US2096544A - Circuit breaker - Google Patents

Description

0a. 19, 1937. AK N 2,096,544 I cmcum BREAKER I Filed Feb. 18, 1936 s Sheets-Sheet 1 @WJJM ATTORNEY 3 Sheets-Sheet 2 J. G. JACKSON Imam? ATTORNEY CIRCUIT BREAKER Filed Feb. 18, 1936 0a. 19, 1937. J. JACKSON CIRCUIT BREAKER Filed Feb. 18, 1936 3 Sheets-Sheet 3 m? .N c w 4 A a Z f m. ,1 w I y: M w 5 T Patented Oct. 19, 1937' CIRCUIT BREAKER John G. Jackson, Square D Compa tion of Michigan Detroit, Mich, assignor to Detroit, Mich, a corpora- Application February 18, 1936, Serial No. 64,575

' 32 Claims. (Cl. 200-116) This invention relates to devices for making and breaking electric circuits and.more particularly to automatic electric circuit breakers.

One object of this invention is to provide an improved multipole circuit breaker which shall be extremely simple and economical and have a minimum or parts.

Another object of this invention is to provide a multipole circuit breaker having a plurality of floating bars carrying contacts at one point and latching at another point and provided with pivotal ax'es manually movable to separate the contacts and about which the bars rotate for automatic operation.

Another object of this invention is to provide a multipole circuit breaker having a plurality o1 floating bars carrying contacts adjacent one end and having latching means at the other end with the latching means joined together for common movement together with a plurality of current responsive means each of which is capable of moving all the latching means to release all the floating bars and in which means is provided for causing further movement of the latching means upon release 01' any one of the floating bars to cause release of all of them and which, furthermore, may be provided with means holding the latching means in an unlatched position after the bars are released. K

Another object of this invention is tdprovide a multipole circuit breaker having a plurality of floating bars carrying contacts at one point and latching at another point, and a plurality of members engaging the bars, with a common manual operating means engaging the members 101' simultaneously moving them with the bars to which they are connected to an open circuit position. I

40 Another object of this invention is to provide a'multipole circuit breaker having a plurality of floating bars carrying contacts at one point and latching at another point, engaged by a plurality of members rectilinearl'y movable to move the 45 contacts to open circuit position whenreleased by the latch and which are rectilinearly movable after automatic release to relatch thebar and which has a small rectilinear movement upon release of the latch to indicate the automatic 50 opening.

Another object of this invention is to provide a multipoie circuit breaker having a plurality 0! bars carrying contacts at one point and biased to move the contacts to separated position with an improved form of common latching means permitting the bars to individually compensate for variations in wear.

Another object of this invention is to provide a latching device for an automatic circuit breaker in which a latch engages a releasable member and is moved by a bimetallic element with interengaging surfaces on the member and latch so that I in its released position the member will hold-the latch to relieve the strain on the bimetallic member. I

Further objects and features of the .invention will be readily apparent to those skilled in the art from the following specifications and the appended drawings illustrating certain embodiments of the invention in which:

Figure 1 is a top plan view of the circuit breaker according to the present invention with a major portion of the top cover broken away to show internal parts. i

Figure 2 is a vertical sectional 'view of the circuit breaker according to the present invention.

Figure 3 is a view similar to Figure 2 showing the parts in manual 01! position.

Figure 4 is a view similar to Figure g showing the parts in automatic trip position.

Figure 5 is a sectional view taken onthe line 5-5 01' Figure 2.

Figure 6 is a sectional view taken on the line 6-4 of Figure 2.

Figure 7 is a side elevational view of a modifl 'i'orrn of latchingelement.

Figure 8 is a front elevational view oi the latching element shown in Figure 7.

The circuit breaker comprises an insulating base I of bakelite or other material having side walls 2 and- I and end flanges 4 serving as barriers between the separate terminals and extending to the full height of the circuit breaker. Within the breaker are portions I in line with the barriers 4, serving asbarriers between the poles and for support of the cover portion and which also e'x tends to the full height oi the breaker. In line with the barriers I and integral therewith but extending for only a portion of the height of the breaker to provide an opening ior an operating member to be hereinafter described are further barrierportionslhavingribsltoincreasethe 1 leakage path between the parts of opponte polarity within the breaker. Bythe barrier portions I and [the-interior oi the breakeris divided into three portions having common openings above the rib 1.

The side walls and the barriers I are provided with pairs oi guiding mlections I and l and with reduced ledge portions Ii adjacent one end.

At this end the exterior of the breaker between the barriers 4 may be provided with ledges for the support of terminal connectors which may comprise interior metallic sleeves 12 having their tops spun over depressed portions l3 in connectors I4 which extend within the interior of the breaker and are there supported upon the ledges ll. Terminal studs l5 may be threaded into the sleeves l2 for attachment of circuit conductors. To the interior lower surfaces of the connectors it are brazed or otherwise attached the stationary contacts l6.

Between the guiding projections 8 and 9 are disposed elements ll which are generally. U- shaped in cross section and having a flat top surface. The legs of the U are of varying lengths as shown and are provided with central slots l8 and i9 aligned with their respective stationary contacts "5 and have a substantially equal depth so that their ends rest at difierent levels in view of the variation of the length of the legs. Within the slots l8 and I 9 are disposed rigid con-' ducting contact bars 2i provided with notches 22 in their top edges which receive theends of slots is and are maintained thereby in proper relation to the other working parts. Light tension springs 23 interconnect members ll and the contact bars 2! and serve to maintain the ends of the slots I9 firmly within the notches 22. The ends of the bars 2! adjacent to' the stationary contacts l6 are provided with contact tips 2% adapted to cooperate therewith to close the circuit through the breaker. The arc chambers surrounding the contacts l6 and 20 are preferably provided with liners 25 of fibre or other material which may be formed from a sheet notched as at-26 and then bent to the rectangular shape shown fitting within the chambers. The ends of the bars 2i remote from the contact tips 24 are provided with latching surfaces 21 adapted to cooperate with latching portions 28 supported on a movable structure to be hereinafter described in detail Heavy compression springs 29 are guided within small cup portions 3! integral with the bottom of the base I and are received within notches 32 in the bottom edges of the bars 2! and bias the bars upwardly against the stationary con tacts l6 and the latching portions 28.

The side walls 2 and 3 at their top are provided with grooves 33 receiving a shaft 34 carrying' a manual operating member 35-having a single exterior handle 36 projecting through the top of the breaker and with an interior portion comprised of three cam surfaces 31, 38 and 39 disposedabove the top faces of the elements ll. Between these surfaces the tip of the interior portion is provided with cutout portions 40 to clear the ridges l on the barriers 6 in the manual off and resetting positions of the handle. These surfaces 31, 38 and 39 are cam surfaces taking the shape shown in cross section in Figures 2, 3 and 4 and each includes a fiat portion 4| forming'a stable support forthe manual off position of the breaker and a resetting tip 42 to be hereinafter explained.

A spring 43 biases the handle for rotation in a clockwise direction as shown and hence maintains cam surfaces 31, 38 and'39 in contact with the top faces of the members H, or if there are inequalities in the dimensions of the parts will maintain whichever one of these surfaces first errgages with its member ll thereaga'inst. If the part dimensions were very accurately made it might be possible to omit the springs 33 and to rely upon spring 43 to bias the members I! firmly within the notches 22 in the bars 2!. However, due to the variations of parts in production manufacture, it might be possible for certain of the members H to be loose within these notches and destroy the accurate positioning of the bars 2i with respect to their latching portions 28. The purpose of maintaining the cam surfaces against the member ll is to provide an on position for the operating handle which shall be different from the overload trip position as will be hereinafter explained.

Above the latching end of the bars 26 the side walls 2' and 3 and the barriers 5 are provided with grooves 45 serving as bearings for a shaft 45 having integrally depending portions 66 disposed between the side walls 2 and 3 and the barrier portions 5. .To the depending portions lB are rigidly secured generally L-shaped elements 4i from the surface of which. the latching portions 23 are pressed. The bases of the L-shaped members ii are provided withupstanding flanges 43 engageable by bimetallic-members 49 as they become heated to move the members 41 to an unlatching position where the latching portions 28 are disengaged from the latching surfaces 21 on the bars 2|. A flexible lead 5i interconnects the free end of each of the bimetals 89 and its corresponding bar 2| and may be rigidly conductingly secured thereto by brazing or in any other manner. Leaf springs 52 attached to the members ll, as for instance by means of a rivet 53 which secures the'member Al to the depending portions 45 onthe shaft 45, are disposed against the faces of the bimetallic members 49 and bias the members 41 in a counter-clockwise direction with respect to the bimetallic members 69.

The supporting and adjusting means for the bimetallic members 49 willv now be described. Between'the barriers 4 on the exterior of the breaker, at the left-hand end as shown, are supported connectors 54 which are rigidly secured in place by having depressed portions 55 into which are spun the tops of metallic inserts 56 having studs 51 extending therethrough. Above the connectors 54 are disposed cup-shaped terminals '58 through which the studs 51 extend and into which may be screwed the nuts 59 threaded upon the stud 51. It is to be understood that this terminal connector arrangement is alternative to that shown at the right-hand end of the breaker and either may be substitutedfor the other if desired. The openings in the bottom of the base -i through which the inserts IZIand'BB and the stud 5'? are inserted are preferably closed as by insulating wax as at 61. The connectors 54 extend into the interior of the breaker and are there bent at right angles to provide vertical portions 62. The connectors 54 are notched as at 63 to clear the projecting portions on the barriers between the breaker poles and the vertical portions 32 are slidablydisposed in vertical notches 64 in the barriers and side walls of the breaker. The central portions of the vertical portions 62 of the connector are pressed out as at 65 and to these portions are rigidly welded or brazed the fixed ends of the bimetallic members 481. Between the vertical portions 32 and the pressed out portions 65 are disposed bridging blocks 36 into which may be threaded adjusting screws Ell. The tops of the vertical portions 62 are preferably bent over as at 58 to maintain the blocks in place. These blocks may be loosely disposed between the portions 62 and t5 and are prevented from vertical removal by $5 curely hold them in vertical position.

the bent over portions 88 and from sidewise removal by engagement with the barrier walls.

Due to the notches 84 and the slots 84 each connector and bimetal assembly may be readily slid into place from the top of the breaker and there secured in place by the turning over of the inserts 58 within the depressed portions 45 of the connectors.

, The ends of the bars 2i adjacent the latching surfaces 21 are provided with inclined surfaces 1| and 12. The surfaces II are provided to cause further opening movement of the latching members 41 upon release of any one of the bars 2|. Due to the inclined portion II, when one bar is released the action of this surface upon the corresponding latching portion 24 will cause a further movement of all the latching members 41 and insure that all the bars will be released upon the release of any one of them and will, therefore, insure, that all the poles of the breaker will be opened if there is an'overload upon any one of them. The inclined surfaces 12 provide ease in resetting of the bars as they will easily slide over'the latching. Portions 28. In enclosing the breaker parts within the interior, the ends are closed by means of two fibre sheets 13 and I4 which are bent at right angles and have one leg disposed beneath the metallic cover I! and the other leg disposed vertically at the ends of the breaker. Between the barriers 4 and I are provided notches 16 into which the'vertical legs of the sheet 14 extend and which serve to se- These sheets may in turn be provided with slots receiving the barriers 4 below the notches I. therein. The sheets are maintained in place by the cover 15 which is in turn sealably secured to the base I by means of rivets 11 extending through openings II in the insulating barriers 5. The sheets I3 and 14 are thick enough to be rigid and when in place serve to seal the mechanism of the breaker from access from the exterior.

The operation of the circuit breaker will now be described. In the position shown in Figure 2 the parts are in their normal or circuit closed position. In this position the current path through each pole of the breaker is from the connector 54 through the portion '4 thereof to the blmetal 49, from the free end of the bimetal through the flexible lead II to the contact bar 2| and thence through the contacts 24 and ii to the opposite connector i4. If it is desired to manually open the contacts to open the circuit through the breaker, the operating handle 44 is rotated clockwise, as shown, into the position shown in Figure 3 with the flat part 4| of the cam surfaces 31, ll and 39 in engagement with the top ilat surfaces of the members l1. As the center of rotation of the operating member is now within the engagement of the flat portion 4| with the member II, this is a stable position which will be maintained by the parts. In this position the members I! have been moved toward the bottom of the circuit breaker compressing the springs 29 and moving the contact tips 24 away from the stationary contacts It into the position shown. In this movement thebars 2| have rotated about their engagement with the latching portions 24 on the members 41. To place the parts again in closed circuit position the handle is rotated counterclockwise from its position in Figure 3 to the position in Figure 2 and the contacts are moved into engagement by the force exerted by the spring 29.

If, while in the closed circuit position of Figure 2, an overload should occur through any pole of the breaker the corresponding bimetal will become heated and will warp in a clockwise direction as shown in Figure 4, whereupon the free end thereof by its engagement with its cooperating portion 44 will rotate the members 41 clockwise, thus moving the latching portions 28 away from the latching surfaces 21 on bars 2i. when a latching portion 24 reaches the edge of a latching surface 21 on any of the bars II that bar will be snapped to the position shown in Figure 4 and by the engagement of its surface 1i with the latching portion 28 will further move the member 41 clockwise and'insure that the other bars will also be released and moved to the same engage the tops of the slots it in the left-hand legs of the members I! as shown in Figure 4. The parts are so related that in the closed circuit position of Figure 2 the handle 38 will be in the position shown due to the bias of the spring 43 pressing against members il. As the springs 29 are very much stronger than the spring 43, when the bars are released on overload the members i! will move upwardly under their bias until the interior portion of the manual operator engages the underside of the cover as shown in Figure 4, thus rotating the handle in a counterclockwise direction and indicating the tripped condition of the'breaker. In the automatic tripping it is noted that the members 41 are rigidly connected to the depending portions 46 on the shaft 45 and move together as a unit. when only a single one of the bimetals 49 is carrying an overload it will move as shown in Figure 4. If the other bimetals are not warped the members 41 corresponding thereto will move toward these bimetals compressing their leaf springs 52.

To reset the breaker, after an automatic opening, the handle is rotated clockwise from the position shown in Figure 4. The blades 2| then move in. straight lines toward the base until the back, edges adjacent to the contact tips 24 engage the bottoms of the arc chambers whereupon further movement of the handle causes the blades 2| to rotate about the pivot formed by the engagement of the notches 22 with the ends of the slots is. As the movement of the handle continues, the inclined surfaces 12 will engage the tops of the latching portions 28 and will move the latches clockwise to permit the latching ends of the bars to pass beyond the latching surfaces. It the bimetal has cooled suiiiciently to permit the members 41 to resume their normal position, release of the handle will then cause the latching tips 21 to be engaged with the latching portions 20 to latch the ends of the bars in position.

In the movement to resetting position, it is necessary to move the handle beyond the position shown in Figure 3 so that the tips 42 of the cam surfaces, 31, 38 and" press upon the top surface of the members i1 and causes a further movement of the members I! toward the base belatching means for the opposite ends of said mem- 3 aooas m handle is moved counterclockwise as from manual o position and the parts are moved into engagement by the bias of springs 29.

In the calibrating of the poles of the breaker adjustment is secured through the adjusting screws 67. By moving these screws inwardly they press against the portions 65 serving to bend them and change the positions of the free ends of the bi-metals, thus regulating the amount of movement that is, necessary for each bimetal to release the latching portions 28 from the latching surfaces 2? on the bars 2|.

A modified form of latching member is shown in Figures '7 and 8. This comprises a shaft 85 having depending portions 86 in which are rigidly embedded or otherwise secured metallic portions all of generally L-shape having tips 88 on the base of the L for engagement with the free end of the bimetals. A spring 89 is provided which constantly biases the latching members 8? in a counterclockwise direction. The latching members are provided with latching surfaces 9! corresponding to the latching portions 28 on the latching members 61 in the form of latching member shown in Figures 1 to 6, inclusive,.and the latching sides of the members are provided with projecting portions 92 engaged by the ends of the bars 2i in their automatically bars will maintain the latching members in their released position due to the engagement of the ends of the bars 26 with thesurfaces 92 on the members. This maintaining of the latching member in its unlatching position removes the strain on the bimetallic member which might occur if the latches were released by the ends of the bar after movement to tripping position.

This aids in preventing a permanent set to the bimetals which might destroy the calibration of While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily appareat to those skilled in the art and the invention I the breaker.

is to be given its broadest possible interpreta-- tion within the terms of the following claims:

What is claimed is:

1. A-multipole circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, current responsive bers, said means releasing all said members upon the occurrence of an overload through any pole of the-breaker to separate all said contact surfaces from said stationary contacts.

'2. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality-of floating members carrying contact surfaces atone point adapted to cooperate with said sta-' tionary contacts, current responsive means for latching said members at another point, said means releasing all said members upon the occurrence of an overload through any pole of the breaker, manual operating means, and means for moving all said contact surfaces away from said stationary contacts in response to movement of said operating means.

3. A multipole electric circuit breaker comprising a plurality of stationary contacts, a plurality of floating members carrying contact surfaces at one point adapted to cooperate with said stationary contacts, currentresponsive latching means for other points on said members, said means releasing all said members upon the occurrence of an overload through any one, biasing means for said members, and-pivotal axes about which the members rotate under the action of said biasing means when released by said latching means.

4. A multipole electric circuit breaker comprising a plurality of stationary contacts, a plurality of members carrying contact surfaces at one point, adapted to cooperate. with said stationary contacts, current responsive latching means for other points on said members, biasing means interjacent said points on said members, pivotal axes for said members interjacent the biasing means and the contact surfaces, means for mov-' ing said. pivotal axes, and guide means for said axes limiting them to a straight line, rectilinear movement.

5. A multipole electric circuit breaker comprising a plurality of stationary contacts a plurality of members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, current responsive latching means for the opposite ends of said. members, pivotal axes about which said members rotate when released by said latching means to efiect automatic separation of the cooperating contacts, manual operating means, and means for causing movement of said pivotal axes in response to movement of said operating means to effect manual separation of said contacts.

6. A multipole electric circuit breaker comprising a plurality-oi stationary contacts, a plurality of members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, current responsive latching means for the opposite ends of said members, pivotal axes about which said members rotate when released by said latching means to effect automatic separation of the cooperating contacts, manual operating means, and means for .moving said pivotal axes in response to movement of said operating means after an automatic separationof the contacts to reset said .members in position to engage the latching means.

'7. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of floating members having. contact surfaces at one point adapted to cooperate with said stationary and contact surfaces about which said members rotate when released by said latching means.

9. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of floating members carrying contact surfaces ad- Jacent to one end-adapted to cooperate with said stationary contacts, current responsive latching means for said members, biasing meansinterjaoent the ends of said members, pivotal axes for said members interjacent the biasing means and contact surfaces about which said members rotate when released by said latching means, and manually operable means for simultaneously moving said pivotal axes to move said contact surfaces away from the stationary contacts to effect manual opening of the circuits through said contacts.

10. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of floating members carrying contact surfaces ad- Jacent to one end adapted to cooperate with said stationary contacts, current responsive latching means engaging adjacent to the opposite ends of said members, a plurality of means biasing said members against said contacts and said latching means, a common manual operating means for said members, and means interconnecting said operating means and said members and operable to move at least the contact carrying ends of said members to a circuit open position.

11. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of members carrying contact surfaces adapted to cooperate with said stationary-contacts, current responsive latching means for said members, a plurality of means biasing said members against said contacts and said latching means, manual operating means for said members, and means interconnecting said operating means and said members and operable to move at least the contact can'ying ends of said members to a circuit open position, said members pivoting about their engagement with said interconnecting means when released by said latching means in response to a current overload.

12. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of floating members carrying contact surfaces adapted to cooperate with said stationary contacts, current responsive latching means engaging said members, .a plurality of means biasing said members against said contacts and said latching means, a plurality of elements engaging said members between the biasing means and the contact surfaces, and common manually operable means for moving said elements to move the contact surfaces away from the contacts.

13. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of members carrying contact surfaces adapted to cooperate with said stationary contacts, current responsive latching means for said members, a

plurality of means biasing "saidmembers against said contacts and said latching means, a plurality of rectilinearly movable elements engaging said members between the biasing means and the contact surfaces, a common manual operating member, and a plurality of surfaces on said operating member engageable with said elements to move the contact surfaces against the biasing means to an open circuit position.

14. A multipole circuit breaker comprisingfa plurality of stationary contacts, a plurality. of members carrying contact surfaces at one point adapted to cooperate with said stationary co tacts, current responsive latching means for other points on said members, biasing means inter-jacent said points on said members, rectilinearly movable elements engaging said members interjacent said biasing means and said one point, said memberspivoting about their engagement with said elements when released by said latching means, and stops on said elements for limiting the rotation of said members after release.

15. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, current responsive gated slots receiving said members and guiding their rotative movement.

16. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, current responsive latching means for the opposite ends of said members, a plurality of means biasing said members against said contacts and latching means, notches in said members between the biasing means and the contact surfaces, a plurality of rectilinearly movable elements engaging the members within the notches, a plurality of springs biasing said elements within the notches, and manual operating means having a plurality of cam surfaces engageable with said elements to move the contact surfaces on said floating member to an open circuit position.

.17. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adJacent to one end adapted to cooperate with said stationary contacts, current responsive latching means for the opposite ends of said members, a plurality of means biasing said members against said contacts and latching means, a plurality of rectilinearly movable elements pivotally engaging the members between the biasing means and the contact surfaces, and a manual operating member for simultaneously moving said elements to move the contact surfaces to an open circuit position.

18. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, current responsive latching means for the opposite ends of said members, a plurality of means biasing said members against said contacts and latching means, a plurality of elements pivotally engaging the members between the biasing means and the contact surfaces, and a manual operating member for simultaneously moving said elements to move the contact surfaces to an open circuit position, said members rotating about their pivotal engagement with said elements when released by said latching means.

19. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adJacent to one end adapted to cooperate with said stationary contacts, current responsive latching means for the opposite ends of said members, a plurality of means biasing said members against said contacts and latching means, a

. plurality of rectilinearly movable elements pivotally engaging the members between the biasing means and the contact surfaces,'a common manual operating member, and a plurality of cam surfaces on the operating member engageable with 10 said elements to move the contact surfaces on the floating members to an 'open circuit position.

20. A multipole electric circuit breaker comprising a plurality of stationary contacts, a plurality of elongated floating members carrying contact surfaces adjacent to one end adapted to cooperate with said stationary contacts and having latching surfacesladjacent to their opposite ends, a plurality of latching surfaces cooperating with said first mentioned surfaces interconnected for common movement as a unit, a plurality of current responsive elements, each connected in series with "one pole of the circuit breaker and each adapted to move said second mentioned latching surfaces as a body, pivotal axes for said members,-

means biasing said members against said latching surfaces and stationary contacts when in the circuit closed position, a common manual operator, and means for moving said pivotal axes in response to movement ofsaid operator to effect manual separation of the cooperating contacts.

21. A multipole circuit breaker comprising a' plurality of stationary contacts, a plurality of floating members having contact surfaces at one point adapted to cooperate with said stationary contacts, latching surfaces adapted to cooperate with other'points on said members, said latching surfaces being joined together for substantially common movement, biasing means intermediate said points on said member, and a plurality of 40 current responsive means fgr causing movement of said surfaces to release said members.

22. A multipole electric circuit breaker comprising a plurality of independent stationary, contacts, a plurality of independent contact bars carrying contact surfaces adapted to cooperate with the stationary contacts and having latching surfaces thereon, a plurality of latching surfaces cooperating with said first mentioned latching surfaces and interconnected for substantially to common movement, a plurality of independent current responsive elements adapted to move said second mentioned latching surfaces, and a pinrality of means independently biasing said contact bars for movement to separate said contact sur- 55 faces when released.

23. A multipole electric circuit breaker comprising a plurality of independent stationary contacts, a plurality of independent contact members carrying contact surfaces adapted to cooperate 60 with the stationary contacts and having latching surfaces thereon, a plurality of latching surfaces cooperating with said first mentioned latching surfaces and interconnected for at least partial common movement, a pluralityof independent vill; current responsive elements adapted to move said second mentioned latching surfaces, a plurality of means independently biasing said contact mem bers for movement to separate said contact surfaces when released, and cooperating surfaces on 70 said bars and connected to said second latching surfaces for causing unlatching movement of the latching surfaces upon release of any one member. 2 A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of 175 floating members having contact surfaces at one point adapted to cooperate with said stationarycontacts, latching surfaces adapted to cooperate with other points on' said members, said latching surfaces being joined together for substantially common movement, biasing means in- 5 termediate said points on said members, pivotal axes for said members interjacent the biasing means and said one point, and a plurality of current responsive means for causing movement of said surfaces to release said members for piv- 10 otal movement about'said axes under the action of said biasing means.

25. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of members having contact surfaces adjacent to one 15 end adapted to cooperate with said stationary contacts, latching surfaces adapted to cooperate with said members adjacent to their opposite end, said latching surfaces being joined together for substantially common movement, biasing 20 means intermediate the ends of said members, pivotal axes for said members interjacent the biasing means and the ends carrying the contact surfaces, means for. simultaneously moving said pivotal axes to move said contact surfaces to a 25 separated position, and a plurality of current responsive means for causing movement of said surfaces to release said members for pivotal movement about said axes under the action of said biasing means. 30 26. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of members having contact surfaces adjacent to one end adapted to cooperate with said stationary contacts, latching surfaces adapted to cooperate 3 with said members adjacent to their opposite end, said latching surfaces being joined together for substantially common movement, biasing means intermediate the ends of said members, pivotalaxes for said members interjacent the biasing 40 means and the ends carrying the contact surfaces, means for simultaneously moving said pivotal axes to move said contact surfaces to a separated position, and a plurality of current responsive means for causing movement of said sur- 45 faces to release said members for pivotal movement about said axes under the action .of said biasing means, said pivotal axes having a longitudinal movement when the members are released to effect an indication of the tripped condition of the circuit breaker.

27. A multipole circuit breaker comprising a plurality of stationary contacts, a plurality of members carrying contact surfaces adapted to cooperate with said stationary contacts, biasing means for said members, latching elements for said members, series connected bimetallic'strips disposed adjacent said elements, each of said elements including a latching surface engageable with a member and an abutment engageable by abimetallic strip, said elements being joined together for at least partial common movement when engaged by any of the bimetallic strips.-

28. .A multipole circuit breaker comprising a plurality of stationaryccntacts, a plurality of members carryingcontact surfaees adjacent to one and adapted to cooperate with said stationary contacts, biasing means for said members, latching means for said members including a plurality of latching surfaces forthe opposite ends of said members, a plurality, of bimetallic strips, flexible leads interconnecting the free ends of said strips and said members, abutment means on said latching means engageable by the free ends of said strips to move all said latching surfaces in response to movement of any strip, and means biasing said abutment means toward said strips.

29. In a multipole automatic electric circuit breaker, a plurality of pairs of separable contacts, a plurality of members releasable to effect automatic separation of said contacts, a latching surface for each of said members, said surfaces being joined together for at least partial common movement, a plurality of bimetallic elements for moving said surfaces to release said members in response to overload, means biasing said latching surfaces to latching position, and inter-engaging surfaces on said members and connected to said surfaces for causing opening movement of said surfaces upon the release of any one member and for holding said surfaces against said biasing means to release the strain on said elements.

30. In a multipole automatic electric circuit breaker, a plurality of pairs of separable contacts, a plurality of members releasable to effect automatic separation of said contacts, a latching surface for each of said members, said surfaces being joined together for at least partial common movement, a plurality of bimetallic elements for moving said surfaces to release said members in response to overload, means biasing said latching surfaces to latching position, and surfaces rigid with said latching surfaces projecting in the path of said members and engageable thereby to hold the latching surfaces against said biasing means and relieve the strain on said elements.

31. In an automatic electric circuit breaker, separable contacts, a member releasable to effect automatic separation of said contacts, a latch engageable with said member, a blmetallicelement for moving said latch to release said member in response to an overload, and interengaging surfaces on said member and latch for holding said latch after release of said member to relieve the strain on said element.

32. In. an automatic electric circuit breaker, separable contacts, a member releasable to effect automatic separation of said contacts, a latch engageable with said member, a bimetallic element for moving said latch to release said member in response to an overload, means biasing said latch into latching position, and a projection on said latch in the path of said member and.

engageable thereby in released position for holding said latch against said bias to relieve the strain on said element.

JOHN G, .mcxsou.

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