US2329362A

US2329362A - Circuit breaker

Info

Publication number: US2329362A
Application number: US720599A
Authority: US
Inventors: Ralph H Swingle
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1934-04-14
Filing date: 1934-04-14
Publication date: 1943-09-14
Anticipated expiration: 1960-09-14

Description

INVENTOR ATTORN Y Sept. 14, 1943. R. H. swlNGLE CIRCUIT BREAKER med Apr-11 14, 1934 4 sheets-sheet 1 aZ/n/ S11/ingle.

WITNESSES /Q- Alm Sept. 14, 1943. Ff. H. swlNGLz-z CIRCUIT BREAKER Flled April 14, 1934 4 Sheets-snee?. 2

WITNESSES: INVENTOR Raga/2 H Swing/ 2 A'TToNE Sept 14, 1943- R. H. swlNGLE 2,329,362

C IRCUIT BRE\KER WITNESSES: INVENTOR .m @am /f amg/g.

ATTORNE Patented Sept. 14, 1943 '1` pler and less expensive to manufacture than the previously known devices of this type.

UNITED STATES PATENT OFFICE CIRCUIT BREAKER pany, East Pittsburgh, Pennsylvania Pa., a corporation of Application April 14, 1934, Serial No. 720,599

84 Claims.

My invention relates to circuit interrupters and particularly to circuit breakers of the type used for controlling lighting and moderate power industrial feeder circuits.

A commercially successful circuit breaker for this type of service must satisfactorily meet very exacting requirements. Among other things, the breaker must positively interrupt large amounts of power without prolonged arcing or other circuit disturbance, and the breaker must be entirely trip free of the operating handle at all times.

As opposed to these operational requirements, a commercially successful breaker must be moderate in price, both because of the large numbers used in even a moderately sized building or factory, and because of the fact that excessively costly breakers cannot be economically justified over the older but less desirable fuse and switch arrangements.

Heretofore, the manufacturers of these devices have endeavored to eect a compromise between these two conflicting sets of requirements. The breakers were manufactured as cheaply as possible consistent with good quality and an ability to meet the necessary requirements as to interrupting ability. The best of the prior art structures, however, was more costly than would be desired, one particularly troublesome element in the problem of cost reduction being the securing of simple means for making the breaker trip free of the operating handle.

The principal object of my invention is, therefore, to provide a simple, inexpensive circuit breaker which will satisfactorily meet the above mentioned operational requirements.

Another object of my invention is to provide a trip-free mechanism suitable for use with manually operable circuit breakers, that shall be sim- A further object of my invention is to provide an improved quick-make and quick-break circuit breaker that shall utilize a minimum possible number of parts.

An ancillary object of my invention is to provide an improved toggle operating mechanism for circuit breakers or like devices which shall utilize a considerably less number of parts than has been heretofore considered necessary.

In carrying out these objects of my invention, I prefer to employ one of the two embodiments of my invention illustrated in the drawings. The simpler of these two preferred embodiments comprises a movable switch arm, an electro-responsive support means for releasably engaging one end of the switch arm to provide a pivot point therefor, guide means for fixing the path of movement of the switch arm, an over-center spring and an operating handle for moving the switch arm to the open and to the closed circuit position with a snap action, and a second spring actuable when the electro-responsive means moves, upon the occurrence of predetermined conditions to disengage the switch arm to cause the switch arm to be moved to the open circuit position. The other preferred embodiment is essentially similar to the simpler form, except that a toggle link mechanism is utilized for causing manual operation of the breaker. Both embodiments are quick-make and quick-break, both are trip free of the operating handle at all times, and both are entirely resettable through movement of the operating handle.

Referring to the drawings,

Figure l is an elevational view, partly in section, of the simpler preferred embodiment of my invention. The moving parts of the breaker are shown in the closed-circuit position.

Fig. 2 is a view similar to Fig. 1 showing the moving parts of the breaker in the open-circuit position.

Fig. 3 is a view similar to Figs. 1 and 2 showing the moving parts of the breaker in the tripped position.

Fig. 4 is a plan view of the circuit breaker illustrated in Figs. 1 and 3. The cover has been removed, and a portion of the operating handle has been cut away in order to more clearly illustrate the structural features involved.

Fig. 5 is a perspective view of the main supporting frame used in the embodiment of my invention illustrated in Figs. 1 and 4.

Fig. 6 is a perspective view of the bimetallic latching member which is utilized in the embodiment of my invention illustrated in Figs. 1 to 4.

Fig. 7 is an elevational view partly in section of the second preferred embodiment of my invention. The moving parts of the breaker are shown in the normal open-circuit position.

Fig. 8 is a view similar to Fig. '7 showing the noving parts of the breaker in the tripped posilOIl.

Fig. 9 is a view similar to Figs. '7 and 8 showing the moving parts of the breaker in the normal closed-circuit position.

Fig. 10 is a sectional view taken on the line X--X of Fig. 9. l

Fig. 11 is a sectional view taken on the line XI-XI of Fig. 9.

Fig. 12 is a perspective view of the support frame for the toggle operating mechanism used in conjunction with the embodiment of my invention shown in Figs. '1 to 11, and

Fig. 13 is a perspective view of the guide frame used in the embodiment of my invention illustrated in Figs. 7 to 1l.

The simpler preferred embodiment of my invention, which is illustrated in Figs. 1 to 6, inclusive, comprises generally a base I of molded insulating material upon which are mounted the main frame 3 of the breaker operating mechanism, the iixed contact 5, the bimetallic electroresponsive support means and trip element 1, and the two terminal strips 9 and II which are utilized for connecting the breaker in the controlled circuit. A floating switch arm I3, which includes a contact member 3| for cooperating with the iixed contact 5, has no permanently fixed pivot point and is adapted to be guided by the main frame 3 of the operating mechanism. A cover I1, likewise of molded insulating material, is provided for enclosing the moving parts of the breaker.

The bimetallic support member and trip element 1 is shown particularly in Fig. 6; it comprises a ilat strip of bimetallic material having an opening I9 for engaging the narrow end portion 2D of the switch arm I3 to provide a pivot point therefor, a bent-over terminal portion 2| which is adapted to be connected to the terminal strip 9 by means of a suitable screw 23. The lower end of the bimetallic trip element 1 is slightly bent so as to facilitate the resetting of the breaker following the tripping operation. A flexible shunt 21 having suitable terminals 29, at either end, is provided for completing the electrical circuit between the bimetallic trip element and the switch arm itself.

In the assembled breaker, the portion of the bimetallic trip element between the terminal portion 2| and the point at which the terminal 29 of the liexible shunt 21 is aiiixed thereto is at al1 times electrically connected in series with the circuit controlled by the breaker. Thus, upon the occurrence of an overloadcondition, the bimetallic element 1 is heated, and if the overload is of suiicient magnitude and duration, moves to release the switch arm I3 so as to cause opening of the breaker.

The switch or contact controlling arm I3 comprises essentially, a flat strip of conducting material having a narrow portion 20 at one end for engaging the thermally responsive support means and trip element 1 and a second narrow portion at the other end for supporting the movable contact member 3|, the second portion 30 being turned at right angles to the plane of the switch yarm proper. A pin 33 is aiiixed to the switch arm I3 intermediate its ends in order to provide means whereby the main operating springs 35 can be connected thereto. A second pin 31 is rigidly affixed to the switch arm adjacent the moving contact 3| and is provided with two rollers 38, one of which is positioned on either side of the switch arm. These rollers 38 engage suitable aligned guide openings 4| in the opposed upstanding sides of the U-shaped portion 39 of the main frame 3, and serve to denne the path of movement of the switch arm.

The electrical circuit for the breaker is comparatively direct. Beginning with terminal strip II, the current flows successively through the stationary Contact 5, the movable contact 3|, the

switch arm I3, the flexible shunt 21, utilized for connecting the switch arm I3 with the bimetallic trip element 1, the current carrying portion of the trip element, and thence through the terminal portion 2| of that element to the other terminal strip 9.

The breaker operating mechanism includes the main frame 3, which serves as a support or base for the moving parts of the breaker, the operating handle 42 which comprises a pair of opposed bell crank levers 43 joined at one end and provided with a handle portion 45 of insulating material for permitting manual operation of the breaker, a pair of over-center operating springs 35 for connecting the operating handle 43 and the switch arm I3 so as to permit the moving contact 3| to be moved to the open and to the closed-circuit positions with a snap action, and a second spring 41 which normally biases the switch arm I3 toward the open-circuit position, but is ineffective to cause the opening of the breaker except upon the actuation of the thermally responsive trip element 1.

The frame 3 is shown particularly in Fig. 5 and comprises the U-shaped portion 39, the opposed sides of which have the slots 4| therein for engaging the guide rollers 38 forming a part of the switch arm I3; a second U-shaped portion 49 having opposed openings 5I therein for engaging the pivot pins 53 which support the operating lever 43 on the mechanism frame; and a third U-shaped portion 55, the opposed sides of which are spaced somewhat more closely together (see Fig. 4) than the sides of the other U-shaped portions in order to provide a guide for the rear portion of the switch arm I3. The upstanding side members which form the third U-shaped portion 55 are connected at their upper end by means of a pin 51 which serves as a stop for preventing undue upward movement of the switch arm I3. The left hand side (Fig. 5) of the U-shaped portion 39 is provided with an arm 59 which is utilized for supporting one end of the second biasing spring 41, the other end of that spring engaging a suitable opening 6| in the switch arm lI3.

The outer end of each of the opposed bell crank levers 43, which, together form the operating handle 42, is provided with a cutout portion 63 for engaging one end of one of the operating springs 35. These cut-out portions 63 are so proportioned that they form knife edges (see Fig. 1), thereby minimizing friction between the handle and the operating springs. The limits of motion in either direction of the operating handle 42, are defined by the members 65 which project outwardly from the sides of the third U-shaped portion 55 of the frame 3. The frame 3 of the operating mechanism is affixed to the base I by means of suitable screw fastenings 61 which engage threaded openings 69 in the lower portion thereof.

The moving parts of this embodiment of my invention are shown in the closed-circuit position in Fig. 1. To open the contacts manually, the handle 42 is moved in a counter-clockwise direction about its pivot point (the pins 53). This movement of the operating handle 42 brings the line of action of the overcenter springs 35 nearer the line connecting the center of the pin 33 used for connecting the springs 35 to the switch arm I3 and the pivot point 1I of the switch arm (the point where the upper surface 13 of the narrow portion 2|) of the switch arm engages the upper end 15 (Fig. 6) of the opening I9 in the bimetallic support member 1). It is then immediately apparent that, since the contacts are held in the closed-circuit position because of the fact that the component of force exerted by the over-center springs 35 tending to move the switch arm I3I in a counter-clockwise direction about its pivot point 1I is greater than the force exerted by the spring 41 tending to open the breaker, a point will be reached Where this component is no longer effective and the switch arm I3 will then begin to move toward the open-circuit position. Once this movement is initiated, it results in a progressive decrease in the effective force tending to hold the breaker closed and the opening operation takes place with a snap action. The handle 42, if released before the opening movement is completed, will automatically move to the position shown in Fig. 2, which is the normal open-circuit position,

due to the fact that the line of action of the f springs 35 moves across the pivot point 53 of the handle 42. This causes the direction of the bias applied to the handle to change so that even if no further manual movement is imparted to the manually engageable portion 45 of the handle, the opening movement will still be completed with a snap action by the springs 35.

To close the contact manually, the operating handle 42 is moved in a clockwise direction from the position shown in Fig. 2. This movement brings the line of action of the over-center springs 35 beneath the line connecting the center of the support pin 33 and the pivot point 1I for the switch arm I3, and as the movement continues, it produces a component of force capable of overcoming the spring 41 Which biases the switch arm I3 toward the open-circuit position, at which time the switch arm begins to move toward the closed-circuit position with a snap action. Continued movement of the handle 42 to the full-on position, or a release of the handle, will then cause the moving parts of the breaker to assume a stable condition. For most satisfactory operation of the breaker, it is desirable that the operating springs 35 be considerably more powerful than the biasing spring 41, and it is also desirable that the outline of the slots 4I in the sides of the U-shaped portion 39 be such that the rollers 38 can move during the normal operation of the breaker in the arc, the center of which is positioned at the pivot point 1I of the switch arm I3. The provision of the guide slots 4I and roller 38 prevents longitudinal movement of the switch arm I3 due to the component of the overcenter springs 35 along the center lien of the switch arm, and thereby relieves the bimetallic element 1 of any cantilever bending stress which would tend to give that element a permanent set, thereby destroying the accuracy of the calibration of the breaker.

When the breaker is in the closed-circuit position and an overload of sufficient magnitude and duration to cause the actuation of the bimetallic trip member 1 occurs, that member moves from the position shown in Fig. 1 so as to disengage the end 20 of the switch arm I3 which normally projects through the opening I9 therein. This position is shown by the dotted lines in Fig. 1. The result of this disengagement is to permit the switch arm I3 to turn about the center of the pin 31 under the biasing action of the overcenter springs 35 and the spring 41. However, as the switch arm I3 moves to a static position with respect to the overcenter springs 35 (that is, the position where the line of action of the overcenter spring 35 coincides with the line connecting the centers of the pins 33 and 31) the overcenter springs 35 become incapable of holding the circuit breaker in the closed circuit position against the biasing action of the spring 41. The obvious result of this is to permit the switch arm I3 to be rotated by the second spring 41, so as to cause the opening of the circuit, The final position of the various moving parts of the circuit breaker, following the release of the switch arm I3 by the bimetallic trip element 1, is shown in Fig. 3. The opening operation once initiated by the release of the switch arm takes place entirely automatically, regardless of the position of the operating handle 42. Thus, the circuit breaker is trip free under all conditions.

Moreover, since the breaker operating mechanism is essentially an overcenter spring device, the movement of the switch arm once initiated takes place with a progressively increasing acceleration. The contacts are thug moved to the open and to the closed-circuit position during both the normal and the tripping operation, with a snap action.

Following the release of the switch arm I3, due to the actuation of the trip device 1 and the resulting opening of the breaker, it is necessary to restore the moving parts of the device to an operative position. This is done by moving the operating handle 42 from the position shown in Fig. 3 to the normal open-circuit position which is shown in Fig. 2. Through this movement of the operating handle, the line of action of the overcenter springs 35, is brought to a position where the springs tend to move the switch arm I3 in a counter-clockwise direction about the center of the roller support pin 31. The eventual result of this movement i5 to cause the narrow portion 20 of the switch arm I3 to reengage the opening I9 in the bimetallic trip element 1. The moving parts of the breaker are then restored to the position shown in Fig. 2, and the breaker may be actuated to closed position by movement of the operating handle 42 exactly as described above.

From the foregoing, it will be seen that the circuit breaker of my invention comprises essentially little more than a oating switch arm, an electro-responsive support for engaging one end of the switch arm so as to provide a pivot point therefor, an overcenter operating spring and a movable operating handle for moving the switch arm to the open and to the closed circuit positions with a snap action, and a biasing spring which biases the contacts toward the open circuit position at all times, but which is ineiiective to cause opening of the breaker except upon the actuation of the thermally responsive trip device. Because of the fact that the contacts are moved to the open circuit position with a snap action, very considerable amounts of power can be interrupted, and if desired, the rating of the breaker may be increased through the provision of a suitable arc extinguishing device. As mentioned above, the circuit breaker of my invention is entirely trip free of the operating handle, and will move to the open circuit position even when the operating handle is held in the full on position, thus the device is capable of meeting all necessary requirements, and yet at the same time it utilizes such a small number of parts that its manufacture involves much less expense than has heretofore been considered necessary.

The embodiment of my invention illustrated in Figs. '1 to 13 operates on essentially the same principle as the previously described embodiment, that is, the switch arm is a full oating lever, one end of which is engaged by an electro-responsive support trip element in order to provide a pivot point for the switch arm, and an operating mechanism pivotally engages the switch arm at an intermediate point in order to permit normal operation of the breaker.

This embodiment, however, utilizes a toggle linkage and an overcenter spring for effecting the normal movement of the switch arm and by virtue of this the contact is rigidly latched against movement when the breaker is in the closed circuit position, due to the toggle links being slightly over-center. This gives higher contact pressure and renders it unlikely that the switch arm will be blown open magnetically by short-circuit currents, thus adapting the breaker for use in circuits carrying heavy currents.

The various parts of this embodiment of my invention are mounted upon a base preferably of molded insulating material, which may be provided with a suitable cover |03 likewise preferably of molded insulating material, for enclosing and protecting the various parts of the breaker. A terminal strip is mounted at either end of the base |0| by means of suitable screw iastenings. The bimetallic support or trip element |01, which is structurally similar to the trip element 1 utilized in the previously described embodiment of my invention, is electrically connected to the left hand terminal strip |05 and is supported upon the base |0| by means of a screw |09, the stationary contact member is aiiixed to the other terminal member |05. A U-shaped frame |I3 (Fig. 13) having a pair of opposed slotted openings ||5 therein is provided for engaging suitable rollers H9 forming a part of the switch arm |1, in order to provide a guide means for the switch arm, and a second U-shaped frame member |2| (Fig. 12) is provided for supporting the various elements of the operating mechanism.

The switch arm |1 comprises a channel shaped member |22 of conducting material which has a narrowed rear portion |23 for engaging the opening |25 in the bimetallic support member |01, and is provided with a spring support arm |21 rigidly aflixed thereto by means of rivets |29, or the like, for supporting the movable contact member |3| which cooperates with the stationary contact member to open or to close the circuit. A pin |33 extends through the opposed side portions of the channel shaped frame member |22 in order to provide a support for the guide rollers ||9, one of which, as mentioned above, is disposed on either side of the switch arm.

The lower toggle link |4| is formed with a bifurcated portion |41 for engaging the channelshaped switch arm |22, a suitable pivot pin |49 extending through the opposed side portions of that member. The upper toggle link |39 is formed of a pair of opposed link members, one of which is disposed on either side of the single element portion of the lower toggle link |4| (see Fig. 1l). The upper end of the toggle link |39 is pivotally supported on a pin |5| which projects outwardly from the upstanding portion |53 of the frame |2|. A spacer |55 is provided for maintaining the proper separation of the parallel links which comprise the toggle link |39 at its upper end, in order to prevent binding of the mechanism. The motion of the upper toggle link |39 about its pivot point (the pin |5|) is dened by a pair of outwardly projecting pins |51 and |59 which securely engage the holes provided in the upper portion |53 of the operating mechanism frame |2|. The overcenter spring |43, which is used for moving the toggle links from one position to the other, is adapted to move as is shown particularly in Figs. 10 and 11 in the space to the right of the toggle links and their motion dening pins |51 and |59.

The U-shaped guide frame 3 is afxed, as is the mechanism frame |2|, to the base |0| by means of suitable screw fastenings |6|. The upstanding side portions |63 are each provided with a slotted opening 5 for engaging the rollers ||9, one of which is axed to either side of the channel shaped frame member |22 by the roller support pin |33. The outline of the slots ||5 is such that the rollers ||9 may move, during the normal operation of the breaker, in an arc having its center at the point |8| where the switch arm ||1 engages the trip latch or support member |01. A pin |61, adapted to extend between the upper end of the opposed side portions |63 of the guide frame |3, provides a support point for the spring |69 which normally biases the switch arm ||1 toward the open circuit position. The lower end of the spring |69 engages a similar pin |1| extending between the opposed side portions of the channel shaped frame |22 of the switch arm.

The electrical circuit through this embodiment of my invention dilers very little from the electrical circuit through the previously described embodiment. Beginning with the left-hand terminal strip |05, the current ows successively through the bent-over terminal portion |13 of the bimetallic support member |01, thence through the current carrying portion |15 of that member, the flexible shunt |11 which with its associated terminals |19 connects the current carrying portion of the bimetallic element with the switch arm ||1, through the switch arm |1 and the resilient support |21 to the movable contact |3|, and thence through the stationary contact to the other terminal strip |05.

This circuit breaker is shown in the open circuit position in Fig. '1. To close the contacts manually, the operating member |35 is moved in a clockwise direction about its pivot point (the pins |31). By virtue of this movement, the line of action of the overcenter operating spring |43 is moved from the position shown in Fig. 7 to a position to the right of the center line of the upper toggle link |39 (the line connecting the center of the knee pivot pin |45 and the toggle support pin |5|.) In this position, the operating spring |43 exerts a component of force tending to move the knee pivot pin of toggle linkage in the direction of the moving contact member |3|, and when the movement of the operating member has progressed a suiicient distance, the knee pivot pin |45 is set in motion. Any movement of this pin results in a progressive increase in the force tending to produce the movement, and as a result the toggle linkage moves with a snap action from the position shown in Fig. 7 to the position shown in Fig. 9. This movement is transmitted to the switch member |1 and that member rotates about its pivot point |8| (the point where the narrowed portion |23 engages opening |25 in the bimetallic support element) from the open-circuit to the closed-circuit position. During the movement, the spring |69 which tends to bias the switch member ||1 to the open circuit position is stressed. The large mechanical advantage of the toggle is such that this spring |69 is ineffective in preventing the closing of the breaker, and, when the breaker is in the closed-circuit position, the position of the switch member frame is denitely determined by a rigid toggle linkage, so that the contact pressure is not lessened by virtue of the biasing force of this spring, but is determined by the force exerted by the resilient support member |21 for the movable contact.

To open the contacts manually, the operating member |35 is moved in a counter-clockwise direction from the position shown in Fig. 9 toward the position shown in Fig. '1. By virtue of this movement, the line of action of the operating spring |43 is moved to the left of the center line of the upper toggle link |39 and as a result exerts a component tending to produce a collapse of the toggle. This collapse of the toggle is further aided by the force exerted by the biasing spring |69, and at a point some distance removed from the normal open circuit position, the toggle collapses and causes the switch arm ||1 to rotate about its pivot point |8| to the open circuit position. The movement of the operating member |35 in the counter-clockwise direction is limited by a portion of the pin |51 which projects outwardly from the upstanding portion |53 of the frame member |2|, and the movement of the operating member in the clockwise direction is limited by a portion |83 which projects outwardly from the frame itself.

When the breaker is in the closed-circuit position and an overload of suhcient magnitude and duration to cause the bimetallic support element |01 to disengage the end |23 of the switch member ||1 occurs, that member becomes essentially a floating lever which is subjected to the force of the biasing spring |69 and which is restrained from free movement by virtue of the position of the toggle links and the engagement of the rollers ||9 with the guide slots ||5. The immediate result of this disengaging is to permit the biasing spring |69 to move the switch arm from the position shown in Fig. 9 to the position shown in Fig. 8. This movement takes place with a snap action, due to the fact that there is no force impeding the movement of the switch member when it is disengaged by the bimetallic support member |01. The movement of the switch member ||1 is not a true rotation about the pivot pin |49, which connects the switch member with the toggle operating mechanism, but is a combination of a rotative and a sliding movement due to the action of the guide slots ||5. The center points and the links of the circuit interruptor are so positioned, however, that the center of the pivot pin |49 is moved only a very slight distance. This prevents the toggle links from being moved out of the overcenter position shown in Figs. 8 and 9 and thus renders the moving parts of the breaker stable. The motion of the switch member ||1 following the actuation of the thermally responsive support member |01 is limited by the engagement of the lower portion of the switch member frame |22 with the central portion |85 of the main operating frame, and the switch arm is rigidly held in the position shown in Fig. 8, due to the fact that the reaction forces of the biasing spring |69 are taken up by the toggle linkage.

Following the opening of the breaker as a result of an overload or abnormal circuit condition capable of producing actuation of the thermally responsive support element |01, it is necessary to restore the moving parts of the breaker to an operative position. This is done by moving the operating member |35 from the position shown in Fig. 8 to the position shown in Fig. 7. Movement in this direction causes the collapse of the toggle linkage from the overcenter position shown in Fig. 8, and as the toggle collapses, the switch member ||1 is moved from the tripped position (Fig. 8) to the normal open circuit, position (Fig. '7), the upward movement of the narrow portion |23 of the frame causing that portion to reengage the opening |25 in the thermally responsive support element which provides a pivot point for the switch arm. This movement of the operating member is all that is necessary to completely reset the breaker, and as soon as this movement has been effected and the narrowed portion of the switch arm ||1 has reengaged the thermally responsive support element, the breaker may be opened and closed manually exactly as described before.

When the breaker is in the closed circuit position, the line of action of the operating spring |43 is in such direction that the operating member |35 is biased to the position shown in Fig. 9, and when the circuit breaker is in the open circuit position, either as a result of the actuation of the trip device |01 or as a result of manual operation, the operating member |35 is biased to the position shown either in Fig. 8 or Fig. 7. rI'hus, the operating member |35 is at all times restrained against undesirable and unnecessary movement. If desired, a suitable indicating means may be provided for showing that the breaker has been opened as a result of the actuation of the trip device |01 and must be reset. Such arrangements are well known to the art, however, and hardly need a detailed description.

The above-described embodiment of my invention is thus seen to comprise a circuit breaker which is quick-make and quick-break, which is manually operable to either open or to close the circuit, and which is automatically operable upon the occurrence of an overload or other circuit disturbances to automatically open the circuit with a snap action of the contacts independently of the position of the operating member. Further, this embodiment of my invention is completely resettable following the automatic opening of the breaker, as a result of the actuation of the electro-responsive trip device, merely by moving the operating member to the opencircuit position. If desired, an arc extinguishing structure may be added to this circuit breaker in order to increase the arc rupturing capacity.

I have thus described two preferred embodiments of my improved circuit interrupter, both of which embody a new principle of circuit breaker design which permits of considerable simplication in the structures heretofore used for accomplishing the objects of my invention. Specifically, I have provided a circuit breaker utilizing a switch member, which is essentially a oating lever, normally biased to the open circuit position by means which is ineffective. except upon the occurrence of predetermined overload conditions, to cause the opening of the breaker.

In the simpler preferred embodiment of my breaker, I have shown how the conventional forms of circuit breakers can be simplified to a device which comprises merely a switch member (formbed of a single flat strip of conducting material), an overcenter spring, an operating 10 handle for moving the switch member to the open and to the closed circuit position, and a bimetallic supported trip element which is effective to cause opening of the breaker upon the occurrence of predetermined conditions.

In the second preferred embodiment of my invention, I have shown how an improved structure can be provided by utilizing a toggle operating mechanism for actuating the switch arm. Both of these structures, however, utilize a iioating switch arm, releasably supported at one end by a thermally responsive device, means, normally ineffective, for biasing the contacts open., and means which engages the switch member intermediate its ends for effecting normal operation thereof with a snap action to both open and closed positions.

In accordance with the patent statutes, I have disclosed the structural details and the mode of operation of certain preferred embodiments of my invention. The principles disclosed, however, are capable of much broader application, and it is my desire that the appended claims shall be given the broadest reasonable construction and shall be limited only by what is explicitly stated therein and by the prior art.

I claim as my invention:

l. In a circuit interrupter, a switch arm, actuating means for moving said switch armjothe open and to the closed-Circuit YPQSiiClIl Wtt snap action, and support means for releasably engaging one end of said"s`v1't`ch`arm;SaidsupW port means including a xedly mounted electroresponsive means operable upon the occurrence of predetermined conditions to cause said supt5- port means to disengage said switch arm.

2. In a circuit interrupter, a contact controlling arm having a pivot point about which it is normally movable, actuating means, including a handle member, for moving said contact controlling arm about said pivot point to the open and to the closed circuit position with a snap action, and support means for the pivot point on said contact controlling arm about which it is normally movable, said support means including a bimetallic member in latching engagement with said contact controlling arm and operable upon the occurrence of predetermined conditions to release and allow movement of said contact controlling arm, said actuating means being operable in response to movement of said handle member to cause said contact controlling arm to move into position to be retained by said support means following each operation of said electro-responsive means.

3. In a circuit interrupter, a contact, an operating arm therefor, support means normally providing a pivot point for said contact operating arm, and actuating means for moving said contact operating arm about said pivot point to open and to close said interrupter with a snap action, said support means including a thermally-responsive member of bimetallic material having a portion engaging said contact operating arm at said pivot point and being movable upon the occurrence of predetermined conditions to release said contact operating arm.

4. In a circuit interrupter, a contact controlling arm having at least one guide pin projecting therefrom, guide means for said guide pin, support means for normally retaining and providing a pivot point for one end of said contact controlling arm, and actuating means for moving said Contact controlling arm to the open circuit position and to the closed circuit position with a snap action, said support means including an electro-responsive means operable upon the occurrence of predetermined conditions tov cause said support means to allow movement of said contact controlling arm.

5. In a circuit interrupter, a switch arm having at least one guide pin projecting therefrom, a guide means for said guide pin, support means for retaining one point of said switch arm to provide a pivot point therefor, and actuating means for moving said switch arm to the open circuit position and to the closed circuit position about said pivot point with a snap action, said support means including a thermally responsive means, at least partially of bimetallic material, that is movable upon the occurrence of predetermined conditions to cause said support means to allow movement of said switch arm to open the circuit.

6. In a circuit interrupter, a switch arm movable to open and to close the circuit, latching means including a xedly mounted electro-responsive element, said latching means normally engaging and supporting one point on said switch arm, and actuating means for moving said switch arm to the open and to the closed-circuit position with a snap action, said electro-responsive element being operable upon the occurrence of predetermined conditions to cause said latching means to disengage and remove the support of said point on the switch arm, said actuating means including means for automatically moving said switch arm to the open circuit position following the removal of the support of said point on the switch arm by said latching means.

7. In a circuit interrupter, a contact controlling arm movable to open and to close the circuit, support means for engaging one point on said contact controlling arm, spring means for biasing said contact controlling arm to the open-circuit position, and actuating means for pivotally moving said Contact controlling arm to the open and to the closed-circuit position with a snap action about said point engaged by the support means, said support means including an electro-responsive element operable upon the occurrence of predetermined conditions to cause said support means to disengage said contact controlling arm, the disengagement of said contact controlling arm permitting said biasing spring to move said contact controlling arm to the open circuit position.

8. In a circuit interrupter, a switch arm, actuating means, including an operating handle, for moving said switch arm to the open and to the closed circuit position with a snap action, and support means for releasably engaging and thereby providing a pivot point for one end of said switch arm, said support means including an electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to disengage said switch arm, the disengaging of said switch arm by said support means causing means associated with said actuating means to automatically move said switch arm to the open-circuit position, independently of the position of said operating 2. In a circuit interrupter, a switch arm movlte open and to close the circuit, means for mormally xedly supporting one point on said switch arm, said supporting means including an electro-responsive element operable upon the occurrence of predetermined conditions to cause said supporting means to disengage and allow movement of said switch arm, and actuating means for said switch arm including an operating handle, an overcenter spring means operable in response to movement of said operating handle to move said switch arm to the open and to the closed circuit position with a snap action, and means for automatically moving said switch arm to the open-circuit position, independently of the position of said operating handle, following the release of said switch arm by said supporting means.

10. In a circuit interrupter, a contact operating ai'm, said contact operating arm being biased to the open circuit position, actuating means for moving said contact operating arm to the open and to the closed-circuit position with a snap action, and support means for releasably engaging and normally holding one end of said contact operating arm at a xed point, said actuating means being capable of retaining said contact operating arm in the closed circuit position against its bias only when said contact operating arm is engaged by said support means, said support means including electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to disengage said contact operating arm. l 1l. In a circuit interrupter, a switch arm, a spring for biasing said switch arm to the open circuit position, actuating means for moving said switch arm to the open and to the closed-circuit position with a snap action, and support means for releasably engaging one end of said switch arm to provide a pivot therefor, said actuating means being capable of restraining said switch arm in the closed circuit position against said biasing means only when said switch arm is engaged by said support means, said support means including thermally responsive means, at least partially of bimetallic material, movable upon the occurrence of predetermined conditions to cause said support means to disengage said switch arm, thereby permitting said biasing means to move said switch arm to the opencircuit position.

12. In a circuit interrupter, a contact moving member, actuating means, including a pair of toggle links, for moving said Contact moving member to the open and to the closed-circuit position with a snap action, and support means for releasably engaging one point on said contact moving member, said support means including an electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to allow movement of said contact moving member.

13. In a circuit interrupter, a switch arm, actuating means including an overcenter spring and a pair of toggle links pivoted at one end to said switch arm for moving said switch arm to the open and to the closed-circuit position with a snap action, and support means for releasably engaging one end of said switch arm to provide a pivot therefor, said support means including an electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to disengage said switch arm.

14. In a circuit interrupter, a contact controlling arm, actuating means, including an overcenter spring and a pair of toggle links, for moving said contact controlling arm to the open and to the closed-circuit position with a snap action, and support means at one point on said contact controlling arm to provide a pivot point therefor, said support means including a thermally responsive means, at least partially of bimetallic material, that is movable upon the occurrence of predetermined conditions to cause movement of said point.

l5. In a circuit interrupter, a switch arm having at least one guide pin projecting therefrom, guide means for said guide pin, support means for releasably engaging one end of said switch arm, and actuating means including an overcenter spring and a pair of toggle links for moving said switch arm to the open-circuit position and to the closed-circuit position with a snap action, said support means including an electroiesponsive means operable upon the occurrence of predetermined conditions to cause said support means to release said switch arm.

16. In a circuit interrupter, a switch arm movable to open and to close the circuit, means, including an electro-responsive element, for supporting one end of said switch arm, and actuating means, including an operating handle and a pair of toggle links, for moving said switch arm to the open and to the closed-circuit positions with a snap action, said electro-responsive element being 'operable upon the occurrence of predetermined conditions to cause said support means to disengage said switch arm, said actuating means including means for automatically moving said switch arm to the open circuit position, independently of the position of said operating handle, following the disengaging of said switch arm by said support means.

17. In a circuit interrupter, a switch arm movable to open and to close the circuit. actuating means, including an operating handle, a pair of toggle links, and a tension spring connected between said handle and the knee of said toggle links for moving said switch arm to the open and to the closed-circuit position with a snap action. and support means for one end of said switch arm, said support means including an electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to release said switch arm, the release of said switch arm by said support means causing means associated with said actuating means to automatically move said switch arm to the open-circuit position, independently of the position of said operating handle.

18. In a circuit interrupter, a switch arm movable to open and to close the circuit, support means for engaging one end of said switch arm, spring means for biasing said switch arm to the open-circuit position, and actuating means including a pair of toggle links and an overcenter spring for moving said switch arm to the open and to the closed-circuit position with a snap action, said support means including an electroresponsive element operable upon the occurrence of predetermined conditions to cause said support means to release said switch arm, the release of said switch arm causing said biasing spring to move said switch arm to the open-circuit position.

19. In a circuit interrupter, a switch arm, a spring for biasing said switch arm to the open circuit position, actuating means, including a pair of toggle links and an overcenter spring, for moving said switch arm to the open and to the closed circuit position with a snap action, and support means for releasably engaging and holding one end of said switch arm at a xed point, said actuating means being capable of retaining said switch arm in the closed circuit position against said biasing means only when said switch arm is engaged by said support means, said support means including electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to disengage said switch arm.

20. In a circuit interrupter, a switch arm, support means for said switch arm to provide a pivot point about which said switch arm normally rotates to open and to close the circuit, said switch arm having a second pivot point about which it may rotate to open the circuit, means biasing said switch arm about said second pivot point to the open-circuit position, and said switch arm being normally operable to rotate about said iirst pivot point to open and to close the circuit with a snap action, said support means including electroresponsive means operable upon the occurrence of predetermined conditions to cause said support means to release said switch arm, said switch arm, when released by said support means, being caused to rotate about said second pivot point by said biasing means to the open-circuit position.

21. In a circuit interrupter, a contact, pivoted actuating means for said contact including a switch arm carrying said contact, an operating handle, and an overcenter spring means operable in response to movement of said operating handle to move said contact to the open and to the closed circuit position with a snap action, and means for normally releasably engaging and supporting one point of said switch arm at a xed point, said supporting means being electro-responsively operable upon the occurrence of predetermined conditions to disengage said point and thereby initiate movement of said switch arm to move said contact to the open circuit position.

22. In a circuit interrupter, a contact, pivoted actuating means for said contact including a switch arm carrying said contact, an operating handle, and a spring, the line of action of which is movable across a pivot point of said actuating means in response to movement of said operating handle to cause said switch arm to move to the open and to the closed circuit position with a snap action, means for releasably supporting one point of said switch arm and providing a pivot point therefor, said supporting means being electroresponsively operable upon the occurrence of predetermined conditions to initiate movement of said switch arm to move said contact to the open circuit position, and said switch arm being movable independently of said supporting means to return to lthe position where it may be again supported by said supporting means.

23. In a circuit interrupter, a contact, pivoted actuating means for said contact including a switch arm carrying said contact, a spring normally biasing said switch arm to the open circuit position, an operating handle, and a second spring, the line of action of which is movable across a pivot point of said actuating means in response to movement of said operating handle to cause said switch arm to move to the open and to the closed circuit position with a snap action, and support; means for releasably engaging one point on said switch arm, the first said biasing spring being incapable of moving said switch arm to the open circuit position when said switch arm is engaged by said support means, and said support means being electro-responsively operable upon the occurrence of predetermined conditions to disengage said support means thereby allowing the first said biasing spring to move said arm to the open circuit position independently of the position of said operating handle.

24. In a circuit interrupter, a switch arm, support means for said switch arm to provide a pivot point therefor, and actuating means for moving said switch arm about said pivot point to open and to close said interrupter, said actuating means including an operating handle and an overcenter spring connected intermediate said operating handle and said switch arm, the line of action of said overcenter spring being movable across the pivot point of said switch arm in response to movement of said operating handle in order that said switch arm shall be moved to the open and to the closed circuit position with a snap action during the normal operation of said interrupter, said support means including an electro-responsive means operable upon the occurrence of predetermined conditions to cause said support means to disengage said switch arm.

25. In a circuit interrupter, a switch arm, support means for said switch arm to provide a pivot point therefor, and actuating means for moving said switch arm about said pivot point to open and to close said interrupter, said actuuating means including a spring which normally biases said switch arm to the open circuit position, an operating handle and an overcenter spring, intermediate said operating handle and said switch arm, the line of action of said overcenter spring being movable across the pivot point of said switch arm in response to movement of said operating handle in order that said switch arm shall be moved to the open and to the closed circuit position with a snap action during the normal operation of said interrupter, said biasing spring being incapable of moving said switch arm to the open circuit position when said switch arm is engaged by said support means, and said support means including an electroresponsive means operable upon the occurrence of predetermined conditions to disengage said support means thereby allowing said biasing spring to move said arm to the open circuit position independently of the position of said operating handle.

26. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm for moving said movable contact between open and closed positions, said operating arm having thermally responsive means engaging and holding one point thereon at a iixed position during normal opening and closing movement, a spring applying a biasing force to said operating arm for the movable contact when in the closed position, said spring then biasing said movable contact into engagement with the other contact and at the same time biasing said operating arm for the movable contact to be disengaged from said thermally responsive means and to cause movement of the movable contact toward open position when released by movement of said thermally responsive means.

27. In a circuit interrupter, a pair of contacts one of which is movable, a oating arm carrying said movable contact thereon and being movable between open and closed positions, thermally responsive latching means at one point on said floating arm carrying the movable contact, means movable to cause the normal movement of said floating arm carrying the movable contact between open and closed position while said latching means are engaged, said means for causing said normal movement including a handle member and a cooperating spring applying a biasing force to said floating arm carrying the movable Contact when in the closed position, said spring then biasing said movable contact into engagement with the other contact and at the same time biasing said floating arm carrying the movable contact to move the movable contact toward open position when said thermally responsive latching means is unlatched.

28. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm for moving said movable contact between open and closed positions, a bimetallic member mounted in a fixed position at one end and having a movable portion releasably engaging one end of said operating arm for the movable contact, a spring applying a biasing force to said operating arm for the movable contact when in the closed position, said spring then biasing said movable contact into engagement with the other contact and at the same time biasing said operating arm for the movable contact to be released from said bimetallic member and to move the movable contact toward open position.

29. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm for moving said movable contact between open and closed positions, said operating arm having current responsive means normally releasably engaging and retaining one point thereof at a fixed point serving as a pivot point about which said operating arm for the movable contact is normally rotatable, a spring applying a biasing force to said operating arm for the movable contact when in the closed position, said spring then biasing said movabie contact into engagement with the other Contact and at the same time biasing said pivot point on the operating armfor the movable contact to move upon release of said current responsive means and move the movable Contact toward open position.

30. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm connected at one end to said movable contact for moving it between open and closed positions, a current responsive member having a portion releasably engaging the other end of said operating arm for the movable contact, means movable to cause the normal movement of said movable contact between open and closed position including a handle member and a cooperating spring applying a biasing force to said operating arm intermediate its ends when in the closed position, said spring then biasing said movable contact into engagement with the other contact and at the same time biasing said operating arm to be released from said current responsive member and to move the movable contact toward open position.

31. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm for moving said movable contact between open and closed positions, said operating arm having means normally releasably retaining one point thereof at a fixed point serving as a pivot point about which said operating arm for the movable contact is normally rotatable to open and closed positions, said releasable retaining means including a pair of latch surfaces engageable and disengageable at said fixed point, means movable to cause the normal movement of said movable contact between open and closed position including a handle member and a cooperating spring applying a biasing force to said operating arm for the movable Contact when in the closed position, said spring then biasing said movable contact into engagement with the other Contact and at the same time biasing said point on the operating arm for the movable contact to move upon release of said retaining means and move the movable contact toward open position.

32. In a circuit interrupter, a base member, a pair of upstanding portions on said base member, a floating switch arm positioned between said upstanding portions and guided thereby, a fixed contact, a movable contact carried at one end of said floating switch arm, a bimetallic member mounted and connected in the electrical circuit through said contacts at one end, the other end portion of said bimetallic member being movable and normally releasably engaging the other end 0f said floating switch arm, a flexible shunt electrically connected at one end to the movable end portion of said bimetallic member and at the other end to said floating switch arm, means for normally operating said oating switch arm to carry said movable contact into and out of engagement with said xed contact, and said operating means including a handle member, the force exerted on which is transmitted to said oating switch arm at a point intermediate its ends.

33. In a circuit interrupter, a base member, a pair of upstanding portions on said base member, a floating switch arm positioned between said upstanding portions and guided thereby, a fixed contact, a movable contact carried at one end of said floating switch arm, a bimetallic member mounted and connected in the electrical circuit through said contacts at one end, the other end portion of said bimetallic member being movable and normally releasably engaging the other end of said floating switch arm, a flexible shunt electrically connected at one end to the movable end portion of said bimetallic member and at the other end to said floating switch arm, means for normally operating said floating switch arm to carry said movable contact into and out of engagement with fixed contact, and said operating means including a handle member and a spring the force exerted by which is applied to said floating switch arm intermediate its ends, said spring when said floating switch arm is in closed circuit position biasing said movable contact into engagement with said fixed contact and biasing said floating switch arm to move when released by said bimetallic member to carry the movable contact out of engagement with said xed contact.

34. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm for normally controlling movement of said movable contact between open and closed positions, said operating arm having means normally releasably retaining one point thereof at a fixed point serving as a pivot point about which said operating arm for the movable contact is normally rotatable to open and closed positions, said retaining means including a pair of latch surfaces engageable and disengageable at said pivot point, means movable to cause the normal movement of said movable contact between open and closed positions including a handle member and a cooperating spring applying a biasing force to said operating arm for the movable contact when in the closed position, said spring then biasing said movable contact into engagement with the other contact and at the same time biasing said point on the operating arm for the movable contact to move upon disengagement of the latch surfaces of said retaining means and move the movable contact toward open position, and said movable contact being movable to open position upon disengagement of the latch surfaces of said retaining means irrespective of the position in which said handle member may be held.

35. In a circuit interrupter, a pair of contacts one of which is movable, an operating arm for moving said movable contact between open and closed positions, said operating arm having means normally releasably engaging and retaining one point thereof at a iixed point serving as a pivot point about which said operating arm for the movable contact is normally rotatable to open and closed positions, means movable to cause the normal movement of said movable contact between `open and closed positions including a handle member and a cooperating spring applying a biasing force to said operating arm for the movable contact when in the closed position, said spring then biasing said movable contact into engagement with the other contact and at the same time biasing said point on the operating arm for the movable contact to be disengaged by said retaining means and move the movable contact toward open position, and said handle member being movable to return said point on the operating arm to the position where it is releasably engaged by said retaining means.

36. In a circuit breaker, a base member of insulating material, a floating switch arm, means for guiding said floating switch arm to move edgewise in a plane substantially perpendicular to the base and for substantially preventing said oating switch arm from moving endwise, a iixed contact, a movable contact carried at one end of said iloating switch arm, a terminal for the circuit breaker mounted on said base, a bimetallic member mounted at its upper end on said terminal member and electrically connected thereto, said bimetallic member extending downwardly toward the base and having its lower end in latching engagement with the end of said floating switch arm in said guide means to open and closed positions.

37. In a circuit breaker, a base member of insulating material, a floating switch arm, means on said base member for guiding said floating switch arm to move bodily in a lateral direction and for holding one point on said floating switch arm from moving in a direction longitudinally thereof, a iixed contact, a movable contact at one end of said switch arm for cooperating with said xed contact, a current-responsive element in latching engagement with the other end of said floating switch arm, a exible member for conducting the current from said current-responsive element to said movable contact, and a spring and an operating member connected to said floating switch arm intermediate its ends for moving it to open and closed positions.

38. In a circuit breaker, a base member of insulating material, a iioating switch arm, means on said base member for guiding said floating switch arm to move bodily in a lateral direction and for holding one point on said iioating switch arm from moving substantially in a direction longitudinally thereof, a fixed contact, a movable contact at one end of said switch arm for cooperating with said fixed contact, a current-responsive element in latching engagement with the other end of said oating switch arm, a flexible member for conducting the current from said current-responsive element to said movable contact, a spring and an operating member connected to said oating switch arm intermediate its ends for moving it to open and closed positions, said spring biasing said floating switch arm when in closed position to hold said moving contact in engagement with said fixed contact and at the same time biasing said floating switch arm to move out of engagement with said current-responsive element and to open the circuit.

39. In a toggle action thermostatic switch, an insulating support, a metal frame carried thereby and having a toggle action device, a freely pivoted catch carried by one part of the toggle action device, a thermostatic latch coacting with the catch, said thermostatic latch releasing said catch upon the occurrence of predetermined current conditions and thereby causing movement of the switch to open position, and a spring movable to carry its line of action across one pivot of the toggle action device to normally both open and close the switch with a snap action.

40. In a toggle action switch, a fixed contact, a movable contact, a spring switch arm for the movable Contact biasing it into engagement with the iixed contact when in closed circuit position, a toggle action device including a catch carried by one part of the device and coacting with the spring switch member when in closed position to normally prevent it from moving automatically to open position, a thermostatic latch coacting with said catch and being releasable therefrom to permit said spring switch arm to move automatically to open position upon the occurrence of a predetermined condition, a handle piece and a spring resiliently connecting said handle piece to said toggle action device for normally moving said spring switch arm to both open and close the circuit with a snap action.

41. In a thermostatic switch, a toggle action device including a plurality of pivoted links, a handle portion and a spring having its line of action movable across the pivot point of one of said links upon movement of the'handle portion for actuating at least one of said links to both open and closed positions with a snap action, a freely pivoted catch carried by one part of the toggle action device by being pivoted to said link movable with a snap action, a thermostatic latch coacting with the catch and holding one point thereof at a fixed point as it is normally moved by said link between open and closed positions, and a spring pressed switch member coacting with said catch and being movable to open circuit position upon release of said catch by said thermostatic switch.

42. In a toggle action switch, a spring switch arm, a toggle action device including a plurality of pivoted links, a handle portion, a spring having its line of action movable across the pivot point of one of said links upon movement of the handle portion for actuating at least one of said links to both open and closed positions with a Snap action, a catch pivoted to one 0f said links of the toggle action device and coacting with the spring switch arm so that when said catch is held in latched position said switch arm is prevented from automatically moving to the open circuit position and a resilient thermostatic latch coacting with said catch to normally hold it in latched position, said thermostatic latch releasing said catch upon the occurrence of a predetermined electrical condition in the circuit of the switch and causing said switch arm to move to open position irrespective of the position in which said handle portion may be held.

43. A snap switch including a stationary contact, a movable contact for coasting therewith and normally biased to the off position, operating mechanism coacting with the movable member and including a ilnger lever, an oscillating member movable upon movement of the finger lever, means pivotally carried by the oscillating member and free to move on occasion of an overload, a thermal element holding said means under normal circuit conditions and a throwing spring coacting with the oscillating member for actuating the same and the said means carried thereby so as to open and close the circuit with a snap action when said finger lever is manually operated and said movable contact being movable to open the circuit with a snap action when the thermal element releases said means.

44. In a snap switch, a stationary contact, a movable contact cooperating therewith and normally biased toward an off position, an oscillating member, a finger lever connected to the oscillating member by a throwing spring interposed between said finger lever and said oscillating member, a latching member mounted on said oscillating member and coacting with the movable switch element to operate the same when the linger lever is manually operated to open and close the circuit, and a thermally actuated member holding said latching member under normal load circuit conditions and adapted to release said latching member on an overload condition, said movable contact moving to off position when the thermally actuated element releases the latching member and said spring actuating the oscillating member when the nger lever starts the oscillating member.

45. A circuit breaker comprising a floatingr switch member, toggle means including a plurality of pivotally connected toggle links, means pivotally supporting said switch member intermediate its ends on one of said toggle links, means biasing said switch member for rotation about said pivot means, a bi-metallic thermal element having a latching portion normally engaging one end of said switch member to restrain said member against rotation about said pivot means, and overcenter spring means for operating said toggle means to move said pivot means, whereby said switch member is pivotally moved about said one end between open and closed circuit positions with a snap action, said thermal element being arranged to release said one end of said switch member upon the occurrence of predetermined current conditions whereupon said switch member rotates about said pivot means to an open circuit position independently of said toggle means.

46. A circuit breaker comprising a floating switch member, movable pivot means for said member, current-responsive latch means normally engaging said switch member, a pair of links, a movable pivot connection joining said links to form a toggle, a connection between one end of said toggle and said pivot means, spring means for operating said toggle with a snap action to thereby move said pivot means between two positions with -a snap action whereby said switch member is pivotally moved about said latch means between open and closed circuit positions, and means biasing said switch member for rotation about said pivot means to an opencircuit position upon release of said latch means in response to predetermined current conditions.

47. A circuit breaker comprising a floating switch member, movable pivot means for supporting said member intermediate its ends, current-responsive latch means normally engaging one end of said switch member, a pair of links, a movable pivot connection joining said links to form a toggle, a connection between one end of said toggle and said pivot means, spring means for operating said toggle with a snap action to thereby move said pivot means between two positions with a snap action whereby said switch member is pivotally moved about said one end between open and closed circuit positions, and means biasing said switch member for rotation about said pivot means to an open-circuit position upon release of said latch means in res'bonse to predetermined current conditions. 48. A circuit breaker comprising a floating l, switch member, movable pivot means for said 22",! member, a bimetallic thermal element having a latching portion abuttingly engaging said switch member remote from said pivot means, a pair of links, a movable pivot connection joining said links to form a toggle, a connection between one end of said toggle and said pivot means, spring means operating said toggle with a snap action for operating said pivot means between two positions whereby said switch member is pivoted about said latching portion of said thermal element between open and closed circuit positions, and means biasing said switch member for rotation about said pivot means to an open-circuit position, said thermal element upon lthe occurrence of predetermined current conditions releasing said switch member for movement about said pivot means.

49. A circuit breaker comprising a frame, a iloating switch member having a pivot pin inter'- mediate its ends, guide means on said frame for i guiding said switch member, means biasing said switch member for rotation about said pivot pin, thermal means for releasably latching said switch member against rotation about said pivot pin, toggle means including a pair of links pivotally connected together and movable with relation to each other to move said pivot pin and to move said switch member along said guide means to operate said switch member between open and closed circuit positions independently of said thermal means, and spring means for operating said toggle means with a snap action to snap said switch member from each position to the other, said thermal means being arranged to release said switch member in response to predetermined current conditions, whereupon said switch member rota-tes about said pivot pin to an open circuit position independently of said toggle means.

50. A circuit breaker comprising a U-shaped frame having guide slots in the opposite legs thereof, a switch member nesting between said frame legs and having a pivot pin extending into said guide slots, said pivot pin being intermediate the ends of said switch member, toggle means for moving said pin along said slot including a ilrst link pivoted on said frame and a second link connected to said first link and to said switch member, a pivoted operating lever, overcenter spring means connected between said operating lever and said first toggle link for operating said Cil toggle to move said pivot pin along said slot in response to movement of said operating lever, thermal means normally restraining one end of said switch member against movement whereby the other end of said switch member is operated between open and closed circuit positions as said pivot pin moves along said slot, and biasing means for operating said switch member to an opencircuit position independently of said operating lever when said one end of said switch member is] released by said thermal means.

51. A circuit breaker comprising a floating switch member, means pivotally supporting said switch member intermediate its ends, said pivot means being mounted for limited movement in a direction substantially at right angles to said switch member so as to provide for movement of said switch member between open and closed circuit positions, means biasing said switch member for rotation about said pivot means, current responsive latch means normally engaging one end of said switch member to secure said switch member against rotation about said pivot means, and overcenter spring operating means connected to said switch member for operating said switch member with a snap action about said one end between its open and closed circuit positions, said current responsive latch means being arranged to release said one end of said switch member upon the occurrence of predetermined current conditions whereupon said switch member is rotated by said biasing means about said pivot means to an open circuit position.

52. A circuit breaker comprising a current carrying switch member, pivot means supporting said switch member intermediate its ends, a switch contact carried by one end of said switch member, means biasing said switch member for rotation about said pivot means to an open circuit position, a bimetallic thermal current rev sponsive element having a latching portion normally engaging the other end of said switch member to restrain said member against rotation about said pivot means to said open circuit position, a guide providing for limited movement of said switch member about said other end as a pivot between open and closed circuit positions, and overcenter spring operating means connected to said switch member for operating said switch member with a snap action between said open and closed circuit positions.

53. In an automatic electric circuit breakery a stationary contact, a switching member having a pivot interjacent its ends and carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means for the opposite end of said member, a manual operator, and overcenter spring means for moving said pivot in response to movement of said operator, said member rotating about said pivot when released by said latching means, and said pivot remaining substantially stationary when said member is released.

54. In an automatic electric circuit breaker, a stationary contact, a switching member having a pivot interjacent its ends and carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means adjacent the opposite end of said member, a pivoted manual operator for said switching member, and overcenter spring means having its line of action movable across the pivot of said operator in response to movement of said operator for alternately biasing said operator to move member rotating about its pivot and carrying its contact surface to ofP' position when released by said latching means, and said pivot of the switching member remaining substantially stationary when said switching member is released.

55. In a circuit breaker, a pair of contacts, one of which is movable, an elongated operating arm for moving said movable contact to and from open and closed positions, said operating arm having thermally responsive means normally engaging one end of the arm and holding said end of the arm in iixed position, said thermally responsive means disengaging said end of the arm upon the occurrence of a predetermined condition, a handle for normally controlling movement of the operating arm about its normally held end as a pivot, a spring arranged to cooperate with the arm for moving it with a snap movement when the arm is moved by the handle, said spring constantly applying a biasing force to said arm when the latter is in the closed position and operating, when the arm is held normally, to bias said movable contact towards and into pressure engagement with the other contact and at the same time biasing said arm towards an open circuit position to cause movement of the movable contact towards open position if and when the arm is released by release movement of said thermally `.responsive means.

for moving said movable contact to and from toward on and ofP' positions, said switching 75 applying a biasing force to s a id arm. when the latter is in the closed positoriand operffIlE,""`'I when the arm is held normallygtobias,saidmove able Contact towards and into pressure engagement with the other contact and at the same time biasing said arm towards an open'circuit position to cause movement of the movable contact towards open position if and when the arm is released by release movement of said thermally responsive means, the arm be i n ga.rlan2edt0. move other than by rotation about itsnormally. held point in the event of a releasaenthereof by the thermally responsive means. N' wmmw" 57. In an automatic electric circuit breaker, a stationary contact, a switching member carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means for the opposite end of said member, means pivotally mounted on a xed part and having a pivotal connection with said member, a manual operator, and spring means interconnecting said operator and member, said spring means moving said member to both open and closed positions in response to movement of said operator.

58. In an automatic electric circuit breaker, a stationary contact, a switching member carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means for the opposite end of said member, link means pivotally mounted on a xed .part and having a pivotal connection with said LIQ 1s moved by the handle, f'said sprcms member, a manual operator, and spring means interconnecting said operator and member, said spring moving said link means about its pivotal mounting in response to movement of said operator to move said member.

59. In an automatic electric circuit breaker, a stationary contact, a switching member carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means for the opposite end of said member, means connected at one point to said member to limit movement of said point to pivotal movement about a fixed point, a manual operator, and spring means interconnecting said operator and member, said spring moving said point on said member about said Xed point in response to movement of said operator to move said member, said member moving to open position under the bias of said spring when released by said current responsive latching means.

60. In an automatic electric circuit breaker, a stationary contact, a switching member carrying a contact surface at one end cooperating with said stationary contact, current responsive latching means for the opposite end of said member, means connected at one point to said member to limit movement of said point to pivotal movement about a xed point, a manual operator, and spring means interconnecting said operator and member, said member moving to open position under the bias of said spring when released by said current responsive latching means, and said operator being operable to move said member into relatched engagement after such release.

6l. In an automatic electric circuit breaker, a stationary contact, a pivoted support, a switching member pivoted to said support and carrying a contact surface at one end adapted to cooperate with said stationary contact, current responsive latching means for the opposite end of said member, a manual operator, spring means connected at one end to said operator and connected at its other end to actuate said member, said spring means moving said support about its pivot to move said member to contacts engaged and disengaged position in response to movement of said operator.

62. In an automatic electric circuit breaker, a stationary contact, a pivoted support, a switching member pivoted to said support and carrying a contact surface at one end adapted to cooperate with said stationary contact, current responsive latching means for the opposite end of said member, a manual operator, spring means connected at one end to said operator and connected at its other end to actuate said member, said spring means moving said support about its pivot to move said member to contacts engaged and disengaged position in response to movement of said operator, said member pivoting about its engagement with said support when released by said latching means to move said contact surface to disengaged position.

63. In an automatic electric circuit breaker, a stationary contact, a pivoted support, a switching member pivoted to said support and carrying a contact surface at one end adapted to cooperate with said stationary contact, current responsive latching means for the opposite end of said member, a manual operator, spring means connected at one end to said operator and connected at its other end to actuate said member, said spring means moving said support about its pivot to move said member to contacts engaged and disengaged position in response to movement of said operator, said member pivoting about its engagement with said support when released by said latching means to move said contact surface to disengaged position, and said operator being operable to move said member into relatched position after such release.

64. In an automatic electric circuit breaker, a switching member carrying a contact surface at one point and a latching surface at another point, a stationary contact in position to be engaged by said contact surface, current responsive latching means engaging said latching surface, a supporting means pivoted on a Xed part and having a pivotal engagement with said member, a manual operator, and over-center spring means for moving said supporting means about its pivot in response to movement of said operator to move said member to circuit closed and circuit open positions, said member being biased for rotation about its pivotal engagement with said supporting means when in the circuit closed position and being restrained from such rotation by said latching means.

65. In an automatic electric circuit breaker, a pivotally mounted support, a switching member pivoted on said support and carrying a contact surface on one side of its pivot and a latching surface at the opposite side, a stationary contact in position to be engaged by said contact surface, a second latching surface cooperating with the first said latching surface and one of said latching surfaces being disengageable from the other in. response to a predetermined current, a manual operator, and means for quickly moving said support about its pivotal mounting in response to movement of said operator to move the switching member to circuit closed and circuit open positions, said member being biased for rotation about its pivot when in circuit closed position and being restrained from such rotation by the engagement of said latching surfaces.

66. In an automatic electric circuit breaker, supporting means pivotally mounted on a fixed part, a switching member pivotally mounted on said supporting means, spring means connected to said member and biasing said member for rotation about its pivotal mounting, a stationary contact, a contact surface adjacent one end of said member cooperating with said contact, current responsive latching means for the opposite end of said member, a manual operator, and spring means interconnecting said operator and said supporting means for moving said supporting means about its pivotal mounting in response to movement of said operator.

67. In an automatic electric circuit breaker, a plvotally mounted support, a switching member pivotally mounted on said support, a stationary contact, a contact surface adjacent to one end of said member cooperating with said contact, current responsive latching means engageable and disengageable at the opposite end of said member, means biasing said member for rotation about its pivotal mounting on said support when released by said latching means, a manual operator, and means for moving said support about its pivotal mounting in response to movement of said operator.

68. In an automatic electric circuit breaker, a pivotally mounted support, a switching member pivotally mounted on said support, a stationary contact, a contact surface adjacent to one end of said member cooperating with said contact, current responsive latching means for the opposite end of said member, means biasing said member for rotation about said support when released by said latching means, a manual operator, and an overcenter spring interconnecting said operator and support for moving said support with a snap action in response to movement of said operator.

69. In an automatic electric circuit breaker, a stationary contact, a iloating switching member carrying a contact surface adjacent to one end cooperating with said stationary contact, latching means for the opposite end of said member, a movable pivot for said member intermediate its ends, a manual operator, over-center spring means for moving said pivot in response to movement of said operator to move said contact surface to a disengaged position, and a current responsive means for moving said latching means to releasing position, said member rotating about said pivot when released by said latching means to move said contact surface to automatically disengaged position.

70. In an automatic electric circuit breaker, a stationary contact, a floating switching member carrying a contact surface adjacent to one end cooperating with said stationary contact, latching means for the opposite end of said member, a movable pivot for said member intermediate its ends, a movable operator, over-center spring means for moving said pivot in response to movement of said operator to move said contact surface to a disengaged position, a current responsive means for moving said latching means to releasing position, said member rotating about said pivot when released by said latching means to move said contact surface to automatically disengaged position, and means for moving said member into reset position in response to movement of said operator after an automatic operation.

71. In an automatic electric circuit breaker, a stationary contact, a iioating switching member carrying a contact surface adjacent to one end cooperating with said stationary contact, latching means for the opposite end of said member, a movable pivot for said member intermediate its ends, a manual operator, over-center spring means for moving said pivot in response to movement of said operator to move said contact surface to a disengaged position, means biasing said member for rotation about said pivot and a current responsive means for moving said latching means to releasing position to permit such rotation in response to a current overload through the breaker.

'72. In an electric switch, a movable contact member, two opposed displaced fulcrums, an actuator for said contact member disposed between said fulcrums and normally bearing and fulcruming on one fulcrum, and means for withdrawing said one fulcrum to effect the fulcruming of the actuator on the other fulcrum.

73. In an electric switch, two opposed displaced fulcrums, an actuator between said fulcrums, spring means exerting pressure on said actuator on the same side of both fulcrums arranged to press said actuator in one direction against one fulcrum and in the opposite direction against the other fulcrum, a contact member operated by said actuator, and means for withdrawing one fulcrum from operative relation with the actuator to eiect the turning of the actuator about the other fulcrum.

74. In an electric switch, a movable contact member, two opposed displaced fulcrums. an

actuator for said contact member disposed between said fulcrums and normally bearing and fulcruming on one fulcrum, a pivoted operating member for normally moving said actuator about said one fulcrum by moving the other fulcrum, an overcenter spring acting on said pivoted operating member and having its effective line of action movable across the pivot of the operating member, and means for withdrawing said one fulcrum to effect the fulcruming of the actuator on the other fulcrum.

75. In an electric switch, two opposed displaced fulcrums, an actuator between said fulcrums, spring means exerting pressure on said actuator on the same side of both fulcrums arranged to press said actuator in one direction against one fulcrum and in the opposite direction against the other fulcrum, a contact member operated by said actuator, a pivoted operating member for normally moving said actuator about said one fulcrum by moving the other fulcrum and said spring means also exerting pressure to alternately bias said operating member to move in opposite directions about its pivot, and means for withdrawing said one fulcrum from operative relation with the actuator to effect the turning of the actuator about the other fulcrum.

76. In a circuit interrupter, a pair of contacts one of which is movable, a switch arm carrying said movable contact thereon, a pivot axis about which said switch arm is normally movable between open and closed positions, a bimetallic latch member acting directly on one point of said switch arm, means movable to cause said normal movement of said switch arm between open and closed position including a handle member and a cooperating spring applying a biasing force to said switch arm, said spring applying a force to said switch arm when in closed position which biases it to move about said pivot axis toward closed position and supplies contact pressure between said contacts and which at the same time biases said switch arm to move to open position upon release of said bimetallic latch member, and said spring applying a force to said switch arm when in the normal open position which tends to move it about said pivot axis toward open position.

'77. In a circuit interrupter, separable contact means, a floating current conducting switch arm movable to actuate said contact means to open and to closed positions, a pivot axis, a bimetallic latching member directly associated with said floating switch arm, said latching member when in normal latching position limiting the movement of said floating switch arm to rotation about said pivot axis and when released permitting movement of the oating switch arm without being limited to rotation about said pivot axis, an operating member normally movable to cause rotation of said floating switch arm about said pivot axis between open and closed positions, an overcenter spring connected at one end directly to said floating switch arm and applying a force thereto which changes in direction during rotation of the oating switch arm about said pivot axis upon movement of said operating member so as to alternately bias the floating switch arm to rotate about said pivot axis to open and to closed positions, said overcenter spring applying a force to said floating switch arm which biases it when in closed position to move to open position upon release of said latching member, and said latching member being automatically releasable upon the occurrence of a predetermined condition and causing movement of the floating switch arm to open position irrespective of the position of said operating member.

78. In a circuit interrupter, a pair of separable contacts; operating means having only two main movable operating members, biasing means and a current responsive bimetallic element, for normally opening and closing said contacts and for opening said contacts upon the occurrence of an overload; one of said two main movable operating members being a handle member and the other being a floating arm carrying one of said contacts; said biasingr means including a spring connected at one end to said floating arm and movable during normal opening and closing of said contacts by said handle member to alter.- nately bias both said handle member and said floating arm to open and closed positions, and said spring when in closed position acting upon movement of said bimetallic element to bias and move said floating arm to open position irrespective of the position of said handle member.

79. In a circuit interrupter, a pair of separable butt contacts, one of said contacts being rigidly mounted in fixed position and the other being movable to open and close the circuit; operating means having only two main movable operating members, biasing means and a bimetallic element, for normally opening and closing said contacts and for opening said contacts upon the occurrence of an overload; one of said two main movable operating members being a handle member and the other being a rigid floating switch arm electrically connected in the circuit and having said movable contact rigidly mounted thereon; said biasing means including a spring connected at one end directly to said floating switch arm, said spring acting when the circuit interrupter is in open position to bias said handle member and said floating switch arm toward open position and acting when the circuit interrupter is in closed position to bias said handle member toward closed position and to bias said oating switch arm toward closed position and supply contact pressure between said rigidly mounted butt contacts, and said spring also acting when the circuit interrupter is in closed position to bias said oating switch arm to move to open circuit position irrespective of the position of said handle member in response to a predetermined movement of said bimetallic element.

80. In a circuit interrupter; a pair of separable contacts; operating means having only two main movable operating members, biasing means and a current responsive bimetallic latching element, for normally opening and closing said contacts while said bimetallic element is in latching position and for opening said contacts upon the occurrence of an overload; one of said two main movable operating members being a handle member and the other being a floating arm carrying one of said contacts; said biasing means including a spring connected at one end to said floating arm and movable during normal opening and closing of said contacts by said handle member to alternately bias both said handle member and said floating arm to open and closed positions, and said spring when in closed position acting upon unlatching movement of said bimetallic element to bias and move said floating arm to open position irrespective of the position of said handle member; and said handle member being movable to cause relatching of said bimetallic element by moving one point on the oating arm while another point thereon bears on a stationary part of the circuit interrupter.

81. A circuit breaker comprising a support having a pair of extensions provided with oppositely disposed concentric grooves, switching means including a switch member movable on said support, transversely extending guide members on said switch member slidable in said grooves, means for actuating said switch member from an open to a closed circuit position, current responsive means releasably securing an end of said switch member, and a spring for biasing said switch member to an open circuit position about a portion of said current responsive means as a fulcrum, a portion of said grooves being formed on a curve having the fulcrum on said current responsive device as a center for preventing longitudinal movement of said switch member when turning about said fulcrum.

82. In a circuit interrupter, a base, a pair of contacts, one of said contacts being rigidly mounted on said base and the other being movable to engage and disengage the rigidly mounted contact, an operating arm for controlling movement of said movable contact, current responsive means normally having latching engagement with said operating arm and providing a fulcrum about which it may pivot, a groove substantially concentric with said fulcrum for guiding and preventing substantially any longitudinal movement of said operating arm when pivoting about said fulcrum, a handle movable between "on and off positions to cause pivotal movement of said operating arm about said fulcrum, a spring acting when the contacts are engaged to bias the moveable contact into pressure engagement with the rigidly mounted contact and acting at the same time to bias said operating arm to move and cause disengagement of said contacts upon unlatching of said fulcrum by said current responsive means due to the occurrence of an abnormal current-l condition, and said spring acting after disengagement of said contacts due to unlatching of said fulcrum to bias said handle to a position away from off position and tobias said operating arm to its unlatched position until said handle is manually moved to off position and said operating arm is returned to latched position, and said spring then biasing said handle to off position until said handle is manually moved toward on position.

83. In a circuit interrupter, a base, a pair of contacts, one of said contacts being mounted on said base and the other being movable to engage and disengage said contact on the base, a unitary operating arm having all parts thereof movable together at all times for controlling movement of said movable contact, current responsive means normally having latching engagement with said operating arm and providing a fulcrum at the point of said latching engagement about which the operating arm may pivot, a handle movable between on and off positions to cause pivotal movement of said operating arm about said fulcrum, a spring acting when the contacts are engaged to bias the movable contact into pressure engagement with the contact on the base and acting at the same time to bias said operating arm to move and cause disengagement of said contacts upon unlatching of said fulcrum by said current responsive means due to the occurrence of an abnormal current condition irrespective of the position in which said handle may be held, and said spring after disengagement of said contacts due to unlatching of said fulcrum acting to maintain said operating arm in its unlatched position unti1 said handle is manually moved to off position for returning said operating arm to latched position.

84. In a circuit interrupter, a base, a pair of butt contacts, one of said contacts being rigidly mounted and the other being movable to engage and disengage said rigidly mounted contact, a unitary operating arm having all parts thereof movable together at all times for controlling movement of said movable contact, bimetallic means normally having latching engagement with said operating arm and providing a fulcrum at the point of said latching engagement about which the operating arm may pivot, guide means for the operating arm comprising a slot and pin with the slot substantially concentric With said fulcrum, a handle movable between ony and off positions to cause pivotal movement of said operating arm about said fulcrum, a spring acting when the contacts are engaged to bias the movable contact into pressure butt engagement with the rigidly mounted contact and acting at the same time to bias said operating arm to move and cause disengagement of said contacts upon release of said fulcrum by said bimetallic means, said disengagement of the contacts due to release by said bimetallic means taking place independently of said handle, and said spring after disengagement of the contacts due to release by said bimetallic means acting to maintain said operating arm in released position and to maintain said handle in a position away from off position until said handle is manually moved to off position for returning said operating arm to its normal latched position and said spring then biasing said handle to off" position until said handle is manually moved toward on position.

RALPH H. SWINGLE.