US2132623A - Circuit breaker - Google Patents

Description

Oct. 1l, 1938. I Q JACKSON AL 2,132,623

CIRCUIT BREAKER Filed March 25, 1935 2 Sheets-Sheet l ATTORNEY Oct. l1, 1938. J. G. JACKSON ET AL CIRCUIT BREAKER Filed March 25, 1955 2 Sheets-Sheet 2 A TTORNEY.

Patented Oct. 11, 1938 UNITED STATES PATENT OFFICE cmcurr susanna Application March 25, 1935, Serial No. 12,798

58 Claims.

- This invention relates generally to apparatus for making and breaking electrical circuits and more particularly to circuit breakers having current responsive devices which operate to automatically break the circuit in response to predetermined current values.

One object of this invention is to provide a circuit 'breaker having an improved construction for producing both quick make and quick break contact operation.

Another object of this invention is to provide a circuit breaker having an over center operating spring with means for quickly moving said spring through dead center position. Another object of this invention is to provide a circuit breaker having an over center operating l spring with means for quickly and positively changing the directional torque of said spring upon the operated element. y `Another object of this invention is to provide an automatic circuit breaker having an over center operating spring with a ilipper element to which the spring is attached and which oscillates between stops to quickly move the spring through dead center position independent of the speed of manual operation.

Another object oi' this invention is to provide an automatic circuit breaker wherein a contact bar having contacts at its ends is reciprocated by means of a pivoted bell crank lever to which an over center operated spring is operatively connected. I

lAnother object of this invention is to provide in an automatic circuit breaker having a support releasable on overload, an improved latch and bimetallic current responsive unit.

Another object oi this invention is to provide in a circuit breaker an improved arc suppressor.

Another object of this invention is to provide in an automatic circuit breaker an improved unit assembly for electrically and mechanically supporting the thermal current responsive bimetallic member.

Another object of this invention is to provide an electric circuit breaker with an improved vent for the arc gases.

Another object ot this invention is to provide an improved construction of multi-pole circuit breaker.

Another object of this invention is to provide a multi-pole circuit breaker having individual switching mechanisms with means for insuring common action of said mechanisms.

Another object of this invention is to provide a multi-pole circuit breaker having individually (Cl. 20o-116) releasable carriers and current responsive latches therefor with means for insuring release of all the carriers upon release of any one.

Further objects and features of the invention will be readily apparent to those skilled in the 5 art from the following specification and the appended drawings illustrating certain preferred embodiments oi' the invention in which:

Figure 1 is a side elevational view of a circuit breaker according to the present invention with 10 the side of the enclosing structure cut away to show the interior of the breaker mechanism with the parts in closed circuit position.

Figure 2 is a top plan view of the circuit breaker shown in Figure l with the cover and handle 1| removed.

Figure 3 is a view similar to Figure 1 but with the parts in normal oil position.

Figure 4 is a view similar to Figure l with the parts in overload ofi position. 20

Figure 5 is an enlarged detail sectional view of the flipper taken on the line 5 5 of Figure 4.

Figure 6 is a. detail view showing a slightly modiiled construction for moving the operating springs through dead center position.

Figure 'l is a plan view of a two pole circuit breaker according to the present invention.

Figure 8 is a detail sectional view showing the spring guides in the circuit breaker of Figure 7 on line 8--8. 30

Referring to the drawings, in which like reference numerals indicate like parts, the enclosing structure for the circuit breaker comprises a base I and a cover 2. 'I'he ends of the cover adjacent to the top are provided with a plurality 35 of slots 3 forming vents for the arc gases. The walls defining the slots are extended past the ends of the cover and are joined together by a bottom portion 4. The vent walls exercise a cooling action upon the arc gases and serve to o lessen the ilame ejected from the vents. The bottom portions 4 constitute baies for directing the arc gases away from the connectors. The top of the cover is provided with a slot 5 through which extends an operating knob 6. 'I'he base I 45 is in the form of a shallow cup in which at opposite ends are disposed stationary contacts l, I. Contact 1 is secured to a conducting connector 9 leading to the exterior of the enclosure. Contact 8 is rigidly secured to one leg of a U-shaped 50 bimetallic member il, to the other leg oi' which is' rigidly secured a conducting connector i2 leading to the exterior of the breaker. The contact I and connector l2 have their ends bent over to engage the bottom of the ls oi the biu metal II and are welded thereto to form a rigid permanent connection. The contact and connector are attached to the same face of the bimetal with the contact overlying the connector and insulated therefrom as by means of an in sulating sheet I3. The contact 8 and connector I2 are rigidly secured to base I and thus support the birnetal ll in operating position.

Over each of the contacts i and 8 is disposed an arc suppressor I@ formed of a plurality of thin, plate-like laminations of U-shape loosely supported upon the base l in spaced relation to the stationary contacts. The legs of the U are disposed on opposite sides of the path of movement of the movable contacts to be hereinafter described and are loosely held in position by means of the shields I5. The shields as shown in the drawings have been cut away to more clearly show the parts of the breaker. They embody a top portion I6 and an end portion l'i having a slot for receiving the movable contact. Side portions depend from the shield to engage the top lamination on the arc suppressor and other side portions I8 extend upwardly to seal the joint between the cover and the base. 'I'he top l5 is open at the end of the enclosure to afford passage for the arc gases between the side portions IB. Shields i9 are provided to seal off the end junctions between the cover and the base.

A bracket 2l is rigidly secured to the base l adjacent the top thereof and extends over the top I6 of one of the barriers I5. On this bracket is pivotally mounted a carrier 22. Upon the carrier 22 intermediate its ends are pivotally mounted a pair of plates 23 disposed on opposite sides of the carrier 22. A conducting bar 2li having contact faces 25 adjacent its ends is pivotally supported on the plates 23 by the pivot 26 which also serves to join the plates 23 together for common movement as a unit. The bar 24 is connected to the pivot 26 through the extension 27 and carrier 22 is similarly cut away to receive this extension in the olf position of the breaker as shown in Figure 3. The carrier 22 is provided with a pin IIJ adapted to be engaged by the surface 20 on the plates 23 and serving as a stop therefor in the overload off position. The plates 23 are equipped with parallel notches 28 in which is disposed a flipper 29 shown in detail in Figure 5. This flipper embodies parallel legs 3l and 32 which are disposed in the notches 23 on opposite sides Of the conducting bar 24 and carrier 22. The legs 3| and 32 of the flipper have a cross bar 33 at their ends and beneath the bar 24 to which cross bar the operating springs 34 and 35 are connected. A U-shaped operating member 36 is fulcrumed in grooves 3l in the bottom of the cupshaped base I. The legs 38 of U-'shaped member 36 are disposed at the extreme sides of the enclosure and operate between stops 3S in the Walls of base I. The member 36 has parallel arms 4I integral therewith and at the extremities of these arms is supported a pin 42 to which the ends of operating springs 34 and 35 are secured. This pin 42 may be grooved to retain the springs at its ends in spaced relation to each other and to the moving parts. The carrier 22 is provided with an extension 3D adapted to be engaged by the pin 42 to limit movement of the member 36 and knob 6 in normal on position. The carrier 22 is further provided with a surface 40 engaged by pin 42 when the knob 6 is moved to the right from overload oi position (Figure 4) to reset the breaker after it has been operated in response to an overload.

To the member 36 is rigidly secured a shield 43 carrying the operating knob 6 which extends through the slot 5, the shield d3 serving to seal this slot. The carrier 22 is provided at its free end with a latching surface M. This carrier is normally held in the position shown in Figures 1 and 3 by means of a latch 45. A supporting plate 46 is rigidly secured to the base I and is provided with grooves adjacent one end thereof. The latch 435 embodies a U-shaped element having legs all also provided with grooves adapted to enter and engage with those on the plate i6 to form a pivotal mounting for the latch 45. The latching surface i4 on the carrier 22 is engaged by the top of the slot between the legs 4l to latch the carrier in place. The connecting portion of the U-shaped latch 65 is return bent as shown to form a second U in a plane at right angles to the first. The legs of the second U are disposed on opposite sides of the bimetal member II and to the leg d8 thereof disposed on the low expansion side of the bim'etal an insulating abutment 49 is adjustably mounted as by means of a stud and nut connection.

A bracket 5l is rigidly secured to the base I and a spring 52 connects the end of leg d8 to bracket 5I to bias the latch 45 toward the carrier 22. The free end of the carrier is provided with a sloping surface 53 which serves to give a further movement to the latch 45 upon release of the latching surface 35. This feature is of advantage in the multi-pole construction to be hereinafter described.

The connectors 9 and I2 extend through the circuit breaker enclosure at opposite ends thereof to form terminals at which electrical connections to the breaker may be made. At each end of the enclosure there is provided a barrier wall 5D at one side of the connector terminal and extending thereabove and therebelow. The portion of this wall below the corresponding connector may be formed integral with the base I, while that above the connector may be integral with the cover 2.

This single barrier permits the use of `an adequately wide terminal without widening the enosure beyond that required by the internal vmechanism. With this barrier arrangement the unit breakers may be mounted side by side in panelboard form and the necessary insulation interposed between adjacent terminals. To permit the reversal of the breaker end for end as may be desirable in building up a particular series, the barrier walls 50 are preferably spaced at diagonally opposite corners in the enclosure to secure the desired uniformity upon reversal. This arrangement of the barrier walls is clearly shown in Figures 1 and 2 of the drawings. With this arrangement of barriers in conjunction with the edgewise mounting of the unit parts of the breaker it is possible to secure a desirable thinness in the complete breaker unit which has not heretofore been possible in the art in circuit breakers of comparable function.

The operation of the breaker described above should be readily apparent. With the parts in the on position as shown in Figure 1, movement of the knob 6 toward the right will move the member 36 and the operating springs 34 and 35. Before these springs have reached the effective dead center position the force of the springs on the ipper 29 will serve to move it Within the slot 28 from the side shown in Figure 1 to the opposite side as in Figure 3, thus quickly flipping the operating springs 34' and 35 past dead center position and causing the bell crank lever formed by plates 23 to rotate counterclockwise into the position shown in Figure 3, moving the contact bar 24 toits "01 position. The flipper slot is shown to be directed toward the left of the bell crank pivot so that the operating springs 34 and 35 will exert a force tending to rotate the bell crank in a clockwise direction, thus maintaining contact pressure even while the flipper is moving to the position of Figure 3, as it can readily be seen that the torque on the bell crank will not change until the flipper actually engages that side of the groove 28. This re'- sults in maintaining pressure on the contacts until it is sharply released by engagement of the flipper with the side of the groove 2l. It is thus impossible to manipulate the knob 6 so as to have a dead center position at which there is no pressure on the contacts and it can be readily seen that the change in pressure on the contact fromfon to ofi position will be brought about quickly regardless of the speed oi. operation of the knob 5 since the operating springs will always be quickly carried past their effective dead center position through the movement of the flipper. The operation from the normal oil.'" position of Figure 3 to on position of Figure 1 is in reverse direction. With the parts in the normal 0E position of Figure 3, movement of the operating handle to the left will move the flipper 29 from the side of the groove shown to the opposite side to move the operating springs through dead center position and thus move the contacts 25 to engaged position. Upon overload, the bimetal I I which is in series with the breaker circuit and is self-heated by the current therethrough, becomes heated and moves in a clockwise direction to engage the stop 49 and move the latch 45 clockwise until it is moved beyond the latching surface 44 whereupon the carrier 22 is released and moves upward to the position shown in Figure 4 under the bias of the operating springs 34 and 35.

The stop 30 is moved above the pin 42 by this movement of the carrier 22 whereupon the member 36 and knob 6 move to their extreme position as viewed in Figure 4. In this movement of the carrier 22 to its released position the plates 23 are prevented from rotating relative to the carrier by engagement of the surface 20 with the pin III and the contact bar 24 is thus quickly moved to off position with a snap action. Upon resetting, the knob 6 is moved to the right whereupon pin 42 engages the surface 40 on the carrier 22 and moves the latching surface 44 downward into position to be engaged by the latch 45, if in the meantime the bimetal II has cooled sufliciently to allow the latch to be pulled to its normal position by the spring 52. When the surface 44 is thus engaged by latch 45 the parts will be reset in their normal position as in Figure 3. Movement of the knob 6 to the left will then move the breaker to its on" position as in Figure 1. It should be noted that the arrangement of parts is such that the pin 42 will not move the cradle to reset position until after the flipper 3l has been moved'to the opposite sidev of the slot by the resetting movement of the handle. In the operation of the circuit breaker mechanism to the "ofi' position either automatically in response to a current overload or in response to movement of the manual operator, should any cooperating pair of contact surfaces tend to stick together it is obvious that due to the pivotal mounting of the conducing -bar 24 the opposite end of the bar will move upwardly due to the action of the biasing springs and this movement will exert a very high pressure duo to the leverage action which will tend to pry loose the movable contact which was stuck or welded to the cooperating stationary contact.

'Ihe arc suppressor I'4 herein shown is built up of a plurality of U-shaped. thin, plate-like 1aminatlons loosely disposed in recesses in the sides of the base I and held therein by the shield I5. The legs of the U are disposed on opposite sides of the path of travel of the conducting bar 24. 'I'he laminations have no insulation other than incidental insulation due to surface oxide and to air space and no attempt is made to insulate them from each other nor is any insulation placed upon the inside surfaces of the laminations to insulate them from any arc which may be formed. 'I'he suppressor in its entirety consistssimplyof the ordinary laminations built up 'ithout any positive attempt to secure insula- In connection with the arc-suppressor herein described, it should be noted that the connectors 9 and I2 have portions extending along side the arc Suppressors and this results in a more complete turn about the laminations and hence increases the strength of the field induced by the current through the connecting member and thus increases the eiiiciency of the magnetic effect.

In Figure 6 a modified means for securing quick movement of the operating springs past dead center is disclosed. The mechanism herein clisclosed is the same as that disclosed in Figures 1 to 4 inclusive except that the plates 23 forming the bell crank are formed with extensions 54 having parallel slots 55 in which is slidably disposed the pin 56 to the ends of which the operating springs 34 and 35 are connected. In this modification as the operating-springs approach dead center position the pin 56 slides within the slot to move the springs past dead center position to change the direction of torque on the bell crank independent of the speed of movement or the holding of the handle at this point. As can be readily seen, this modification does not have the sharp snap action present in the flipper arrangement disclosed in connection with Figures l to 4 inclusive as the friction on the pin 56 is considerable and the component of force tending to shift the pin within the slot 55 is small. Furthermore, the direction of the torque on the bell crank is not sharply changed as in the flipper when it strikes the side of the groove but in the present modification the direction of the torque will change while the pin 56 is still in motion within the slot. This modification, however, is an improvement over the arrangement wherein the spring is connected to the lever at a xed point as it prevents holding of the operating springs on dead center position. The fiipper arrangement previously described, however, is a great improvement over this arrangement and is the preferred construction.

In Figure 7 a multi-pole breaker is illustrated, the one specifically shown being two polealthough it is obvious that as many poles as-desired may be built up in the' same manner. This breaker is shown with the handle and cover removed. The base in the multi-pole arrangement may be simply a plurality of the bases shown and described in the breakers of Figures 1 to 4 inclusive joined together in any mechanical manner and with the barrier 63 disposed between individual breaker mechanisms. Or alternatively a unitary base may be used and the individual mechanisms'mounted-'on this base in a similar manner. The multi-pole breaker, according to the present invention, embodies a plurality of individual breaker mechanisms as previously described mounted side by side either on a single base or on a plurality of mechanically connected individual bases. As shown in Figure 7, the individual units are joined together at three points-the latches 135 are rigidly connected by a cross bar 51; the members 35 are rigidly connected together by a cross bar 58, a single centrally arranged operating handle being connected to the bar 58 as by the stud 59. The third connection between the individual elements involves the operating springs and is shown in detail in Figure 8. In the multi-pole arrangement each spring is equipped with a spring guide 6i which comprises a finger extending down within the coil spring. These spring guides are pivotally mounted on the pin 42 and extend thereabove and are rigidly connected together as by a connecting bar B2. This construction insures simultaneous operation of the individual mechanisms in the multipole breaker. The members 36 are joined together and have a common operating knob so that the operating members will have the same movement at all times. In this connection, due to differences in centers, it might be possible to Ithrow one of the operating mechanisms over center to move its contacts while by holding the handle the other mechanisms might not be operated. However, the spring guides and common connecting bar obviate this possibility as the flipping of the operating springs o1' any one mechanism will move the corresponding spring guides and the connecting bar and will thus move the spring guides on the other mechanisms which in turn will move their operating springs sulficiently to insure movement of the flipper and actuations of their mechanisms. This common connection of the spring guides for the operating springs thus insures common actuation of the individual mechanisms at the same time.

With the latches rigidly joined together as by the bar 51, the deflection of any bimetal will move all the individual latches to release the individual carriers. However, due to play or twisting of the parts, it might ordinarily be possible to release one carrier without unlatching all of them. The surface 53 on'the end of the car'rier 22, however, causes a further movement ,of the latching members 45 by the inclined surface 53 of the carrier which is released engaging its latch and thus moving all of them a further distance forward and thus insuring opening of all the breakers. As a substitute for or in conjunction with the inclined suriace 53 a nubbin or other protuberance Vmight be placed on the surface of the latch 65 further movement of the latching members. y This construction is illustrated in Figure 6 in Vwhich is shown the pivoted latch 45 provided with a bridging bar 51 and with a nubbin 64 on the face of the latch in the path of the end of the pivoted carrier 22. As the surface 53 engages this nubbin, it can be readily understood that there will be a further movement of the latch in its unlatching direction to insure disengagement from all the carriers 22. The operation of the multi-pole breaker is the same as that of the single pole breakerpreviously described with the exception that the connecting bars insure common actuation of all the breaker mechanisms at the same time.

While the circuit breaker has been disclosed as using two operating springs, these springs have duplicate functions in so far as the ordinary 0peration of the breaker is concerned and it is obvious that a single spring may be used without changing the principles of operation. The double spring, however, has the advantages of symmetry, no sideward or twisting forces and a safety factor as one spring will operate the breaker'if the other should break.

While certain preferred embodiments of the invention have been specifically described and illustrated, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the-following claims. y

What is claimed is:

1. In a circuit breaker, stationary and movable contacts, a movable element having an operative connection to the movable contact, a movable member, a spring biasing said element and movable by said member through a dead center position to actuate said element in dierent directions, and means to quickly move the spring through its dead center position irrespective of of the speed of movement of said member when said member has been manually operated to a certain position.

2. In a circuit breaker, a pivoted element, a contact mounted thereon, a movable member, a spring biasing said element and connected to said member and movable therewith past the pivot of said element to eiect snap movement of said contact, the end of the spring remote from said member being movable relative to said element in a certain manually operated position of said member to move said spring through the eiective dead center position independently of further movement of said member.

3. In a circuit breaker, a pivoted element, a

contact mounted thereon, a movable member, a spring biasing said element and connected to said member and movable therewith past the pivot of said element to eiect snap movement of said contact, and means for moving said spring quickly through dead center position irrespective of the speed of the movement of said member when said member has been manually operated to a certain position. g 4. A circuitbreaker comprising a base, a stationary contact on said base, a movable contact, a pivotal element operatively connected to said movable contact, a manually operable member, an over center spring operated by said member to move said element and means to quickly move said spring past dead center irrespective of the speed of operation of said member when said member has been manually operated to a certain position.

5. In a circuit breaker, a movable contact, a pivoted element having operative connection therewith, a movable member, a spring biasing said element about its pivot and movable on opposite sides of the pivot point by said member,

and means for moving said spring quickly through ment about its pivot and connected to said memv torque of said spring independently of the speed of movement oi' said member, said element being pivoted on a normally stationary, latched mem- 1 ber, said latched member being releasable on overload ior movement vunder the bias ci said operating spring. l Y

8. In a circuit breaker, a movable contact, a pivoted element having operative yconnection therewith,` a movable member, a spring biasing said element about its pivot and movable on opposite sides of the pivot point by said member, and means for moving saidspring quicklythrough dead center position v.irrespective of the speed'of movement ofthe member,"the pivot oi'saidelement being normally stationary but releasable on 'overload to eiect automatic movement oi' said contact'.

9. A circuit breaker'comprlsing abase, an losbridging conducting bar having contact surfaces on its ends pivotally mountedon said element and a spring interconnecting said member and element and moved' past the operating center of said element by movement of said member to reciprocate said bar, and means constituting the connection between said spring and said element for quickly changing the direction of torque on said element independently of the speed of movement of said member.

10. In a circuit breaker, stationary and movable contacts, a pivotal element operatively connected to said movable contact, a second element pivotally mounted on said irst element, an overcenter spring connected to said second. element, and amovable member i'or moving said spring to its voperating positions, the second element serving to quickly move said spring through the dead center position of said first element.

1l. In a circuit breaker, stationary and movable contacts, a pivotal element operatively connected to said movable contact, a second element pivotally connected to said first element, 'stops on the irst element for limiting the movement o! said second element, an over-center spring connected to said second element, and a movable member for moving said spring to its operating positions, the second element serving to quickly move said spring through the dead center position of said ilrst element.

12. In a circuit breakenstationary and movable contacts, a pivotal element operatively connected to said movable contact, a second element pivotally connected to the nrst element, means limiting the pivotal movement oi' the second element, an over-center operating spring connected to said second element, and a movable member for moving the spring through the pivot of the second element, the resulting movement of the second element quickly moving the spring current responsive latch4 for through the pivot of the ilrst element, irrespective os the speed oi movement of said member.

13. In a circuit breaker, spaced, stationary contacts, a conducting bar having contact faces on its ends, adapted to cooperate with said stationary contacts, an oscillatable operating hanf'le. a iatched, normally stationary supporting member releasable on overload to separate the contacts, a bell crank lever pivoted on said member, said bar being pivotally mounted on one end of said lever, a notch in the other end o! said lever, an element disposed insaid notch for movement between the sides oi said notch and an operating spring interconnecting the free end oi' said element and said operating handle.

14. A circuit breaker comprising a base, a manually operable U-shaped member, a support pivotally mounted on said base'between' the leg of said U and normally held in iixed position by a current responsive latch, an element pivotedon said support, a movable contact carried by said element, a notch in said element, a ilipper movably received in said notch, an operating spring interconnecting said ilipper and member, said v ilipper serving to quicklyv move said spring past the operating pivot oi said element.`

15. In a circuit breaker,.a pivoted carrier, a said carrier, a bell crank lever pivoted on said carrier, said lever comprising parallel plates disposed on"opposite sides of said ycarrie a contact bar pivoted on Y said lever between said plates, parallel notches irrsaid plates, a ilipper having parallel legs reoeived in saidv notches on opposite sides oi said Abar, an operating member and an operating spring' interconnecting said member and ilipper.

i6. In a circuit breaker, a pivoted carrier, a current responsive latch for said carrier. a bell crank lever pivoted on said contact carried by said lever, a substantially V- shaped notch in said bell crank, a iiipper disposed in said notch. an operating member, an operating spring interconnecting said member and ilipper. the point oi said V being on the side of the pivot of said lever opposite from thecontact, the spring being on opposite sides oi the dead center position in the extreme positions of the ilipper whereby pressure will be maintained on the contact until sharply released by movement of the ilipper to one extremepontion. l

l'l. In a circuit breaker,a pivoted element. a contact carried thereby, a slot in said element, a freely movable pin slidable in said slot, a manually oscillatable member, an`operating spring interconnecting said member and pin and movable by said member past the pivot of said element, said pin sliding in said slot to quickly move said spring past dead center position independently oi' the speed of movement oi' said member.

18. In a circuit breaker, a support, a lever pivoted on said support, a spring operatively connected to said lever and movable past its pivot to move the lever in opposite directions, spaced stationary contacts, a bridging contact bar pivotally mounted on said lever, and a manually operable member for moving said spring to eilect snap operation of said contact bar.

19. In a circuit breaker, a bell crank lever, a spring operatively connected thereto and movable past the operating pivot to reciprocate said bell crank, a contact bar pivotally mounted on said bell crank and a manually operable member connected to said spring for movement past said pivot to eil'ect snap operation oi' said contact bar.

20. In a circuit breaker, a pivoted bell crank carrier, a movablel lever, a spring operatively connected thereto and movable past the pivot to reciprocate said bell crank, a contact bar pivotally mounted on said bell crank and a manually operable member con- .nected to'said spring for movement past said pivot to effect snap operation of said contact bar, said bell crank being pivoted on a latclied vmember, automatically releasablevto effect movement of said bar in responsive to a circuit condition,

2l. A circuit breakercomprising a base, an oscillatable member supported on said base, a support pivotally mounted on said base and normally held in fixed position by a current responsive latch, an element pivoted on said support, a bridging conducting bar having contact surfaces on its ends pivotally mounted on said element and a spring interconnecting said member and element and moved past the operating center of said element by movement of said member to reciprocate said bar with a snap action.

22. In a circuit breaker, spaced stationary contacts, a relatively long conducting bar adapted to bridge said contacts, movable contacts mounted on said bar adjacent the ends thereof, and mechanism for reciprocating said bar, said mechanism having a free pivotal connection to said bar adjacent to the central portion thereof, whereby upon actuation of said mechanism to separate the contacts a prying action will be exerted upon any weld which may occur between one pair of cooperating contacts.

23. In a circuit breaker, spaced stationary contacts, a relatively long conducting bar adapted to bridge said contacts, movable contacts mounted on said bar adjacent to the ends thereof, mechanism for reciprocating said bar, said mechanism having a free pivotal connection to said bar whereby upon actuation of said mechanism to separate the contacts a prying action will be exerted upon any weld which may occur between one pair of cooperating contacts, and means for limiting the separating movement of each end of the bar to insure the proper spacing between both pairs of contacts.

24. In a circuit breaker, spaced stationary contacts, a relatively long conducting bar adapted to bridge said contacts, movable contacts mounted on said bar adjacent the ends thereof, mechanism for reciprocating said bar, said mechanism having a free pivotal connectionto said bar adjacent to the central portion thereof, whereby upon actuation of said mechanism to separate the contacts a prying action will be exerted upon any weld which may occur between one pair of cooperating contacts, and stops above each of the stationary contacts for limiting the upward movement of each end of the bar to insure proper spacing between both pairs of contacts,

- 25. In a circuit breaker, a base, a relatively thin supporting member pivotally mounted edgewise to the base, a relatively thin lever pivotally mounted on said member, a relatively thin bridging contact bar pivotally mounted on said leverl edgewise to the base and in the plane of said member, a current responsive latch for said member, an overcenter operating spring operatively connected to said lever, and a manually operable member for moving said spring.

26. In a circuit breaker, a base, a relatively thin supporting member pivotally mounted edgewise to the base, a pair of relatively thin plates pivoted on either side of said member, a relatively thin bridging contact bar pivotally mounted between said plates edgewise to the base,

' a current responsive latch for said member, an

over-center operating spring operatively connected to saidplates, and a vmanually operable member for moving said spring.

27. In a circuit breaker, a base, a relatively thin supporting member pivotally mounted edgewise to the base, a pair of relatively thin plates pivoted on either side of said member for common movement, a relatively thin bridging contact bar pivotally mounted between said plates edgewise to the base and in the plane of said member, complementary male and female formations on said member and bar adapted to mate in one position, a current responsive latch for said member, an aver-center operating spring operatively connected to said plates, and a manually operable means yfor moving said spring.

28. In a circuit breaker, a base, spaced stationary contacts supported on said base, a relatively thin supporting member pivotally mounted edgewise to the base, a relatively thin lever pivotally mounted on said member, a relatively thin bridging contact bar pivotally mounted on said lever edgewise to the base and in the plane of said member, contact faces adjacent to the opposite ends of said bar adapted to make butt contact with said stationary contacts, a current responsive latch for said member, an over-center operating spring operatively connected to said lever, and a manually operable means for moving said spring.

29. In a circuit breaker, an elongated, box-like enclosure, separable contacts and manual and automatic means for actuating said contacts` mounted within the enclosure, terminal connectors extending from said enclosure at opposite ends thereof, and a single barrier wall extending from each end of the enclosure alongside of and above and below said connectors.

30. A circuit breaker as defined in claim 29 in which the barrier walls are located at diagonally opposite corners of the enclosure to provide uniformity when reversed end for end.

31. In a circuit breaker, a base, spaced stationary contacts mounted on said base, a bridging contact bar supported edgewise to the base, mechanism for manually and automatically reciprocating said bar including a pivoted support, a latch therefor and a bimetallic member for moving said latch, said bar being disposed and movable between the legs of said member.

32. In a circuit breaker, a-base, spaced stationary contacts mounted on said'base, a pivoted support, a U-shaped latch for said support, a U-shaped bimetallic member for moving said latch, said latch and member being located between said contacts with their planes at right angles to a line therebetween, a bridging contact bar mounted on said support through an intermediate pivoted lever, means for moving said lever to reciprocate the bar, said bar being disposed and movable edgewise to the base and between the legs of said latch and bimetallic member.

33. In a circuit breaker, stationary and movable contacts, a member releasable to eiect automatic separation of said contacts, a current responsive latch for said member comprising a U-shaped, series connected bimetal, a pivoted element biased toward said member and having a latching surface on one side of said bimetal engaged by said member, said element having a portion extending on the other side of said bimetal and engageable thereby for movement to releasing position.

34. In a circuit breaker, stationary and movaisaess able contacts. a member releasable to effect automatic separation of said contacts, a current responsive latch for said member comprising a U-shap'ed, series connected bimetal, a pivoted element biased toward said member and having a latching surface on one side of said bimetal engaged by said member, said element having a portion extending on the other side of said bimetal and an adjustable insulating striker on said portion in the path of movement of said bimetal for moving said element to releasing position.

35. In a circuit breaker, a normally stationary support mounted adjacent one endyon a f lxed pivot, means latching the other end of said support, bimetallic means for automatically releasing said latch, said latch comprising a support engaging portion on the high expansion side of said bimetal and an adjustable stop supporting portion on the low expansion side of the bimetal, said stop being engaged by the bimetal to move the latch away from the support, and

' means biasing said latch toward the support.

36. In a circuit breaker, a releasable support mounted on a fixed pivot and biased for movement to released position, a latch for said support, said latch comprising a U-shaped element having the free end of said'support within the slot and engaging the top thereof as a latching surface, the connecting portion of the U being extended and return bent into a U-shape at right angles to the first U, a bimetallic member between the legs of said second U and an adjustable member on the leg adjacent the low expansion side of the bimetal and in position to be engaged thereby to move the latch.

37. In a circuit breaker, a releasable support mounted on a fixed pivot and biased for movement to released position, a latch for said support, said latch comprising a U-shaped element having the free end of said support within the slot and engaging the top thereof as a latching surface, the connecting portion of the U being extended and return bent into a U-shape at right angles to the first U, a bimetallic member between the legs of said second U and an adjust-` able member on the leg adjacent the low expansion side of the bimetal and in position to be engaged thereby to move the latch and a spring biasing said latching element toward said support.

38. In a multi-pole circuit breaker, a plurality of sets of stationary and movable contacts, a bimetallic element in series with each of said sets a plurality of means normally separately movable for effecting separation of their corresponding sets of contacts, and means for automatically effecting release of said plurality of means in response to movement of any one bimetallic element including latching surfaces for said plurality of means progressively movable in common by any one of said bimetallic elements.

39. In a multi-pole circuit breaker, a plurality of sets of stationary and movable contacts, a bimetallic element in series with each of said sets,

supporting members for the movable contactsv individually movable to separate their corresponding set of contacts, and means for effecting common releasing movement of all said members .by the movement of any one of said bimetallic elements comprising latching surfaces for said members rigidly 'joined together for common movement directly responsive to the movement of any one of said bimetallic elements.

40. In a multi-pole circuit breaker, a plurality of sets of stationary and movable contacts, a bimetallic element in series with each of said sets, said elements being aligned in a common plane, a plurality of means normally separately movable for effecting Separation of the corresponding set of contacts, and means for automatically eifecting release of all of said first mentioned means in response to movement of any one of the bimetallic elements including-latching surfaces for said nrst mtioned means rigidly .joined together for common movement and disposed on one side of the plane of said elements, and actuating surfaces rigidly connected to said latching surfaces and disposed on the opposite side of the plane of said elements and in the path of movement thereof.

4l. In a multi-pole circuit breaker, a plurality of sets of stationary and movable contacts, a plurality of members individually releasable to effect automatic separation of their corresponding sets of contacts, a bimetallic element in series with each said sets of contacts, pivoted latching elements biased toward said members and having latching surfaces on one side of said bimetallic eiements and portions extending on the opposite side of said bimetallic elements and engageable thereby for movement to releasing position, said latching lements being rigidly connected for common movement by any one of the bimetallic elements.

42. A multi-pole circuit breaker comprising a plurality of complete single pole mechanisms mounted side by side, said mechanisms including individual current responsive latches and individual manually actuated elements, means rigidly interconnecting said latches for common movement, means rigidly interconnecting said elements, and a single operating handle for manually moving said elements.

43. A multi-pole circuit breaker comprising a plurality of single pole mechanisms mounted side by side, said mechanisms including individual current responsive latches, individual members engaging said latches and releasable thereby to separate the corresponding cooperating contacts and individual actuating elements for manually operating said contacts and resetting said members, means rigidly connecting said latches for common movement to release said members, means rigidly connecting said elements for common manual movement, and a single operating handle connected to said last mentioned means.

44. In a `multi-pole circuit breaker, individual switching mechanism, over center operating springs for 'said mechanisms controlled by a common a manually operable member, spring guides for said springs and means rigidly interconnecting said guides to insure common movement of said springs through their dead center positions.

45. In a multi-pole circuit breaker, a plurality of individual members releasable on over-load, interconnected latching means for said members, individual switching mechanisms operated byover center springs controlled by a manually operable member, spring guides for said springs' and means rigidly interconnecting said guides to insure common operation of said mechanisms.

46. In a multi-pole circuit breaker, a plurality of duplicate single pole units mounted side by side, each of said units having an element releasable on overload, a latch for said element,

a manually osclllatabie operating member, at

least one over center operating spring and a spring guide therefor, means rigidly interconnecting said latches, means rigidly interconnecting said members and means rigidly interconnecting said spring guides.

47; In a multi-pole circuit breaker, a plurality of duplicate single pole units mounted side by side, each of said units having an element releasable on overload to separate the contacts, a latch for said element, a manual operating member, and contact making and breaking mechansm operated by at least one over center spring under the control of said operating member, a spring guide for each of said springs and means rigidly interconnecting said guides to insure common movement of said springs past theirA dead center positions.

48. In a multi-pole circuit breaker, a plurality of sets of cooperating contacts, a plurality of individually releasable members for effecting separation of their corresponding sets of contacts, a plurality of latching surfaces for said members y mounted for common movement to releasing position, a plurality of current responsive means for moving the latching surfaces, and means for insuring the release of all said members upon the release of any one.

49. In a multi-pole circuit breaker, a plurality of sets of'cooperating contacts, a plurality of individually releasable members for eiecting separation of their corresponding sets of contacts,

a plurality of latching surfaces for said members mounted for common movement to releasing position, a plurality of current responsive means for moving the latching surfaces, and means for insuring the release of all said members upon the release of any one, said means including interfering portions on the members and rigid with'the latching surfaces for eiecting further releasing movement of the surfaces upon the release of any one member.

50. In a multi-pole circuit breaker, a plurality of sets of cooperating contacts, a plurality of individually releasable members for effecting separation of their corresponding sets of contacts, a common latching element including individual latching' surfaces for said members, a plurality of current responsive means for moving said latching element, and projections on the element above each latching surface in the path of the members, whereby the release of any one member will cause a further releasing movement of the element to insure release of al1 the members.

5l. In a' multi-pole circuit breaker having a group of individual releasable carriers, a group of substantially rigidly connected latches for said carriers, current responsive means for progressively moving said latches, means on the elements of at least one of said groups for effecting further releasing movement of the latching group upon release of any one of the carriers.

52. In a multi-pole circuit breaker, a plurality of individual releasable carriers, a latch for each of said carriers, current responsive means, for

, progressively moving each of said latches, and

,means rigidly connecting said latches for moveof closely spaced slots extending through a wall of the enclosure in plane substantially parallel to the path of the arc providing cooling surfaces for the arc gases. y

54. In an electric circuit breaker, separable contacts, mechanism for automatically separating said contacts in response to an overload, an enclosure for said contacts and mechanism, and a vent for the gases of an arm formed by the separation of said contacts, said vent comprising a plurality of closely spaced slots extending through a wall of said enclosure in planes substantially parallel to the path of the arc, the walls between adjacent slots having surfaces extending in the path of the arc gases a distance greater than the thickness of the enclosure wall.

55. In an electric circuit breaker, separable contacts, mechanism for automatically separating said contacts in response to an overload, an enclosure for said contacts and mechanism, and a vent for the gases of an arc formed by the separation of said contacts, said vent comprising a plurality of closely spaced slots extending through the upper portion of a Wall` of said enclosure, the Walls between adjacent slots having surfaces extending in the path of the arc gases a distance greater than the thickness of the enclosure wall, and a projection on the enclosure wall below said slots for directing the arc gases away from the part of the breaker below the slots.

56. In an automatic electric circuit breaker, separable contacts, manual and automatic means for causing separation of said contacts, said auto-A matic means including a current traversed bimetallic element adapted to be so deiiected when heated by an overload current passing therethrough as to initiate separation of said contacts, an enclosure for said contacts and means, a terminal at the exterior of; said enclosure for the attachment of a circuit wire, a connector leading from said terminal into said enclosure and having one end of said bimetal rigidly welded thereto in supported relation, the other end of said bimetal being srially connected with said contacts.

57. In an automatic electric circuit breaker, a base,` a cover for said base forming a scalable enclosure, separable contacts andmanual and automatic means for causing separation of said contacts mounted within said enclosure, said automatic means including a current traversed bimetallic element adapted to be so deiiected when heated by an overload current passing therethrough as to initiate separation of said contacts, a connector mounted on said base and having its opposite ends in the interior and at the exterior of the enclosure, the exterior end of the connector forming a termnalfor the circuit breaker and adapted to be connectedto a circuit wire, the interior end of said connector having one end of said bimetallic element rigidly welded thereto in supported relation, and means connecting the opposite end of said element to one of said separable contacts to place the element in series circuit therewith.

58. In an automatic electric circuit breaker, a base, a cover for said base forming a scalable enclosure, stationary and movable contacts and manual and automatic means for causing movement .of said movable contact mounted within said enclosure, said automatic means including a lU-shaped, current traversed bimetallic element overload current passing therethrough as to initiate separation o1' said contacts, a connector mounted on said base and having its opposite ends in the interior and at the exterior of the enclosure, the exterior end of the connector forming a terminal for the circuit breaker and adapted to be connected to a circuit wire, the interior end of said connector having one ieg of said bimetallic element rigidly welded thereto in supported relation, the other leg of said bimetallic element having a rigidly welded connection with said stationary contact to place the element in series circuit with the breaker.

JOHN G. JACKSON. g WALLACE T. ALLEN.

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