one end to the projection 25 extending Ifrom the yoke arm 21 and is rotatably mounted at its other end on the extension of the shaft 22 thru the supporting brackets 23. The line contact 11 is resiliently mounted on the end of the con- 10 tact finger 26 which preferably is formed of insulating material and is carried by the bent member 24. The line contact 11 engages with and bridges between a contact at the end of the post 27 extending from the base and another contact not shown which is 1ocated within the arc chute 28 adjacent the ma netic blowout coil 29.

he auxiliary switch 17 is employed for controllin the operating electromagnet 10 as set fort more fully hereinafter and is operated thru the agency of the rollers 30 carried on opposite sides of the plunger 18 on the pin 31 which engage with the operating arm 32 resiliently mounted on the frame of the. electro-magnet 10. This operating arm is arranged to operate the auxiliary switch mechanism in the manner more fully described and claimed in my application Serial #167,281 filed February 10, 1927.

With the arrangement just described it will be apparent that the line contact 11 is operated to the closed position immediately upon the operation of the plunger 18 by the electro-magnet 10. The accelerating contact 12 and 13, however, are operated in a timed sequence after operation of the line contact 11 in the following manner. The projection 40 which extends on the opposite side of the yoke arm 21 from the projection 25 engages with one end of the compression spring 41, the other end of which rests against the end of the bracket 42 carried by the arm 43. This arm 43 terminates in the yoke 44 at its upper end which straddles the yoke arm 21 and is xedly secured tothe shaft 22. Thus upon operation of the plunger 18 the spring 41 will be compressed and the arm 43 thereby biased to rotate the shaft 22 in a clockwise direction.

The rotation of the shaft 22, however,l is retarded by the time element device 14, which is shown as of the type described and claimed in m co-pen'ding application Serial #161,- 919 led Jan. 18, 1927, altho other suitable types of time element devices may Ibe employed. Briefly the time element device 14 as shown, is of the escapement type having a pendulum timing pawl operated thru multiplying gearing connected with the rotatable shaft 45 carrying the ratchet toothed pinion 46. The curved rack 47 which is suitably mounted on the lower end of the arm 43 is provided with ratchet teeth which engage with the teeth on the pinion 46 when the arm 43 and the shaft 22 are rotated in the clockwise direction, but which moves freely upon rotation thereof in the opposite direction. Thus it will be evident that immediately upon operation of the plunger 18 to close the line Contact 11, the shaft 22 is set into rotation in the clockwise direction with: the rotation thereof retarded by the timing device 14.

The retarded rotation of the shaft 22 effects operation of the acceleratin contacts 12 and 13 in timed sequence thru t e agency .ly to be received into the space 59 thereof with the contact slidably mounted on the supporting bolt 54. The spring 55 is interposed between the contact operating eles ment 50 and the Contact to provide a resilient mounting therefor. The switch element 50 is rotatively supported on the shaft 52 and the cooperating toothed actuating element 51 is secured to the shaft 22 so that its angular position thereon may be adjusted. As shown the actuating element 51 is secured to the shaft 22 by the set screw 53.

As shown in Fig. 3 the switch element 50 is provided With a substantially cylindrical hub 56 from which the contact carrying arm 57 extends. The three gear teeth 58, 59 and 60 are formed on the hub 56 substantially opposite the arm 57. It will be observed that the tooth 59 is of shorter length thanthe adjacent teeth 58 and 60 thereby providing a space or depression 59 at the end of the tooth 59 and between the adjacent teeth 58 and 60.

The cooperating actuating element 51 is of general annular shape with the two gear teeth 61 and 62 formed thereon. Furthermore, the actuating element 51 is provided with a cylindrical projection or flanged portion forming a collar 63 of the same height as each of the teeth 61 and 62 and extending from the outside faces thereof. The width of this annular flanged portion or collar 63 is less than the Width of the teeth so as readipreviously referred to, with the cylindrical surface of the collar 63 substantlally in engagement with the points of the adjacent teeth 58 and 60. It will of course be observed that the end of the hub 56 carrying the depression 59 forms an extension of the portion of the hub carrying the gear tooth 59.

Preferably the switch element 50 and the actuating element 51 therefore both are formed of a mouldable insulating material, such as bakelite or the like with the various gear teeth, projecting collar, and arm all formed integral therewith, although these members obviously may be made of other material and in any other desired manner such as by die casting or the like. l

Referring again to Fig. 1 it will be seen that the motor accelerating contact- 13 likewise is resiliently carried upon the switch arm 50' which is operated by the rotatable member 51 mounted on the shaft 22 in the same manner as the actuating element 51 for the switch arm 50. These parts may be exact duplicates in all respects and in order to obtain sequential operation of the accel erating contact 12 and 13, the respective actuating members 50 and 50 are mounted on the shaft 22 with the teeth thereof out of alignment. While only the two sequentially operable motor accelerating contacts 12 and 13 are shown in the particular form of motor starting switch illustrated, it will be evident that any desired additional number of sequentially operable contacts may be provided slmply by extending the shaft 22 and the shaft 52 and mounting additional switch arms and operating elements thereon in the same manner as described above.

The manner in which the switch arm 50 is operated by the operating member 51 may be best understood by referring to Figs. 4 and 5 which diagrammatically represent the relationship between these parts during different phases of operation. In Fig. 4 the operating element 51 is shown adjusted on the shaft 22 by'means of the set screw 53 in such a position that the tooth 62 meshes between the short tooth 59 and the long tooth 58 on the hub of the switch arm 5() with the tooth 61 on the opposite side of the tooth 58. In this relation the switch member 58 is held with the contact 12 carried thereby out of engagement with the co-operating fixed contact 12 which are mounted on the base 16. It will be evident that upon rotation of the tooth actuating element 51, in a clockwise direction7 the switch arm 50 will be rotated in the opposite direction thereby carrying the contact 12 into engagement with the fixed contact 12. the spring 55 permitting contact l2 to seat itself in good circuit closing engagement with the fixed contacts as indicated in FiO'. 5.

It lwill be observed that as the tooth 62 on the actuating element 51 moves out of meshing relationship with the oint of the tooth 58 on the hub of the switch member 50, as indicated in Fig. 5 the anged or collar portion 63 of the actuating element 51 is rotated into the space at the end of the short tooth 59 with the cylindrical surface thereof in close rotating engagement with the adjacent teeth 58 and 60. This eiectively locks the switch arm 50 in the operated position upon continued rotation of the shaft 22 carrying the actuating element 51. Thus it will be apparent that with the shaft 22 provided with a plurality of actuating elements 51 mounted with the teeth out .of alignment, the corresponding switch members will be operated in sequence and each locked in the operated position upon continued rotation of the shaft 22.

Assuming that the rotation of shaft is continued in the clockwise direction suiiiciently to carry the teeth 61 and 62 well out of meshing relationship with the co-operating teeth on the hub of the switch member 50, upon reversed rotation of the shaft 22 no movement of the switch member 50, will occur until the tooth 62 returns intov meshing engagement between the teeth 58 and 59 on the hub of the switch member. Thereupon the tooth 62 drives the short tooth 59 and thereby rotates the switch member 50 inthe clockwise direction to disengage the contact 12 and the fixed contact 12 and return the switch member 50 to the position in which it is shown in Fig. 4..

In case it should be desired to continue the counter clockwise rotation vof the shaft 22 and arrange the switch member 50 so as to be locked in the open position, the -switch member 50 may be provided with the additional teeth 701and 71 and the actuating element 51 provided with the additional tooth 72 as shown in Fig. 6. In this modified contact operating arrangement the tooth is shorter than the adjacent teeth 58 and 71 in order to provide space at the end of the tooth 70 for receiving the cylindrical locking portion 63 of the actuating element 51. Thus upon continued rotation of the shaft 22 in the counter-clockwise direction so as to unmesh the tooth 61 and 72 from the co-operating teeth on the hub of switch member, the cylindrical flange portion 63 of the actuating element 51 projecting from the tooth 72 isreceived in sliding engagement between the adjacent teeth 71 and 58, so as to lock the switch member 50 in the open position. The operation of this modified form of tooth arrangement in operating the switch arm 50 to the circuit closing position and locking the same therein is accomplished in substantially the same manner as previously described.

With the switch mechanism shown in Fig. l connected to control the starting of an electric motor as diagrammatically shown in Fig. 7, the o eration is as follows. Closure of the push utton 75 serves to energize the operating electro-magnet 10 thru a circuit extending from the upper supply line L, the stop push button 76, the start push button 75, the auxiliary switch 17 and a portion of the winding of the electro-magnet 10 to the lower supply line L. The resulting attraction of the core 18 immediately closes the motor line switch l1 to connect the motor M to the supply line L with all of the resistance R in the motor circuits. At the same time the auxiliary switch 17 completes a holding circuit extending thru the stop push button 76 and the entire winding of the electro-magnet 10. The attraction of core 18 also sets up a strain in the compression spring 41 tending to rotate the shaft 22 in a clockwise direction under the retarding iniiuence of the timing device 14. As the rotation of shaft 22 continues, the motor accelerating contact l2 and 13 are operated in timed sequence by the successive intermeshing of the teeth on the actuating elements 51 and 51 with the teeth of the hubs of the switch members 50 and 50 in the manner described in connection with Figs. 4 and 5. In each case continued rotation of the shaft 22 serves to lock the corresponding contact arm in the circuit closing las position. The retarded rotation of the shaft 22 continues until the end of the projection 42 on the arm 40 engages with the connecting link 19 on the pin 20 in the same relative po- 5 sition as shown in Fig. 1. The sequence of operating contacts 12 and 13 readily may be varied simply by adjusting the relative angular positions of the actuating elements 51 and 51 on the shaft 22. l Also adjustment of the timing device 14 p ermits the time delay action thereof to be varied through a relatively wide range.

The sequential closing of the contact 12 and 13 serves to cut out the resistor R from l the motor circuit at time intervals suiicient;

to permit the motor to accelerate to full running speed without drawing on excessive current from the supply lines.

To stop motor M, the stop push button 76 n is actuated thereby de-energizing the magnet 10. The core 18 immediately falls thereby -first operating the line contact 11 out of engagement with the cooperating stationary contacts to break the motor circuit before the opening of the motor accelerating contact 11 and 12 is effected. This is due to the fact that the motor line Contact 11 is directly connected through the bent member 24 and the yoke arm 21 with the plunger 18,while a certain rotation of the operating shaft 22 in the counter-clockwise direction is required to effect the sequential opening of the accelerating contacts 12 and 13. This arrangement insures that all of the circuit interrupting' duty is imposed upon the line contact 11, which is provided with the magnetic arc blowout 29 and the arc chute 28 so as to electively take care of any arcs occurring upon interruption of the motor circuit. Thus,

40 with this arrangement there is no necessity for providing accelerating contacts with arc blowout devices. Since the line contact 11 is both closed and opened before the sequential closure and opening of accelerating contacts 12 and 13 occurs.

After the opening of the line contact 11 the continued movement of the plunger 18 to the unattracted position rotates the shaft 22 dueto the engagement of the pin 20 and the link 18 with the upturned end of the bracket 42 carried by the arc 43 so as to return all of the parts to their initial position, as' shown in Fig. 1. The ratchet teeth on the pinion 46 and rack 47 are so formed that the rack rides over the pinion during this return movement without actuating the timing device. In this way the switch contacts are opened immediately upon deenergization of the operating electromagnet preparatory to 00 restarting the motor and removing the sections of the starting resistance in timed sequence upon subsequent operation of the start push button.

It should be noted that the improvements 05 of the present invention permit the several accelerating switch contacts to be operated in timed sequence -by the successive intermeshing of toothed gear elements after operation of the plunger of theoperating electromagnet to the attracted position. This insures, particularly in alternatin current service, that the excessive energization ofthe electromagnet required to move the plunger is maintained only momentarily. Furthermore, the line switch contact always is closed as well as opened before corresponding operation of the accelerating contacts. Also by proper arrangement o-f the timing device and of the yielding connection through ywhich the operating electromagnet rotates the operating shaft any desired amount of retarded rotation thereof may be obtained so as to operate any desired number of accelerating conta cts in timed sequence. Since the adjustable intermeshing toothed contact operating ele' ments provided for operating and locking the individual accelerating contacts in position are duplicates, it will be evident that a switch having the desired number of sequentially operable contacts and in which the sequence of intermeshing of the toothed elements may be varied at will can be built up in a relatively simple manner. Moreover, the particular intermeshing tooth switch operating arrangement permits the use of relatively few and simple switch parts formed of moulded insulating material at low cost but` which insure long life and freedom from insulation troubles.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, a movable member having teeth formed thereon, and a relativel movable operating member having teethI formed thereon for cooperating with the said teeth on the irst member to operate the first member between predetermined positions during one portion of the movement of said operating member and having a flanged portion formed thereon for cooperating with the teeth on the iirst member for locking said first member in one of said positions during another portion of the movement of said operating member.

2. An electric switch including` relatively movable circuit controlling contacts, a contact operating member provided with gear teeth, one tooth being of less length than the adjacent teeth, and an actuating element having a gear tooth operable into and out of meshing engagement with said one tooth and provided with a projection operable into the space between said adjacent teeth at the end of said one tooth for holding said contact operating member in-a predetermined position 125 when said gear teeth are unmeshed.

3. In combination, relatively movable members, and a pair of toothed elements op erable into meshing engagement for operating said members, one of said toothed ele- `ments having a flanged portion of lesser width than a tooth and extending from the face of one tooth-thereof, and the other element having a tooth shortened for receiving said flanged portion into the space between the adjacent teeth at the end thereof for holding the members in a predetermined position when said toothed elements are unmeshed.

4t In a controlling mechanism, a movable controlling element having a hub at one end thereof for mounting the movable controlling element for pivotal movement about the axis of said hub, and a rotatably mounted operating member having a plur-ality of gea`r teeth formed in circumferential spaced alinement on the periphery thereof and provided with a circular flange extending from vthe face of one of said teeth to form a cylindrical surface including the point of said tooth, the hub of said controlling member being provided with gear teeth for meshing with the teeth on said operating member and h-aving a space provided between certain of said teeth for receiving said projection to lock the said controlling member in a definite controlling position upon the unmeshing of said teeth.

5. An electric switch including a fixed contact, a movable Contact, an arm having means for mounting said movable contact at one end thereof and having a hub at the other end thereof for rotatably7 supporting the arm, said hub being provided with a plurality of gear teeth arranged with a short tooth between a pair of longer teeth to provide a spacel therebetween at the end of Ysaid short tooth, and a rotatably mounted operating member provided with a tooth for meshing between the said short tooth and one of said pair of longer teeth to rotate said hub upon rotation of said operating member and having a portion adapted to be rotated into said space in rotating engagement with said pair of longer teeth for locking the said arm in a predetermined position simultaneously with the unmeshing of said tooth upon continued rotation of said operating member.

6. An electric switch including a pivotally mounted switch member having a contact arm extending therefrom and provided with gear teeth on the opposite side of the pivot with one tooth shorter than the adjacent teeth, and a rotatable actuating element therefor provided with gear teeth operable into and out of meshing relationship with the gear teeth on said pivoted switch member and having a cylindrical portion rotatable into the space between said adjacent teeth at the end of said one tooth for holding said contact in a predetermined position upon the unmeshing of said gear teeth.

7 In a multiple contact switch, the combination of a rotatable member, a plurality of toothed members mounted thereon with the teeth of the members out of alignment and a plurality of cooperating toothed switch members mounted for meshing with said toothed members to effect sequential operation thereof upon rotation of said rotatable member. f

8. In a multiple contact switch, the combination of a plurality of contacts, a rotatable shaft, a plurality of toothed members Iadjustably mounted thereon and each having a flanged portion extending from a tooth thereof, and toothed contact operating members mounted for meshing with said toothed members on said shaft to effect sequential operation of the said contacts upon rotation of said shaft, each contact operating member having a sp-ace between two teeth thereof for receiving the fianged portion of the cooperating toothed member to lock the contact operating member in position after operation thereof.

9. In a multiple Contact switch, the combination of a plurality of coaxially'mounted rotatable switch members, each having a toothed portion, a rotatable shaft mounted in spaced alignment with said switch members and having a plurality of toothed gear members mounted thereon with the teeth of the gear members out of alignment for meshing with the toothed portions of said switch members to effect sequential operation thereof upon rotation of said shaft, said toothed gear members being provided with means cooperating with the teeth on said switch members for holding said switch members fixed in a predetermined position upon continued rotation of said shaft.

10. A multiple contact time element switch including a plurality of coaxially mounted rotatable switch members, each having a. toothed hub, an operating shaft therefor having a plurality of toothed gear members adjustably mounted thereon for operating said switch members in a predetermined sequence, an operating electromagnet yieldingly connected to rotate said operating shaft, and time element means for retarding the rotation of said shaft.

11. In a multiple contact time element switch, a rotatably mounted shaft, a lever arm rotatably mounted on said shaft and having a projection extending therefrom, a second lever arm lixedly mounted on said shaft and having a projection extending in spaced opposing relation with the projection of said first arm, a compression spring interposed between said projections, an electromagnet connected to operate said first arm to place said spring under compression and thereby bias said shaft for rotation, a time element device connected with said second arm for retarding the rotation of said shaft, a plurality of rotatably mounted switch members disposed Q electromagnet for rotating sald other shaft in spaced alignment with said shaft and having teeth formed thereon, and cooperating toothed members mounted on said shaft in meshing relation with the teeth of said switch members for operating the same in timed sequence.

12. In a multiple contact time element switch, a pair of shafts mounted in alignment, means for effecting retarded rotation of one of the shafts, a plurality of switch members having hubs rotatably mounted on said other shaft, said hubs being provided with teeth, and cooperating toothed members adjustably mounted on said first shaft for operation into and out of meshing engagement with the toothed hubs of said switch members to effect sequential operation thereof upon retarded rotation of said first shaft, each of said toothed members being provided with means cooperating with a plurality of teeth on the hub of the corresponding switch member for holding the same in a predetermined position during a portion of the rotation of said first shaft.

13. A multiple contact time element switch 'including a base, a plurality of stationary contacts mounted in alignment thereon, a pair of shafts mounted in spaced alignment with said base, a plurality of switch members having hubs rotatably mounted on one of said shafts and provided with movable contacts disposed in cooperating circuit controlling relation with said fixed contacts, each of said hubs having a plurality of teeth formed thereon with a short tooth between a pair of longer teeth to provide a space at the end of the short tooth, a plurality of toothed gear members mounted on the other shaft with the teeth thereof out of alignment and in meshing relationship with the teeth on said hubs for insuring sequential operation of said movable switch members upon rotation of said other shaft, each of said tooth gear members having a portion adapted to be rotated into the space at the end of the short tooth on the hub of the corresponding switch member for locking said switch member in a predetermined position upon the unmeshing of the teeth on the hub and the gear member, an

and having a resilient connection therewith, and a rotatable time element device connected with said shaft for delaying the rotation thereof.

' 14. In combination, a plurality of switch contacts each operable between two positions, a common operating means therefor, and connections through which the operating means ecct operation of a portion of the contacts to each position before operation of the remaining contacts to the corresponding position.

15. In combination, a plurality of switch contacts operable between two positions, an electro-responsive device having a movable member for operating said contacts to each po s1t1on, and operating connections between sald'movable member and said contacts including a plurality of successively intermeshing gear elements for effecting operation of one of the contacts to each position before operation of the other contacts in sequence to a corresponding position.

16. In combination, tacts `each operable between two rotatable shaft having a plurality of successively intermeshing gear elements associated therewith for effecting sequential operation of a portion of said contacts to each pos1t1on upon rotation of the shaft in a corresponding direction, an electro-responsive device for rotating said shaft in each direction, and independently operable `means associated with the electro-responsive device for operating a different ortion of said contacts to each position be ore rotation of the rotatable shaft to effect sequential operation of said first portion of said contacts to the corresponding position.

17. In combination, a plurality of contacts each operable between two positions, a first movable member for operating one of the said contacts to each position, a second movable member having a plurality of successively intermeshing toothed elements associated therewith for effecting sequential operation of the other of said contacts to each position, means `including a yielding connection for consecutively operating said first and second members in each direction, and means independent of said yielding connection for operating said first and second members in the other direction.

18. A multiple contact electromagnetic switch comprising a plurality of contacts each operable between two positions, a ro tatably mounted shaft having a plurality of successively intermeshing toothed elements associated therewith for effecting sequential operation Of-a portion of said contacts between said positions, a member pivotally mounted on said shaft for effecting o eration of a different portion of said contact tween said positions, an operating electromagnet having a movable member connected to operate said pivotally mounted member in one direction upon energization of the electromagnet and in the other direction upon deenergization of the electromagnet, .and means including a resilient connection and a time delay mechanism for effecting rotation of said shaft after operation of said pivot,-

a plurality .of conitlons, a

ally mounted member in one of said direc-v q tions.

19. A multiple contact time element switch comprising a plurality of contacts operable between two positions, an operating electromagnet therefor having a movable magnetic member mechanically connected to operate a portion of the contactsto one position upon energization of the electromagnet and to another position upon deenergization of the electromagnet, connections between said movable member and a different portion of said contacts including a rotatable shaft having a plurality of successively intermeshing toothed operating elements associated therewith for effecting sequential operations of said different portionot said contacts to each position after operation of said one portion of the contacts to the corresponding position, and a time delay device associated With said shaft for effecting operation of the said different portion of the contacts to one position in timed sequence.

20. In combination, a movable member provided with a gear tooth, a locking projection on said member opposite the end of said gear tooth, an actuating element having gear teeth operable into and out of engagement with said tooth on said member to move said member, and a locking projection on said element extending beyond the ends of said gear teeth for slidably engaging said locking member when said element is moved to disengage said tooth thereby to hold said member in a predetermined position.

21. In combination, a ivoted member provided With a gear toot and a projection axially extending from said gear tooth, an actuating element having gear teeth operable into and out of engagement with said tooth on said member to move said member, and a portion carried by said element arranged to engage said projection when said element is moved to disengage said tooth and thereby hold said movable member in a predetermined position.

22. In combination, a movable member provided with a plurality of gear teeth, one tooth being of less length than the adjacent teeth, and an actuating element having a gear tooth movable into and out of meshing engagement with said one tooth to move said member, and a projection on said actuating element arranged to move into the space between said adjacent teeth When said actuating element is moved to disengage'said teeth to hold said movable member in a predetermined position.

23. In combination, a member having a gear tooth, means supporting said member for rotation about a predetermined axis, said member being provided With a depression axially extending from said gear tooth, an actuating element having gear teeth operable into and out of engagement with said tooth to move said member about its axis, and a locking projection on said element axially extending from said gear teeth and having a curved surface slidable into VAsaid depression for locking said member in a predetermined position for movement of said element with its gear teeth out of engagement with said teeth.

24. An electric switch including relatively movable circuit controlling contacts, a contact operating member having -a gear tooth, means supporting said member for rotation about a predetermined axis, said member being provided with a depression axially extending from said gear tooth, an actuating element having gear teeth operable into and out of engagement with said tooth to move said contact operating members about its axis, and a locking projection on said element axially extending from said gear teeth and having a. curved surface slidable into said depression for locking said member in a predetermined position for movement of said element with its gear teeth out of engagement with said tooth.

ROBERT W. GOFF.

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