US1583939A - Detent-tripping mechanism for socket switches - Google Patents

Description

May 11 1926.

R. D. SMITH DETENT TRIPPING MECHANISM FOR SOCKET S WITCHES Filed Nov. 7 8,

Patented May 11, 1926.

UNITED RAYMOND D. SMITH, OF SCARSDALE, NEW YORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO TREMONT PRODUCTS CORPORATION. OF BOSTON, MASSACHUSETTS, A.

CORPORATION OF MASSACHUSETTS.

DETENT-TRIIPPING MECHANISM FOR SOCKET SWITCHES.

Application filed November 8, 1920. Serial No. 422,751.

This invention relates to a detent-tripping arrangement, specifically but not exclusively for pull socket switches, wherein a common, manually actuable means is employed co-operatively with a resilient means and a detent to tension a controlled mechanical element for'movement normally prevented by said detent and subsequently to release said element from restraint by said detent by mechanically tripping the latter.

The broad object of the invention is to provide in a partially automatic apparatus (such as a pull socket switch partially governable by a thermostatic detent) having a single, manually actuable element for controlling the same (such as a spring restored pull chain), a tripping mechanism whereby when tension is established by one full stroke of said element for later causing automatic detent-delayed movement of an operative part (such as a switch circuit controller) a subsequent manual actuation of said element will operate to tri the detent and release said part immediately to permit its said movement.

The novel principles embodied in my present invention may advantageously be applied to delayed cut-offs for pull sockets of the general type disclosed in my copending application, Serial No. 421,556 filed Nov. 3, 1920. The type of switch here employed as the delayed cut-off above mentioned includes a current distributor arranged to be established under tension tending to move the same to break the circuit but permitted so to move only upon. thermostatically caused retraction of a nornn'llly restraining detent, such retraction taking place after a substantial interval of time such as that required for the thermal energization of the thermostat by the electric current. In the most simple form of the above described switch. however, no means is provided for manually causing direct and immediate circuit-breaking switch action if desired but the operator must always wait upon the delayed-acting automatic switch action above described.

The only means that have heretofore been provided in this connection for manually causing direct and immediate cut-off action independently of the thermostatic delayed acting detent has consisted in a co-operative formation of the engaging portions of the above mentioned current distributor and the thermostatically.controlled detent hook, whereby an unusually forceful pull on the switch control chain operates to force the detent hook out of engagement with the distributor by excessive thrust of the latter on the intercepting portion of the, former to permit circuit-breaking movement of the distributor. This arrangement depends in operation upon a proper balancing of co-operative spring forces and causes strain and wear upon parts necessarily employed which are comparatively small and delicate.

Accordingly, in applying my invention to improve the operating conditions described above, the particular object is to provide a tripping device for the. detent hook whereby, preferably, a repetition of the initial stroke of the pull chain subsequent to the stroke thereof that places the current distributor under tensioned restraint by said detent hook, is operative to retract the detent hook from intercepting engagement with the distributor in a natural, un-- as shown on the accompanying drawings in which:

F 1g. 1 1s a view of the complete socket switch in elevation, the caslng and certain other parts being partially broken away to show the interior switch structure in which is embodied my improved detent tripping 95 mechanism.

Fig. 2 is a plan view of the switch mechanism taken partly insection on the plane 22 in Fig. 1 and showing the relation of parts when the lamp circuit is normally 100 closed.

Fig. 3 is an enlarged fragmentary view in elevation looking in the direction of arrow 3 in Fig. 2, but showing the switch rotor positioned for circuit breaking movement and restrained 1n circuit making pos1- lost motion tooth engagement concerned in the detent tripping operation.

Fig. 8 illustrates a modification of the tripping mechanism.

Fig. 9 is a front elevation of the structure in Fig. 8 showing certain parts sectioned on plane 99 of that figure.

Fig. 10 shows a further modified form of tripping mechanism.

In the drawings, a single part when appearing in more than one view is designated by the same reference numeral;

In general construction the socket switch structure incorporating my improved detent tripping mechanism is of the usual form comprising within an outer casing 9 and retaining cap 10, two bracket-connected upper and lower blocks 11 and 1.2 respectively between which is mounted the switch mechanism, and from the lower of which blocks depends the threaded receptacle 13 for an incandescentlamp 14-, two of the block-connecting brackets having binding post screws 16, 16 to accommodate the socket leadwires 17, 17.

The switch mechanism includes a centrally plvoted, axially slidable, conductive plate rotor-20, having oppositely disposed contact-wiping arms 21 suitably formed to ride over stationary, inclined contact plates 22 for controlling the lamp circuit. The rotor 20 is rotated in stages and at each full increment of rotor movement the arms 21, 21 are advanced progressively overone of two pairs of diametrically opposite inclined steps, one of said pairs comprising the blank steps 25, 25 and the other of said pairs comprislng the steps 26, 26 which carry respectively the contact plates 22, 22, above mentioned.

The rotor 20 is advanced by successive forward strokes of an oscillatory actuator 30, axially slidable with the" rotor on the common pivot post 29, through the one-way driving engagement of pawl teeth 31 on said actuator with corresponding ratchet teeth 32 on said rotor,--such engagement being established by the coiled spring 33, which exerts axial tension pressing the actuator against the rotor and the rotor against the incline steps and which also exerts torsional tension on the actuator operative after a driving stroke thereof to return it to the beginning of its stroke, or positioned against ing shoulders 36, terminating each of the incline steps 25 and 26 serve as stationary ratchet teeth to prevent return of the rotor f plate 20 with the actuator 30 after a full driving stroke of the latter.

The relative position of the actuator stops 3 1 and 35 and of the step shoulders 36 is such that a full driving stroke of the actuator advances the plate arms 21 fully over the shoulders which terminate the steps 25, 25 after which the actuator will obviously be returned by spring 33 and in its lowest rotative plane to such an extent that the pawl teeth 31 retreat to a position for engagement with the next succeeding ratchet teeth 32 respectively and in my present improvement I so position the stop 34: that on each return of the actuator'the extent of its retreat is sufiicient to provide an appreciably lost motion or back-lash in the tooth-engaging relation such as shown at 37 in Fig. 7. The purpose of this back lash is, to permit in one position of the parts, a repetition of the initial part of the actuator driving stroke, before driving engagement occurs between the pawl and ratchet teeth 31, and 32,-this repeated movement being utilized for tripping a detent in a manner and for a purpose later to be described.

The position of the shoulders 36 that in spring 33 tends to cause said arms 21 to slide rotatively forward, and to be dis charged from contact plates 22 onto the succeeding blank steps 25, 25, to break the circuit through the lamp. Before such discharge takes place, however, the rotative advance'of the rotor 20 is positively arrested by engagement of a projecting spur 44 on the edge of the rotor 20 (of which there are two on diametrically opposite sides of the rotor) with a detent hook 40, pivoted to swing on a stud 41 mounted on the insulating block 12. -At this time the plate rotor 20 and its arms are positioned as shown in full lines in Fig. 3.

The electric circuit connections and contact arrangement are such that advance of the rotor 20 to its position shown in Fig. 3 electrically energizes a normally de-energized resistance wire 45-that is wound about and in heating relation to a bi-metallic thermostat 46 anchored at one end to the bracket 47, so that heat begins to be delivered to said thermostat and after a designed interval of time required to raise the thermostat to a certain temperature (which time may conveniently be from one to two minutes) a straightening, or outbending, of the thermostat occurs suflicient to retract the detent hook from restraining engagement with spur 44 as shown in Fig. 5. The spring 33 then acts to discharge the rotor as above described automatically to extinguish the lamp. I When so discharged, the rotor-spur 44 drops to a lower plane than the intercepting end of hook 40, so that said hook does not become again operative to prevent further advance of the same spur when the thermostat cools.

It may be desired, however, to cause circuit-breaking movement of the switch rotor 20 independently of this thermostaticallycaused detent release which depends for operation on action of the electric current. Especially is this true of the types of pull socket switches disclosed in my co-pending applications, Serial No. 422,750, filed Nov. 8, 1920, and Serial N 0. 421,554 filed Nov. 3, 1920, to which types of switches my present improvement is equally adaptable. Among other accomplishments the present invention specifically provides an improved means to this end, in a form of mechanism whereby the detent hook 40 may be mechanically and directly tripped by a partial forward stroke on the actuator after its return from the forward or driving stroke that places the rotor under control of the thermostatically operated detent hook 40.

In the present embodiment of my invention a tripping extension for said detent hook is provided, preferably in the form of a light leaf spring 50, that may be riveted or otherwise secured to the hook 40 and extending therefrom inwardly in substantially tangential relation to the circular path of a peripheral edge of the actuator 30. This actuator, as commonly constructed, comprises a relatively thick segmentary plate 51 made of fibre, or other suitable insulating material, secured to the under surface of which is a relatively thin, punched-metal piece 52 formed to serve as a hub for the actuator,

and from which piece the pawl teeth 31 are struck downwardly. The plate 51 also carries spaced radially outwardly from the hub piece 52, a punched-metal channel-guide anchorage 53 for the pull chain 55. The peripheral edge of the actuator above referred to may comprise merely the edge of the relatively thick fibre plate, whichv as herein shown, is formed with a radially outwardly extending spur formation 56.

It will be clear that the normal travel of the spur formation 56, during a normal driving stroke of the actuator, is normally in a helical path relative to the axis of oscillation of the actuator, because of the mounting ping extension 50 is axially removed from the said helical path it is clearly shown in Figs. 2 and 5 that the end of said extension is normally positioned within the circular radial extent of said path, so that engagement of said extension with said spur will occur if the actuator 20 is maintained substantially in its highest plane when it is returned to the beginning of its driving stroke. When the rotor 20 is arrested in its position as shown in Fig. 3, however, it is evident that the actuator will be maintained in its highest plane, as shown in that figure, so that on return of the actuator after the driving stroke that so positions said rotor, the spring leaf tripping extension 50 will yield radially outwardly to permit the passage of the spur 56 near the end of the return actuator stroke, immediately snapping back into the path of said spur after the passage of the latter, so that at the beginning of a subsequent forward stroke of the actuator,

the spur is operative to trip the detent 40 through longitudinal thrust on the extension 50, and before driving engagement occurs between teeth 31 and 32, because of the backlashshown in Fig. 7 and heretofore described.

This tripping of the detent releases the rotor for its spring caused discharge from the contact plates 22 exactly as in the case of thermostatic retraction of the detent; and the rotor spur 44 and the actuator spur 56 both drop instantly to their lowest plane, as indicated by the positions 44*, and 56*, respectively, in Fig. 4, whereby the rotative parts are free for further advance circuitcontrolling movement.

.Tn Fig. 5 the broken line position of the resilient detent extension 50 shows the change in position of this extension relative tothe path of the actuator spur 56 when the thermostat is heated. It will be understood from reference to this figure and to Fig. 4, that such change in position of the extension 50 constitutes ingeneral a movement radially inwardly toward the actuator pivot 29 anch rises to a higher plane. Such interference would be of a nature to cramp and distort the resilient extension 50, as the actuator spur would be beneath and operative to force the extension upwardly edgewise. To prevent such condition the extension 50 is formed with a cam ear 57 at the bottom edge of its free end, and a co-operative bevel is formed at 58 on the upper peripheral edge of the actuator fibre plate 51, in the vicinity of the spur 56,-this cam ear and. bevel co-acting to cause a natural and unstrained yielding of the extension 50 in its designed direction of fiexure away from the path of the actuator,

to prevent possible injury to the extension 50, if the switch is actuated before the thermostat has become cool. The nature of the impingement that under these conditions might occur between the bevelled edge of 58 of the actuator and the cam car 57 is clearly shown in Fig. 6.

It will be appreciated that the arrangement described above utilizes a natural condition of relative and absolute actuator movement already inherent in the well known type of pull socket switch for producing a permutation detent tripping function that provides for the operator the ability by successive manual strokes on the actuator pull chain to conveniently and selectively establish the switch in any of its designed operating positions, without delay or con straint, and requiring no special or unusual method of chain-manipulation.

Specifically, the operative effects that are available by the operator in a socket switch embodying my improved detent trip-ping mechanism are the ability by successive actuations of the usual pull chain first,-to light the lamp by one full stroke of said chain;

second, when through with the light to actuate the switch by a subsequent pull chain stroke for automatically eifecting delayed lamp extinguishment; third, to cause immediat and undela-yed extinguishment of the lamp, if desired, by repeating the initial part of the last mentioned stroke; or as an alternative to this last mentioned operation, a repetition of the full chain stroke that actuates the switch to effect delayed automatic lamp extinguishment, may be made, which will momentarily extinguish the lamp, but immediately reestablish it in normally lighted condition, for continuous use.

I have thus provided a pull socket switch free from undesirable mechanical features, either as to complication or delicacy, and a switch that is manually governable by a single pull chain to light and extinguish a lamp as usual, but also containing means, operative when desired, to delay the circuit breaking action of the switch.

It is to be understood that the mechanical principles underlying my invention do not hmit its embodiment to the exact or even substantial form heretofore described. For instance, as shown in Fig. 8, I may mount a resilient tripping extension on the. actuator fibre. plate 51 and arrange the same for yielding flexure, not in a radial plane relative to the axis of the actuator pivot, but in'a plane substantially parallal to said axis. In thls case, I may employ a rigid projection 61 extending from the detent hook 40 to a position for being tripped by said extension 60 according to the operative principles of my invention heretofore described.

In Fig. 10, a modification is shown wherein provision is made for varying the nature of displacement of the tripping extension when the thermostat moves to its heated position as shown in Fig. 5. Here the tripping extension appears as a rigid strut arm 62 pivoted at 63 and having a stop limiting spur 64. The strut arm 62 is yieldingly maintained in its normal full line position by a light leaf spring 65 that may conveniently be anchored in a slot in the top of hook pivot stud 41 so that the strut may move back as required to some such position as is shown in dotted lines in Fig. 10 when engaged by the actuator in its return movement. A projecting bracket 66 also extends from this stud and has a turned down extremity 67 engaging with the tripping arm 62 to limit the movement of the same toward the center of the switch structure,the operative effect of said constraint being to prevent interference-causing displacement of the trippingextension 62, such as shown in Fig. 5. Obviously a constraining bracket such as 66 could be employed with the type of tripping extension shown in F igs. l to 6 inclusive, in place of said cam ear and bevel formations. Y

The features of the improvement residing in the thermostatic control mechanism 40, 41, 46 etc. and . co-operative switch contacts 21, 22, 38' etc. per se, are not claimed in this application but are the subject matter of claims in my co-pending application Serial No. 421,556, filed November 3, 1920.

The pull socket structure herein disclosed is of the simple type for supporting and governing a single incandescent lamp, the cooperative switch circuits terminating in rotor-bridged contact plates carried on two of only four detent step formations. The switch may however have more steps and more contact plates for governing additional circuits such as for a second switch-goveined lamp or dimming device for the usual lamp. There would clearly be no definite sequence of operation to which such multiple switch arrangement would be restricted, such se quence depending entirely on the consecutive arrangement of steps and the thermo-detent tripping device herein disclosed could be applied equally well to any step.

Numerous other possible variations in form and arrangement of details will suggest themselves to a mechanic and obvious ly the novel mechanical principles involved. in my present invention are adaptable to types of apparatus other than socket switches.

I do not, therefore, limit the scope of my 'by a forward stroke of said element to tension said device for forward automatic circuit-governingimovement; a detent normally arranged to prevent said movement; and tripping mechanism for releasing said controller from restraint by said detent, operatively actuable directly by a repetition of said forward stroke of said element,

2. An electric switch having in combination, relatively movable contacts; an oscillatory actuator with a limited stroke, including a spring automatically to restore it to a normal position, and arranged by full strokes alternately to close the switch and to place it under control of automatic electric devices adapted to cause its delayed openin said devices, including a detent normal y adapted to prevent opening of the switch; and means co-operative between said actuator and detent, when said switch is placed under control of said devices and when .iaid actuator is then returned to its normal position, adapted to release said detent by further movement of said actuator.

3. Permutation switch mechanism embodying in combination, an oscillatory drivin element having a limited stroke; and a riven switch circuit controller, both adjacently rotatable and axially slidable upon a common pivot, said element and controller being maintained in pawl-and-ratchet driving engagement by tension exerted axially on said element; a contact-carrying step disposed in the path of said controller to oppose said tension and formed to resent a riding surface thereto inclined obliquely to the plane of controller rotation, whereby mounting of said step by said controller causes said element to rise from a lower plane at the beginning of its driving stroke to a higher plane at the end of said stroke; detent means operative to retain said controller nearthe top of said step, whereby said element is then retained in said higlier plane, during its return stroke; and tripping mechanism for said detent means positioned to be operatively engaged by said element only when the latter is near the beginning of its driving stroke and in said higher plane, whereby a subsequent forward stroke of said element actuates said mechanism to release said controller from restraint by said detent means.

4. In a pull socket switch for an incandescent lamp', the combination with a movable switch circuit-controller progressively movable to light and extinguish the lamp by successive strokes of a manually-operable spring-returned actuator, of detent means operatively related to said controller and electrically governed thereby automatically to delay the lamp-extinguishing movement of said rotor a substantial period of time after the stroke of said actuator adapted to cause said action; and means whereby the repetition of said actuator stroke renders inoperative said detent means, thereby to cause immediate lamp extinguishment.

5. A pull socket switch having a step-bystep, rotatable, double-ended, conductive, current-switching member; circularly disposed stationary contacts arranged to be engaged by the ends of said member, inclined along the axis of rotation of said member toward said member, and mounted on insulating formations constituting teeth to prevent movement of said member in one direction, the terminal portion of said contacts being oppositely inclined; an oscillatory actuator arranged, relatively to said member,

' oppositely to said contacts, concentrically pivoted with said member, having pawl-andratchet engagement therewith, and further having a stop-limited stroke; a coiled spring arranged co-axially of the common pivot of said member and actuator and to exert axial pressure and torsional stress on said actuator; electrical means, including a detent, arranged to hold said member in electrical contact on said terminal portion and then to release said member; and tripping means for said detent arranged to be energized by said actuator only when the latter is returned rotatively to its normal position and is axiall displaced by retention of sai member y said detent.

6. In a pull socket switch, embodyingl a circuit-controlling rotor; pawland-ratc et actuating mechanism therefor including a awl device having a limited forward stroke or rotatively advancin said rotor over angular contact carrying onnations circularly arranged in the path of sald rotor to prevent backward movement of the latter, and further embodying common resilient means for rotatively returning said device the beginning of its stroke and for maintammg operative engagement of said device w th said rotor and thereby of said rotor with said formations, in combination; a stationary contact formation co-operatlvely arranged with an engaging portion of said rotor, in one position thereof, so that the thrust of said resilient means opposes backward movement of said rotor, and tends to discharge said rotor rotatively forwardly from said formation to break the circuit; a detent normally positioned to arrest forward movement of said rotor from its said position; and tripping means arranged to be operatively actuated by said device only upon a repeated forward stroke of said device subsequent to the establishment of said rotor in its said position.

7. In a pull socket switch embodying a circuit-controlling rotor; pawl-and-ratchet actuating mechanism therefor including a pawl device having a limited stroke for rotatively advancing said rotor over angular contact-carrying tooth-formations circularly arranged in the path of said rotor to prevent backward movement of the latter; and resilient means for rotatively returning said device after its stroke and for maintaining operative engagement of said device with said rotor and of said rotor with said formations, in combination; a co-operative detent arrangement operative to arrest both advance and backward movement of said rotor when the latter is established in a certain circuit making position by one advance stroke of said device; resilient means energized by said stroke of said device and tendmg to advance said rotor from 1ts said position to break the circuit; and mechanism for tripping said detent arrangement to release said rotor, o erable by said device only upon a repeated orward stroke of said device subsequent to the establishment of said rotor in its said position.

8. In anelectric switch, including manually actuable mechanism for tripping a switch governing detent that is normally movable between an interceptive and a retractive position by automatically-acting means electrically governed through said switch, the combination, with said detent, of a pivoted oscillatory switch actuator normally constrained for limited advance and return strokes in a normal helical path relative to its pivotal axis; means to constrain the rotative oscillations of said actuator to substantially a single plane when said switch isunder control of said detent and auto- -matically-acting means; a resilient tripping further arranged when said detent occupies.

its said" retracted position to lie in said helical path; said extension being co-operatively positioned and formed with an engaging port-ion of said actuator to permit the rotative return stroke of said actuator in said plane, and to be engaged positively thereby to trip said detent upon the subsequent advance stroke of said actuator, together with a co-operative cam formation on said detent extension and on said actuator arranged to cause normal yielding displacement of said resilient extension from the helical path of said actuator to permit the passage of the latter when said detent occupies its said retracted position.

9. In an electric switch, including-manually actuable mechanism for tripping a switch governing detent, the combination, with said detent, of a pivoted oscillatory switch actuator normally constrained for limited advance and return strokes in a normal helical path relative to its pivotal axis; means to constrain the rotative oscillations of said actuator to substantially a single plane when said switch is under control of said detent, a resilient trippingvextension carried by said detent in said plane and arranged to lie within the radial extent of said helical path but axially removed from said path; said extension being co-operatively positioned and formed with an engaging portion of said actuator to permit the rotative return stroke of said actuator in said plane, and to be engaged positively thereby to trip said detent upon the subsequent advance stroke of said actuator.

10. A detent and detent-tripping arrangement, embodying an oscillatory drive mem her having a limited stroke; a driven element; means including an element-engaging detent to detain said element after a full driving stroke of said member and further then to tension said element for automatic further movement and comprising instrumentalities adapted to cause such movement, said element,-member, and means being cooperatively arranged so that said member,

during its return stroke, is maintained in a different plane of rotation than that occupied by it after such further movement of said element; and a cooperative tooth formation on said member and resilient finger on said detent arranged to engage when said member is in said different plane, and then topermit escape of said member on its said return stroke, but then to release said detent from said element on a forward movement of said member.

11. A detent and detent-tripping arrangement, embodying an oscillatory drive member having a limited stroke; a driven element; means including an element-engaging detent to detain said element after a full driving stroke of said member and further then to tension said element for automatic further movement and comprising instrumentalities adapted to cause such movement, said element, member, and means being cooperatively arranged so that said member, during its return stroke, is maintained in a different plane of rotation than that 00- cupied by it after such further movement of said element; and a cooperative tooth formation on said member and resilient finger on said detent arranged to engage when said member is in said different plane, and then to permit escape of said member on its said return stroke, but then to release said detent from said element on a forward movement of said member; said member and extension carried by said finger being also co-opera-' tively formed and positioned to cause escapement of said finger from said member on a forward stroke of the latter in the plane occupied by it after said further movement of said element.

12. In a pull socket switch adapted to be operated by successive actuations of a controlling pull chain, and incorporating agencies automatically operative to delay circuit breaking movement of the switch, means whereby successive actuations of said pull chain respectively make the circuit, establish the switch under control of said agencies and then move the switch directly to break the circuit.

13. In a pull chain operated socket switch, the combination of automatic mechanism arranged to cause self-delayed circuit-breaking movement of the switch, instrumentalities whereby one actuation of the pull chain energizes said mechanism, and means whereby a subsequent actuation of the pull chain operates the switch directly to break the circuit.

14. A switch for an electric circuit having contacts, a contact controlling member movable by successive movements to make and break the circuit, slow action controlling instrumentalitiesto delay the circuit changing elfect of the movement of said member 'for a substantial interval of time, and means whereby subsequent movement of said member establishes the circuit change irrespective of the action of said intrumentalities.

15. A switch for an electric circuit having contacts, a contact controlling member means to move the same for effecting a circuit change, slow action controlling means to delay the circuit changing effect of said member for a substantial interval to time after movement thereof, and means operative through subsequent movement of said member unretardedly to produce said circuit change.

16. A switch for an electric circuit having contacts, a contact controlling member movable by successive movements to make and break the circuit, slow action controlling instrumentalities to delay the breaking of said circuit for a substantial interval of time, and means whereby subsequent movement of said member may'break said circuit immediately irrespective of the control by said instrumentalities.

17. A switch for an electric circuit having contacts, a contact controlling member movable by successive movements to make and break the circuit, a thermo-electric control device todelay the current changing effect of a movement of said member for a substantial interval of time after said movement, and means whereby subsequent movement of said member establishes said current changing efi'ect irrespective of the control of said instrumentalities.

18. A switch for an electric circuit having contacts, a contact controlling member movable by successivemove-ments to make and break. the circuit, a thermo-electrically controlled detent to delay the current changing efiectof a movement of said member for a substantial interval of time after said movement, and means whereby subsequent movement of said member withdraws said detent.

19. A pull socket switch for an incandescent lamp having contacts, an actuator, successive actuations of which make and break the lamp circuit, a thermo-electrically controlled detent to delay the breaking of the circuit, and means whereby a subsequent movement of the actuator withdraws the detentpermitting immediate breaking of the circuit.

20. A socket switch for an incandescent lamp having an oscillatory actuator, a rotary contact controller adapted to be advanced progressively step by step by successive movements of the actuator to make and break the lamp circuit, athermoelectric control device to delay the breaking of the circuit for a substantial interval of time, and means whereby a subsequent movement of the actuator serves to break the circuit irrespective of the control device.

21. A socket switch for an incandescent lamp having an oscillator actuator, a rotary contact controller a apted to be advanced progressively step by step by successive movements of the actuator to make and break the lamp circuit, a thermo-electrically controlled detent to delay the completion of the circuit breaking movement of the controller for a substantial interval of time following the circuit breaking movement of said actuator, and. a detent' release mechanism adapted to be actuated by a subsequent movement of the actuator to cause immediate breaking of the circuit when desired.

22. A switch for an electric circuit having a movable circuit control member adapted to make and break the circuit, means to impart movement thereto to produce a given circuit changin efiect, adetent to arrest the movement 0 the same toretard the said and break the lamp circuit, a detent to arrest movement-of the same to retard the circuit breaking movement of said member, a thermo-electric control device for the detent, a supplemental detent control movable independently of both the control member and the thermo-electric control device to independently withdraw the detent, and a manually operable actuator for said supplemental detent control.

24. 'A switch for an electric circuit having a movable circuit control member adapted to inakeand break the circuit, a slow acting control device combined with means to retard the circuit changing movement of said 'member for a substantial interval of time,

means movable independently of said memher and device for independently actuating said means to cause unretarded circuit changing movement, and actuating means for said independently movable means.

25. A socket switch for an incandescent lamp having a movable circuit control member adapted to make and break the lamp circuit, a manually operable actuator adapted to move said member ,for lighting and extinguishing the lamp, a detent operatively related to said member, electrically governed means to control the detent to delay the lamp extinguishment for a substantial period of time after t-helamp extinguishing movement of the actuator, and means to move the detent by a repetition of the actuator movement to cause immediate lamp extinguishment.

26. A socket switch for an incandescent lamp having an actuator adapted to operate the switch, and incorporating agencies automatically operative to retard lamp extinguishment for a substantial period of time following a lamp extinguishing movement of the actuator, and having also means to produce, an unretarded extinguishment of the lamp through a subsequent actuation of the actuating device.

Signed at Boston, in the county of Suffolk ahd Commonwealth of Massachusetts, this 5th day of November, 1920.

RAYMOND B. SMITH.

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