US2270150A - Electric switch - Google Patents

Description

Jan. 13, 1942. E. H. TAYLOR ELECTRIC SWITCH Filed oct'. 3, 1958 2 sheets-sheet 1 Inversion, CLM n4.

Jan. 13,- 1942. E. H. TAYLOR 2,270,150

' ELECTRIC SWITCH Filed oct. :5, 1958 2 sheets-Sheet 2 "fPatented Jan.. 13, 1942 ELECTRIC SWITCH Elmer H. Taylor, Newburyport, Mass., assignor to The Chase-Shawmut Company, Newburyport, Mass., a corporation of Massachusetts Application October 3, 1938, Serial No'. 233,006 y (Cl. 20D-116) '21 Claims.

This invention relates to electric switches or circuit controllers of the manually opened and closed and overload responsive opening type` especially designed for thecontrol and protection of motors and circuits of moderate power but not restricted to this type of service.

The present invention is inthe nature of an improvement on the invention .disclosed and claimed in my copending application Serial No.

132,735, filed March 24, 193'?, now FatentNo.'

2,160,236, issued May 30, ,1939. l

The circuit controller or interrupter of the present invention includes an actuator normally pivotal or movable about a center on an electroresponsive removable pivot or fulcrum for effecting opening and closing movementsof the movable switch member under manual control and movable about a second center upon removal of the electro-responsive fulcrum to effect automatic overload opening of the interrupter free from control by a manually operable operating member.

Objects of the present invention. are to improve i and simplify the construction and improve the v operation of the interrupter; an improved form of actuator and movable switch member; an improved construction of the actuator and manual operating member by which the initial movement of the operating member in a circuit closing di- 4 rection is relatively strongly opposed for a part of the movement `of the operating member and thereafter the resistance to movement is reduced so that the interrupter is caused to bev closed rapidly; an improved construction and disposi-v tion of the parts insuring long operating life relatively free from wear; and an improved .and economical construction and arrangement of the thermoresponsive elements and associated parts.

Fig. 1 is a plan viewo! the circuit interrupter` embodying the vpresent rinvention within its enclosing casing.

Fig. 2 is an end elevation of the interrupter of Fig. 1`

Fig. 3 is an enlarged sectional elevation taken along line 3-3 of Fig. l and illustrating in full lines the circuit closed position of the parts and in dotted lines the electrically tripped circuit open condition of the parts.

Fig. 4 is a view similar to Fig. 3 of the essential elements of Fig. 3 in the manually circuitopened position thereof.

Fig.,5 is a view of the parts of Fig. 4 in a partially manually displaced position towards circuit closed position.

Fig. 6 is a transverse sectional elevation taken along line 6 6 of Fig. 3.

Fig. '7 is a perspective view of the insulating supporting block for the current conducting and t operating elements o! the interrupter.

Fig. 8 is an end elevation particularly illustrataing the electro-responsive tripping mechanism taken along line 8--3 of Fig. 3.

Fig. 9 is a perspective view of the pivotal supporting bracket for the manually operating member.

Fig.` 10 is a perspective view of the manually operating member.

Fig. 11 is a perspective view of the actuator.

Fig. 12 is a perspective view,of the stationary.

contact terminal.

Fig. 13 is a perspective view of the terminal associated directly with the tripping elements.

Fig. 14 is a plan view of the block supporting strap.. 'I'he circuit invention is contained within an enclosing casing 20 and includes an insulating block 22 secured by screws 24k to the under face of a supporting strap 26v which has end extensions 28 seated upon in-` wardly directed ears 30 of the casing and secured removably thereto by screws 32. The strap 23 has a longitudinally4 elongated opening or slot 34 in which a part of the manual operating member 36 of the interrupter is located and through which the operating. handle 38 thereof projects. The engagement between the handle and the end walls of` the slot 34 dene the circuit open and closed positions of the operating member.

The casing is provided with a cover 40 secured to the strap 26 by screws 42 and having a slot 44 therethrough which registers with the slot 34 of the strap. f

The insulating block 22 supports the circuit interrupter. The block has a relatively deep well or chamber l46 containing the major portion of the interrupter elements. The bottom orfloor 43 of the well supports a bracket 50, Figs. 3, 6 and 9, comprising a iiat bottom .plate 52, the integral sides oi which are upturned to provide parallel spaced upstanding arms 54 having aligned holes $6 therethrough adapted loosely to receive a pivot pin 58 on which are disposed the operating member 36 and an actuating memberor actuator 60, Figs. 3, 6 and 11. closely confronts one end of the pin and the opposite side wall 64 of the block has an inwardly directed vertical rib 66 which closely confronts the other end of the pin so thatd the pin cannot interrupter embodying the present- 'I'he side wall 62 of the block escape from its supporting bracket when the bracket is in place within the block. The bracket is secured to the block by screws 68 screwbimetal member.

ber 00. 'I'he strip at the other end of the lat straight portion 18 is reilexed into S coniiguration or is provided with a pair of oppositely retlexed resilient loops 82 and 84, respectively, which underlie the iiat portion oi' the strip. The

end part `80 of the strip is reilexed vertically may be cut away below the face to provide a notched portion 92 into which a part of the operating member 86 can move without engagement with the bimetal strip.`

A stationary contact member 94, Figs. 3 and 12,

` cooperates with the movable contact member 80 and is disposed thereunder and in line therewith. Said stationary contact member is carried by a terminal structure 8B having a iiat ear S8 tothe upper face of which the contact member 04 is secured. Said ear 08 is disposed upon a ledge |00 in the well elevated above the floor 48, the ear being clamped onto said ledge by suitable means as the screw |02.

Said ear 88 is .integral with and cutstands laterally from the bottom edge of a vertical plate |04 of the terminal structure. Said plate extends into the well 46 through a narrow vertical slot |06 in the end wall I 08 of the block and is provided at its outerl end part with a laterally outstanding conductor receiving ear ||0 parallel with the ear 98. Said plate ||0 is seated upon a horizontal external shelf |2 of lthe block 22 and has a conductor clamping screw i4 screwthreaded thereinto, the shelf ||2 having a recess H0 in its top face into which the end of the screw can project freely. 'I'he outer end of the slot |00 in the vblock 22 .is provided with an end wall ||8 against which the outer end of the plate portion |04 of the terminal structure is adapted to abut; and the inner face of lthe conductor receiving ear ||0 is adapted to abut against the outer face oi' the wall |00. Thus the location of the terminal structure in the block is defined and the terminal structure needs only to be fixed in position by the screw |82.

The block is provided at the opposite end thereof with a second terminal comprising a conductor receiving plate |20, Figs. 3 and 13, seated upon the shelf |22 of the block disposed approximately at the level of the shelf 2 and secured to said shelf by suitable means as a screw, not shown, passed upwardly through the block and screw- 'threaded into a screw-threaded hole |24 of the plate 2'6. Aconductor is adapted to be clamped onto said plate by a terminal screw |26. Said plate at the side facing the Well 46 of the block is integrally provided with an upstanding intermediate part |28 having a horizontally reflexed end part |30 projecting into the Well.

,A current-traversed heating grid or resistor |32 for the bimetal member 16 has one end |33 clamped upon the part |30 by the screw |34 and is disposed parallel with and suitably close to the Said heater grid has a lower end part |36 that extends forwardly to the bracket 50 and is secured mechanically and electrically thereto by a screw |38 passed through the looped end |31 ofthe part |36 and screwthreaded removably into an upstanding side ear or arm 54 of the bracket. Thus the circuit is completed between the two terminal structures and the heater element or grid is removably connected in series with the circuit through the interrupter and can be removed and replaced by one of different characteristics when desired.

While the bimetal member is here shown as receiving energy for operation by an external heater the bimetal member can be caused to operate in any other desired Way now well known in the art. The actuating'member or actuator Eil, Figs. 3 and 1l, comprises a cam plate |40iformed of in sulating material, preferably molded of an artificial resin, and a thinner metal latch plate |42. The two plates are disposed side by side in engagement and are secured fixedly together by suitable means as rivets |44. 'I'he actuator is interposed between the operating member 35 and the movable switch member and is adapted lto be engaged with both; and the laces of the cam 'plate |40 that engage said members are adapted to project outwardly beyond the metal latch plate sufficiently so that the latch plate does not engage the members.

The latch plate |42 is provided with an endwise extended latch arm |46 which is adapted normally to overlie and be seated upon and fulcrum in contact with the top edge or latch engaging face of the bimetal member 16 -ln the manual opening and closing movements oi the switch. The bimetal member thus constitutes a fulcrum for the actuator and defines the center about which the actuator pivots during the manual operation y of the switch. The cam and latch plates of the actuator are provided with aligned passages |40 and |50 therethrough through which the pivot pin 58 is passed loosely. The passages are vertically elongated and the opposite side walls thereof are arcuate, being struck from the top face 90 of the bimetal member as a center and thus permit unrestrained vertical swinging movement of the actuator about the face 90 as a center while maintaining the actuator in engagement with the bimetal member in its normal or unwarped position.

The cam plate |40 of the actuator is provided at its end opposite the latch extension |46 with a cam projection |52 which overlies the intermediate portion of the flat part 18 of the movable contact member and is adapted to press downwardly thereupon and also to slide somewhat over the face thereof to move the switch member from circuit open to circuit closed position. In the switch closed position the cam projection |52 lies on the side of the pivot pin 58 opposite the bi- 'metal member. The vertical movement of. the actuating member is eiected by movements of the manual operating member as will be explained hereinafter.

- The S curve of the movable switch member provided by the loops 82, 84 is particularly effective in obtaining circuit control through the actuator as the loops not only provide a long resilient part to the movable switch member but the movable switch membery can swing angularly about the loops and also can be moved bodily downwardly by fulcruming on the stationary contact'member 04 through the flexing of the loops and during the final part of the movement of the actuator int fully closed position.

The cam plate |40 oi theactuator is provided on one side with an arcuate or circular face |54 suitably struck from the center of the pin 58 when the actuator is in its lowermost switch closed position, and on the other side with a flat inclined face |56. The flat and the arcuate faces intersect at a relatively sharp angle thereby providing a relatively sharp cam point or edge |58.

Said cam point preferably is located about in the vertical line through the pivot pin 58 when thel switch is in manually .open position, as illustrated in Fig. 4. This position of the cam point and the inclination of the at face |52 causes considerable eifort to be placed initially upon the manual operating memberin a switch closing direction and thereby compels the rapid closing of the switch. This action will be explained further on in connection with the description of the operating member.

The operating member 38 is 'generally sectoral in shape and has the arcuate portion |80 from which the handle 38 rises and the two spaced triangularly shaped depending plates or legs |52, |04', having-aligned passages |80 therethrough in which the pivot pin 58 is located loosely. The plate or leg |64. is offset'from the arcuate body |80 by an arciate connecting member or wall |58, all parts being integral and preferably molded from an artificial resin.

The actuator is located loosely on the pivot pin 58 in the space or recess between the plates or legs |52, |64.v Said recess is formed with a straight top wall having a camming engagement with the straight and circular portions |58, |54 of the actuator andthe cam point |58 thereof. Said cam face |10 is inclined somewhat away from perpendicular relation with a radial line drawn between the center of the pivot pin 50 and the center of the handle so that, when the operating member is in the switch closed position, the face slopes in a'direction to provide a rapid or snap action to the circuit opening movement of the parts. The right hand end wall |12 of the recess is slightly inclined to the right away from perpendicular relation with the wp wall |18. The opposite wall |14 is spaced suillciently away from the actuator to clear it in its movements. The left hand end of the arcuate portion |80 isprovided'with an end face |10 which confronts a face of the switch operating cam |52 of the actuator and forms an abutment assisting in limiting movement of the actuator in a circuit opening direction as illustrated in Fig. 4.

The operation of the device is essentially as follows:

With the operating member in the lett hand position illustrated in Fig. 4 and with the latch projection |48 in engagement with the bimetal strut 10 the relation between the actuator and the operating member is such that the arcuate lportion |40 of the actuator is engaged with the end wall |12 of the operating member while the Eat face |58 of the actuator is engaged with the top wall |10 of the actuating member, the inherent spring action of the movable switch member maintaining the parts yieldingly in the aforesaid relation with the actuator in an uppermost position or with the pivotvpin 58 in the lower portion of the passage |48 of the actuator. On moving the operating member in a clockwise direction or toward the right, as4 illustrated in Fig. 5, to close the switch the cam wall |10 of the operating member is so displaced as to reduce its inclination with respect to the actuator and at the same time the point of contact between it and the cam point'l58 of the actuator .is lowered so as to move the actuator downward, thereby ultimately eifecting the closing of the switch when the operating member reaches a nal switch closed position, as illustrated in Fig. 3. In this position the cam face |10 of the actuator has passed over the cam point and into engagement with the circular portion |54 of the actuator.

The inherent spring action of the movable switch member maintains the operating member in itsl switch closed position since the cam face |10 of the operating member is now oppositely inclined so that the pressure of theactuator acting on said earn face tends to urge the operating member further into a switch closed position. Thus the line of pressure between the actuator and the operating member shifts from an initial position where the pressure opposes the closing movement of the operating member to a second position where the line of pressure-assists the closing movement of the operating member.

The initial inclination of the cam face |10 of the operating member is relatively great so that on the first part of the movement of the operating member into switch closed position considerable force has to be exerted on the operating member but since the opposite to such movement becomes reduced rapidly on further displacement of the operating member the result is that the force on the operating member becomes excessive and the member is caused to be moved rapidly into switch closed position.

On manual switch opening movement the operating member is moved in the opposite direction.` The pressure on the operating member required for manual opening is relatively slight and when the angularity of the cam face |10 of the operating member shifts to the other side of the horizontal the pressure of the actuating member thereon assists in the opening movement with a rapid or snap action.

The constant engagement between the movable switch member, actuator and operating member due to the inherent spring action of the movable switch member, in combination with the guidingaction of the pivot pin 58 maintains the latch projection of the actuator in engagement with the bimetal strut.

. When the parts are in the circuit closed posiv tion and an overload traverses the device .the heater grid |32 imparts suflicient heat to the bimetal strip 10 to cause it to warp out from.

under the latch projection |46 of the actuator. The actuator then is unsupported against the pressure of the movable switch member since the pin 58 opposite the bimetal strip. The pressure exerted between the switch member and the actuator causes the actuator to move in a clockwise direction, initially pivoting about the pivot pin 58 with the arcuate face |54 moving over the cam face of the operating member and subsequently moving somewhat upwards or laterally on the pivot pin into the final circuit open dotted line position of Fig. 3, where the latch projection |46 engages the movable switch member close to the upper bend 82. This action takes place free from restraint by the operating member and either without effecting a movement of the operating member or by causing a movement of the operating member into the dotted line position as illustrated depending upon the inclination of the cam face |10 of the operating member.

The actuator is reset into engagement with the cooled bimetal strip by movement of the operating member into a switch open position. This movement causes the engagement of the fiat face |56 of the actuator and the cam face |10 of the operating member or the engagement of the abutment |16 of the operating member with the cam projection |52 of the actuator to rotate the actuator in a eounterclockwise direction so that the latch projection |46 rides upwardly over the inner face ot the bimetal strip, flexing the strip into a position above the top thereof whereupon the strip will snap into its normal position under the latch projection.

The positioning of the bimetal strip 'I6 so that it is in proper relation with the latch projection I of the actuator to disengage the projection at the intended current traversing the interrupter is effected by bending the depending ear 'l0 of the mechanism-supporting bracket 50 slightly to one side or the other of the vertical. This is a convenient, economical and accurate manner of Calibrating the device.

I claim: y

1. In an electric circuit interruptor, a movable switch member, spring means urging said switch member constantly in a circuit opening direction, a pivotally supported actuator iree to move relatively to said contact member acting on said switch member, and a pivoted operator for .said actuator arranged to move the latter in a circuit closing direction against the action of said spring means, said operator and said actuator having cooperating cam faces shiftable relatively to each other to oppositely inclined positions to effect circuit opening and closing movement of said actuator by said operator and to hold said operator releasably in both circuit closed and circuit open positions.

2. In an electric circuit controller, a movable contact member, spring means biasing said con tact member for movement toward a circuit open position, a pivoted actuator free to move .relatively to said contact member for moving said contact member toward switch closed position against the bias of said spring means, and a pivoted operating member for moving said actuator'between circuit open and closed positions, said actuator having a cam projectionand said operating member having a cam face cooperating with said projection to move said actuator between circuit open and closed positions in response to corresponding movement of said operating member, said cam face being shiitable in position on movement of said operating member from a position where said actuator exerts pressure in a circuit opening direction on said oper-V ating member to an oppositely inclined position where said actuator exerts pressure on said oper ating member in a circuit closing direction.

3. In an electric circuit controller, a spring urged movable switch member, an actuator bearing on said switch member, a pivotal support for said actuator, an operating member having a pivotal support between the pivotal support for said actuator and the point of contact between said actuator and movable switch member, said actuator having a cam projection and said operating member having a cooperating cam face arranged to effect movement of said actuator between circuit `open and closed positions on corresponding movements of said operating member.

'4. In an electric circuit controller, a spring urged movable switch member, an actuator bearing on said switch member, a pivotal support for said actuator, an operating member having a pivotal support between the pivotal support for said actuator and the point of contact between said actuator and movable switch member, said actuator having a cam projection and said operating member having a cooperating cam face arranged to effect movement of said actuator between circuit open and closed positions on corresponding movements of said operating member, the inclination of said cam face being relatively reversed on movements of said operating member between circuit open and circuit closed positions to cause said actuator to exert pressure on said operating member in a circuit opening direction for one inclination of said cam face and in a circuit closing direction for an opposite inclination of said cam face.

5. In an electric circuit controller, a spring biased movable switch member, a pivoted actuator bearing thereon having a cam projection, and a pivoted operating member having a cam :face engageable with said projection, said cam face having a sharp inclination with respect to said projection when said operating member is in switch open position and a lesser angularity in an intermediate position.

In an electric circuit interruptor, a spring biased movable switch member, a pivoted actuator bearing on said switch member and having a cam projection, a pivoted operating member having a cam face disposed on the side of its pivot opposite said movable switch member and there engageable with said cam projection and cooperating therewith to move said actuating member in switch closing and opening directions in response to corresponding movements of said operating member, said cam face having relatively reversed inclinations in circuit open and circuit closed positions of said operating member to effect application of pressure in opposite directions on said operating member in said positions by said actuator.

7. In an electric circuit controller, a switch member movable in opposite directions to effect closing and opening of the circuit, a spring acting constantly on said switch member tending to move it in one of its two directions of movement, an actuator bearing on said spring-urged switch member and movable in directions corresponding to circuit opening and closing movements of said switch member, a removable pivotal support for said actuator, and a pivoted operating member, said operating member and said actuator having cooperating cam surfaces shaped and disposed to effect movements of said actuator about its pivotal support upon movement of said operating member between circuit open and closed positions thereof, said spring being responsive to the fect movement of said actuator and said operating member in a circuit opening direction.

8. In an electric circuit controller, a spring 4urged movable switch member, an operating member, a pivotal support for said operating member including a pivot pin, an actuator having pressure engagement with said spring urged switch member and with said operating member and also having a cam engagement with said operating member by which movement oi said operating member between circuit open and closed positions thereof eiect a corresponding movement of said actuator and switch member, a removable pivotal support for said actuator, said actuator having an elongated passage therethrough in which said pivot pin is disposed, said pivot pin being disposed between the point of engagement between said actuator and said switch member and said removable support and constituting a center about which said actuator can turn upon removal of said removable'support.

circuit closed position to position said camface to cause said actuator to maintain said operating member in circuitl closed position at least A during an initial part of the independent circuit opening movement of said actuator in response to the removal of said removable pivotal support.

l2. In an electric circuit controller, a supporting frame having upstanding arms, a pivot pin y extended between said arms, a spring urged movable switch member located between said arms under said pin, a movable operating member having spaced side plates forming a recess between them pivoted on said pin and upstanding thereabove, an actuator in' said recess loose on said pin having in said recess an arcuate cam face and a cam projection, said actuator also having a cam bearing on said switch member on one side of said pin and cam projection and y tom of-said recess confronting said arcuate cam 9. In an electric circuit-controller, a movable spring urgedswitch member, an actuator bearing at one end on said switch member and at its other end having a removable pivotal support, a pivot pin passed loosely through said actuator, an operating member pivoted on said pivot pin, said actuator having an arcuate cam -face terminated in a cam projection, said operating member having a cam face engageable with said arcuate cam face and said projection and being reversible in inclination upon move-- ments of said operating member between `circuit open and closed positions thereof to effect corresponding movements o'f said actuator and switch member, and means guiding said actuator for movement in a circuitopening direction vin engagement with said operating member upon withdrawal of said removable pivotal support.

1 0. In an electric circuit controller, a spring y urged movable switch member, an actuator disposed above said switch member having cam engagement therewith at one end and having at itsother end a removable pivotal support, said actuator having on that side opposite said switch member an arcuate cam face and a cam projection, a pivoted operating member having a flat cam face engageable. with said cam projection and arcuate cam face, said operating member being movable between circuit open and closed positions to effect relative reversal of the inclination of said cam face, and means for guiding said actuator for movement in contact with said operating member -in a switch opening direction independently of corresponding movement of said 4 operating member upon removal of said removable support.

11; In an electric circuit controller, a pivot pin, an operating member having spaced arms reverse the inclination of said cam face and effect movements of said actuator between circuit a removable pivotal support for said actuator on the other side of said pin and cam projection, said actuator having a flat cam face in the botiace andY cam projection of said actuator and cooperating therewith to eiect movements of said actuator between circuit closed andl open positions upon corresponding movements of said operating member, said operating member also having a part engageable with said actuator to support it for movement independently of said operating member into switch closed position upon the removal of 'said removable support.

13. In an electric controller, a'. spring urged movable switch member, a pivoted operating member for effecting movement of said switch member between circuit open and closed positions, an actuator interposed between said operating member and switch member for transferring movement of one to the other, said actuator comprising combined metal and insulating plates, said insulating plate and said operating member having cooperating? cam .Faces for transferring movement between said switch member and operating member, said metal plate having a-latch projection and a pivotal support yfcgi said actuator removably engageable with said atch projection.

14. In an electric circuit interrupter, a station-4 ary contact, a movable switch member comprising a resilient strip having a contact-carrying part and a resilient compressible part having upper, intermediate and lower generally parallel sections constituting an S-bend underlying the contact-carrying part and also uhaving an anchored end, and operating mechanism including means disposed and arranged to exert pressure on said switch member at one side of said S-bend and in a direction to compress it and effect bodily movement of the movable switch member about said stationary contact as a pivot.

15. In an electric circuit interrupter, a brack. et comprising a plate having upstanding spaced arms and an intermediate downturned ear, a movable switch member comprising at-'least in part a resilient strip having an end anchored to said earand an intermediate reflexed compressible resilient part and a contact-carryingl part closed and circuit open positions and when in 76 disposed between said arms, operating mechanism including a member disposed between said arms and bearing directly on said contact-carrying part, and means for reciprocating said member in a direction to compress said intermediate resilientpart.

16. In an electric switch, a supporting bracket comprising a plate having spaced upstanding arms and an intermediate downturned ear, a movable switch member comprising at least in part a resilient strip having an end part anchored to said ear, a reilexed Spring-Palit and a contact-carrying part disposed above said plate between said arms, a bimetal strip fixed to said ear and extended thereabove, an actuator located between and supported by said ears having a latch part engaged removably by said bimetal strip and a cam part bearing on the contact-canrying part of said movable switch member, an. operating member pivoted on said arms and independent of said actuator and having cam surfaces engageable with said actuator for reciprocating it about said bimetal strip to open and close the switch, and means for effecting the current-responsive warping of said bimetal strip and remove it from supporting relation with said actuator to eiect automatic opening of the switch.

17. In an electric switch, an insulating block having a well, a bracket on the noor oi the well having spaced arms extended upwardly above the floor, a movable switch member carried by and having a resilient connection with said bracket and a movable arm disposed between said arms having a contact on the free end thereof, said well having a ledge elevated above said floor under said contact member. a iixed contact member on said ledge under and cooperating with ,L

said movable contact member, and operating mechanism carried by said arms for operating said movable switch member.

13. In an electric switch, an insulating bloeit having a Well, a bracket on the floor ci the well having spaced arms extended upwardly above the floor, a movable switch member carried by and having a resilient connection with said bracket and a movable arm disposed between said arms having a contact on the free end thereol', said Well having a ledge elevated above said door under said contact member, a fixed con tact structure comprising a plate located edgein a slot in said block having a lateral con ledge and a lateral terminal ear at the other end external of said block, and operating mechem carried by said arms for operating said, movable switch member.

In. an, electric circuit interrupter, the com ""nation ci an actuator having a part movable opposite directions to enect opening and clos-I carrying ear at one end disposed on said ing movements of the interrupter. operating means i'or moving said actuator having an overcenter action which permits a slight movement oi said actuator away from extreme interrupterclosed position in the movement of the operating means to the full interrupter-closed position thereof while maintaining the interrupter closed. a stationary contact, and a cooperating movable switch arm operated by the actuator having a contact and a part engaged and moved by the ac tuator and spring means urging said arm against said actuator and bearing on a par-t of said arm located with' respect to the contact and actuator that the arm can fulcrum on said stationary contact by ilexing said spring means while maintaining its engagement with the stationary contact on the aforesaid slight over-center retraction movement of the actuator.

20. An electric circuit interrupter comprising a stationary switch member, a movable switch member having spring means urging it constantly for movement ln a circuit-opening direction, an actuator having a lower part bearing on said movable switch member and an upper part, and an operator having a hat cam tace engaged by said upper part, said operator having a pivotal support on which the operator is movable to tilt the iiat cam lace in opposite directions in engagement with said 'upper part for moving said actuator in circuit opening and closing directions.

21. In an electric switch, a supporting bracket, a movable switch member attached to said bracket, operating mechanism for said switch member including an operating handle having va pivotal connection with said bracket, an actuator carried by said bracket interposed between said handle and switch member and having means by which it is actuated by movements of said handle to open and close the switch member, and a current responsive bimetal member carried by said bracket and normally engaged with said actuating member to permit .movements ci said handle in opposite directions to move said actuating member in switch closing and opening directions, said bimetal member being warpable away engagement with said actuating member to permit said actuating mem- Tber to move independently ci.' control oi said handle to open 4the switch.

H'. TAYLOR.

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