US2977442A - Circuit breaker having transversely movable operating elements - Google Patents

Description

March 28, 1961 w. H. MIDDENDORF 2,977,442

CIRCUIT BREAKER HAVING TRANSVERSELY MOVABLE OPERATING ELEMENTS Filed July 30, 1958 3 Sheets-Sheet 1 A TTOENEY5.

CIRCUIT BR'EA H. MIDDENDORF KER HAVING TRANSVERSELY MOVABLE OPERATING ELEMENTS Filed July 30, 1958 e5 74 27 G8 70 In 4i 25 5G, I l g ZG II III! n l 4 11.! II II II II 3 Sheets-Sheet 2 ZMZMX J [I I7 32 O 26 :4 as

IN VENTOR.

HTTOENE Y 5.

l E F :::::::I MM 35 m h d 140 I March 28, 1961 H. MIDDENDORF 2,977,442

CIRCUIT BREAKER HAVING TRANSVERSELY MOVABLE OPERATING ELEMENTS Filed July :50. 1 8

3 Sheets-Sheet 3 H 154 I I 150 l l7 HIJVENTOR. I

ATTOMEY i d a s Paw) CIRCUIT BREAKER HAVING TRANSVERSELY MOVABLE OPERATING ELEMENTS William H. Middendorf, Covington, Ky., assignor to The Wadsworth Electric Manufacturing Company, Inc., Covington, Ky., a corporation of Kentucky Filed July 30, 1958, Ser. No. 752,034

17 Claims. (Cl. 200-'-116) This invention relates to circuit breakers and more particularly to a circuit breaker having operating elements positioned and operated in such a manner as to provide an optimum ratio of base length to base width for any prescribed breaker base area.

In the design of a combination of a group of circuit breakers within a single enclosure it can be demonstrated that to conserve on the dimensions of the enclosure while complying with the Underwriters standards that there is an optimum ratio of breaker base length to base width for any prescribed base area. For breakers having the characteristics of quick make and break, the optimum length/width ratio is less than that found in circuit breakers presently in use. In order to design a breaker having the desired reduced ratio while maintaining the essential features of quick make and break, the applicant has disposed the principal breaker operating elements, that is, a contact carrying bar and a reset bar, normal to the base of the breaker and the operating handle at the top of the breaker. The operating handle has been provided with cam surfaces cooperating with the top portions of the contact bar and reset bar in order to manipulate the contact bar and reset bar in a plane transverse to the plane of the circuit breaker thereby permitting a quick make and break operation. The present invention is predicated upon the concept of disposing the reset bar and contact bar normal to the base rather than parallel thereto. This concept enables substantial reduction of base length since need for the extra space normally occupied by bars arranged parallel to the base is completely eliminated.

More specifically, the circuit breaker of the present invention comprises a contact bar carrying a contact engageable with a fixed contact and centrally pivotally mounted, a reset bar centrally pivotally mounted in spaced generally parallel relation to said contact bar, and springs joining the opposing end portions of the said bars to form a quadrangular linkage system therewith. This system has a position of equilibrium in which the contacts are open, but is dynamically unbalanced when the contacts are closed. An operating handle cooperates with adjacent ends of said bars to pivot them in the plane of the breaker and transverse to the plane of the breaker in order to move the breaker elements to their operational positions. Current responsive latch means associated with the reset bar controls the circuit interrupting function of the breaker.

It has been a further objective of the invention to pro vide a quick make and break type circuit breaker having a contact bar and a reset bar disposed normal to the breaker base and an operating handle with cams in engagement with the contact bar and reset bar, the cams pivoting the bars in the plane of the circuit breaker and transversely to the plane of the circuit breaker to shift the elements to their operating positions.

Another objective of the invention has been to provide a circuit breaker as described in the preceding paragraph in which a cam surface on the operating handle ing the elements in manual off position.

pivots the contact bar transversely upon movement of the operating handle to open the contacts so that the movable contact will wipe the fixed contact preliminary to opening, thereby freeing the contacts from any bond which might normally impede their opening.

It has been another objective of the invention to provide a circuit breaker as described above in which the spring joining the contact bar and reset bar adjacent said operating handle is strained during the first portion of the movement of the operating handle toward makeposition while the contact bar is restrained from moving; and after latching is effected, the contact bar is released whereby the spring snaps the contact bar into make" position.

It has been another objective of the invention to provide a circuit breaker as described above in which the contact bar is snapped to break" or open position by the combined action of the two springs acting upon the quadrangular linkage system as the springs return the system to an equilibrium position.

It has been another objective of the invention to prm vide a circuit breaker having a high load interrupting capacity while at the same time providing an optimum ratio of base length to base width and a minimum base area. This objective is accomplished by providing a reset bar and contact bar generally normal to the base of the circuit breaker and providing an operating handle with cam surfaces engageable with the extremity of the bars remote from the base to pivot the bars in the plane of the circuit breaker and transversely to the plane of the circuit breaker to effect quick make and break.

-It has been another objective of the invention to pro-, vide a circuit breaker as described above in which a 0111', rent responsive latch element cooperates with a latch surface on the reset bar, the breaker being tripped by movement of the current responsive element in the plane of the circuit breaker; and the circuit breaker being manually tripped by transverse pivotal movement of the reset bar.

It has been another objective of the invention to pro vide a circuit breaker as described above in which the condition of the circuit breaker is indicated by the position of the operating handle which is absolutely controlled by the position of either the contact bar or the reset bar.

It has been another objective of the invention to provide a circuit breaker as described above in which the reset bar which carries a latch surface is spring biased transversely at its pivot point, the latch surface and the current responsive latch element being designed to latch irrespective of the eltect of the transverse spring on the position of the reset bar.

It has been still another objective of the invention to provide a circuit breaker having a contact bar which is mounted for pivotal movement in the plane of the circuit breaker and transversely to the plane of the circuit breaker, the contact bar carrying a current responsive latching element and, the contact bar having a double bearing design which stabilizes the contact bar against pivoting in a third plane which would tend to bring the latch element out of alignment.

These and other objectives of the invention will become more readily apparent from the following detailed description taken in conjunction with the drawings in which:

Fig. l is a sectional view of a circuit breaker, showing the elements in make position, constructed in accordance with the invention.

Fig. 2 is a cross-sectional view taken along lines 22 of Fig. 1.

Fig. 3 is a cross-sectional view similar to Fig. 1 showismssa .,Eig..4 is afragmentary view showing the engagement of the operating handle with the reset bar.

Fig. is a fragmentary view showing the engagement of'the operating handle'with the contact bar. I I

5 Fig. 6 is a cross sectional view similar to Fig. 1 showing: the elements in tripped position. 7

Fig. 7, is a cross-sectional view similar to Fig. 1 showing the elements in resetting position.

Fig. 8;is a cross-sectional view taken along lines 8-8 of'Fig. 1.

Fig. 9 is a cross-sectional view taken along lines 9-9 showing a double pole common trip design for the breaker ofFig; 1. 7 Fig. 10 is a fragmentary view of an ambient temperaturecomp'ensator.

Fig. 11' is 'a fragmentary view of the latch elements.

Fig. 12 is a cross-sectional view of an alternative form ofthe invention showing the contacts in make position. Fig. 13 is a cross-sectional view similar to Fig. 12 showing the elements in their tripped position.

Fig. 14 is a cross-sectional view similar to Fig. 12 showing the elements in a resetting position.

Fig. 15 is a cross-sectional view taken along lines 15-15 of Fig. 12.

Fig. 16 'is a cross-sectional view taken along lines 16-16 of Fig. 12.

Fig. 17' is a cross-sectional view. taken along lines 17--17 of Fig. 12, and

Fig. 18 is a cross-sectional view taken along lines 18-18 of Fig. 12. The elements of the circuit breaker as shown in Fig. 1 are disposed in a casing 20 having side walls 21 and 22, a base-or bottom wall 23, end walls 24 and 25, and a top wall 26. The end wall 24 is recessed at 27 to receive a solderless terminal connector 28. End wall has a pair ofterminal jaws 30 for embracing a bus bar blade to provide the other terminal connection.

The top wall 26 has an opening 31 through which projects an operating handle 32 pivotally mounted as at 33 at the side walls 21 and 22. A contact bar 34 is pivoted on a pin 35 and carries at its lower end a movable contact 36 engageable with a fixed contact 37 com nected by a strap 38 to the terminal jaws 30. A bimetallic element 40 is fixed at its lower end 41 to the contact bar 34 and, at its free upper end 42, is connected by a pigtail 43 to a strap 44 forming a part of the solderless terminal connector 28. The free upper end 42 of the hi metallic element 40 carriesa latch element 45 by means of a support 46. The support 46 may be of ferroinagnetic material to form a part of a magnetic circuit of the type disclosed Patent'No. 2,716,679.. Thus the latch element 45 may be moved in response either to an overload current passing through the bimetallic element 40 or through electro magnetic means operating on the support 46.

i The movement ofthe contact bar 34 is controlled in part by the combination of a reset bar 50 connected at its lower end by a tension spring 51 and at the upper end by a tension spring 52 to the lower and upper ends respec- :tively of the contact bar 34; and a latch 53 having a latching surface 54 engageable with a latch element 45. The resetbar 50 is pivoted to the casing 20 bya pin 47 and is urged in a sidewise direction by a compression spring'55 Figs. 1 and 8) in order to move the reset bar and its associated latch surface 54 into latching position.

' The bimetallic element 40 may be provided with an automatic ambient temperature compensator of the type shown in Fig. 10. Instead of rigidly mounting latch 53 on reset bar 50 as shown in Fig. 1, the latch 53 may be mounted at one end of a bimetal 49, the other end of the bimetal being fixed to the reset bar. By proper selection of the characteristics of the bimetal 49 in relation to the Ibimetal 40, changes in ambient temperatures will cause both bimetals to move their respective latch members by equal amounts to avoid. displacement of the latch memhers. 53. ancv with. respect to.v achother. Thus, r gard.- less of the ambient temperature, the predetermined overlcgad current which trips the breaker will remain invaria le.

The reset bar has an elongated slot 56 about which it is pivoted, and a calibrating screw 57 threaded into the contact bar and engageable with the pin 47 for shifting the reset bar 50 toward the left or right as viewed in Fig. 1 to change the position of the latch surface 54 with respect to the latch element 45. The springs 51 and 52 normally urge the pin 47 and screw 57 into engagement with each other. Thus the circuit breaker'can be set to trip at different overload currents depending upon the relative position of the latch surface 54 and latch element 45 which is determined by the position to, which the calibrating screw 57 moves the reset bar 50.

The reset bar 50 has a lower end 60 confined within a space 61forme'd betweenthe side wall 21and a block 62 (Fig. 4). The lower end 60, being confined, causes the reset bar 50, to pivot about the lower end from the solid line position tothe dotted line position of Fig. 4 when a transverse force is applied to the upper end of the reset bar. This movement will cause the latching surface 54 carried by the reset bar to slide out of engagement with the latch element- 45.

The movement of the contact bar 34 and the reset bar 50 is controlledin part by the lower extremity of the operating handle 32. The operating handle 32 has a projection 65 having an inclined cam surface 66 (Figs. 1 and 4) and a cam groove 67 which cooperate with the upper end portion 68 and the integral projection 70 thereon of the reset bar. Movement of the operating handle in acounter clockwise direction as viewed in Fig. 1 causes the inclined surface 66 to bear against the reset bar to force the reset bar into the dotted line position in Fig. 4. Clockwise movement of the operating handle 32 from the position shown in Fig. 3 causes an engagement of the reset bar projection 70 in the cam groove 67 and the consequent counter clockwise movement of the reset bar 50.

At the other side of the lower extremity of the operating handle 32 is an inclined surface 71 and a cam groove 72 which cooperates with the upper end 73 of the contact bar 34 and a projection 74 integral with the end of the contact bar. When the operating handle is moved counter clockwise as viewed in Fig. 1, the projection 74 is forced by the inclined'surface 71 toward the side walls 21 of the breaker thereby causing the contact bar to pivot about the pin 35 from the solid line position to the dotted line position of Fig. 5. When the operating handle is moved clockwise from the position shown in Fig. 3 to that of Fig. 1, the projection 74 moves into engagement with the groove 72 and is prevented from further movement until it passes beyond the groove over a shoulder formed by the inclined surface 71.

Operation When the circuit breaker is in the condition shown in Fig. l, the contacts 36 and 37 are closed. The springs 51 and 52 which have an equilibrium as shown in Fig. 3 are strained and in this condition urge the contact and reset bars toward an equilibrium position in which the con .tacts would be open. The latching engagement of the sur To trip the circuit breaker manually, the operating 'h'andle' 32 is'moved' counter clockwise from the position ofFiggiltothe position of Fig. 3. In so moving. the disposition of the operating-elements with'respect toeachother causes the following predetermined sequence of steps to take place:

First the inclined surface 66 in engagement with the upper end of the reset bar causes the reset bar to pivot transversely. The transverse shifting of the reset bar will slide the latch surface 54 out of an engagement with the latch element 45 to release the reset bar so that the elements may take the equilibrium position shown in Fig. 3.

Simultaneously with the transverse shifting of the reset bar, the inclined surface 71 of the operating handle acts upon the upper end of the contact bar to pivot the contact bar transversely as indicated in Fig. 5. The transverse pivoting of the contact bar causes the movable contact 36 to wipe across the fixed contact 37 thereby freeing the contacts from any corrosion or the like which might tend to resist the quick release of the contacts.

The movement of the upper end of the contact bar over the inclined surface 71 is important not only for the wiping action described above but even more important avoids pivoting of the contact bar in the plane of the breaker until after the latching surface has been disengaged. Were it not for this design, the operating handle would, on manual trip, break the, contacts gradually by causing the contact bar to pivot in the plane of the breaker at the beginning of the movement to manual off. The slow break of the contacts obviously would be undesirable for it is likely that an arc would be drawn which, if occurring very many times, would destroy the contacts.

As indicated above, after the latching surfaces have been disengaged, both springs cause the quadrangle formed by the springs and bars to return to the position of equilibrium shown in Fig. 3.

Automatic trip In the automatic tripping of the circuit breaker, the latch element 45 is withdrawn from engagement with the latching surface 54 either by an overload current causing the bending of the bimetal 40 or by electro magnetic means operating on the armature formed by support 46.

When the surfaces disengage, the operating elements shift to the position shown in Fig. 6 under the action of the stressed springs returning to their equilibrium position. Toward the end of the clockwise rotation of the resetbar, the projection 70 on the reset bar strikes a projection 80 which causes the handle 32 to take a new position indicating the tripped condition.

Circuit closing operation To close the contacts from the tripped position of Fig. 6, the operating handle must first be moved to the position of Fig. 3. If the breaker has been tripped manually the elements are in the position of Fig. 3.

To close the contacts, the elements are shifted from the position shown in Fig. 3 through the position shown in Fig. 7 to the position shown in Fig. 1. Again, the elements cooperate to move in a predetermined sequence. First, the projection 70 is engaged in the cam groove 67 on-the operatinghandle and begins to pivot the reset barcounter clockwise.- Thecontact bar is carried with the reset bar by virtue of the strong spring 52 interconnecting the barsuntil the projection 74 on the contact b'ar engages the cam groove 72. Thereafter, the cam 72 prevents further counter clockwise movement on the contact bar, while the reset bar continues to pivot counter clockwise.

The second step in the'sequence (illustrated in Fig. 7) 'isthe passing, of the latch surface 54 beyond the point of engagement with latching element 45 until the surface 54iis directly over the element 45., The movement of the surface 54 past the element 45 and then directly over it, ispermitted by the ,yielding and'subsequent side- 'wtse' urging of the spring 55, the upper edge of the memher 53 being inclined slightly to permit it to be forced past the element 45. (See Fig. 11.)

In the third step in the sequence, the projection 70 on the reset bar 50 passes over the peak of the groove 67 in the operating handle thereby escaping handle projection 65 permitting the reset bar to swing clockwise and the latch surface 54 to mate with the latch element 45.

The fourth step in the sequence occurs after the operating handle 32 has been rotated a distance clockwise beyond the position of Fig. 7 to bring the projection 74 on the contact bar beyond the peak of its groove 72. In this position the spring 52 snaps the contact bar counter clockwise to close the contacts 36 and 37. At

the end of the sequence, the circuit breaker elements are in the positions shown in Fig. 1.

Fig. 9 shows the manner in which two circuit breakers of the type described above can be combined for double pole common trip action by use of the mechanism shown in my co-pending application Ser. No. 642,035, filed February 25, 1957. A fiber trip member has two holes 86 by which the member is mounted on the latch 53 of each circuit breaker. If the latch on the left side is tripped, latch 53 snaps downwardly causing the member 85 to pivot counter clockwise about the point of engagement of projection 87 with the side walls 21. The counter clockwise rotation of the member 85 causes a transverse movement of the latch 53 of the right hand breaker to release it from the latch element 45. Thus after the left breaker trips, the right hand breaker will also be caused to trip without stressing the current responsive element.

Conversely after latch 53 of the right hand element is tripped, it will be moved downwardly pivoting the member 85 about the point of engagement about the projection 88 with the side wall 21 of the left hand breaker. The clockwise pivoting of the member 85 will move the latch 53 of the left hand breaker transversely to release it from the latch element 45. Thus after the right hand breaker trips, the left hand breaker will also be tripped without stressing the current responsive element.

An alternative embodiment of the invention is illustrated in Figs. 12 to 18. In this embodiment like numbers but in the hundred series will be applied to the elements similar to the elements of the embodiment in Figs. 1-11.

The principal difference between the two embodiments resides in the latch mechanism and the manner in which it is mounted. In the first embodiment, the current responsive latching element 45 is mounted by means of bimetal 40 on the contact bar. In the alternative embodiment on the other hand, one end of the bimetal is fixed to a strap 144 directly connected to a solderless connector 128. At the end of the member 140 remote from the strap 144 a latch support 146 carrying a latch element 145 is mounted. The latch support 146 may, as in the previous embodiment, be of term magnetic material to serve as an armature in a magnetic type overload circuit. The current path in this embodiment between the solderless connector 128 and a pair of bus blades receiving jaws 130 is through the strap 144, the bimetal 140, a pigtail 143, a movable contact 136, a fixed contact 137 and strap 138 connected to the jaws 130. There are other differences between the breaker of Figs. 12 to 18 and the breaker of Figs. 1 to 11 but these ditferent structures function substantially identically to the comparable structure of Figs. 1 to 11. Thus it is demonstrated, through the adoption of different structures that the invention can take different forms without departing from the inventive principle.

One of the differences resides in the substitution for the projection 70 on the reset bar of an L-shaped flange 169 having a projection which cooperates with the inclined cam surface 166 and the cam groove 167 onjthe operating handle as shown in Figs. 12 to 18.

The principle of the operation of an alternative embodimentis illustrated in Figs. 12-to 14.

desired.

7 a Manual of In manually opening the'contacts 136 and 137 of the circuit breaker, the operating handle is shifted counter clockwise from the position shown in Fig. 12. In so shifting the operating handle, the inclined surface 166 bears against the projection of 170 of the reset bar and moves the projection transversely (toward the right in Fig. .17). The first movement of the projection 170 causes a pivoting of the reset bar about its pivot pin 147 in a plane transverse to the plane of the circuit breaker. This pivotal movement causes the transverse movement of latch surface 154 on the reset bar, bringing it out of engagement with the latch surface 145 on current responsive element. The latching surface having been disengaged, the springs 151 and 152 return the quadrangle which they form'with the reset and contact bars to a position of equilibrium in which the contacts are opened. r

Automatic trip In the automatic tripping of the circuit breaker, the elements move from the position of Fig. 12 to that of Fig. 13. The first step of the tripping is the transverse movement of support 146 either by electro magnetic attraction or by the bending of the bimetallic element 140 by the overload current. When the displacement of support 146 has reached a predetermined point, the latch element 145 moves out of engagement with the reset bar latch element 154. At this instant, the springs 151 and 152 snap the contact and reset bars to their equilibrium position of Fig. 13. This clockwise movement of the reset bar 150 brings the projection 170 carried thereby into engagement with a projectin180 on the operating handle 132 so as to move the operating handle positively to a position identical to the tripped position of the circuit breaker.

Closing the contacts,

' In order to close the contacts 136 and 137, the operating handle must be moved counter clockwise to a position beyond that shown in Fig. 14. This position would be similar to that of Fig. 3 insofar as the relationship of the operating handle to the contact and reset bars is concerned.

In closing the contacts the operating handle is moved clockwise to bring the cam groove 167 into engagement with the reset bar projection 170 and to start the counter clockwise pivoting of the reset bar which through the operation of spring 152 will effect the counter clockwise pivoting of the contact bar 134 until its projection 174 moves into engagement with a cam groove 172 on the operating handle. Engagement of the projection 174 with the cam groove 172 prevents further counter clockwise movement of the contact bar while the reset bar continues its counter clockwise movement increasing its stress on spring 152. When the elements have reached the position shown in Fig. 14, the latch members 145 and 154 have attained the position necessary for engagement. Continued movement of the operating handle firstcauses the reset bar projection 170 to move beyond the peak of the cam groove 167 and, under the force of the springs acting on the reset bar, pivots about the latching element's. Immediately thereafter, the projection 174 on the contact bar rides over the peak of cam groove 167 thereby freeing thereset bar from the restraint imposed by the .pperatinghandle. Accordingly, the contact bar snaps to the closed positionshown in Fig. 12; I

I It should befunderstood that the configuration of the camgrooves and inclined surfaces can be altered to a certain extent. without affecting the operating of the invention. For example, instead of grooves 167 and 172, shoulders might be formed on the operating handle to, confine the .movementofthe contactand reset bars as 3 .Ina general anner, while there has been disclosed in v the above description, .what is deemed to be the most serrate invention 'as comprehended within the scope of the accompanying claims.

Having described my invention, 1 claim: I

1. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact b-ar carrying a Contact engageable with said fixed contact and centrally pivoted on said post'in saidcasing, a reset bar centrally pivoted in. said casing in spaced generally parallel relation to said contact bar, tension springs joining each of the opposing end portions of said contact bar and reset .bar, said springs forming a quadrangular link age system with said bars, latch means associated with said reset bar, an operatinghandle mounted in said casing for movement at "least between latched and reset positions, cam surfaces on said handle engaging the ends of said bars, a first of said cam'surfaces to pivot said reset harm a plane transverse to a plane perpendicular to said pivot post during movement to reset" position, a second of said cam surfaces on said handle to pivot said reset bar parallel Iosaid plane during-movement to latched position, said-second cam surfaces shifting said reset bar to a position in which said springs are stressed'when said breaker is latched with said contacts engaged,- said spring returning said quadrangular linkage system to an equilibrium position in which said springs are least strained when said breaker is unlatched thereby snapping said contact out of engagement.

2. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivoted on saidpost in said casing, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar, tension springs joining each of the opposing end portions of said contact bar and reset bar, said springs forming a quadrangular linkage system with said bars, latch' means associated with said reset bar, an operating handle mounted in said casing for movement between latched and reset positions, cam surfaces on said handle engaging the ends of said bars, a first of said cam surfaces to pivot said reset bar in a plane transverse to a plane perpendicular to said pivot post during movement to reset position, a second of said cam surfaces on said handle to, pivot said reset bar parallel to said plane during movement to latched position, said cam surfaces shifting said reset bar first to effect latching of said latch means and to stress said springs, and thereafter to release said contact bar to snap said contacts into engagement, said springs returning said quadangular linkage systemto an equilibrium position in which said springs are least strained when said breaker is unlatched thereby snapping said contact-out of engagement. 7 v

' 3. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying acontact engageable with said fixed contact and centrally pivoted on said post in said casing, a reset bar centrally pivoted in said casing-in spaced generally parallel relation to said contact bar, tension. springs joining each of .the opposing end portions of said contact barv and reset bar, said springs formin'ga quadrangular linkage system with. said .b'ars,l'an, operating handle movably mounted in said casingfcam ,surfaces onasaid handle engaging the ends, of said bars to pivot at least 7 to a position inwhich said springs are stressed when said breaker is latched with said contacts engaged, said'spring s r tu nin sai uad s l n y tqm o 14 e iibr a qt i sc rwhi hsei s ri gs neare t, was

when said breaker is unlatchedthereby snapping said contacts out of engagement.

4. A circuit breaker comprising, a casing, a contact fixed in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivotally mounted in said casing, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar, tension springs joining each of the opposing ends of said contact bar and resetbar, said springs forming a parallelogram with said bars, an operating handle pivotally mounted in said casing, cam surfaces on said handle engaging the ends of said bars to pivot at least said reset bar in transverse and longitudinal planes, said cams shifting said bars to a parallelogram position in which said springs are stressed when said breaker is latched with said contacts engaged, said springs returning said parallelogram to an equlibriurn, rectangular position when said breaker is unlatched thereby by snapping said contacts out of engagement.

5. A circuit breaker comprising, a casing, a contact fixed in said casing, a contact bar carrying at one end a contact engageable with said fixed contact and centrally pivoted in said casing, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar, tension springs of unequal strength joining each of the opposing end portions of said contact bar and reset bar, the stronger of said springs joining the ends remote from said contacts, said springs forming a quadrangular linkage system with said bars and normally urging said bars to an open. position, an operating handle movably mounted in said casing and engageable with said bars, said handle, when moved to make position pivoting said reset bar to strain said stronger spring more than the other spring thereby to bring and maintain said contacts together, latch means holding said reset bar in make position against the tendency of said springs to return said bars to a normal unlatched position.

6. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivoted on said post in said casing, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar, tension springs joining each of the opposing end portions of said contact bar and reset bar, said springs forming a quadrangle with said bars, an operating handle movably mounted in said casing, cam surfaces on said handle engaging the ends of said bars to pivot at least said reset bar transversely and parallel to a plane perpendicular to said pivot post, said cams shifting said bars to a position in which said springs are stressed when said breaker is latched with said contacts engaged, said springs returning said quadrangle to an equilibrium position in which said springs are least strained when said breaker is unlatched thereby snapping said contacts out of engagement, said cam surfaces, upon movement of said handle to latched position, positively pivoting said reset bar while blocking movement of said contact bar until latching is effected, and upon movement of said handle in a reverse direction, said cam surfaces by-passing said contact bar while pivoting said reset bar in a transverse direction to effect unlatching.

7. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivoted on said post in said casing, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar, tension springs joining each of the opposing end portions of said contact bar and reset bar, said springs forming a quadrangle with said bars, an operating handle movably mounted in said casing, cam surfaces on said handle engaging the ends of said bars to pivot at least said reset bars transversely and parallel to a plane perpendicular to said pivot post, said cams shifting said bars to a position in which said springs are stressed when said breaker is'latched with said contacts engaged, said springs returning said quadrangle to an equilibrium position in which said springs are least strained when said breaker is unlatched thereby snapping said contacts out of engagement, said cam surfaces, upon movement of said handle from a latched position to an unlatched position, by-passing said contact bar while pivoting said reset bar in a transverse direction to efiect unlatching.

8. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivoted on said post in said casing, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar, tension springs joining each of the opposing end portions of said contact bar and reset bar, said springs forming a quadrangle with said bars, an operating handle movably mounted in said casing, cam surfaces on said handle engaging the ends of said bars to pivot at least said reset bar transversely and parallel to a plane perpendicular to said pivot post, said cams shifting said bars to a position in which said springs are stressed when said breaker is latched with said contacts engaged, said springs returning said quadrangle to an equilibrium position in which said springs are least strained when said breaker is unlatched thereby snapping said contacts out of engagement, said cam surfaces, upon movement of said handle to latched position, positively pivoting said reset bar while blocking movement of said contact bar until latching is effected, and thereafter releasing said contact bar to snap said contacts into engagement.

9. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivoted on said post in said casing, a current overload element mounted for movement parallel to a plane perpendicular to said pivot post and carrying a latch surface thereon, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact bar and carrying a latch surface engageable with said element latch surface, tension springs joining each of the opposing end portions of said contact bar and reset bar, said springs forming a quadrangle with said bars, an operating handle movably mounted in said casing, cam surfaces on said handle engaging the ends of said bars to pivot at least said reset bar transversely and parallel to said plane, said cams shifting said bars to a position in which said springs are stressed when said surfaces are latched with said contacts engaged, latch surfaces being disengageable to trip said breaker by movement of said overload element parallel to said plane, and by movement of said reset bar transversely to said plane.

10. A circuit breaker comprising, a casing, a fixed contact mounted in said casing, a vertically disposed contact bar mounted in said casing for movement to bring a contact carried thereby to open and closed positions with respect to said fixed contact, reset bar vertically mounted in said casing, resilient means connecting said reset bar to said contact bar, an operating handle mounted for movement at the top of said casing, cam

surfaces on said handle engaging the upper ends of said bars to pivot at least said reset bar in two planes transversely of each other to etfect opening and closing respectively of said contacts.

11. A circuit breaker comprising, a casing, a contact fixed in said casing, a pivot post in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally pivoted on said post in said casing, a current overload element mounted for movement parallel to a plane perpendicular to said pivot post and having a latch surface thereon, a reset bar centrally pivoted in said casing in spaced generally parallel relation to said contact surfaces on said handle engaging the ends of said bars to pivot at least said reset bar transversely and parallel to said plane, said cams shifting said bars to a position in which said springs are stressed when said surfaces are latched with said contacts engaged, latch surfaces being disengagable to trip said breaker by movement of said overload element in a plane parallel to said plane.

12. A circuit breaker comprising, a casing, a contact fixed in said casing, a transverse pivot post fixed in said casing, a contact bar carrying a contact engageable with said fixed contact and centrally 'pivotally mounted on said post, said contact bar having a transversely projecting ear, engaging said post to form a bearing to provide transverse stability for said contact bar, a reset bar centrally pivoted in said casing in spaced generally parallel --relation to said contact bar, tension springs joining'each of the opposing ends of said contact bar and reset bar, said springs forming a quadrangle with said bars, an operating handle pivotally mounted in said casing, cam surfaces on said handle engaging the ends of said bars to pivot said bars in transverse and longitudinal planes, said cams shifting said bars to a position in which said springs are stressed when said breaker is latched with said contacts engaged, said springs returning said quadrangle to an equilibrium position in which said springs .are least strained when said breaker is unlatched thereby snapping said contacts out of engagement.

13. A circuit breaker comprising, a casing, a fixed contact mounted in said casing, a vertically disposed contact bar mounted in said casing for movement to bring a contact carried thereby to open and closed positions with respect to said fixed contact, reset bar vertically mounted in said casing, and operably connected to said contact bar, tension springs joining the upper and lower ends of said bars, said springs being least strained when said contacts are opened, an operating handle mounted for movement at the top of said casing, cam surfaces on said handle engaging the upper ends of said bars to pivot at least said reset bar in two planes transversely to each other to effect opening and closing respectively of said contacts.

14. A circuit breaker comprising, a casing, a fixed contact mounted in said casing, a vertically disposed contact bar mounted in said casing for movement in a plane to bring a contact carried thereby to a closed position with respect to said fixed contact, reset bar vertically mounted in said casing, latch means associated with said reset bar and operably connected to said contact bar, tension springs joining the upper and lower ends of said bars, an operating handle mounted for movement at the top of said casing, cam surfaces on said handle engaging the upper ends of said bars to pivot at least said reset bar transverse to said plane of movement of said contact bar to effect unlatching of said reset bar, and spring means normally urging said reset bar transversely toward a position in which latching can be maintained.

15. A circuit breaker comprising, a casing, a fixed con- .tact mounted in said casing, a vertically disposed contact bar mounted in said casing for movement in a plane to and operably connected; to said contact bar, tension springs joining the upper andv lower ends of said bars, an

operating handle mounted for movement at the top of said casing, cam surfaces on said handle engaging the upper ends of said bars to pivot at least said reset bar in planes transverse and parallel to said plane of movement of said contact bar to effect opening and closing respectively of said contacts, said cam surfaces including a first surface normal to said plane for pivoting said reset bar in a direction to close said contacts and said latch means, a second surface inclined to said plane to pivot said reset bar in a transverse direction to effect opening of said contacts, and a third surface for holding said switchbar against closing said contacts until said latch means is closed.

16. A circuit breaker comprising, a casing, a fixed contact mounted in said casing, a vertically disposed contact bar mounted in said casing for movement in a plane to bring a contact carried thereby to a closed position with respect to said fixed contact, reset bar vertically mounted in said casing, and operably connected to said contact bar, an operating handle mounted for movement at the top of said casing, cam surfaces on said handle engaging the upper ends of said bars to pivot at least said reset bar parallel and transversely to said plane of movement of said contact bar to effect closing and opening respectively of said contacts, said transverse pivoting movement of said reset bar causing said bar carried contact to transversely wipe said fixed contact ing, a vertically disposed contact bar centrally pivotally mounted on said post in said casing for movement to bring a contact carried thereby to open and closed positions, a vertically disposed reset bar having a central hole, a pin in said casing projecting through said reset bar hole to pivotally mount said reset bar, a latch surface on said reset bar adjacent said hole and cooperating with a latch element, movable in response to overload current in said casing to block pivotal movement of said reset bar when said contacts are closed, means for adjusting said reset bar with respect to said pin to selectively bring said latch surface toward and away from said latch element thereby. varying the movement of said latch References Cited in the file of this patent UNITED STATES PATENTS 2,210,870 Platz Aug. 6, 1940 2,254,067 Frank Aug. 26, 1941 2,534,938 Woodward Dec. 19, 1950 2,686,241 v Straub etal Aug. 10, 1954 2,701,829 Krieger Feb. 8, 1955 2,813,168 Mascioli et al Nov. 12, 1957

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