US3783215A - Positive on position indicator - Google Patents

Abstract

A molded case circuit breaker having spring powered over-center toggle contact operating mechanisms is provided with means to prevent the operating handle from moving to its off position unless the contacts are open. This means may engage the toggle near the knee thereof to assist in driving the toggle over center during opening movement of the handle.

Description

United States Patent [1 1 Brumfield Jan. 1, 1974 I5 POSITIVE ON POSITION INDICATOR 5.194900 7/1905 Epstein 200/010. 42 ux 0 [75] Inventor: John C. Brumfield, Drexel H Pa 3,l8..,l57 5/l965 Brumficld .I 200/1536 A$5lgnee5 pg Corporation, Primary Examiner-J. R. Scott Philad lph Assistant Examiner-Robert A. Vanderhye [22] Filed July 27 1972 Att0rneySidney G. Faber et al.

21 A l. N 275 622 1 pp 0 [57 ABSTRACT 52 U.S. Cl. 200/153 G, 200/1310. 42 A molded case drcu" breaker having Spring POwered 51 Im. Cl. H01h 3/46 Over-Center mggle Operating mechanisms is 58 Field of Search... ZOO/DIG. 42; 153 G, Provided with means 1mm"t the Operating handle 200/153 H, 67 PK, 167 337/59; 335/191 from 'moving to its off position unless the contacts are open. This means may engage the toggle near the knee [56] References Cited thereof to assist in driving the toggle over center dur- UNITED STATES PATENTS ing opening movement of the handle. 3,605,051 9/1971 Casey et al ZOO/DIG. 42 UX 9 Claims, 10 Drawing Figures PATENTEDJAX 1 m4 SHEET 30$ 6 PATENTEDJAK I I974 SHEET 5 (If 6 POSITIVE N POSITION INDICATOR This invention relates to circuit breakers having spring powered contact operating mechanisms and relates more particularly to circuit breakers of this type having novel means to prevent the circuit breaker handle from indicating an off condition unless the contacts are actually separated.

In many circuit breakers having over-center toggle type contact operating mechanisms, it is possible to move the handle to the off or open circuit position even though the contacts are closed because of welding or otherwise. This creates a dangerous condition because a serviceman will feel confident that the load-circuit being protected by the breaker is deenergized.

The prior art has sought to cope with this condition by constructing so-called visible break switches. In some cases inspection of the contacts of visible break switches requires the housing to be open. In other cases the housing may have a transparent part through which the contacts are visible, but this part soon becomes dirty so that view of the contacts becomes obstructed. In any event, the aforesaid prior art constructions require the servicemen to perform an extra procedure to determine whether the contacts are really open.

This invention provides a lever that positively prevents the handle from assuming its off position unless the contacts are open. In particular, this lever is connected between the operating member and frame of the contact operating member in such a manner that movement of the handle toward its off position moves the lever so that a projection thereon moves toward the knee of the mechanism toggle. The toggle will collapse only if the movable contact carrier moves to open circuit position.

Thus, if the contacts open, the toggle will collapse and will not block movement of the lever projection as the lever is moved by the handle as the latter moves toward its off position. However, if the contacts remain closed for any reason, the toggle cannot collapse and in the extended position thereof will block movement of the lever projection. This prevents movement of the lever which in turn prevents the handle from moving to its circuit open position.

Accordingly, a primary object of the instant invention is to provide novel means to prevent a circuit breaker handle from moving to its off position while the contacts remain closed.

Another object is to provide means of this type especially constructed for use with a spring powered overcenter toggle contact operating mechanism.

Still another object is to provide means of this type consisting of a lever whose movement is restrained by the toggle when extended and under such conditions the lever restrains movement of the operating handle to its open position.

These objects as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. I is a plan view of a circuit breaker constructed in accordance with teachings of the instant invention.

FIG. 2 is a longitudinal cross-section taken through line 2-2 of FIG. 1, looking in the direction of arrows 2-2 and including a handle operating mechanism, not shown in FIG. 1.

FIG. 3 is an exploded perspective of one overcenter toggle mechanism and selected elements connected thereto.

FIG. 4 is an exploded perspective of the movable contact structure for one pole.

FIG. 5 is a side elevation of the spring supporting operating member of the contact operating mechanism.

FIGS. 6 and 7 are plan and side elevations respectively of the operating member of FIG. 5, looking in the directions of the respective arrows 6-6 and 7-7 of FIG. 5.

FIG. 8 is a side elevation of the contact operating mechanism for one pole with the near side of the frame removed.

FIG. 9 is an end view of one side of the mechanism frame showing mounting of a positive ON indicator lever and the position of the latter relative to elements of the mechanism that cooperate with this lever.

FIG. 10 is an enlarged fragmentary longitudinal cross-section of the handle showing its mounting to the operating member of the center pole.

Now referring to the figures. Three phase molded case circuit breaker 25 of FIGS. 1 and 2 includes an individual over-center spring-powered toggle operating mechanism. Prior art examples of circuit breakers having more than a single operating mechanism for all phases are disclosed in U. S. Pat. Nos. 2,067,935 and 3,125,653.

Circuit breaker 25 includes a molded housing constructed of base 26 and removable cover 27 joined along line 28 and provided with longitudinal internal partitions 31, 32 which divide housing 26, 27 into three longitudinally extending compartments, one for each phase of circuit breaker 25. Cover 27 is provided with aperture 29 through which stubby bifurcated extension 33 of operating handle means 30 extends. Each section of handle extension 33 receives an individual pin 34 extending upwardly from the web portion ofinverted generally U-shaped operating yoke member 35 of the center phase. Operating members 35 of the outer phases are each secured to handle means 30 by a pair of screws 152.

Member 35 is pivoted to the spaced arms of generally U-shaped operating mechanism frame 36 at outwardly extending lugs 37. Bolts 48, received by threaded apertures of inturned edges 36a at the bottom of frame 36, fixedly secure the latter to base 26. Transverse tie member 49 is riveted to the arms of frame 36 to maintain spacing therebetween and to stabilize the frame structure.

Four-tensioned coil springs 38, each connected at one end thereof to the web of operating member 35, combine to constitute the main operating spring means for the overcenter toggle-type contact operating mechanism. The other ends of springs 38 are connected to spaced plates 39, 39 that are pivotally mounted to toggle knee pin 41 connecting upper 42 and lower 43 toggle links. The upper ends of upper toggle links 42 are pivotally connected to the spaced arms of latchable cradle 40 at pins 44, and the lower ends of lower toggle links 43 are pivotally connected to contact carrier 45 by rod 46 that extends between the spaced arms of contact carrier 45. The spaced arms of cradle 40 are positioned adjacent the inner surfaces of the spaced arms of frame 36 and are pivotally connected thereto by pins 47 that are secured to frame 36.

Under normal operating conditions plate 51, secured to web 40a of cradle 40, is in engagement with forward latching surface 52 of auxiliary latch 53. The latter is loosely mounted to pivot rod 55 extending between the spaced arm of mechanism frame 36 and slightly outboard thereof. The coiled end sections of torsion spring member 56 are wound about pivot rod 55, with the ends of these sections bearing against rod 57 and auxiliary latch 53 to bias the latter counterclockwise against stop rod 58. The ends of rods 57 and 58 are supported by the arms of frame 36. Leaf spring 73 secured to auxiliary latch 53 bears against pivot rod 55 biasing latch 53, so that rod 55 will normally lie at the central portion of V-shaped notch 74 of primary latch 53.

The ends of rod 55 projecting outboard of mechanism frame 36 are engaged by the hooked portions at the forward extension 59 of the arms for U-shaped trip unit frame 60, whose web portion is seated on a forward surface of load strap 61, being secured thereto by bolts 62 that extend through clearance apertures in strap 61 and are received by threaded inserts molded in base 26.

Rear latch tip 54 engages latch tip 63 at the U-shaped forward arm of primary latch 65, whose rear latch tip 64 is engaged by latch plate 67 mounted on one leg of L-shaped carrier 66. Primary latch 65 is pivotally mounted to trip unit frame 60 at stub shaft 69, and the carrier is pivoted on rod 68 to frame 60. Tension spring 75 biases primary latch 65 in a clockwise direction about pivot 69. Theother leg of carrier 66 is provided with transversely extending pin 71 that projects into triangular window 72 of primary latch 65 at a portion thereof near rear latch tip 64, for a reason to be hereinafter explained. Tension spring 76, connected between frame 60 and carrier extension 66a, biases carrier 66 in a'counterclockwise direction about its pivot 68 toward latching position.

When automatic tripping occurs, carrier 66 in the faulted phase is moved clockwise either by the deflection of bimetal 77 or movement of magnetic armature 78, causing latch plate 67 to release primary latch 65, which in turn releases secondary latch 53 and permits main operating springs 38 to rotate cradle 40 in a counterclockwise direction to break toggle 42, 43. The force from main spring 38 acts through cradle 40, primary latch 53, and secondary latch 65 to drive cam surface 78, bounding opening 72, against extension 71 to rotate carrier 66 clockwise, with surface 79 thereof engaging ear 81 of extension 82 on tripper bar 80 which extends between all three phases. This causes tripper bar 80 to rotate in a counterclockwise direction, so that extensions 82 in the non-faulted phases rotate counterclockwise with cam surfaces 83 thereof engaging transversely extending pin 84 of carriers 66 in the nonfaulted phases, rotating them clockwise or in the trip ping direction, to release the cradle latching systems in the non-faulted phases, so that the contacts of all three phases are open.

In order to prevent closing of the contacts of any one phase before the operating mechanisms of all phases are latched, circuit breaker 25 is provided with a defeater latching system including defeater latch 80' and defeater lever 90. Latch 80' is pivotally mounted upon rod 55 and includes protrusion 81' extending over the rear of cradle 40 when the latter is in latched position. Latch 80' further includes protrusion 82' extending over the forward end of defeater lever 90 in slot 91 thereof. Coiled tension spring 83 is connected between stop rod 57 and latch passing partially around rod 55, to bias latch 80 in a counterclockwise direction about its pivot 55 and maintaining this pivot in the basic position at the right end of slot 84 in latch 80. This basic position is established through the engagement of latch stop surface 86 and stop rod 57.

Slot 91 is in the web of the U-shaped forward portion of latch lever 90, with the U arms having pivot pin 69 for lever extending therethrough. Rear portion 89 of lever 90 is positioned below and in interfering relationship with transverse pin 71 mounted to latch plate carrier 66.

During normal relatching of circuit breaker 25, inwardly protruding portions of the operating member 35 arms engage outboard portions of pin 44 to pivot cradle 40 clockwise, whereby the latter cams defeater latch 80' away and moves below auxiliary latch 53. Upon release of the circuit breaker operating handle 30, the elements of the latch train 53, 65, 66 move into place. However, should any of these elements fail to properly engage or should cradle 40 not have been moved far enough to engage auxiliary latch 53, cradle 40 will pick up defeater latch protrusion 81', causing clockwise rotation of defeater latch 80. In turn, this causes defeater latch protrusion 82 to engage defeater lever 90 and rotate the latter counterclockwise, with the rear end 89 thereof contacting carrier extension 71 so that latch plate carrier 66 is pivoted in a clockwise or latch train releasing direction. During this releasing movement of carrier 66, surface 79 thereof engages nose 81 of one trip bar extension 82 to rotate common tripper bar 80 in a counterclockwise direction, with the other extensions 82 on bar 80 engaging pins 84 on the latch plate carriers 66 of the other poles, thereby causing the latch systems of all other poles to be released.

The lower end of bimetal 77 is fixedly secured to shading coil 99, and these elements are fixedly secured to molded frame member secured to trip unit frame 60. The horizontal leg of inverted U-shaped stationary magnetic frame member 98 passes through the center of coil 99. Member 98 is secured to the rear of frame 60, with the vertical legs of member 98 being on opposite sides of load strap 61. The other U-shaped magnetic frame member 96 is secured directly to load strap 61, with the ends of the arms for frame members 96 and 98 confronting one another in spaced relationship. Thus, current flowing in load strap 61 generates flux in magnetic frame 96, 98 which induces current flow in shading coil 99 and thereby generates heat that is conducted to bimetal 77 for heating thereof. Coiled tension spring 97, connected between armature 78 and an element mounted to the rear transverse part 60a of frame 60, biases the former away from two spaced legs 98a extending upward from the horizontal leg of member 98, and is drawn downward toward legs 98a when overload currents generate sufficient magnetic flux in magnetic frame 78, 96, 98.

With particular reference to FIG. 4, it is seen that the movable contact structure for each phase of circuit breaker 25 includes eight main contacts 103-110 and a single arcing contact 101. The latter contact 101 is mounted at the forward end of arm 112, which is pivotally mounted to carrier 45 at toggle connecting rod 46. Main contacts 103-110 are arranged in two parallel rows positioned to the rear of arcing contact 101 and disposed at right angles to the plane of movement of arcing contact arm 112.

Main contacts 103-106 in the forward row are mounted to individual contact arms 113-116 respectively, all pivotally mounted to carrier 45 on rod 46. Main contacts 107-110 in the rear row are mounted to the forward end of the respective contact arms 117-120, respectively, pivotally mounted to carrier 45 on rod 102. All of the contact arms 112-120 are connected to load strap 61 by means of individual stacks 121 of flexible sheet conductors. Contact arms 113-116 are in alignment with and extend over therespective contact arms 117-120, so that the latter group of arms 117-120 block downward movement of the former group of arms 113-116 to establish the open circuit position of contacts 103-106 in a manner which will hereinafter be seen. The open'circuit position for arcing contact arm 112 is established through engagement thereof with aligned pins 123, 124 which mount the respective pairs of main contacts 117, 118 and 119, 120 to auxiliary carriers 125, 126 respectively. Notch 122 along the lower edge of arcing contact arm 112 provides clearance for pins 123, 124.

Auxiliary carrier 125 is an inverted U-shaped member whose arms extend downwardly through cutouts 131, 132 in the web portion of contact carrier 45 and straddle four contact arms 113, 114, 117, 118. Pin 123 secures contacts 117, 118 to the lower ends of the arms comprising auxiliary carrier 125. The web of auxiliary carrier 125 is biased towards the web of contact carrier 45 by coiled compression spring 127, which is wound around the threaded body of bolt 128 whose head is positioned below the web portions of contact carrier 45. Self-locking nut 133 mounted to bolt 128 is rotated to adjust the loading of spring 127, with the rectangular shoulder of bolt 128 cooperating with rectangular cutout in carrier 45 to prevent rotation of bolt 128. Thus it is seen that in the open circuit position, spring 127 biases the web of auxiliary contact carrier 125 against the web of contact carrier 45, and when the contacts are closed there is a space between the webs of these contact carriers 45, 125, so that the force exerted by spring 127 acts to bias contacts 107, 108 into firm electrical engagement with their respective cooperating contact portions on line strap 136.

The mounting of contact arms 119, 120 to auxiliary contact carrier 126 and mounting of the latter to contact carrier 45 is the same as the mounting of contact arms 117, 118 and auxiliary carrier 125, so that this description will not be repeated. Biasing forces for each of'the contacts 103-106 in the forward row are provided by individual coiled compression springs 138, and each ,of these springs is mounted in the same way so that only the mounting of one of these springs will be described. The lower end of spring 138 extends into depression 139 in the upper surface of main contact arm 1 13, and the rear of spring 138 extends into tubular support 141 through the open bottom thereof. Support 141 is mounted to the upper surface of carrier 45 at the web portion thereof, and its upper end is threaded to receive adjusting screw 142 whose lower end bears against disc 143 abutting the upper end of spring 138. If screw 142 is adjusted to set the contact pressure exerted by spring 138, lock nut 144 is tightened to lock this adjustment.

In order to increase the area of engagement between main contacts 103-110 and their respective cooperating stationary main contacts in the very limited space available, it is noted that each of themain contacts is provided with a portion extending outward of its respective contact arm. That is, in order to utilize the space below arcing contact 112, main contacts 104, 105, 108, 109 have been extended beyond their respective contact arms 114, 115, 118, 119 to project below arcing contact arm 112. Similarly, main contacts 103, 106, 107, 1 10 have been extended outboard from their respective contact arms 1 13, 1 16, 117, 120, to lie in the space below the outboard arms of auxiliary contact carrier 125, 126 and other elements used to connect the movable contact structure to the contact operating mechanism.

The forward end of arcing contact arm 112 is biased downward away from the web portion of contact carrier 45 by coiled compression spring 171 whose lower end is positioned by pin 172 extending upward from arm 112. The upper end of spring 171 extends into tubular member 173, on the upper surface of the carrier 45 web portion, through the bottom of member 173 and abuts the closed upper end thereof.

The spaced arms of contact carrier 45 are provided with rearward extensions 45a, 45b that are spaced by and secured to shouldered cylindrical tube 146. After all contact structures, operating mechanisms, latching devices, and automatic trip units are mounted to base 26, and all adjustments to these mechanisms have been made, the contact structures of all phases are operated to the closed circuit position, so that the tubular members 146 of all phases are axially aligned and are positioned above barriers 31, 32 and the longitudinal sides of base 26. Thereafter, cylindrical tie bar 147 is driven longitudinally in the members 146 of all phases to con- 7 stitute a rigid mechanical connection between the movable contact structures of all phases. The fit between tie rod 147 and tubular members 146 is tight enough to prevent unintentional axial movement of tie rod 147, yet permits tie rod 147 to be removed for convenient servicing and replacement of parts. Mechanism frame 36 is provided with aligned elongated slots 148 to provide clearances for movement of rod 147 during opening and closing of the movable contact structures.

The construction of operating member 35 is best seen by reference to FIGS. 5-9. In particular, inverted U-shaped operating member 35'includes spaced arms 201, 202 connected at their upper ends by web 203. Each arm is provided with an inwardly extending cradle engaging resetting protrusion 204, and an elongated slot 205 which receives outwardly extending pin 211 at the upper end of an individual S-shaped lever 210 which, as will hereinafter be described, functions as the key element of a positive ON indicating means. Web 203 is provided with four pairs of apertures 213, 214 through which the upper ends of springs 38 are hooked. Threaded apertures 215 in web 203 receive the threaded ends of shoulder pins 34 (FIG. 10) in the case of the center pole mechanism, and for the outer poles threaded apertures 215 receive fastening bolts 152.

The lower or free end of each arm 201, 202 is providecl with a pair of arcuate bearing notches 238, 239. During assembly of the contact operating mechanism, frame supported bearing studs 37 are received by bearing notches 238, and in this position of operating member 35springs 38 are substantially relaxed, thereby permitting the mechanism elements to be moved readily to positions where they may be assembled conveniently.

After the mechanism elements are assembled, operating member 35 is moved to a new position wherein bearing studs 37 are received by arcuate notches 239. This repositioning of operating member 35 fully loads springs 38 forcontact operation and contact pressure. This increase in spring pressure results from the fact that the distance between web 203, and operating bearing notch 239 is greater than the distance between assembly bearing notch 238 and spring supporting web 203, so that the repositioning of operating member 35 moves the upper ends of main spring sections 38 away from the lower ends thereof which are secured to members 39 pivotally mounted on toggle knee. Each S- shaped lever 210 is pivotally mounted to a pin 209 extending outward from the side of mechanism frame 36 (See FIGS. 8 and 9). At a point between pivot 209 and pin 211, lever 210 is provided with pin means 212 extending inwardly through a clearance aperture 191 in frame 36 to cooperate with lower toggle link 43 and prevent operating member 35, and handle 30 secured thereto, from moving to a contact open position unless the contacts are actually open.

More particularly, when handle 30 is moved in a clockwise direction with respect to FIG. 8 to open circuit breaker 25, acting through pin 211 in slot 205, operating member 35 moves lever 210 clockwise about pivot 209. This moves pin 212 on lever 210 toward knee 41 of toggle 42, 43. However, unless toggle 42, 43 collapses, and this may only occur when contact carrier 45 moves to open circuit position, lower toggle link 43 blocks movement of pin 212 so that pin 211 prevents handle 30 from pivoting clockwise to open circuit position. In the event there is a minor malfunction of the contact operating mechanism causing carrier 45 to stick in contact closed position, the engagement of pin 212 with link 43 may collapse toggle 42, 43 to bring about contact opening.

The constructions and functions of insulating disks 235, 236 (FIG. 10) mounted on movable contact tie bar 147, and barrier sheets 231, 232 mounted to handle by screws 230 are described in one or more of the copending applications referred to in the following paragraph of this application. Similarly, the constructions and functions of roller 222 and washers 223 all mounted to handle extension 33 by roll pin 233 are described in one or more of the aforesaid copending applications.

For those features of construction in circuit breaker 25 that have not been described in detail herein, reference is made to one or more of the copending applications Ser. Nos. 275,568, 275,577, 275,446, 275,578, 275,507, 275,454, 275,508, 275,621, 275,623,

- 275,624, 275,569, 275,522, 275,52l, and 275,523, all

filed of even date herewith, and all assigned to the assignee of the instant invention.

. Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now become apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

l. A circuit breaker including cooperating contact means, an overcenter toggle mechanism for moving said contact means between open'and closed positions,

and a handle operable between circuit breaker ON and OFF positions corresponding to the respective open and closed positions of said contact means; said mechanism including toggle means operatively connected to said contact means, main spring means operatively connected to said toggle means to furnish opening and closing forces for said contact means, and an operating member connected to said handle and movable therewith to change the relative positions of the line of action of said means and the knee of said toggle means for driving the toggle means overcenter thereby opening and closing said contact means; pivoted lever means connected to said operating member and having a part cooperating with said toggle means to block movement of said lever means in a first direction until said toggle means is collapsed in a contact means opening direction; with movement of said lever means in a first direction being blocked by said toggle means, said lever means acting through said operating member restraining said handle from moving to its said OFF position; said mechanism also including a frame; one end of said lever means being pivotally mounted to fixed pivot means on said frame with the other end of said lever means being connected to said operating member so as to normally be movable thereby; said part of said lever means cooperating with said toggle means being disposed between said fixed pivot means and the connection between said lever means and said operating member.

2. A circuit breaker as set forth in claim 1 in which one end of the main spring means is connected to the operating member and the other end thereof is connected to the knee of the toggle means; said operating member being mounted to said frame on another fixed pivot means.

3. A circuit breaker as set forth in claim 1 in which the frame includes spaced side walls between which said toggle means is disposed; said lever means including first and second levers disposed adjacent to and movable parallel to the respective side walls.

4. A circuit breaker as set forth in claim 3 in which the operating member is generally of inverted U-shape having first and second arms connected at their upper ends by a web to which the main spring means is connected; said arms at their lower ends being mounted to the respective side walls on another fixed pivot means.

5. A circuit breaker as set forth in claim 4 in which the first and second levers are connected to the respective first and second arms.

6. A circuit breaker as set forth in claim 5 in which individual cooperating pin-slot means connect the levers to the respective arms.

7. A circuit breaker as set forth in claim 6 in which the levers are disposed outboard of said side walls and the side walls are disposed between the arms of the operating member.

8. A circuit breaker as set forth in claim 7 in which the ends of said levers connected to the arms of the operating member are interposed between said arms and the side walls of the frame.

9. A circuit breaker as set forth in claimB in which the connection between each of the first and second levers and the respective first and second arms includes a pin extending outward from the lever into a slot in the arm.

Claims (9)

1. A circuit breaker including cooperating contact means, an overcenter toggle mechanism for moving said contact means between open and closed positions, and a handle operable between circuit breaker ON and OFF positions corresponding to the respective open and closed positions of said contact means; said mechanism including toggle means operatively connected to said contact means, main spring means operatively connected to said toggle means to furnish opening and closing forces for said contact means, and an operating member connected to said handle and movable therewith to change the relative positions of the line of action of said means and the knee of said toggle means for driving the toggle means overcenter thereby opening and closing said contact means; pivoted lever means connected to said operating member and having a part cooperating with said toggle means to block movement of said lever means in a first direction until said toggle means is collapsed in a contact means opening direction; with movement of said lever means in a first direction being blocked by said toggle means, said lever means acting through said operating member restraining said handle from moving to its said OFF position; said mechanism also including a frame; one end of said lever means being pivotally mounted to fixed pivot means on said frame with the other end of said lever means being connected to said operating member so as to normally be movable thereby; said part of said lever means cooperating with said toggle means being disposed between said fixed pivot means and the connection between said lever means and said operating member.

2. A circuit breaker as set forth in claim 1 in which one end of the main spring means is connected to the operating member and the other end thereof is connected to the knee of the toggle means; said operating member being mounted to said frame on another fixed pivot means.

3. A circuit breaker as set forth in claim 1 in which the frame includes spaced side walls between which said toggle means is disposed; said lever means including first and second levers disposed adjacent to and movable parallel to the respective side walls.

4. A circuit breaker as set forth in claim 3 in which the operating member is generally of inverted U-shape having first and second arms connected at their upper ends by a web to which the main spring means is connected; said arms at their lower ends being mounted to the respective side walls on another fixed pivot means.

5. A circuit breaker as set forth in claim 4 in which the first and second levers are connected to the respective first and second arms.

6. A circuit breaker as set forth in claim 5 in which individual cooperating pin-slot means connect the levers to the respective arms.

7. A circuit breaker as set forth in claim 6 in which the levers are disposed outboard of said side walls and the side walls are disposed between the arms of the operating member.

8. A circuit breaker as set forth in claim 7 in which the ends of said levers connected to the arms of the operating member are interposed between said arms and the side walls of the frame.

9. A circuit breaker as set forth in claim 8 in which the connection between each of the first and second levers and the respective first aNd second arms includes a pin extending outward from the lever into a slot in the arm.

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