US2067797A - Circuit breaker - Google Patents

Description

Jan. 12, 1937. R. w. SMITH CIRCUIT BREAKER Filed may 6, 193e 2 Sheets-Sheet 1 .n vf .m e www@ Lmwdvt .Qt AC.A VP 5 IbJ//v o. R

R. W. SMITH CIRCUIT BREAKER Filed May 6, 1936 2 Sheets-Sheet, v2

Patented Jan. 12, 1937 UNITED STATES `PATENT OFFICE CIRCUIT BREAKER Application May 6, 1936, Serialv No. 78,177

16 Claims. (Cl. 20o-109) My invention relates to circuit breakers, more particularly to circuitbreakers of the type provided With manual mechanism for operating the circuit controlling contacts between open and closed circuit positions, and with automatic tripping means for operating the contacts to open circuit position upon the occurrence of predetermined current conditions, and has for an object the provision of a simple, reliable, and inexpensive trip device of this type Which is substantially shockproof.

Combined automatic and manual circuit, breakers of the above type have recently found considerable =industriall application in connection with which a high degreeof reliability is imperative. For example, in order to be entirely satisfactory, the circuit breaker must operate automatically to interrupt the circuitwhenever predetermined current conditions occur, and should never operate accidentally to interrupt the circuit in the absence of such predetermined current conditions. In many cases, the circuit breaker is mounted on a support which is sub` jected to recurrent jars or shocks. This is especially true in connection with circuit breakers applied to the control of the various electrical circuits oni/a naval vessel, for example, as a battleship or a destroyer. In such installations, the circuit breaker is subjected to shocks of considerable magnitude each time that a gun is red, and it will be obvious that accidental tripping of the circuit breaker upon the occurrence of such a shock would be highly unsatisfactory. While Various types of thermal or magnetic tripfdevices have heretofore been employed, many of which are to'a large extentsatisfactory, much is yet to be desired in an electromagnetically operated 'trip device for a circuit breaker, which trip device is extremely sensitive-and which i's substantially unaffected byshocks or jars imparted tothe circuit breaker. Accordingly, it is a further object of my invention to provide an extremely sensitive electromagnetic trip device of this character Iwhich is operable substantially instantaneously to trip the circuit breaker in response to predetermined current conditions and which is substantially shockproof.

In carrying out my invention in one form, I

. provide a trip device for a circuit breaker, which trip device includes a pivoted latch member biasedfor movement to releasing position and Lnormally restrained in a latching position by a rotatable trip shaft, together with substantially shockproof, electromagnetic means for rotating the trip shaft to release the latch member upon the occurrence of predetermined current conditions.

More specifically, the latch member is provided with a latching tip arranged normally to engage the periphery of the trip shaft, the trip shaft being statically balanced and provided with a transverse notch through which the'latch tip moves upon a predetermined rotation vof the shaft. The pivot of the latch member and the axis of the trip shaft are so related that the latching tip moves along an arc passing substantially through the center of the shaft and engages the periphery of the shaft substantially tangeniially so as to exert substantially no rotative moment on the shaft, the notch being cut back past the center of the shaft to permit movement of the latching tip therethrough. The shockproof electromagnetic means comprises a magnetizable armature pivoted at its center of gravity so as to be substantially unaffected by shocks transmitted to the pivot from the base of the circuit breaker, and means for biasing the armature to an unattracted position, together With shock absorbent, resilient stop means for arresting the armature in its unattracted position against the force of the biasing means and for preventing the transmission of shocks to the armature through the stop means. Stationary magnetic means are also provided, energizable in accordance with the current flowing in the circuit breaker, for attracting the armature against its bias, to rotate the trip shaft and'release the latch member upon the occurrence of predetermined current conditions.

tional view showing the trip device in its tripped position; Fig. 5 is a'fragmentary end view partly in section showing the trip device in elevation; Fig; 6 is a skeleton perspective View illustrating the trip device somewhat diagrammatically; and Figs. '7, 8, and 9 are detail views, partly in section, showing 4the relation of various parts of the trip device.

Referring now to the drawings, I have shown my invention as embodied in a trip device l0. 56

which trip device is shown as applied to a multiple pole circuit breaker of the type described and claimed in a copending application of Leonard J. Linde, Serial No. 5036, lled February 5, 1935, which has become Patent No. 2,047,829 on July 14, 1936, which patent is assigned to the same assignee as the present invention.

For the purposes of the present invention, this circuit breaker may be described as comprising a base II on which' are mounted a plurality of compression chamber type interrupters I2, each of which is provided with a reciprocally removable contact I3 arranged for movement into and out of engagement with a fixed contact (not shown) extending into the compression chamber and being supported by a suitable conductor bar i4. Mounted on the middle one of' the compression chambers I2 is a supporting frame which comprises a pair of spaced apart elongate plates i5, each of which extends outwardly over the moveable contact-end o1' the compression chamber to provide a support for the circuit breaker operating mechanism.

As is more fully described in the above referred to Linde patent, an operating member I6 is pivotally supported on the extending portions of the plates I 5 and is provided with an operating handle I1 formed yof suitable molded insulation. A pair of pins I3 which are secured to the operating member I6, in alinement with each other, .and extending laterally from opposite sides of the operating member respectively engage the adjacent ends of a pair of over-center spring devices i3? the other end of each over-center spring device being connected by means of a suitable linkage which includes a pair of toggle links and 2i to a U-shaped operating ringer 22 (Fig. `2) carried by a rotatable insulated cross-bar 23. As shown in Fig. 2, the substantially triangular link 20 which is engaged by a pin 24 carried by the overcenter spring devices I3 is pivotally mounted on a xed pin 25 and the ends of the link 2l are respectively connected to the triangular link 2,0 and to the operating finger 22.

The insulated cross-bar 23 extendsacross the three poles of the circuit breaker, the ends of the cross-bar being journaled in suitable bearings 26 (Fig. 1) carried by the base I I. Each of the movable contacts I3 is connected to the cross-bar 23 by a pair of operating fingers 21, the upper ends of which support Van operating pin 28 extending through a suitable aperture in the end of the fixed contact I3. It will thus be seen that when the operating member IB is moved about its pvot, the over-center spring devices I9 are carried overcenter and rotate the toggle link 20 about its pivot to actuate the toggle and rotatev the crossbar 23 so as to move all of the contacts I3between open and closed circuit positions with a snap action. l

In order to provide for automatic tripping or the circuit breaker, the operating mechanism is provided with a U-shaped tripping member 30 which is pivotally mounted on the supporting v plates I 5k and is provided with a portion (not shown) arranged to engage the pin 24 and rotate the link 20 about itsv pivot to operate they toggle against the force exerted by the over-center spring devices I9, thereby to rotate the cross-bar 23 and move the contacts I3 to their open circuit positions independently of the manually operable mechanism. Suitable tripping springs 3| (Fig. 1) arranged between the portions of the frame plates I 5 which overlie the compression chamber I2 are provided for normally biasing the tripping member 30 to its tripping position, a pair of operating straps 32 being arranged with their adjacent opposite ends connected respectively to a movable thrust bar 33 engaged by the tripping springs 3| and to suitabler pins 34 carried by the tripping member 30. The tripping member 3U is normally held in its latched-in position against the force exerted by the tripping springs 3| by my improved trip device I0 and the operating element IE ls provided with a shoulder portion 35 which cooperates with a shoulder 36 on the tripping member 3i) to return the tripping member to its latchedinposition after the circuit breaker has been automatically opened thereby. It is believed that the operating mechanism which is more fully described in the above referred to Linde patent will be understood clearly from the foregoing descrption.

My improved trip device `lll is supported on a sub-base 31 which may be secured in any suitable manner to the main base II and which is provided with three transversely extending conductors 38, the opposite ends oi' which are respectively connected to suitable terminals 39 and to associated flexible conductors 40, the opposite ends of the ilexible conductors being respectively connected to the movable contacts I3. Thus the circuit through each pole of the circuit breakerrnay be traced from one of the terminals 39 through the conductors 38 and 4D, the movu able contact I3, the fixed contact (not shown) and by Way of the conductor bar I4 to another terminal member 4i.

Supported centrally of the sub-base 31 1 provide a pair of spaced apart supporting plates 42 and 43 (Fig. 5) the upper ends of which are connected together by a spacing member 44, each of the plates 42 and 43 beingconnected 'to one of the frame plates I5 by a bracing` member 45.

In order to restrain the tripping member 3B in the latched-in position shown in Figs. 1 and 2, I provide a latching member 4E which is pivotedl on a pin 41 supported by the plates 42 and 43 and which is provided with a latch tip 4B and a roller 4B, the roller 49 being arranged to engage a cam carried by the yoke portion or the tripping member 30. Associated with the latching memberl `is a spring 5I which surrounds the shaft 41 and tends to rotate the latching member 46,. in a clockwise direction, as viewed in the drawings. It will be apparent, however, that the cam 50 exerts a force on the roller 43 when the roller and the cam 'are in the engaging position shown in Fig. 2, which force tends to rotate the latching member in a counterclockwise direction about the pivot pin 41. This latter force which is exerted by the tripping springs 3l, is considerably greater than. the force of the spring 5I0 and consequently the latching member 4B is predominantly biased for movement in a counterclockwise direction from the latching position shown in Figs. 2 and 3 to the releasing position shownin Fig. 4, movement or the latching member to this releasing position normally being restrained by engagement of the latch tip 4B with the periphery of a rotatable trip shaft 52.

As shown, the trip shaft 52 is supported in suitable slots 53,(Figs. 3 and 4) formed in the supporting plates 42 and 43 and is restrained against transverse movement `in these slots by a pair of notched locking members 54 which, as shown best in Fig. 2, are arranged outside of the plates 42 and 43 and are pivotally mounted on the opposite extending ends of the pin 41. These locking members, as shown, are normally held in locking relation with the trip shaft 52 by suitable screws 55which threadedly engage the supporting plates 42 and 43. The rotatable trip shaft 52, as shown best in Fig. 6, is provided with a plurality of transversely extending arms or trip paddles 56, one of which is arranged adjacent each pole of the circuit breaker. The two outer paddles 56 are formed of insulating material and the middle one of these trip paddles is connected to a spring 51, the otherv end of which is connected to a fixed pin 58 so as to bias the trip shaft for rotation in a clockwise direction. Normally, the trip shaft is retained in the position shown best in Fig. 3 by an'adjustable stop member 59 which is supported on a lug 60 extending inwardly lfrom the supporting plate 42, one end-of the stop member 59 being arranged to engage the lower end of the middle trip paddlel 56. v

In order that the latching member 46 may be released for movement in a counter-clockwise direction in accordance with its bias upon rotation of the trip shaft in a counter-clockwise direction from the position shown in Fig. 3, a portion of the trip shaft in alinement with the latch tip 48 is provided with a notch 6| through which the end of the latch tip moves upon rotation of the trip shaft 52 to a predetermined position.

Although my invention is not, limited thereto, Y

I prefer to arrange the trip shaft 52 and the transversely extending arms or paddles 56 as a v statically balanced unit which is journaled for rotation about an axis passing substantially through the center of gravity of the unit. Such a statically balanced trip shaft is specifically described and claimed in a oopending application of Joseph W. Seaman, Serial No. 78,179, filed May 6, 1936, which application is assigned to the same assignee as the present invention and it has been found that by reason of the statical ly balanced condition of the trip shaft, the shocks imparted to the base of the circuit breaker will exert substantially no rotative moment on the trip shaft.

As indicated above, latch member 46 is released for movement to its releasing position by rotation of the tripshaft 52 against the bias of the spring 51 and it will be understood that the sensitivity of the trip device I is to a large extent dependent upon the force necessary to rrotate the trip shaft. Accordingly, the spring 51 is just strong enough for resetting purposes and the relation of the latching member 46'to the shaft 52 is so adjusted that the latch tip 48 exerts substantially no rotative movement to the shaft.

It will, of course, be apparent that the latch tip 48 which is urged toward the trip shaft 52 by the force of the tripping springs 3| transmitted through the cam 50 and the roller 49 exerts a force of considerable magnitude on the shaft 52. In accordance with my invention, however, the pivot 41 of the latching member 46 and-the axis of the trip shaft 52 are so related that thelatch.

tip 48 moves along an arc passing substantially through the center of the shaft 52. Thus, as shown best in Fig. 8, the latch tip engages the periphery of the shaft 52 substantiallyV tangentially and exerts a substantial radial force on the shaft 52. The notch 6I in the shaft is cut back slightly past the middle of the shaft so that the latch tip 48 is free to move along its arcthrough the center of the shaft when the shaft is rotated to the position shown in Fig. 9. Thus, the only rotative force tending to restrain v:the shaft 52 in its normal position is the force i, on the spring 51 andthe force due to friction between the vlatch tip and the shaft, which frictional force may be minimized by polishing both the latch tip 48 and the periphery of the shaft.

In order to rotate the shaft 52 from its normal position so as to effect release of the tripping member 30 and operation of the circuit breaker to its open circuit position upon the ocvcui-rence of predetermined current conditions, I Yprovide a plurality of shock-proof electromagnetic devices, one of which is associated with each pole of the circuit breaker. These electromagnetic devices are identical in construction and' accordingly only one device will be described.

As shown best in Fig. 5, each electromagnetic device comprises a U-shaped frame 62 formed of non-magnetic material, which frame encircles the conductor 38 and is provided at its open upper end with a pivot pin 63 on which is mount- -ed a magnetizable armature 64. Also, encircling the conductor 38, with its legs extending through suitable apertures in the yoke of the U-shaped member 62, is a U-shaped magnetizable member 65, the legs of which provide pole pieces for attracting the lower end of the pivoted armatura 64 when a predetermined current flows through the conductor 38.

Extending outwardly from the upper end of the magnetizable armature 64 is an adjustable screw 66, the outer end of which is arranged to engage the associated trip arm 56on the trip shaft 52 so as to rotate the trip shaft when the arma ture 64 is attracted by the magnetizable member 65. The armature 64 is normally biased to the unattractf-d position shown inthe drawings by a spring 61k one end of which is secured to a suitable'screw 68 which extends through the yoke portion of theA magnetizable member 65 and the conductor 38 (Fig. the other end of the spring being secured to an adjustable member 69 carried by the upper end of the armature 64,

In 'order to render the armature 64 substantially shock-proof, the armature is pivoted at substantially its center of gravity and accordingly shocks transmitted from the base of the circuit breaker through the U-shaped supporting member 62 will exert substantially no rotative force on the armature. In order further to render the amature shock-proof, I provide resilient stop means for restraining the armature in its unatftracted position against the bias of the spring 61 and for absorbing shocks transmitted from the circuit breaker base through the stop means. As shown, this resilient stop means comprises a fixed and `adjustable screw or stop which is supported on a pin 1I extending between the legs .of the U-shaped support 62, one end of the stop 10 being arranged to engage the free end of a shock-absorbingv leaf spring 12, the opposite end of which is secured to the armature 64 as by At the 12 must be such that shocks will not be transmitted to the armature from the stop 10. Accordingly, the leaf spring 12 is formed of relatively light material and the free end ofthe spring is restrained under tension closely adjacent the lower end of the armature B4 by a suitable pin 14 having an enlarged head, as shown best in Fig. 7. Thus, the spring 12 exerts a force which is great enough to maintain the armature 64 out of contact with the fixed stop 10 and at the same time leaf spring 12 has 'sufficient resilience to absorb substantially all ofV the shocks imparted to the stop 10.

In the preferred form of my invention shown, it will be seen that the end of the shock spring 11 secured to the amature 64 is arranged on one side of the pivot 63 and that the spring extends across the pivot, the free end of the spring which engages the stop 10 being disposed on the opDOsite side of the pivot 63. While my invention is not limited. thereto I have found that this particular arrangement of the shock spring on the armature is highly eilicient in preventing the transmission of shocks to the armature.

It is now believed that a complete understanding of my invention will be facilitated by a description of the operation of the circuit breaker upon the occurrence of predetermined current conditions. With the circuit breaker in the closed circuit position, shown best in Figs. 1, 2 and 3, it will be seen that the tripping member M is restrained against clockwise movement by engagement of the cam 50 with the roller 48, and that the latching member 46 is restrained against counterclockwise movement to its re leasing position by engagement 0f the latch tip 48 with the periphery of the trip shaft 52. Upon the occurrence of predetermined current conditions, one or more of the stationary mag netizable members 65 will be so energized as to attract the lower end of the associated arma ture 64, and accordingly, the armature will rotate in a counter-clockwise directionv about its pivot against the bias of the spring 61, the extending screw 66 thereupon engaging the associated one of the trip arms QB and rotating the trip shaft 52 in a counterclockwise direction from the posi'A tion shown best in Figs. 3 and 8.

As soon as the trip shaft 52 occupies the posiM tion shown in Fig. 9, it will be apparent that the latch tip 4l is released for movement through the notch 6|, Fig. 9 showing the position of the parts an instant after the latch tip 48 is released. Accordingly, the latch member 46 rotates in a counterclockwise direction from the latching poM sition shown in Figs. 2 and 3 to the releasing position shown in Fig. 4 under the force exerted on the roller 49 by the cam 50. When the roller 49 moves out of engagement with the upper surface of the cam 50 during this rotation of the latching member 46, the tripping member is released for movement in a clockwise direction from the position shown in Fig. 2 to the tripping positionL shown in Fig. 4, and accordingly, the movable contacts I3 of .the circuit breaker are operated to their open circuit positions in the manner described above. It will be understood 0f course that as soon as the circuit is interrupted, the magnetizable members 65 are deenergized, and accordingly, the armatures 64 are returned to their normal, unattracted positions by the springs 61. The nal position of the various parts of the trip device after a tripping operation 1s shown in Fig. 4, and it will be understood that the roller 49 is held in engagement with the side of the cam I0, as shown by the spring 5I.

In order to reset the tripping device prior to reclosure oi' the circuit breaker after an automatic operation to the open circuit position, it is necessary to operate the handle I1 in a counterclockwise direction from the position shown in Fig. 2. As is more fully described in the above referred to Linde application, during this counterclockwise movement of the handle Il, the shoulder on the operating member I6 engages the shoulder 36 on the tripping member titi, and accordingly, the trippingmember 30 is moved in a counterclockwise direction against the bias of the tripping springs 3i. During this counterclockwise movement of the tripping member Sil, the roller 49 moves along the side of the cam 50 and as soon as the cam 50 reaches a position slightly below the roller 49, the latching member 46 moves in a clockwise direction under thc bias of the spring 5| to a position in which the roller 49 is directly above the upper surface ci the cam 5U. A suitable stop member 'l5 (Fig. 3), which extends outwardly from the frame plate 43, serves to retain the latching member 46 in this reset position. During this movement oi the latching member 46`in a clockwise direction, as will be apparent upon reference to Fig. 4, the end of the latch tip 48 engages the base of the slot Si and rotates the trip shaft 52 in a ccunteiclock Wise direction against the bias of the spring 5l'. Accordingly, the spring 5| must be somewhat stronger than the spring 5l'.

As soon as the latch tip 48 moves out oi' slot 6l the spring 5l' returns the trip shaft 52 to the normal position shown in Figs. 2, 3 and 4, so

. that upon release of the operating handle il, the

trip device will be held in its normal position, shown best in Figs. 2 and 3. Immediately upon the release of the operating handle Il, the trip-- ping member 30 of course tends to move in clockwise direction under the force exerted by the tripping springs 3l. The upper surface of the cam 5U, however, engages the roller 49 and 'tends to rotate the latching member 46 in a counter clockwise direction. As indicated above'howh4 ever, the trip shaft 52 now occupies its. normal. position, and accordingly, the latch tip 48 engages the periphery of the trip shaft El so as to restrain the latching member 4E and the tripping member.` 3U in the respective positions shown in Fig. 2. The circuit breaker may now be re closed simply by returning the handle il' to the position shown in Fig. 2,as is more iully described in the above referred to Linde patent.

While l Vhave shown a particular embodiment f of my invention, it will be understood, oi course, that I do not wish to be limited thereto since many modifications may be made and i, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a trip device for a circuit breaker, the combination of a rotatable trip shaft, and a pivoted latching member biased for movement from a latching to a releasing position having a latch tip normally engaging said shaft to restrain said latchlng member in said latching position, the pivot of said latching member and the axis of said shaft being so related that said latch tip tangentially engages said shaft to exert a substantially radial force thereon, whereby substan tially no rotative moment is exerted on said shaft by said latching member, said trip shalt having a transversely extending notch therein through which said latch tip moves to said releasing position upon rotation of said trip shaft to a predetermined position.

2. In a trip device for a circuit breaker, the

combination of a cylindrical ltrip shaft mounted for rotation about a longitudinal axis, and a pivoted latching member biased for movement from a latching to a releasing position having a latch tip normally engaging the periphery of said shaft to restrain said latching member in said latching position, the pivot of said latching member and said axis of said shaft being so related that said latch tip tangentially engages the periphery of said shaft to exert a substantially radial force thereon, whereby substantially no rotative moment is exerted on said shaft by said latching member, said trip shaft having a transversely extending notch therein through` which said latch tip moves to said releasing position upon rotation of said trip shaft yto a predetermined position.

3. In a trip device for a circuit breaker, the combination of a rotatable trip shaft, and a pivoted latching member biased for movement from a latching to a releasing position' having a latch tip normally engaging said shaft to restrain said latching member in said latching position, the pivot of said latching member being so related to said shaft that said latch tip moves along an arc passing substantially through the axis of said shaft, whereby substantially no rotative moment is exerted on said shaft by said latching member, said shaft having a' transverse slot extending slightly more than half-way through said shaft so that upon rotation of said Shaft to a predetermined position said latch tip is released for movement along said arc to said releasing position.

4. In a trip device for a circuit breaker, the

,. combination of a cylindrical trip shaft mounted for rotation about a longitudinal axis, and a pivoted latching member biased for movement from may freely move along said arc when said shaft is rotated to a predetermined position to release said latching member for movement to said releasing position.

5. A trip device for a circuit breakercomprising a pivoted latching member biasedjor movement from a latching to a releasing position, a statically balanced trip shaft journaled for rotation, said latching member having a latch tip normally engaging the periphery of said trip shaft to restrain said latching member in said latching position, the pivot. of said latching member being so related to the axis of said shaft that said latch tip is movable along an arc passing through said axis and tangentially'engages the periphery of said shaft whereby substantially no rotative mo- -i ment is exerted on said shaft by said latching member, said shaft having a transverse notch extending more than halfway through said shaft, and current responsive means for rotating said shaft to a position in which said latch tip is released for movement along said arc through said notch, said latching member thereupon moving to said )releasing .f position.

Y6. In a trip device for a circuit breaker, the combination of a releasable latching mechanism,

and shockproof current responsive means for releasing said mechanism comprising a movable magnetizable member, means pivotally mounting said member for rotation about its center oi' gravity, whereby the rotative position of said member is substantially unaffected by shocks imparted to said pivot means, means biasing said magnetizable member forrotation in one direction, resilient stop means for restraining said member in a predetermined position against the force of said biasing means and for preventing the tarnsmission of shocks from said stop means to said member, whereby sai-d member is substantially unaffected by shocks imparted to said stop means, and electromagnetic means for rotating said magnetizable member against the force of said biasing means to effect release of said mechanism.

7. In a trip device for a circuit breaker, the combination of releasable latching mechanism, and shock-prooftcurrent responsive means for releasing said mechanism comprising a movable magnetizable member, means pivotally mounting said member for rotation about its center of gravity, whereby the rotative position of said member is substantially unaffected by shocks imparted to said pivot means, means biasing said magnetizablemember for rotation in one direction, a xed stop adjacent said magnetizable member, a shock-absorbing spring carried by said member and arranged to engage said stop to restrain said member in a predetermined position, the stiffness of said shock spring being such that said member is held out of direct engagesaid predetermined position against the force of said biasing means to effect release of saidlatclring mechanism.

8. In a trip device fora circuit breaker, the

combination of releasable latching mechanism,

and shockproof current responsive means for releasing said/ mechanism comprising a movable magnetizable member, means pivotally mounting said member for rotation about .its center of gravy ity, whereby the rotative position of said member is substantially unaffected by shocks imparted to said pivot means, means'biasing said magnetizable member for rotation in one direc` Ation, a flxedstop adjacent one end of said magnetizable member, a relatively long leaf spring having one end secured to said member and its free end arranged to engage said stop to restrain said. member in a predetermined position, the

length and stiffness of said leaf spring being .mounting said armature for movement about its center of gravity, whereby the position of said armature relative to said pivot meansis substantially unaffected by shocks imparted to said pivot means, means biasing said armature for movement Vfabout its pivot in one direction, resillent stop means for restraining said amature in a predetermined position against the force oi' said biasing means and for preventing the transmission to said amature of shocks imparted to said stop means, and electromagnetic means energizable to attract said armature against the force oi said biasing means.

10. A shockprooi' electromagnetic release device comprising an armature, means pivotally mounting said armature for movement about its center of gravity whereby the position of said amature relative to said pivot means is substantially unaffected by shocks imparted to said pivot means, means biasing said armature for pivotal movement in one direction, a fixed stop adjacent one end of said amature, a relatively long leaf spring carried by said armature arranged to engage said stop, the length'4 and stinness of said leaf spring being such that said armature is held out of direct engagement with said stop against the force of said biasing means to prevent the transmission to said amature of shocks imparted to said stop means, said leaf spring absorbing substantially all of said shocks, and electromagnetic means energizable to at tract said amature against the force of said biasing means.

1i. A shockproof electromagnetic release device comprising an amature, means pivotally mounting said armature for movement about its center of gravity whereby the position of said armature relative to said pivot means is substantially unaffected by shocks imparted to said pivot means, means biasing said armature for pivotal movement in one direction, a fixed stop adjacent a portion of said amature on one side ment with said stop against the force of said biasing means to prevent the transmission to said amature of shocks imparted to said stop means, said leaf spring absorbing substantially all of said shocks and electromagnetic means energizable to attract said amature against the force oi' said biasing means.

12. In a shockproof trip device, a releasing member pivoted for movement between two positions, means biasing said member toward one ol.'y

said positions, rigid stop means arranged in the path of movement of said member for restraining `said member in said one position, and a shockabsorbing spring carried by said member and arranged to engage said stop means, the stiffness oi' said shock spring being proportioned relative to the strength of said biasing means and the mass of said member so as to hold said member out of direct engagement with said rigid stop means to prevent the transmission to said member oi' shocks imparted to said stop means, said shock spring absorbing substantially all oi' said shocks, and means for moving said member to the other of said two positions against the force of said biasing means. A.

13. 'in a shockproof trip device, a releasing member pivoted substantially at its center of gravity, means biasing said element for pivotal movement in one direction, a xed stop arranged in the path of movement of said member, a relatively light'leaf spring extending longitudinally of said member with one end rigidly secured f-thereto. means for restraining the other end of said spring under tension in close proximity to said member, a portion of said spring being arw ranged to engage said stop to restrain said member in a predetermined position, the tension in said spring being such as to hold said member ont of direct engagement with said stop against the force of said biasing means to prevent the transmission to said member of shocks imparted to Asaid stop, said relatively light spring absorbing tions, means biasing said member toward one oi said positions, a fixed stop arranged on one side of the pivot of said member in the path of moven ment of said member, a relatively light leaf spring extending longitudinally of said member with yone end rigidly secured to said member on the opposite side of said pivot, means for restraining the other end of said spring under tension in close proximity to said member, a portion of said spring being arranged to engage said stop to restrain said member in a predetermined position, the tension in said spring being such as to hold said member out of direct engagement with said stop against the force of said biasing means to prevent the transmission to said member of shocks imparted to said stop, said relatively light lealY spring absorbing substantially all of said shocks, and means for moving saidmember about its pivot against the force of said biasing means.

l5. A trip device for a circuit breaker comprism ing a rotatable trip shaft, a pivotedL latching i member biased for movement from a latching to a releasing position having a latch tip normally engaging said shaft to restrain said latching member in said latching position, the pivot oi latching member and the axis of said shaft being so related that said latch tip tangentially engages said Ishaft to exert a substantially radial force thereon whereby substantially no rotative mo ment is exerted on said shaft by said latching member, said4 trip shaft having a transversely,T extending notch therein through which said laten tip moves upon rotation oi said trip shaft to a predetermined position, means for rotating said trip shaft including an armature pivotally mount-- ed at its center of gravity, means biasing said r armature for movement in one direction, resilient `stop means for restraining said amature in a biasing means to rotate said trip shaft whereupon said latch tip is released for movement through said notch to said releasing position.

16. A trip device for a circuit breaker comprising a cylindrical trip shaft mounted for rota tion about a longitudinal axis, a pivoted latching member biased forv movement from a latching to a .releasing position having alatch tip normally engaging the periphery of saidshaft to restrain said latching member in said latching position. the pivot of said latching member being so related to said axis that said latch tip moves along an are intersecting said axis, whereby substantially no rotative moment is exerted on said shaft by said latching member, said shaft having a transverse notch therein extending more than half way through said shaft so that said latch tip may freely move along said arc when said shaft is rotated to a predetermined position, means for rotating said shaft including an armature, means pivotally mounting said armature for movement about its center of gravity whereby the position of said armature relative to said pivot means is y substantially unaffected by shocks imparted to said pivot means, means biasing said armature for pivotal movement in one direction, a fixed stop adjacent one end of said armature, a relatively long leaf spring carried by said armature arranged to engage said stop, the length and sti'- ness of said leaf spring being such that said armature is iheld out of direct engagement with said stop against the force of said biasing means to prevent the transmission to said armature of shocks imparted to said stop means, said leaf spring absorbing substantially all of said shocks, and electromagnetic means for attracting said amature against the force of said biasing means to rotate said trip shaft whereupon said latch tip is released for movement through said notch to said releasing position.-

' ROBERT W. SMITH.

DISC I Al M E R 2,067,797.-Robe1"t W. Smith, Alden, Pa. CIRCUIT BREAKER. Patent dated Jan- Ilary 12, 1937 Disclaimer led February 17, 1938, by the assignee, General Electric Company. Hereby enters this disclaimer to claims 1, 2, 3, and 4 of said Letters Patent.

[Oficial Gazette March 15, 1988.]

DISC I Al M E R 2,067,797.R0be1"t W. Smith, Alden, Pe. CIRCUIT BREAKER. Patent dated January 12, 1937. Disclaimer filed February 17,1938, by the assignee, General Electric Company. Hereby enters this disclaimer to claims 1, 2, 3, and 4 of seid Letters Patent.

[Oficial Gazette March 15, 1938.]

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