US2491657A - Shockproof tripping armature - Google Patents

Description

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/'/.C, Graf/ef r/Z Patented Dec. 20, 1949 UNITED STATES PATENT GF'FI-CE SHOCKPROOF TRIPPIIIG ARMATURE Herbert C. Graves, Jr., West Chester, Pa., assignery toV I-T-E Circuit Breaker Company,` Philadelphia, Pa., a corporation of.'r Pennsylvania Application May 28, 1943 Serial No. 488,841

8 Claims.

My present invention relates to circuit breakers and more particularly to tripping mechanisms therefor which are so arranged that while they may quickly respond to overcurrent or short circuit conditions of a predetermined nature, they will be ineffective to result in false tripping of the circuit breaker in the event of physical impact or shock.

More specifically, my invention provides means for absorbing the kinetic energy of a moving armature of a tripping mechanism. Where the movement of the armature has resulted from a sharp physical shock; and the arrangement of such means so that it will not impede movement of the 'armature in response to predetermined circuit conditions.

In the construction and operation of most circuit breakers, a movable Contact arm is normally spring biased toward open position and is held in closed position where the movable contact is in current conducting relation with the stationary contact by a plurality of links or toggles, which in turn are supported by a latch. Movement of the latch to non-supporting position will thus permit the opening spring to be effective.

In circuit breakers of this type, a tripping mechanism is provided which will automatically operate the latch to non-supporting position upon the occurrence of predetermined circuit conditions.

Generally, such overcurrent devices include a series coil `which energizes a magnet in accordance with the load conditions. An armature is arranged in such manner that it may be attracted by the magnet, but is normally biased away from the magnet. Upon the occurrence of no importance in ordinary stationarily mounted circuit breakers. Where, however, the circuit breaker is to be subject to sudden and extreme physical shocks or impacts, false operation of the armature may be induced by reason of such shocks or impacts to cause the armature to move to trip the circuit breaker.

This problem is of utmost importance in the case of circuit breakers mounted on naval vessels.

Originally, circuit breakers intended to be used on naval vessels were designed with sufficient shock resistance to remain closed with some degrec of consistency under conditions of broadsides red by ships on which the circuit breakers were located. While such shock resisting arrangements might have tended to slow up the tripping operation of the circuit breaker, they nevertheless made it possible, under most such shock conditions, (arising from recoil of gun re) to maintain the circuit breaker in closed position by reason of its inherent design.

The introduction of aerial warfare into naval combat has posed an entirely new problem in the design of circuit breakers suitable for combat vessels. It has been found that tremendous shocks, far exceeding a broadside shock, are imposed by near misses of bombs dropped from planes. The intensity of these shocks has resulted in a considerable modification in the design and test requirements of such devices, in order to assure their suitability for application on ships. The shock tests have been increased many fold over the old requirements. Materials and switchboard structures have been modied in the effort to preventv false tripping.

One of the essential elements which has been requiredvto be modified, owing to this change in naval combat tactics, is the overcurrent feature off the circuit breakers.

Since previous circuit breaker structures were found unsuitable with respect to physical shocks of this kind, hold-in and lock-in devices were incorporated to prevent breakers fromopening under conditions of shock. Many` such hold-ins and lock-ins for preventing false tripping under shock conditions were designed actually to engage the latch or the armature and prevent any movement thereof while the hold-in or lock-in device was in `Lroerative position: other hold-in or lock-in devices have been designed to support the breaker mechanism links or toggles irrespective of movement of the latch.

It has been recognized, however, that hold-ins or lock-insof this type. While of real importance and usefulness, were rather an immediate wav of dealing with a pressing problem and were hazardous inA that they prevented the automatic opening of the circuit breaker under short circuit conditions when thebreakers werev locked closed.

The primary object, therefore, of the present invention is the arrangement of the tripping armature of a circuit breaker, so that it will be readily responsive to selected overcurrent and short circuit conditions, while it will not be movable in response to physical shock conditions to a sufcient extent to trip the circuit breaker.

The ultimate desideratum is to produce a tripping mechanism which will be quick acting, will respond freely to circuit conditions; but which will not respond to physical shocks; in other words, one which will distinguish between circuit conditions to which it should respond and physical shocks to which it should not respond.

Several methods have previously been attempted in order to attain a result of this type. The oldest form consists of balancing the armature so as to prevent its operation on shocks from any direction. A proper balancing of the armature may actually result in preventing faulty operation or undesired operation under physical shock conditions. However, the balancing of the armature, as well as of its time delay sucker disc to produce a perfectly balanced system, increases the weight thereof and its inertia.

Also, when the armature is balanced, in addition to being heavier, it may still give faulty operation by virtue of a stop against which it must rest. This stop, working against one portion of the armature, may give it a rotational movement with reference to the pivot pin of the armature. IIhat is, the physical shock to the vessel itself, resulting from a near miss of an aerial bomb, or a direct hit in some part will be transmitted to the stop, and from the stop will be transmitted with virtually ballistic forceto the armature.

In any event, in a device having such a stop, rotational movement is bound to result as an incident of shock. This will necessarily result in movement of the armature, and its very inertia carries it through to trip the breaker.

My present invention overcomes all of these undesirable previously existing characteristics by latching the armature in an automatically releasable manner, so that:

1. The armature need not be balanced.

2. The weight of the time-delay sucker disc need not be counterbalanced.

3. The rotational impulse, given to the armature as a result of shock, does not result in tripping of the breaker.

4. The armature does not require counterbalancing and the resultant increase in inertia.

Essentially, my invention contemplates that the initial force of movement of the armature, owing to physical shock, be absorbed by causing it to strike against a movable but heavier mass.

Thus, while the armature may be given an initial almost ballistic movement by a physical shock and although, through its own inertia, it would then normally continue through to trip, a relatively heavy mass is interposed in its path of movement; and the work done by the armature in causing this mass to begin to move absorbs all of the energy of the moving armature, and causes it to come to rest while the interposed mass continues its movement. The interposed mass is arranged, however, so that its movement has no operational effect, that is the movement of the mass will not trip the breaker nor cause the armature to trip the breaker; and thus, this mass acts as a shock absorber.

The action, above described, is virtually the same as that which occurs when a billiard ball moving quickly strikes another ball and comesto a dead stop; while the other ball absorbs all the energy of the first ball and is thus brought into rapid movement.

The physical shock to which a ship is subjected by a bomb or broadside impinges on the armature a force which, while it is considerably more intense than the pull exerted by its magnet, is of much shorter duration, being substantially instantaneous. On the other hand, the magnetic pull lasts as long as the short circuit or overcurrent condition exists. My novel structure thus, in effect, provides a time distinguishing characteristic responsive to the longer but less intense magnetic pull, but unresponsive to instantaneous physical shock.

It must here be borne in mind that the kind of physical shock thus guarded against is not so much the accelerating action of movement or heeling over ol' the ship as a whole, but rather the wave motion or vibration transmitted through the metallic structure of the vessel at a speed of the order of 16,000 feet per second and having a force directly proportionate to the impact. Thus should a bomb explode at or near one end of the ship, that impact will be transmitted through the metallic structure of the vessel to everything in contact therewith almost instantaneously and long before the ship as a whole begins to heel, swerve, skid, or otherwise move in response thereto.

Another and most important object of my invention, therefore, is the provision of means for absorbing the kinetic energy of a moving armature where the movement of the armature has resulted from a sharp physical shock.

Another and corollary object of my invention is the arrangement of such means so that it will be ineffective to prevent the complete movement of the armature in response to predetermined overcurrent or short circuit conditions.

A further object of my present invention is the arrangement of a circuit breaker armature and magnet in such manner that an additional mass is interposed in the path of movement of the armature toward the magnet, so that the armature must impart motion to this mass in the course of its movement toward the magnet.

Another object of my invention includes the arrangement of such mass in the path of movement of the armature to the magnet, so that the said physical mass will be effective to absorb the kinetic energy of the moving armature owing to a physical shock, but will not be effective to prevent the movement of the armature toward the magnet under conditions in which the magnet exerts a pull on the armature which exceeds a predetermined amount.

Another and more speciiic object of my invention is the provision of a rotatably mounted mass in the path of movement of the armature toward the magnet, wherein a portion of the armature will strike a portion of the rotatably mounted mass during the course of its movement to the magnet, and wherein the rotatably mounted mass will be brought into movement, and thereby exhaust all of the kinetic energy of the armature owing to the physical shock; but where the rotatable mass will continue to move out of the path of movement of the armature where a steady vpull is exerted on the armature to a predetermined extent by the magnet.

Another and more specific object of my invention is the arrangement of such a physical mass so that it will be given a plurality of short motions in different directions in the course of the movement of the armature toward the magnet; so that in the event that the armature is brought into '2,49 new movement by physical shock, themulti-directional movement of the mass.V will absorb the kinetic energy of the armature; while, under the influence of a steady pull of predetermined extent exerted by the magnet, this multi-direction movement of the mass willpermit the armature to reach the magnet.

Another object of my invention is the provision of means for attaining proper sequential operation of main and subsidiary circuit breakers in the event of a short circuit condition in a subsidiary circuit.

These and many other objects of my invention will become apparent in the following description and drawings in which:

Figure 1 is somewhat schematic cross-sectional view of a circuit breaker showing the mounting thereon of a shock proof tripping unit of my invention, the circuit breaker being shown in the closed position.

Figure 2 is a view corresponding to that of FigureV 1 showing the circuit breaker in tripped position at the moment that the armature has been fully attracted by the magnet.

Figure 3 is a side view of the overcurrent feature of the circuit breaker of Figure 1, showingthe condition of the elements at rest and the armature in the non-tripping position.

Figure 4 is a view corresponding to that of Figure 3 showing the condition of the elements of Figure 3 under shock or physical impact conditions and demonstrating the manner in which the kinetic energy of the armature is absorbed by the rotatable mass interposed in the path of movement thereof.

Figure 5 is a view corresponding to that of Figure 3 and 4 showing the armature in fully attracted position to trip the circuit breaker, and demonstrating the manner in which the mass interposed in the path of movement of the armature may, when the armature is attracted by the magnet, be moved to a position which permits the armature to complete its tripping movement.

Figure 6 is an isometric View of the overcurrent device of Figures 3 to 5 showing the armature in non-tripping position.

Figure 7 is a front elevation view of the overcurrent feature in non-tripping position, taken from line 'l-'l of Figure 1 looking in the direction of the arrows.

Figure 8 is a schematic representation of the principles involved in the absorption of the kinetic energy of the armature during its movement under physical shock conditions.

Figure 9 is a side View of a slightly modified form of shock absorbing armature construction showing the armature and associated elements in the at-rest position.

Figure 10 is a View corresponding to that of Figure 9 showing the armature of Figure 9 in the shock absorbing position.

Figure 11 is a view corresponding to that of Figures 9 and 10 showing the armature in the fully tripped position.

Figure 12 is a front View of the armature assembly.

Figure 13 is a side View of an additional modiiied form of shock absorbing arrangement for an overcurrent, feature showing the armature and shock absorbing elements in the at-rest position.

Figure 14 is a view corresponding substantially to that of Figure 13 showing the arrangement of the elements of Figure 13 in the shock absorbing position. l

Figure 15 is a side` View corresponding to that of Figures 13 and 14 showing the arrangement of the elements thereof in the fully tripped position. Figure 16 is a schematic side Viewv of a modified form of overload feature showing the position of the elements in the at-rest position.

Figure. 17 corresponds to that of Figure 16 and illustrates one shock absorbing position of the members of Figure 16.

Figure 18 corresponds to Figures 16 and 17 illustrating another shock. absorbing position of the elements of Figures 16 and 17.

Figure 19 corresponds to Figures 16, 17 and 18 showing the fully tripped position of the members.

Figure 20 is an isometric view showing the relationship of the parts ofthe elements of Figures 16 to 20.

Figure 21 is a side View of a still further modied form of shock absorbing arrangement for the overcurrent feature showing the armature and shock absorbing elements in the at-rest position.

Figure 22 is a view corresponding to that of Figure 2l showing the arrangement of the elements of Figure 21 in shock absorbing position.

Figure 23 is a view corresponding to that of Figures 2l and 22 showing the arrangement of the elements in the fully tripped position.

Referring now to Figures 1 and 2, I have here shown somewhat schematically atypical form of circuit breaker in which my overcurrent feature is particularly useful. The circuit breaker itself forms no part of the present invention but is constructed and operates substantially in accordance with the disclosure of application Serial No. 332,637 of William M. Scott, Jr., now Patent 2,251,884, assigned to the assignee of the present invention.

However, a brief description of the operation of the circuitV breaker will be useful in order fully to understand the function of the overcurrent feature of the present invention:

The circuit breaker of Figures 1 and 2 cornprises a back panel 26 through which is mounted the back connection studs 2-I and 22. Current is led from the back connection stud 2| through the main stationary contact 23 to the main movable contact 24, then through the pigtail 25 to the terminal block 26, and then through the lower back connection stud 22. An overcurrent coil 35 is arranged to be energized by current passing through the lower back connection stud 22, and in turn energizes the magnet 3i of the overcurrent feature. The movable contact 2li is rotatably mounted at 35 on the movable contact carrying arm 36, which in turn is mounted on the contact bar 31. This contact bar is rotatable clockwise and counterclockwise on bearings (not shown), in order to cause the contact arm 36 to move between the closed and open positions of Figures 1 and 2.

An arm lil, rigidly secured to the contact carrying bar 31, is pivotally connected at its outer end to the link i12 which extends from the operating mechanism 43. Details of the operating mechanism are not here shown, but-it is sufficient to note that the raising of the solenoid armature le will be effective to operate the operating mechanism to raise the link 42 to Icause rotation of the movable contact carrying arm 36 from the position of Figure 2 to the position of Figure 1; or the handle member 45 may be effective to perform the same operation..

Any suitable latch member may be utilized within the operating mechanism 43 to support the link 42 in the position of Figure 1. This latch may be so arranged that movement of the arm 4'! from the position shown in Figure 1 to the position shown in Figure 2 will serve to trip the latch and thus remove support from the link 42.

The operating mechanism contained within the housing i3 may be of the type which is more fully described in detail in the application of Frank J. Pokorny, Ser. No. 339,682, now Patent 2,390,735, assigned to the assignee of the present invention.

The various other elements of the circuit breaker structure shown in Figures 1 and 2 are described in full detail in the applications above noted; and since the particular form of circuit breaker is no part of the present invention, and since the shockproof overcurrent feature of the present invention may be applied to many types of circuit breakers, the details of the particular circuit breaker here shown will not be further described.

The entire overcurrent feature 50 of Figures 1 and 2 is more clearly shown in Figures 3 to 8 inclusive.

Figure 3 shows the overcurrent feature in a condition where the position of all of its elements correspond to the condition of Figure l. The position of the elements of the overcurrent feature of Figure 5 corresponds to that of Figure 2.

Referring now to Figure 3, the armature comprises a member 6B of magnetizable material, preferably laminar in form, and mounted on the arms 6I, which in turn are rotatable on the pin 62. A striking member t4, preferably one on each side of the armature, is also rotatably mounted on the pin 62. This striking member is integrated in any suitable manner with the armature member so that it will operate therewith as a single unit. In the construction here shown, this is achieved through a pin 65, carried by the armature-carrying arm l l, which passes through a suitable opening in an extending lug 66 of the striking member 64.

It will be clear from the various positions of the armature shown in Figures 3, 4, and 5 that the striking member 64 is essentially to be regarded as a part of or an extension of the armature movable therewith at all times. Thus, Where the armature is moved from the at-rest or normal position of Figure 3 (hereinafter to be described) to the position of Figure 4 by a physical shock, the striking member moves therewith, as is clear from Figure 4; and when the armature is fully attracted to the tripping position, as shown in Figure 5, the striking member 64 also moves therewith.

A mass 'lil is rotatably mounted on each side of the armature on the pin 1I. The effectiveness of the mass lil, which is relatively great with respect to the mass of the armature 60 and its attached parts, may, where it is deemed desirable, be increased by mounting additional Weight members l2 on the pin 'il and connecting these weight members to the mass 'Hlv in any suitable manner as, for instance, by the bolts or rivets 13.

The striking member 64, in the embodiment here shown, is shaped somewhat in the manner of an escapement lock and is provided with an inwardly projecting abutment 15. The abutment 'l5 is so arranged that on rotation of the armature and striking member from the position shown in Figure 3 to the position shown in Figure 4 it will come squarely into contact with the abutting surface 16 on the rotatably mounted mass 1D. This latter abutting surface 16 is defined by a lower ledge on the mass 1U, which ledge, in its maximum counterclockwise position shown in Figure 3, provides just sufficient clearance for receiving the surface of the lower end 8l of the striking member 64. This surface 8l is curved on a radius r from the pin 62, and this radius is equal to the distance from the pin 62 to the lower edge of the abutment 'i6 of the mass ID (when the elements are in the position of Figures 3 and 4); so that when the abutment 'l5 on the striking member 64 is rotated into contact with the abutment 'I6 on the mass 1B, they will meet squarely, as shown in Figure 4. Likewise, the surface 80 of the mass lll is so arranged that in the positions of Figures 3 and 4 all parts thereof will be at a distance greater than the radius from SEZ-8|, so that the surface 8l may clear the surface 8D.

It will now be clear that in the event of a physical shock, which causes the armature Bil and its carrying arm El to rotate upwardly with respect to Figure 3, the striking member 64 will rotate in a clockwise direction with the armature. This simultaneous clockwise rotation of the striking member will result in the abutment 'l5 thereof striking against the abutment 163 of the mass 1U. The torque in the rotating armature Bil, its carrying arm 6l, and the striking member S4 will thus ce absorbed by the mass 1E) and the additional weights 'l2 which are integral therewith. These latter members lil and i2 will thus be brought into rotation and will fully absorb all of the kinetic energy of the members 6B, 6I and 64.

Consequently, any physical shock or impact which will jar the armature into movement will cause the striking member to drive against the mass 'l0 and 1L.. The absorption of energy of movement of the armature with the transfer of this energy into rotational movement of the mass 'l0 and its weight 'l2 around the pin 'll will thus bring the armature te to a halt in the position of Figure 4 before it engages the tripping mechanism.

The armature 6D and its associated elements 6| and 64 will thus be restored to its normal position while the mass Ill-'l2 moves. The angular movement of mass 'IU-82 and the speed thereof will depend, of course, on the comparative mass of members 'l0-12 with respect to the mass oi' members 60-6l-64 and the initial speed originally imparted to the members Gli-6 I-64.

In any event, the mere fact that the much greater mass 'I0-'l2 is brought into movement by the operation previously described will result in the halting of movement of the members t- 6l--64.

The relative masses of the two members are such that this absorption of the kinetic energy of the moving armature is complete at the moment that the armature mass impacts mass H3-72 and the latter is brought into movement.

It will be understood, of course, that these movements are predicated on the fact that the shock which set the armature members in motion, while tremendous, is instantaneous; so that when the armature dissipates its kinetic energy in the mass 'Hl-"l2, it no longer drives toward the trip position, but rather is restored to the normal position.

It is essential that the parts be so arranged that the very physical shock which brings the armature into movement will not be effective to move the mass l0-'l2 to a position where it will no longer block the movement of the armature.

Accordingly, the striking member 64 is provided on the side thereof opposite the abutment 15 With-fan .extension 83, which extension (in the positionI of Figure 3) rests .opposite the recessed surface 85 of the mass 10.

Inthe position of rest of Figure 3, the mean distance cZ-from the center of pin 62 to the surface 85 is substantially equal to the radius r, while the space between the end 83 of the striking member 64 and the -surface 85 is less than the height of the abutments 15 and 16. Consequently, under conditions of extreme physical shock, which may result not only in the movement of the armature but also in the simultaneous rotation of the mass 1li- 12, the rotation of the mass 19-12 is limited toa degree of movement equal to the space between surfaces 85 and 33. In other words, under extreme physical shock both members 64 and may rotate, but the latter will not succeed in moving surface83 out of the path of surface v85. Accordingly, the latter surface will strike against surface 83 stopping further movement of member 10; but since this degree of movement is not sufficient to cause a complete lack of registry of the abutments and 16, then,*on continued movement of member 64, the abutment 15 will still be lin a position to strike against the abutment 16 in order that the mass 1'6-12 may absorb the shock of movement of the members 60-6'|'62.

As will be clear in Figure' 4, however, when the abutment 15 vstrikes against the abutment 1'e, the extension `83 of the rstriking member has moved out of registry with the surface 85 of the mass and into a position where'it is opposite the surface 95 of the mass, the latter surface being recessed from the surface 85. Herma greater clearance is provided between the surface 90 and end 83 to permit rotation'of themass A1li-12. This clearance is here shown as greater than the sum of the heights of the abutments 15 and 16.

Accordingly,'when extreme physical shock occurs,`even though the armature and the mass are simultaneouslybrought into movement, the mass is preventedfrom moving'to a position where it will fail 'to absorb vthe impact of the armature until'this actual impact occurs.

"At the time of this impact, the members move to a position where the mass is lfree to rotate, so that rotativev movement may be imparted to the mass so that it may, on the initiation of such rotation, absorb the Vshock of movement of the armature. Y

As will be obvious from Figures 3, 4, and. 5, a latch'engaging member 92 is rotatably mounted and rotatable with the pin 62. An adjusting screw 93, carried by the arm 6 I, bears against the surface 94 ofthe latch engaging member 92, so that when the armature 60 and its arm 46l rises, the latch engaging `member 9'2 is caused to rotate ina clockwise direction.

As willbe seen in Figure 3, the latch engaging member in the at-rest `position of the overcurrent feature is completely out of engagement with the latch tripping arm 41.

In the position of Figure 4, where theshock absorbing condition is shown, it is clear lthat although the latch tripping member 92 has been rotated tovso'me extent in a clockwise direction, it has not been rotated sufficiently to engage the latch tripping arm 41.

In the position shown in Figure 5., where the armature has been moved by magnetic pull to its full extent, the latch tripping member 62 has engaged the' arm 41 and rotated the same suiciently to result in a tripping operation.

As seen in Figures 6 and 7, the latch tripping arm 92 is biased against'the adjusting screw l93 by the coil spring 96, the center portion of which bears against the surface 91 of thelatch tripping arm 92, and the ends of which bear againstv portions of the arms 6I, the coil spring, of course, surrounding the pin 62. The coil spring is sufciently strong,fso that while itwill yield under the influence of the rotation of the adjusting screw so that it may -properly be adjusted with respect to the distance of member 92 from 41, it will not yield under the influence of an impact transmitted from the adjusting screw 93 to the base of the arm 92.; so that to all intents and purposes (except for the provision for adjustment) the member 92 is integral with members 60- 6|-64.

Thus far, the shock-absorbing aspect of the overcurrent feature has been described. 'It is, of course, essential that this shock absorbing arrangement be such that on actual selected circuit conditions the magnet 3|, when energized, will be able nevertheless to attract thearmature. `This condition will be obvious from an inspection of Figures 4 and 5.

Figure 4 has thus far been described solely from the point of 4View of the shockabsorbing aspect of the invention. However, Figure 4 represents an intermediate stage which occurs not only during movement of member 64 by shock but also during an overload condition where the magnet aiiirmatively and continuously attracts the armature 60. In this case, under such continuous attraction by the magnet-3|, the'v armature 60 will rise'so that the abutment 15 strikes 4against the abutment 16.

This movement is to be distinguished from the previously described operation where the armature rose only under a shock. In the latter case, the force of the shock was `expended at the moment the mass'was brought into movement, since the armature element, when 'striking the mass element, hadonly its own kinetic energy to give up. The absorption of this energy resulted in stopping the armature.

Under an overcurrent condition, yon the other hand, the magnetic pull due to current conditions which causes the armature to rise is continuous during 'the 'rising of the armature and even after abutment 15 strikes abutment 16. Consequently, when the abutment 15 strikes the abutment 16, as shown in Figure 4, the energy which causes the armature to rise is not dissipated, andthe pull of the magnet 3| nevertheless continues. Consequently, the abutment 15 bears'with continuous pressure against the abutment 16 to rotate the mass 10 about its pivot v1| tothe position shown in Figure 5, wherethe abutments 15 and 16 no longer'engage each other. The armature is then free of mass 10 and continues to rise to the fully tripped lposition of Figure 5 where it may exert all its tripping power on trip lever 41 through lever 92. vI-Icre again, the curvature and surfaces of the various elements are important.

Thus, although theoretically it is possible that the surfaces 15 and 16 will separate and move from the position of Figure 4 to the position of Figure 5, when each of these surfaces is normal to their respective directions of movement at the time of. impact, I have found from actual experiinentthat it is desirable to impart a slight slope to these surfaces, in order to permit them to slide with respect toeach other from the position of Figure fl. to the position of Figure 5. This slope has been shown in'A exaggerated form in the drawl1 ings of Figures 3, 4, and 5, but is actually of the order of one or two degrees.

The surfaces 15 and 16 can, of course, move from the relative position of Figure 4 to the relative position of Figure 5 only if net components are in substantially opposite directions. That this condition exists, however, is obvious from an examination of the relative centers about which these abutments rotate. The abutment 15 rotates about the pin 62 under shock or overcurrent conditions in a clockwise direction. The abutment 16 rotates about the pin 1| under shock or overcurrent conditions in a clockwise direction. Since pin 1| is lower than pin 62 and to the left thereof (with respect to Figures 3, 4, and 5), then the continuous movement of these abutments will result in abutment 15 rising and abutment 16 dropping. This actually occurs as is shown by a comparison of Figures 4 and 5.

Accordingly, during overcurrent conditionsv where the armature 60 is continuously attracted by the magnet 3|, the abutment 15 is brought against the abutment 16; and under the continuous rotational movement imparted to the abutment 15 by the magnet and armature, it continues to slide off abutment 16, pushing abutment 16 downwardly until the surface 8| rides up onto the ledge |00. When the surface 8| thus comes into contact with the ledge there is no further impediment to the movement of abutment 15, and consequently the armature 60 may now rise to the pole of magnet 3|, thus tripping the latch. The addition of the shockproof feature to the tripping armature nevertheless results in substantially no appreciable time delay in actual tripping under overcurrent conditions, although, if desired, a time delay may be secured. Under such overcurrent the armature is attracted so that the abutment 15 strikes the abutment 16; and under the continuous pull of the magnet on the armature the abutment 15 simply slides up with respect to abutment 16, and thus rotates the mass 10 out of the way to permit the armature to be moved to full trip position. The slope of abutments 15 and 16 permits this easy separation to occur.

It will be obvious, of course. that the slight slope. previously mentioned, which is given to the abutments 15 and 16, should be only just suicient to permit the members to slide apart under the influence of a continuous pull exerted by the magnet. It has been found that this result may be achieved. as above pointed out, by a slope of the order of one or two degrees to the axis of movement of the abutment 15 at the time it strikes the abutment 16.

In Figures 6 and '1, the actual practical physical embodiment of the structures herein described is shown.

Side plates 0 serve as a housing for the armature and shock absorbing features. Additional L-shaned plates I are secured to anges ||2 of the side plates in order to provide additional support for the pins 1| which have been described. Upper flanges ||3 on the side plates provide means for securely mounting the magnet 3| with respect to the armature. The armature 50 is carried by the arms 6| which are rotatable about the pin 62; the pin 62 is provided with extensions |5 of reduced diameter extending through openings in the side plates; cotter pins I |6 serve to secure the pin in position. Pin 65 is simply for the purpose, previously described, of integrating the striking member 64 with the armature 60 and its arms 6|. This pin, as is obvious from Figure 12 6, is carried by the arms 6| and extends through openings in the lug 56 and the striking member 64.

Since it is desired that all of the weight be in the mass 10 and its associated weights 12, rather than in the armature and its associated members, the arms 6| are only sufciently heavy to provide an appropriate support for the armature 60; and the striking member G4 has an opening |20 in order to decrease its weight. Of course, all of these members must7 however, be sufficiently strong to withstand the shocks which are to be anticipated.

Each mass 10 on each side is rotatable on the pin 1| which is mounted in suitable openings in plates and ||0 on each side. The additional weights 12, which increase the mass of the member 10, are mounted on each side thereof. As shown in Figure '1, these weights are spaced apart sufficiently to permit the striking member 64 to move freely therebetween.

Spacer members |22 of suflicient Width may be mounted on the pins 16 between the plates l l 0 and the weights 12, in order to ensure proper registry between the striking member 64 and the mass 10.

A tension spring |30 may be provided at each side connected at one end to a pin |3| carried by a weight 12, and at the other end to a lug |32 carried by the plate in order to return the mass 10-12 to the rest position of Figures 3 and 6. This spring need exert only suiiicient force to return the members to the position shown and is not maintained primarily for use asa shock absorbing element, since shock absorption takes place, as above described, by reason of the fact that all of the kinetic energy of a smaller mass is absorbed when it strikes the larger mass and causes the larger mass to move.

The at-rest position of the weights of Figures 3 and 6 may be determined by the fact that the end |40 of the weights 12 bear against the lower reentrant flange |l|| of the vertical plates The at-rest position of the armature is determined by any suitable stop or by any timedelay element, such as a dashpot, which is connected thereto.

As will now be obvious, my invention applies DAlamberts principle of inertia reaction of a mass; i. e., that the energy of movement oi a light mass may be imparted to a heavy mass to cause it to take up all the motion of the iirst mass. The relative masses may, of course, be greatly disparate, but this is limited, however, by the fact that the armature and its associated members must be suiiiciently heavy to have sufiicient strength for withstanding the physical shocks; and the larger mass must be suiciently small so that it can be rotated by the armature and be enclosed in a relatively small housing, so that the size of the circuit breaker need not be increased thereby or the elements of the circuit breaker be disarranged.

This limitation, however, may be overcome by the relative arrangement of the parts, as shown in Figures 3 to 5, wherein the abutment 15 is at a relatively great distance from the center of movement of the members 60|5|64, and thus has relatively little leverage, while the abutment 15 of the mass 10 is relatively close to the center of rotation 1|.

As a matter of fact, the abutment 15 is so arranged that it moves around the center 62 and just under the center 1 This relative arrangement of the radial distances of the respective striking abutments from the main lines.

lar pieces of equipment.

their respective centers of rotation multiplies the effective mass ofr the members 'EDTZ "and 1'dis-- penses with 'the necessity for using relatively large masses to effect shock absorption.

In Figure 8 I `have shown lin very schematic form the eiect of this displacementof theabutments from their centers of rotation.

The member 54' of Figure 8 correspondsroug'h ly to the striking member 64; the 'gear teeth A115 correspond roughly to the abutment fifths-pinion 'it' corresponds roughly to the mass 1U; While the weight 12', secured to the pinion 10', corresponds roughly to the additional weights 12'-"car ried by the mass.

Here it will be seen that any movement imparted to the member 64 resulting inrotatlon'of the pinion l and the mass 12 will be at a greater mechanical disadvantage with respect'to the mass 'i2' so that the mass 12 has beenfeffectively multiplied. This essentially is the :condition which is'obtained by arranging the members 'of Figures 3 to 7 so that the abutment-15 is relatively much further from its center 'of rotation than is the abutment 16.

In the foregoing, I have described a shockproo armature which will be inoperativeto trip a circuit breaker on the occurrence of an extreme physical shock, even though it will be readily operable onv the occurrence of overcurrent conditio'ns to effect a tripping operation.

The principle involved is, as above'p'ointed out, similar to that of a billiard ball movingfrapidly over the surface oi'a tablastriking Vanothe'r'billiard ball, and immediately coming Vto' rest 'while it imparts movement to the second ball.

By the vmeans described, it becomes'feasible completely to dispense with hold-in and 4lock-in 'features and the attendant diiliculties thereof which have been previously described.

While hold-in or lock-in features may beand are useful and important, where, for some unusual reason, it is necessary to vma-intain a circuit breaker closed, irrespective of current conditions, and while they are necessary-as attachments to circuit breakers which havealreadybeen designed and built, the present invention is designed primarily to make such hold-incr lock-in elements unnecessary.

As above pointed out, the immediate reaction to the discovery that the severe physical impact of near misses of aerial bombs resulting invirtually unpredictable forces was to'provide schemes for definitely locking the circuit breaker so: that it could not react to 'such forces; and thus re sulted in the development of positive hold-ins and lock-ins. The present invention is kdesigned to obviate substantially 'all necessity for such hold-ins or lock-in features and tol provide a suitable shock-absorbing element which adds no substantial weight to the armature and which will positively prevent false operation of the armature under physical impact. The shock-proof element herein disclosed lwill not interfere but rather will aid proper sequential operation of circuit breakers.

In the proper arrangement ofcircuits-on battleships, as Well as elsewhere, t'it is desirable-toerrange the circuit interrupters so that 4in the event of overcurrent or short circuit on iasubsidiary line, the circuit breaker protecting rvthat. line will trip before any o f thel circuit breakersprotectingl Thus, for proper sequential' operation, a circuit breaker protecting a particular piece of equipment should'trip beforev the circuit breaker' protectingr a 'plurality' of lines to'simi- -This latter circuit "taneous; 'and the initial vmovement given to these Varmatures `under .such overcurrent (while perhaps not as great as that which would beim- 'parted theretounder the physical shock of an aerial bomb) is relatively very great.

Consequently, even though the armature-0f the 'circuit breaker protecting the V-faulty piece 'of equipment trips the circuit breaken'the armaitures ofthe more important circuit breakers may, because of'their inertia, follow through lto complete a tripping operation. This may occurin spite of the fact'that the excess magnetic attraction has ceasedlbecause the circuit vbreaker protectingthe faulty piece-of equipmentrhas interrupted the short circuit.

However, the interposition of 'the venergyiabsorbing element in the path of movement of each ofthe Varmatures ensuresthat should the overcurrent i 'condition lbe 'cleared by interruption of 'the subsidiary breaker before the armature off the :main breaker has' removed its mass'from its' path to 'complete a tripping opera-tion, the inertia energy of movement of this armature will be fully -absorbed by its associated mass and 'Will not follows/through to'trip. This will be particularly true -slo'ped to eiect'" this result. Thus, surface Vt3 of striking --member 'may be sloped atan angle 1to1' the' radia-n d so' that-when the said surface'33 lissubjected to a force having a vector substantially perpendicular thereto, striking membertll -anditsassociated armature would be subjected toa counterc-lockwise rotative force around pin 62. -With respect to the showing of Figure, such `a slope, although it may be relatively slight,

would make 'surface rmore-nearly vertical.

VV:Surface 85 of mass 'ID may then'be correspond igly-fsloped, so that when yitstrikes .surface 83 fit lwill impart'to'it the counterclo'ckwise.rotative force-above mentioned.

Novwshoulda physical shock occur, imparting clockwise movement to the armature andthe strikingmember 64-in the manner previously described, andatthesame time imparting a clock- Wise-movement to mass 'l also fin the manner f previouslyvdescribed; then the slopedr surfaces 83 and will be brought into violent contact. The lslopefof these surfaces would then immediately impart a counter'cl'ockwise' rotative force to the striking member-134 and itsarmature to cause V'it to rebound and prevent a false tripping opera- 'The i degree' of'fcounterclockwise force thus imparted depends of cou-rse on the slope of' surfaces i83'fand-'S85. rAfr'elatively slight slope of the order mores? l l tation o1' the armature under physical shock and drive it back. A greater slope will positively absorb any force which may be imparted to the armature. A lesser slope Will absorb the rotative force of the armature in virtually every instance; but the abutments 15 and 16 serve as a positive safety factor in the event such absorption does not occur.

By this means a definite cam action is provided to return the armature to its original position under shock. Under condition of violent shock, the movement of the armature is at extremely high speed; and this positive return action, made possible by sloping of surfaces 83 and 85 becomes important, since the members may osclllate several times in their limited movement.

The same basic principle applies where surfaces 83 and 85 are sloped as Where surfaces 83 and 85 are not sloped. The energy of movement of the armature is absorbed by the mass 18; and the armature, after imparting all its energy to the mass is immediately brought to a stop. Where surfaces 83 and 85 are sloped, however, the kinetic energy of the mass 18 is also utilized to increase the degree and speed of absorption of the energy of the armature and to positively drive the armature back.

Such sloping of surfaces 83 and 85 will not however interfere with a tripping operation where magnet 3| is energized suiiiciently to attract the armature. In this instance, surfaces 83 and 85 would not ordinarily be brought into contact; but, if they are, the continued attraction by the magnet which applies a positive continued rotative movement to the armature (while mass 10 is not subjected to any such continuous movement) will enable the armature to move the mass out of the way to enable it to trip.

The principles heretofore set forth in connection with Figures 1 to 8 may, of course, be applied in many modified forms to various types of structures, all following substantially the same principle.

In Figures 9 to 12 I have shown one such modified form which utilizes substantially the same elements. In this form, the overcurrent magnet 23| is supported in any suitable manner in the housing 28D. An armature 26|) is rotatably mounted on pin 262 and may be attracted by the magnet 23|. The armature 260 and the magnet 23| are of a well-known type and require no further description. It is sufficient to point out, however, that the adjusting screw 293 on the armature when it is attracted will strike against the arm 241 and will cause this arm to trip.

The striking member 264 is centrally located, as shown in Figure 12, with respect to the armature and extends beyond the pin 262. As has previously been pointed out, it is essential that the striking member be integrated with the armature. Consequently, the striking member 264 has an extension 264e, within the laminations of the armature through which the rivets 26|, which secure together laminations of the armature, pass. A mass 210 is rotatable on the pin 21| and has secured thereto additional weights 212 on either side which are also rotatable on the pin 21|, these weights 212 being integrated with the mass 21|) by the pins 213 which pass through the weights and the mass. Consequently, the members 210-212 form a single integral rotatable weight which operates in substantially the manner previously described.

The striking member 264 is again of escapement formation andhas an extension 28| provided with an abutment 215. This abutment may 16 bear against the abutment pin 216 of the mass 21B- 212. The abutment pin 216, instead of being a specic part of member 218, as in the previous case, is simply a pin securely mounted between opposite plates 212.

Should a physical shock imparted to the armature cause it to move toward the magnet, then, as shown in Figure 10, the abutment 215 will strike the abutment pin 216; and thus the kinetic energy of the moving armature will be absorbed by the mass 210--212 which will then rotate. Since all of the moving energy of the armature will thus be transmitted to the mass Nfl-212, the armature will have no further moment toward the magnet, and a tripping operation will not occur.

Here again, the member 210 is so arranged that should it rotate under physical shock, such rotation will be prevented in the first instance by the ledge 285 of the member 2'56 bearing against the extension 283 of the striking member 268. Consequently, the mass 210--212 cannot under a physical shock rotate into a position where it cannot be engaged by the armature until the armature itself has struck the mass and initiated its movement.

When, as shown in Figure 10, the abutment 215 of the striking member 264 strikes the abutment pin 216 of the mass, then the extension 283 of the striking member moves opposite the recess 290 so that the mass may now rotate. The fact that the surface 298 may now strike against the extension 283 does not interfere with the operation of the shock absorber. All of the moving energy of the armature is absorbed when the mass 21D-212 begins to rotate. Consequently, the armature will normally fall back.

The striking of surface 298 against the extension 283 will have the additional eiect of causing the armature to snap back from the position of Figure 10 to the position of Figure 9.

As previously described, should an overcurrent occur where the magnet attracts the armature, then the armature will first move from the position of Figure 9 to the position of Figure l0; but, owing to the fact that the energy of movement of the armature is not dissipated at this time, but rather he magnet still remains energized to continue to attract the armature and the effective force of the magnet has been increased owing to the greater proximity of the armature, the abutment pin 215 will now push on the abutment 216, pushing it out of the way, as shown in Fig. 1l, so that the armature may reach the magnet.

The operation of the shock absorbing overcurrent feature of Figures 9 to 12 thus follows exactly the principles described in connection with Figures l to 8 and requires here no further elaboration.

It is suiicient to point out, however, that, as seen in Figure l2, the weights 212 are greatly increased, and the armature is relatively lighter. The weight of the striking member 264 is substantially decreased by the curved recess 296. The weight 210-212 is maintained in the at-rest position of Figure 9 by the tension spring 236 which biases the member 216 to a position where its surface 28D bears against the extension 28|. The spring 230 is simply a resetting spring and for purposes of the present invention should not be regarded as having any shock absorbing value.

The responsiveness of the armature to overcurrent conditlons may be varied by the adjustable tension spring 220, Fig. 1l, which at one end is secured to the armature and at the other end is secured to a slide member 22| threaded on the acercar vertical adjusting' screw` 222 which is' mounted' for' rotatable movement onlyL in ther bearingsl 2123, 2242 The pin 2621. which` supports' the` armature, and the pin 21|, which supports' the" weights, are carried between the-sideplates Hl off the" housing and are heldin place by' appropriate Cotterv pins'v 246.

The operation of this overloadI feature is ex'- actly' similar' to that which. has been previously described in connection with Figures ltot;

In: the present case; the' abutment 215i of the striking member 26k shouldl (inV Figure 10)* move intov engagement with the abutment pin- 2.1 (i along. a line which. is substantiallyV an extensim of a radius thereon Therel would beno'. substantial impediment to the. attraction of, the. armature by' the magnet while: the: armature. moves from. t'fl'ie".`

positionioi Figure 10` to: the position 0E Figure.'v 11. The. abutmentI 2F15 may however' be' made to strike. the pin. 216i along. a'. line which is' one;or1'

two: degrees. to theright. or a radius parallel'. to the: path. of movement or. the abutment 2:15'.

Such; slight. displacement by' one? deg-ree willA not interfere with. the: slo'ck. transmitting: charaeter:- of the operation when abutment'.` 211.5: strikes pin. 213;. but Will',. when. the: magnet. attracts the armature',v permitithe abutment 2.15' readily to displace. thepin 216i and'.I slide` over the:` san-ieg. as` shown-ain Figure lill, toresult: in: tripping. the; cirs-zcuitbreaker...

The. armature may be proviued with a. suitable time delay element',. preferably; one which effects-i a time delay under relatively low over'current conditionsg. butt-iss instantaneous/r under high'. over.- cu-rrent's'; or.' short circuits..

In 10"-1` have: shawn a. dashpot' El l1' secured: to the. hlousingir of: the .overcurrentfeature and.. having a tubular member 214i connected by' pini 212;- to the armature@ Thetubular member: contains a compression spring the lower.' end.; of. which bears against thee baseof the tubeand the upper end.` o'f which bears against the-adjust,- ing.- nutA 21.51 Nut 21|.5f is. mountedA onv link 2113. which passes; througharr opening.' in the base. of thetube and isconnected tov the sucker disc 2M; of the dashpot.

The. compressione spring. isv adjusted so that, atovercurrent. conditions. of. predetermineda max.-

imum intensityit issubstantially uncoI-npressible-I and thus acts as' a rigid member connecting sucker disc 2M` and link 2 lf3'to-the.tube:2l=l which is connected' to the armature. The time delay afforded bythey dashpot is thusy obtained..

But. the compression spring is soA adjusted` that under short circuit conditions r excessive overcurrent. conditions, they attraction of the. magnet by the armature will be sufficient to compresslthe.

spring. Under suchV conditions, the armature pulling on ther tube. 2| I- will.' draw itup, compress.- ing` thespring. between. the base. of4 the tube and. the nutZ I5 on linlr 213. Accordinglmthe. arma.- ture may then respond instantaneously irrespec` tive of the time delay for which sucker disc 2114 is adjusted..

Many other modcationsof the basic principles hereindescribedshould now be obvious.

One additional such modied form' is: shownin Figures 13, 14, andV where, however, substantially'the' same basic principles arev applied'.

In Figure 13 I have shown' an armature 360*V which' is rotatably' mountedI on the pin 362" and which is arrangedr to be attractedJ by' the magnet 331' under` overcurrentV conditions; The magnet 33t is energized in any suitable manner as, for

instance, by" the` coil" 33D". This armature and magnet arrangement is weil known andl requires' no' furtherV description. It is` obvious, however; thatvrhen' the` adjustable screw'3`93' on' the' arma'- ture' strike's't'he tripping arm 3'41, the' latch inthe" operating mechanism may be released on' rotation orarnr 34:1' to open the circuit breaker.

A weight 31e is' also' rotatablyY mounted on pin 352;' such1 weight may, of' course; be mounted on either'v side of" the armature' and' may be sym'- metrically arranged in such manner` that" any" weight" 31"@ may' interchangeably' be used' on` the' right' or` left' side. The" Weight is' also` by' this mea-ns perfectly balanced and thus sh'oi'ildl not rotate'onthe occurrence of a' shock; The-weight is provided with a recess' 380 defining an abut# ting' surf-aceJ 3115i TheA armature is provided with an abutment pin 315.

Should; a physical shock causethe' arma-ture 360i to; rise, then thepin* 315 thereofwill, as; shown inl Figurel 14, strike the abuttingsurface 31d of the weight,- thusimparting all of" the energy' of-` the arma-ture to the weight 3-1f' andi causing the'.sainetorotate.V rLhe ltineticY energyoi the armature'. will` thus be absorbedg atl the moment the rriovement.thereof.v is imparted totheA weight.vv 3150; and; thev weight- 3110r begins' to. rotate.

'Ilhe weight 3.10. is. sor mounted. with'A respect t'o' the base 3H or". the l'iousingA thatA the. end' 341k thereof; wilr strike:- the base: 3H of. thev housing: before; the: surface 3.99V within: the recess 380e can: strikeA the pin 3,15. Accordingly,Y the. Weight. 310s cannot follow throughso that the. surface 39115- thereon, hitting the pinA 315 would strike the armature 3stto urge` it. intov tripping position.. By this means also shock absorption. isL achieved in accordance with the principles already set forth.

In.' the event of any overcurrent resulting in appropriate energization .of the maghetto-attract the armature, the armature 360 will first move from the position of Figure 13` tothe position of Figure.Y 14. Since. the magnet, however, is energized and the armature is thus continuously attractedY after the armature has come into con.- tact with the weight 31o, the continuously applied force willl place the weight' STU in motion andthe armature will continue to move to' a point where all of' the parts assume the position shown in lFigure 1'5 and' the tripping arm 3141' contacted.

Here again, all of' the' principles previously' de'- scrib'ed' apply' and need' no' further elucidatibn'.

The at-rest'postion of the Weight 31tisrnai`ntained by' the tension spring' 382i connected at one endVs to.7 apin 3833 of the Weight andi at'- theother end to a bolt 3811 of the-housing. TheE stud? 386-, cush'ionedlby compression.I spring-385, will act as ashock absorber when the mass 316i all'slba'clt-l after hav-ing absorbed. the: sh0ck.

Many other modications. of my shock-absorb ing; device utilizing; the: same principles arepossi.d ble.. 'I.hus, v for instant-ze, in. Figures 16 to.: 20`v I have-shown one further. such modification where the. weight is. given a multi-directionaly movement to eiect shock absorption.

In these iiguresl an` overcurrent magnet 43|. is. arranged toV attract an armature 46d which is mounted" on the arms 451, which in turn are. rotatable about the pin 4F52'. The tripping' element 4'92` of` the armature and the operation thereof corresponds exactly' to the' tripping ele"- ment' 92' of Figm'es' 1 to 8 and is' arranged' to engage' the' tripping' arm' M1' of the' operating' mechanism when the arma-ture has been* f'ul'y attracted".

19 Armature 465 is provided with a pair of extending arms 464 which between them support a striking pin 415. A weight 410 is mounted for rotation in either direction on a pin 41 I. The striking pin 415 passes through the zig-Zag vertical slot 485 in the weight 410.

When the armature is at rest, the position of all of the elements is that shown in Figure 16.

Should a physical shock be imparted to the armature causing the same to rise, then, as shown in Figure 17, the striking pin 415 will strike against the abutting surface 416 within the zig-zag slot 480. Since' the abutting surface 415 is in this case at a substantial angle to the direction of movement of the pin 415, the weight 410 will immediately rotate to the position shown in Figure 18 where the surface 485 of the slot will strike the pin 415.

The kinetic energy movement of the armature, owing to physical shock, should be absorbed immediately upon the beginning of movement fo the weight 410 from the position of Figure 17 to the position of Figure 18; and the armature will no longer continue to rise toward the magnet 431; and the members will fall back to the position of Figure 16.

Should there, however, be any residual energy left in the armature after the pin 415 strikes surface 415, then the striking of surface 4&5 against the pin 415 should serve to absorb this further energy. However, should there be even further residual energy in the armature, then, when the pin 415 strikes against surface 490 within the slot, additional rotational movement will be imparted to the weight 410 in an opposite direction thus absorbing all of the kinetic energy of the armature.

In most cases, all of the kinetic energy of the armature will be absorbed when the pin 415 strikes surface 415 within the slot, and the further slignt rotation movement imparted to the weight 411i will be sumcient to halt the movement of the armature. The rotational movement thus imparted to the weight 415 is itself absorbed when the surface 455 thereof comes into contact with the pin 415. Should there now bey any residual movement within the weight 410 or in the armature 450, all of this residual movement will be absorbed when the pin 415 strikes surface 450. In this case, the movement of the Weight in one direction must be completely reversed, thus absorbing all of the energy of movement of both the weight and the armature; and the armature and weight will then drop back to the position of Figure 16.

In the event, however, that the magnet is energized under overcurrent or short circuit conditions to attract the armature, then, even after the pin 415 strikes surface 416, the continued energization of the magnet will continue to draw the armature up so that the weight will oscillate back and forth as the armature rises from the position of Figure 16 to that of Figures 17 and 18 to the tripped position of Figure 19. Here again, the principles previously described are completely applicable. In this case, as well, the full energy of movement of the armature should be absorbed when the weight begins to move. However, the fact that the weight must oscillate back and forth as the armature rises ensures that the moving energy of the armature is completely absorbed.

In Figures 21, 22, and 23, I have shown a 20 modification of the construction of Figures 13, 14, and 15 wherein the shock absorbing element is in contact with the armature in the at-rest position but serves to absorb any shock transmitted to the armature.

In Figure 2l I have shown an armature 560 which is rotatably mounted on the pin 562 and is adapted to be attracted by magnet 53| under overcurrent conditions. This magnet is energized in any suitable manner as, for instance, by the coil 5311.

The armature and magnet arrangement correspond substantially to that of Figures 13 to 15; and the operation wherein the adjustable screw 593 strikes the tripping arm 541, and the resultant release of the tripping mechanism of the circuit breaker also corresponds to that described in connection with Figures 13 to 15.

Weight 518 is also rotatably mounted on pin 552. A similar weight may be mounted on opposite sides of the armature and may, if desired, be symmetrically arranged so that weights may be interchangeably used on either side. The weight is also symmetrically balanced around the pivot point 562 so that it itself is substantially shock-proof.

Weight 510 is provided with a recess 580 defning an abutting surface 516 which bears against the abutment pin 515 of the armature 560. Should a physical shock for any reason be transmitted to the armature 560, then this shock through the abutment pin 515 will be transmitted to the abutting surface 516 and hence to the weight 5113.

The movement of the armature 560 in consequence of the shock will thus be transmitted to the weight 510, and the kinetic energy of movement of the armature will thus be immediately imparted to the weight 510 so that the weight will rotate from the position shown in Figure 21 to the position shown in Figure 22.

Owing to the fact that the kinetic energy of movement of the armature 560 is thus absorbed by the bringing of the weight 510 into movement, the armature 560 will move only slightly and will come to a stop, as shown in Figure 22, while the weight 510 continues to move.

Weight 510 is so mounted with respect to the base 5H of the housing that the end 545 thereof will strike the said base before the surface 590 of the recess 580 can strike pin 515.

Accordingly, weight 510 will not follow through to vpush the armature upwardly. By this means, the shock transmitted to the armature will be transmitted to the weight 515 and absorbed by the movement thereof.

In the event of an overcurrent resulting in energization of magnet 531, the armature 550, under` the continuously applied force of the magnet, will move from the position shown in Figure 21 to the position shown in Figure 23. The continuously applied force of the magnet will in such case be suflicient to rotate not merely the armature but the Weight itself.

The at-rest position of weight 511) is maintained by the tension spring 582 connected at one end to a pin 583 of the weight, and at the other end to a bolt 534 of the housing.

In various experiments and tests which have been made with these various modifications, I have found that the construction shown in Figures 1 to 8 is at present the preferred form. Its efficiency is such that in some instances it may be perfectly feasible to dispense with part or all 2li ofthe; additional weights 'l2V and tofrelyr entirelyl onthefmember 1.0;

The basic principles described. in connection with; Figures. 1- to 8 are present in all of the other' modifications., The essential element is that, kinetic energy of movement of the armature, as aresult of physical shock, is imparted to a mass,

which; maybe greater or'which is at a. mechanical.

advantage with respect to the armature and its parts; and the initiation of movement of this greater mass absorbs all of the kinetic energy of the. armature, so that the armaturen@ longer continues to rise under the inuence of such shock.

Also, thev arrangement ofthe shock absorbing member is such that under. overload conditions, it will" be automatically moved out of the way without creating any appreciable delays in the response of.' the armature, so that the armature may move, through its full cycle to trip the circuit breaker open under overload. or short circuit conditions.

In the foregoing, I! have described my invention in several modifications which are to be regarded merely illustrative ofthe basic principles involved-L Many other modifications and variations of my invention should now be obvious to those skilled in the art without departing from the spirit thereof. Accordingly, I prefer to be bound not by the specific disclosure herein, but only by the appended claims.

I claim:

1. A trip device for a circuit breaker comprising a trip member movable to cause opening of the circuit breaker, means comprising a movable mass having a plurality of projections, one of said projections being in the path of movement of said trip member, said mass being set in motion by impact with said trip member in response to a jarring force, and said mass when in motion impinging another of said projections on said trip member to prevent movement of said trip member in opening direction and extent sufiicient to cause opening of the circuit breaker.

2. In a circuit breaker, a magnet having a pivoted armature, a striking member secured to and movable with said armature and having an abutment on one side thereof and an extension on the other side thereof, a pivoted mass having a recessed surface opposite said extension, an abutment opposite said abutment on said striking member, the mean distance from the center of the pivot of said striking member to said recessed surface on said mass being substantially equal to the distance from said pivot to the end of said abutment on said striking member and the distance between the end of said extension on said striking member and said recessed surface on said mass being less than the height of the abutments on said mass and said striking member and the mass being pivoted at a point so that the rotation of said mass is limited to a degree of movement equal to the space between said extension on said striking member and said recess on said mass, which degree of movement is less than sufficient to move said extension out of the path of said recess whereby said surface and recess will engage and stop further movement of said striking member of said mass before said abutments disengage, and said mass will absorb the shock of movement of said striking member, the surfaces of said extension and recess beingsloped at an angle to the radius to said pivot of said striking member so that when said sur- 22 face; extension, isv engaged by said recesa. it. is subjected to a forcefhaving avector substantially perpendicular to the radius andtherstriking. mem' ber will besubjected to a rotated'forcfe: inthev op'- posite direction from said shock.

3. In a, circuit breaker; aI magnet having' a pivoted member operable about its pivot in re;- sponse to, the energization ofT said magnet and: also operable about. its pivot in response: to a; shock, a; pivoted mass having asurface in the: path of movement of said member andi engageable by said member when said: member moves about its pivot irl-.response to shock, said member:

having; a suriace'in the pathv of movement, of said;

masswhen said mass moves in response to impact from said member, for limiting movement of said- '.iass.

e. In a circuit breaker, a magnet having; a pivoted member operable about its pivot re'.-

sponse tothe energization of said magnetand-i. also operable about its pivot in response: to.; a:

shock, a. lpivoted mass having a surface; in the;v path. of.' movement of said: member and engage able byA said member when. saidl member moves.

about its pivot in: response; to shock,.said member' having a surface in the path of movement of said mass when said mass moves in response to impact from said member, for limiting movement of said mass to maintain said mass in the path of movement of said member and limit movement of said member.

5. In a circuit breaker, a magnet having a pivoted member operable about its pivot in response to the energization of said magnet and Ialso operable about its pivot in response to a shock, a pivoted mass having .a surface in the path of movement of said member and engagelable by said member when said member moves about its pivot in response to shock, said member having a surface in the path of movement of said m-ass when said mass moves in response to impact from said mem-ber, for limiting movement of said mass to maintain said mass in the path of movement of said member :and limit movement of said member, said mass having a recess, which, when said member is moved in response to the energization of said magnet and in turn moves said mass with said member, permits said mass to be moved out of the path of movement of said member to permit movement of said member beyond said previously mentioned limit of movement of said member.

6. In a circuit breaker, a magnet having a pivoted armature, a striking member secured to and movable -with said armature and having an abutment on one side thereof .and an extension on the other side thereof, .a pivoted mass having a recessed surface opposite said extension, lan abutment opposite said abutment -on said striking member, the mean distance `from the center of the pivot of said striking member to said recessed surface on said mass being substantially equal to the distance from said ypivot to the end yof said abutment on said striking member and the -distance between the end of said extension on said striking member and said recessed surface lon said mass lbeing less than the height ofthe abutments on said mass and said striking member and the mass being pivoted at a point so that the rotation of said mass is limited to ya degree of movement equal to the space between said extension on said striking member and said recess on said mass, which degree of movement is less than suflicient to move said extension out of the path of said recess whereby said surface and

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