US2130368A - Automatic circuit breaker - Google Patents

Description

Sept. 20, 1938. J. SACHS 2,130,368

AUTOMATIC CIRCUIT BREAKER Filed Aug. 21, 1937 2 Sheets-Sheet 1 Fig.1 2

Sept. 20, 1938. J SACHS 2,130,368

AUTOMATIC CIRCUIT BREAKER Filed Aug. 21, 1957 2 Sheets-Sheet 2 Inventor ias uf fizjfs Patented Sept. 20, 1938 PATENT OFFICE AUTOMATIC CIRCUIT BREAKER Joseph Sachs, West Hartford, Conn., assignor to Colts Patent Fire Arms Manufacturing Company, Hartford, Conn., a corporation of Connecticut Application August 21, 1937, Serial No. 160,249

14 Claims.

This invention relates particularly to a circuit breaker of the type disclosed in my Patent No. 1,812,843, dated June 30, 1931. In a circuit breaker of this type there is provided at least one stationary contact, a movable contact member carrying at least one movable contact adapted to engage the stationary contact, an actuator movably connected with the contact member, an electroresponsive latch bodily movable with the contact member and normally connecting it with the actuator for movement in unison therewith, and an operating means, as for instance toggle links, connected with the actuator for moving or holding it and for thus moving or holding the contact member.

As disclosed in my said prior patent and in my other prior patents showing circuit breakers of this general type the latch engages directly with the actuator. In accordance with the present invention, however, the latch engages a movable trip member which is separate from the actuator but is normally mechanically connected therewith. This makes it possible for the actuator and the latch to be each located in the most advantageous relationship to the contact member. The actuator can be located so as to effectively enable the operating means to move or hold the contact member, the major portion of the necessary force being transmitted directly to the contact member independently of the trip member and latch.

Preferably the reduction in force transmitted to the latch is efiected by mechanismproviding a plurality of levers having force reducing ratios.

In the accompanying drawings two alternative embodiments of the invention are shown but it will be understood that the drawings are intended for illustrative purposes only and are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

Fig. 1 is a central longitudinal sectional view through a circuit breaker embodying the invention.

Fig. 2 is a transverse sectional view taken along the line 2--2 of Fig. 1.

Fig. 3 is a fragmentary transverse sectional view taken along the line 3--3 of Fig. 1.

Fig. 4 is a view similar to Fig. l but showing the parts in the positions which they occupy when the circuit breaker is opened automatically with the handle held in closed-circuit position.

Fig. 5 is a view similar to Figs. 1 and 4 but showing the parts in open-circuit position.

Fig. 6 is a central longitudinal sectional view through an alternative circuit breaker embodying the invention.

Fig. 7 is a transverse sectional view taken along the line 'I'I of Fig. 6.

Fig. 8 is a view similar to Fig. 6 but showing the parts in the positions which they occupy when the circuit breaker is opened automatically with the handle held in closed-circuit position.

Fig. 9 is a view similar to Figs. 6 and 8 but showing the parts in open-circuit position.

Referring to the drawings, particularly Figs. 1 to 5 thereof, I represents as an entirety a casing or housing which is shown as molded from a suitable insulating material. This housing is closed at the sides and is substantially closed at the ends and at the rear, but it is open at the front where there is provided a removable insulating cover 2 normally held in place by screws 3, 3.

A contact 4 is mounted within the housing I near the rear thereof, this contact being carried by a resilient conductor 5 held in place by a screw 6 connected with a suitable wire connecting terminal such as a nut I. The contact I is the rupture contact, and ordinarily it is stationary or substantially so. For convenience it will be herein designated as the stationary contact. Also mounted on the housing is a stationary conductor 8 held in place by a screw 9. Connected with the conductor 8 is a suitable wire connecting terminal such as a nut III.

Movably mounted within the housing I is a contact carrying member I I which as illustrated comprises two insulating plates II, II which are spaced apart transversely. Although the invention is not necessarily so limited, the contact carrying member II is shown as being pivotally movable. It is mounted upon a transverse pivot pin I2 which extends transversely through the insulating plates II", II and into holes in the side wall of the housing I. Extending transversely between the plates II, II is a metallic bar I3 which carries a movable contact I4 adapted to engage the stationary contact 4 as shown in Fig. l.

The contact member I I is biased for movement in the circuit-opening or contact disengaging direction, and as shown such biasing is effected by means of a coil spring I5. This spring is contained within a telescoping housing I6, one portion of which is pivotally connected to the contact member and the other portion of which is seated in a recess in the rear wall of the housing.

An actuator I1 is provided which is connected with the contact member II so as to be movable relatively thereto and so as to be also bodily movable therewith. The actuator may be variously constructed, but it is shown as being of bell-crank form and as being pivotally connected with the contact member by means of a transverse pivot pin l8 which extends through openings in the side plates H I I of the contact member. Bushings I9, I 9 serve to hold the actuator H in its normal central position, As hereinafter explained in detail the actuator is normally held against pivotal movement with respect to the contact member.

A suitable operating means is provided, this means preferably comprising two links or members 20 and 2| pivotally connected with each other at 22. The link or member 20 is formed to also constitute a handle and it is pivotally mounted on a transverse pivot pin 23 extending into suitable holes in the side walls of the housing l. A portion of the handle member 20 projects through a suitable opening in the cover 2 so as to be conveniently accessible for manual operation. The handle member is biased for movement in the clockwise or circuit-opening direction by means of a spring 24 surrounding the hub 20.

The link 2| of the operating means is pivotally connected at 25 with one arm E1 of the actuator 1. With the parts in the position shown in Fig. 1 the two members or links 20 and 2| constitute an overset toggle which holds the contact member in its contact engaging or circuit-closing position. Movement of the links 20 and 2| beyond the position shown in Fig. 1 is prevented by means of a transverse stop rod 26 extending transversely between the side walls of the housing.

Movably connected with the contact member H is trip member 21. In the construction. as illustrated the trip member is movable about the same axis as the contact member itself and is mounted upon the same pivot pin i2. Bushings 28, 28 hold the trip member in central position. Normally the trip member is held in fixed relationship with the contact member and to this end they are normally connected by means of an electro-responsive latch which is carried by the contact member and which releasably engages the trip member.

As concerns the present invention I do not narrowly limit myself as to the exact character of the electro-responsive latch but I prefer and have shown a latch which consists of a bi-metallic thermally responsive strip 29. This strip carries a transverse latch bar 29a which normally engages with the trip member 21. Preferably, but not necessarily, the latch 29 is electrically connected to form a part of the circuit and to be directly heated bythe current. As shown the latch 29 is rigidly connected at one end with the transverse bar i3, being thus electrically connected at the said end with the movable contact l4. The other end ofthe bi-metallic latch 29 is electrically connected with the aforesaid stationary conductor 8 by means of a flexible conductor 30. Thus with the parts in closed circuit position an electrical connection is established from the terminal 1 through the conductor 5 and the contacts 4 and i4 and thence through the bimetallic latch 29 and the flexible conductor 30 to the stationary conductor 8 and the" terminal Ill.

The herein disclosed construction wherein a flexible conductor serves as the connection between a stationary conductor and a bodily movable bi-metallic latch is not claimed in this application. The said construction is disclosed and claimed in my co-pending application for Automatic circuit breaker Serial No. 152,020, filed July 6, 1937.

The actuator i1 is suitably connected with the trip member 21 so that the actuator is held in fixed relationship with the contact member so long as the latch 29 holds the trip member in fixed relationship. As shown, the connecting means is a link 3| pivotally connected at 32 with the trip member between the ends thereof and pivotally connected at 33 with the arm |1 of the actuator.

With the parts in closed-circuit position, as shown in Fig. 1, the overset toggle 20, 2| prevents circuit-opening movement as the result of the bias of the spring l5. The pressure exerted by the said spring l5 and the pressure exerted on the contact l4 by the contact 4 are transmitted through the link 2| to the operating member 20 and serve to normally hold the operating membeer in its closed-circuit position against the bias in the circuit-opening direction exerted by the spring 24.

The toggle operating means 29, 2| can be manually released by moving the operating member 20 in the clockwise direction suiliciently to break the toggle. Thereupon the parts move to the open-circuit position as shown in Fig. 5 under.

the influence of the springs i5 and 24. The before-mentioned stop rod 26 engages the top edges of the plates H II to limit movement in the circuit-opening direction.

As already stated the latch 29 is responsive to current in the circuit, being preferably connected electrically to form a part of the circuit. Upon the attainment of excess current conditions in the circuit the bi-metallic latch is heated by reason of the current therein, and it is deflected rearward so that the latch bar 29* is disengaged from the trip member 21. If the operating member is manually held in closed-circuit position as shown in Fig. 4, the contact member will move automatically to its open-circuit position under the influence of the spring l5 as soon as the trip member 21 is released by the latch 29. This will be more readily apparent when itis observed from an inspection of Fig. 1 that the pressure normally transmitted through the link 2| tends to move both the actuator and the trip member in the clockwise direction, such clockwise movement being resisted solely by the latch 29. When the latch releases the trip member such clockwise movement takes place, and the contact member moves to its open-circuit position.

If the operating member 20 be released after the parts have reached the position shown in Fig. 4, the said operating member will be automatically moved by the spring 24 to its opencircuit position as shown in Fig. 5 and it will carry with it the parts 2|, I1, 3| and 21 thus eflecting re-engagement, of the latch with the trip member, assuming that the latch has cooled sufliciently to permit such reengagement. It will be understood that ordinarily the operating member is not held in its closed-circuit position as shown in Fig. 4 and that the operating member moves to its open-circuit position practically simultaneously with the movement of the contact member to its open-circuit position. Thus in normal overload operation the parts move automatically from the closed-circuit positions shown in Fig. 1 to the open-circuit positions as shown in Fig. 5 rela'tchingtaking place automatically as soon as the bi-metallic latch cools.-

It will be apparent that the provision of an actuator separate from the trip member enables the actuator to be conveniently located in the most advantageous relationship with respect to the contact member. With a pivoted contact member as shown in Figs. 1 to 5 the actuator can be located at a considerable distance from the pivotal axis, the trip member being located at the axis when that is found to be desirable. The major portion of the pressure, stress or force necessary to move and hold the contact member is transmitted directly from the actuator to the contact member, the trip member and the latch being subjected to only a small force which is merely sufilcient to normally prevent movement of the actuator with respect to the contact member.

As shown the effective length a of the arm i1 is approximately one-half of the effective length b of the arm I1", and therefore the force transmitted to the link 3| is reduced by about one-half on account of the ratio between the said effective lengths. The force transmitted to the latch is still further reduced by reason of the connection of the link 3| at a point between the ends of the trip member 21. As shown the distance is about one-half of the total length d of the trip member, and therefore the force transmitted to the latch 291s reduced to about one-halfof that in the link 31. By reason of this double reduction, the force at the latch is only about one-fourth of the total force which is transmitted through the link 21 and which is necessary to move and hold the contact member. The actual ratio between the force exerted by the link 2| and that applied to the latch 23 can be readily varied as required, by changing the ratios between the effective lengths a, b, and c, d.

. While I have shown only two levers having force reducing ratios, that is the actuator l1 and the trip member 21, it will be understood that the invention is not limited to any specific number of such levers.

The circuit breaker shown in Figs. 6 to 9 is similar in principle to that shown in Figs. 1 to 5, but difiers essentially in that the contact member moves rectilinearly instead of pivotally. It also difiers in that there are two stationary contacts and two movable contacts thus providing for two separate breaks in the circuit.

Referring particularly to Figs. 6 to 9, 34 represents as an entirety a casing or housing which is shown as molded from a suitable insulating material. This housing is closed at the sides and is substantially closed at the ends and the rear. but is open at the front where there is provided a removable insulating cover 35 normally held in place by screws 36, 36.

Two stationary contacts 31 and 38 are mounted within the housing 34 near the rear thereof, these contacts being carried by resilient conductors 39 and 40. The conductors 39 and 40 are held in place by means of flanged metallic tubes or hollow rivets 4i and 42. These are interiorily threaded to receive screws 43 and 44 which constitute wire connecting terminals.

Within the housing 34 is a movable contact carrying member 45 which as illustrated comprises two insulating plates 45, 45 which are spaced apart transversely. The contact member, instead of being pivotally mounted as shown in Figs. 1 to 5, is rectilinearly movable toward and away from the rear wall of the housing. The plates 45, 45 are rectangular and their end edges are guided by the end walls of the housing. Ribs 46, 46 formed on the housing also engage the plates to guide them.

Extending transversely between the insulating plates 45", 45 is an insulating plate 41. The said plates 45, 45 are also connected by two transverse metallic bars 48 and 49 which respectively carry movable contacts 50 and 51 adapted to engage the respective stationary contacts 31 and 38 as shown in Fig. 6.

The contact member 45 is biased for movement in the circuit-opening or contact disengaging direction, and as shown such biasing is effected by means of a coil spring 52. This spring is posiiioned in part within a recess in the rear wall of the housing and it reacts at the front against the said insulating transverse plate 41. The spring 52 is preferably enclosed in a tubular member 53 which is in telescopic relationship with the recess in the housing.

An actuator 54 is provided which is connected with the contact member 45 so as to be movable relatively thereto and so as to be also bodily movable therewith. The actuator as shown is of hellcrank form and it is pivotally connected with the contact member by means of a transverse pivot pin 55 which extends through openings in the side plates of the said member. Bushings 56, 56 serve to hold the actuator 54 in its normal central position.

A suitable operating means is provided, this means preferably comprising two links or members 51 and 58 pivotally connected with each other at 59. The link or member 51 is formed to also constitute a handle and it is pivotally mounted on a transverse pivot pin 60 extending into suitable holes in the side walls of the housing. A portion of the handle member 51 projects through a suitable opening in the cover 35 so as to be conveniently accessible for manual operation. The handle member is biased for movement in the clockwise or circuit-opening direction by means of a spring 6| surrounding the hub 51'.

The link 58 of the operating means is pivotally connected at 62 with one arm 54 of the actuator 54. With the parts in the position shown in Fig. 6 the two members or links 51 and 58 constitute an overset toggle which holds the contact member in its contact engaging or circuit-closing position. Movement of the links 51 and 58 be yond the position shown in Fig. 6 is prevented by means of a transverse stop rod 63 extending transversely between the side walls of the housing.

Movably connected with the contact member 45 is a trip member 64 which is carried by the contact member and pivotally connected therewith by means of a transverse pivot pin 65 extending between the side plate of the said member. Bushings 66, 66 hold the trip member in central position. The trip member is norma ly held in fixed relationship with the contact member by means of an electro-responsive latch 61 which is preferably similar to the latch 29 already described in connection with Figs. 1 to 5. The bi-metallic strip or latch 61 is rigidly connected at one end with the transverse bar 49, being thus electrically connected at the said end with the movable contact 51. The other end. of the bi-metallic latch is electrically connected with the other transverse bar 48 and hence with the other movable contact 50 by means of a flexible conductor 68. Thus with the parts in closed-circuit position an electrical connection is established from the terminal 43 through the conductor 39, contacts 31 and 50, to the flexible conductor 68 and the latch 61 and thence. through the contacts and 38 and the conductor 40 to the terminal 44.

The actuator 54 is suitably connected with the trip member 6% so that the actuator is held in fixed relationship with the contact member so long as the latch 6'? holds the trip member in fixed relationship. As shown, the connecting means is a link 89 pivotally connected at lit with the trip member and pivotally connected at it with the arm 5% of the actuator.

With the parts in closed-circuit position as shown in Fig. 6, the overset toggle 51!, 5d prevents circuit-opening movement as a result of the bias of the spring 52. The pressure exerted by the said spring 5'2 and the pressure exerted by the contacts 31 and 38 on the contacts 50 and 5t are transmitted through the link 58 to the operating member 51 and serve to hold the operating member in its closed-circuit position against the bias in the circuit-opening direction exerted by the spring 6|.

The toggle operating means 51, 58 can be manually released by moving the operating member 51 in the clockwise direction sufiiciently to break the toggle. Thereupon the parts move to the open-circuit position as shown in Fig. 9 under the influence of the springs 52 and Si. The beforementioned stop rod 63 and another stop rod 1| engage the top edges of the plates 45, 45 to limit movement in the circuit-opening direction.

The automatic opening as the result of overload is very similar to that already described in connection with Figs. 1 to 5 and detailed repetition is unnecessary. It is suflicient to point out that upon release of the trip member 64 by the latch 61 the trip member and actuator move in the counter-clockwise direction sumciently to break the toggle at 51. 58 and at the same time to permit the contact member to move forward. If the operating member be held in closed position the parts will assume the relative position shown in Fig. 8; but if the operating member is not held the parts will move to the relative positions shown in F18. 9.

As already pointed out in connection with Figs. 1 to 5, the construction makes it possible for the actuator to be located in the position which is most advantageous; and with a rectilinearly movable contact member it is preferred to have the actuator at or near the center of thecontact member as is shown. The trip member can be located wherever required to accommodate itself to the position of the latch. The force transmitted to the latch can be reduced as desired by properly determining the relationship of the parts all as explained in detail in connection with Figs. 1 to 5.

What I claim is:

1. An automatic circuit breaker comprising in combination, a stationary electric contact, a movable contact member biased. in the circuit-opening direction and including an electric contact engageable with the stationary contact, an actuator, connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, and means normally enabling the trip member to hold the actuator in fixed relationship with the contact member and serving upon release of the trip member to permit relative movement of the actuator and to thus permit automatic circuit-opening movement of the contact member.

2. An automatic circuit breaker comprising in combination, a stationary electric contact, a movable contact member biased in the circuit-opening direction and including an. electric contact engageable with the stationary contact, an actuator connected with the contact member for movement bodily therewith and also for pivotal movement relative thereto, operating means enaging the actuator to control it, a separate trip member pivotally movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch being adapted upon the attainment of abnormal current conditions in the circuit to automatically move so as to release the trip member for independent pivotal movement, and a link pivotally connected with the actuator and with the trip member and normally serving to hold the actuator in fixed relationship with the contact member, the said link serving upon release of the trip member to permit relative movement of the actuator and to thus permit automatic circuit-opening movement of the contact member.

3. An automatic circuit breaker comprising in combination, a stationary electric contact, a movable contact member biased in the circuitopening direction and including an electric contact engageable with the stationary contact, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member movable relatively to the contact member, a bodily movable bi-metallic latch electrically connected in the circuit and normally mechanically connecting the contact member and the trip member to maintain them in fixed relationship, the said latch being adapted upon the attainment of abnormal current conditions therein to automatically deflect from its normal relationship so as to disengage the trip member and permit independent movement thereof, and means normally enabling the trip member to hold the actuator in fixed relationship with the contact member and serving upon release of the trip member to permit relative movement of the actuator and to thus pemiit automatic circuitopening movement of the contact member.

4. An automatic circuit breaker comprising in combination, a stationary electric contact, a movable contact member biased in the circuitopening direction and including an electric contact engageable with the stationary contact, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, a separate trip member movable relatively to the contact member, an electro-responlsively controlled latch normally connecting the contact member and. the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, means normally enabling the trip member to hold the actuator in fixed relationship with the contact member and serving upon release of the trip member to permit relative movement of the actuator, and toggle links connected with the actuator to control it and adapted when in overset relationship to normally hold the actuator and the contact member in their closedcircuit positions, the said links being normally held in their said overset relationship by pressure transmitted from the contact member and being biased for movement to their open-circuit relationship when such pressure is reduced by reason of the relative movement of the actuator upon release of the trip member.

5. An automatic circuit breaker comprising in combination, a stationary electric contact, a pivotally movable contact member biased in the circult-opening direction and including an electric contact engageable with the stationary contact, an actuator connected with the contact member for movement bodily therewith and also for pivotal movement relative thereto about an aXis separated from the pivotal axis of the said member, operating means engaging the actuator to move it, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch being adapted upon the attainment of abnormal current conditions in the circuit to automatically move so as to release the trip member for independent movement, and means normally enabling the trip member to hold the actuator in fixed relationship with the contact member and serving upon release of the trip member to permit relative pivotal movement of the actuator and to thus permit automatic pivotal circuit-opening movement of the contact member.

6. The combination in an automatic circuit breaker, of a stationary electric contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable with the stationary contact, an actuator connected with the contact member for bodily movement therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, and a mechanical connection between the actuator and the trip member normally serving to hold the actuator against relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-owning movement of the contact member, the said connection being so related to the actuator and the trip member that the force transmitted from the actuator to the latch is substantially less than the total force transmitted from the operating means to the actuator.

7. The combination in an automatic circuit breaker, of a stationary electric contact, a movable contact member biased in the circuit opening direction and including an electric contact engageable with the stationary contact, an actuator connected with the contact member for bodily movement therewith and also for movement relative thereto, operating means engaging the actuator to move it, a separate trip member movable relatively to the contact member, a bodily movable electro-responsive bi-metallic latch normally mechanically connecting the contact member and the trip member to maintain them in fixed relationship, the said latch being adapted upon the attainment of abnormal cur- I rent conditions in the circuit to automatically deflect from its normal relationship so as to release the trip member for independent movement, and a mechanical connection between the actuator and the trip member normally serving to hold the actuator against relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-opening movement of the contact member, the said connection being so related to the actuator and the trip member that the force transmitted from the actuator to the latch is substantially less than the total force transmitted from the operating means to the actuator.

8. The combination in an automatic circuit breaker, of a stationary electric contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable with the stationary contact, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, an actuator separate from the trip member and connected with the contact member for bodily movement therewith and also for movement relative thereto, toggle links connected with the actuator to move it and adapted to assume an overset position corresponding to the closed-circuit position of the contact member, and a mechanical connection between the actuator and the trip member normally serving to hold the actuator against relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-opening movement of the contact member, the said connection being so related to the actuator and the trip member that the force transmitted from the actuator to the latch is substantially less than the total force transmitted from the toggle links to the actuator.

9. The combination in an automatic circuit breaker, of a stationary electric contact, a movable contact member biased in the circuit opening direction and including an electric contact engageable with the stationary contact, a bellcrank connected with the contact member for bodily movement therewith and also for pivotal movement relative thereto, the said bell-crank having arms of unequal effective lengths, operating means engaging the shorter arm of the bell-crank, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, and a mechanical connection between the longer arm of the bell-crank and the trip member normally serving to hold the bell-crank against relative pivotal movement and serving upon release of the trip member to permit such pivotal movement and to thus permit automatic circuitopening movement of the contact member.

10. The combination in an automatic circuit breaker, of a stationary electric contact, a movable contact member biased in the circuit-opening direction and including an electric contact cngageahle with the stationary contact, an elec= tro-responsively controlled latch bodily movable with the contact member and also separately movable upon the attainment of abnormal cur= rent conditions in the circuit, an operating rnem= her, and mechanism connecting the operating member with the contact member for normal control thereof and having releasable engage= ment with the latch whereby independent cir cult-opening movement or the contact member is permitted upon separate movement of the latch as aforesaid, the said mechanism serving to effect a double reduction in the force transmitted from the operating member to the latch.

11. The combination in an automatic circuit breaker, of a stationary electric contact, a movable contact member biased in the circuit-opening direction and including an electric contact engageable with the stationary contact, an actuator connected with the contact member for bodily movement therewith and also for movement relative thereto, operating means engaging theactuator to control it, a separate trip member movable relatively to the contact member, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip member for independent movement, and a mechanical connection between the actuator and the trip member normally serving to hold the actuator against relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-opening movement 01' the contact member, the said connection being so related to the actuator that the force transmitted to the connection is substantially less than that transmitted from the operating means to the actuator and the said connection being so related to the trip member that the force transmitted to the latch is substantially less than that transmitted from the actuator to the connection.

12. In an automatic circuit breaker, the combination of a stationary electric contact, a rectilinearly movable contact member biased in the circuit-opening direction and including an electric contact engageable with the stationary contact. an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member connected with the contact member for bodily movement therewith and also for movement relative thereto, an electro-responsively controlled latch normally connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions in the circuit to release the trip membar for independent movement, and means me chanically connecting the actuator with the trip member to normally hold the actuator against menace relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-opening movement oi the contact member.

13. In an automatic circuit breaker, the combination oi two stationary electric contacts spaced apart, a rectilinearly movable contact member biased in the circuit-opening direction and including two electric contacts engageable with the respective stationary contacts, an actuator connected with the contact member for bodily movement therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member connected with the contact member for bodily movement therewith and also for movement relative thereto, a bodily movable bi-metallic latch electrically connected between the movable contacts and normally mechanically connecting the contact member and the trip member to maintain them in fixed relationship, the said latch serving upon the attainment of abnormal current conditions therein to automatically deflect so as to release the trip member for independent movement, and means mechanically connecting the actuator with the trip member to normally hold the actuator against relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-opening movement of the contact member.

14. In an automatic circuit breaker, the combination of two stationary electric contacts spaced apart, a rectilinearly movable contact member biased in the circuit-opening direction and including two electric contacts engageable with the respective stationary contacts, an actuator connected with the contact member for movement bodily therewith and also for movement relative thereto, operating means engaging the actuator to control it, a separate trip member connected with the contact member for bodily movement therewith and also for movement relative thereto, a bodily movable bi-metallic latch electrically connected between the movable contacts and normally mechanically connecting the contact member and the trip member to maintainthem in fixed relationship, the said latch serving upon the attainment of abnormal current conditions therein to automatically deflect so as to release the trip member for independent movement, and a mechanical connection between the actuator and the trip member normally serving to hold the actuator against relative movement and serving upon release of the trip member to permit such relative movement and to thus permit automatic circuit-opening movement or the contact member, the said connection being so related to. the actuator and the trip member that the force transmitted from the actuator to the latch is substantially less than-the total force transmitted from the operating means to the actuator.

JOSEPH salons.

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