US2931869A - Electric switch - Google Patents

Description

April 5, 1960 E. J. FRANK 2,931,869

ELECTRIC SWITCH Filed Dec. 9,'195'1 s sheets-sheet 1 'IIIIIIIIIII IT-lven tor: Edward J.k Fra k.,

bg ff/57AM VIDE l April 5, 1960 E. J. FRANK 2,931,869

' ELECTRIC SWITCH Fiied Deo. 9. 1957 v 3 Sheets-Sheet 2 Invent-or: Edward J. Frank,

be m His Attov'neg.

April 5, 1960 E. J.. FRANK 2,931,869

ELECTRIC SWITCH Filed Dec. 9, 1957 3 Sheets-Sheet 3 Inventor: Edward. J` Frank,

IOW/JH ma Attorneg.

2,931,869 ELECTRIC swrrcn Edward J. Frank, Springfield, Pa., assigner toGeneral Electric Company, a corporation of New York Application December 9, 1957, Serial No. 701,590

8 Claims. (Cl. 200-6'7) This invention realtes to an electric switch which utilizes energy derived from an overcenter spring for producing both opening and closing operations. More particularly, the invention relates to a switch of this type in which operations can be initiated either manually by means of a suitable oscillatable lever or automatically by operation of a small unidirectional motor.

'I'he invention is particularly concerned with providing an inexpensive switch of the above type which is capable of closing at high speed, without momentary hesitation or reversal, against large inrush currents, such as, for eX- ample, those currents encountered when switching uncharged capacitor banks into an electrical system.

It is, of course, desirable that the overcenter operating spring be of the smallest practical size capable of producing the desired operating speeds and forces. This follows from the fact that the smaller is this spring, the smaller will be the motor required for charging the spring, and, as a result, the more compact and inexpensive w ill be the overall operating mechanism. It is, therefore, an object of my inventionv Vto provide, for a switchof this general type, a compact and inexpensive operating mechanism which is capable of deriving the required operating forces and speeds from an overcenter spring of minimum size.

It is another object of this invention to construct the operating mechanism in such a manner that manual operation of the switch can readilybe accomplished free from any interference by the power-operating means and without the need for disengaging a clutch or for disassembling partsof the mechanism.

Another object is to construct the mechanism n such a manner that switch-closing forces can be delivered through the mechanism to the contacts by non-yielding structure forming a power path which bypassesrthe overcenter spring. y This becomes desirable in the event that it is. necessary to supplement the action of the spring when closing against high inrush currents.

In carrying out my invention in one form, I provide a switch comprising a movable contact, an actuating lever coupled to the contacts, and a rock shaft through which operating power is delivered to the actuating lever and the movable contact. Secured to the rock shaft is a toggle link which coacts with an overcenter spring to form a toggle. Means is provided for rotating the rock shaft in one direction to charge the spring and drive the toggle linkvinto an overcenter position relative to the spring, whereupon the kspring discharges and continues motion of the link and the rock shaft. After the spring has driven the toggle link a substantial distance overcenter, an Vabutment which is positively connected to the toggle link impacts against the actuating lever, thus driving the contact through an operating stroke. During initial overcenter movement the abutment was spaced froml 2,931,8@9 Patented Apr. 5, 1960 producing the desired high speeds and forces required for closing against large inrush currents. l

Iny accordance with another aspect of my invention, the overcenter spring acts to effect a contact-opening stroke in response to the toggles being driven in one direction through center, and a contact-closing stroke in response to the toggles being driven in an opposite direction through center. For driving the toggle through center in either of these directions, a motor is arranged to drive a rotatable caml unidirectionally about a predetermined axis of rotation. Forces from the cam are transmitted to an oscillatable crank coupled to the rock shaft and oscillatable about a predetermined pivot axis laterally offset from said axis of rotation. The crank carries first and second cam followers at angularly spaced locations about said pivot axis. One of these followers coacts with the outer surface of the cam to drive the rock shaft in one direction in response to a partial rotation of the same, whereas the other follower coacts with the outer surface of the cam to drive the rock shaft in an opposite direction in response to added rotation of the, cam.

For a better understanding of my invention, reference may be had to the following ,description taken in connection with the accompanying drawings, wherein:

Fig. 1 is a side elevational view, partly in section, of an electric switch embodying my invention.

Fig. 2 is a sectional view taken along the section line 2 2 of Fig. 1. In this view the switch is in its open position. v

Fig. 3 is a view similar to that of Fig. 2 but with the .switch in its closed position.

Fig. 4 is a sectional view taken along the line 4 4 of Fig. l showing a cam-type coupling which is relied upon for transmitting operating power to the switch.

Fig. 5 is a perspective view of the certain components of theswitch when in its closed position.

Y Fig. 6 is a schematic diagram of an electrical control for the switch.

Fig. 7 isV a view similar to that of Fig. 4 but illustrating a modified form of cam-type coupling.

Referring now to Fig. 1, it will be seen that the switch comprises a metallic tank 10 having a cover 11 suitably secured thereto. Projecting through the cover 11 and supported thereon is a pair of conventional high-voltage terminal bushings 12. Each of these bushings 12 comprises a centrally disposed conductor 13 electrically connected to a stationary contact 14 supported at the lower end of the bushing.

When the switch is in its closed position, the stationary contacts 1 4 are electrically interconnected by a conductive bridging member 15 carrying movable contacts 16 at its opposite ends. When the switch is in its open position, as shown in Fig. l, this bridging member and the contacts 16 are vertically spaced from the stationary contacts 14. Closing is effected by driving the bridging member 15 vertically upwardly into a position wherein the movable contacts 16 are in circuit-closing engagement with the stationary contacts 14. y

Preferably, each of the stationary contacts 14 comprises a pair of spaced apart conductive fingers 17 biased toward each other by suitable compression springs 1S, as shown in Fig. 3. The upper-ends of the adjacent fingers 17 are forced into firm current-carrying engagement with the lower end of the conductive stud 13, whereas the lower ends of the adjacent fingers 17 are adapted to receive therebetween one of the movable contacts 16. As shown in Fig. 3,v when the switch is in closed position, the springs 18 force the fingers 17 into firm circuit-closing engagement with the contact 16.

For driving the bridging member 15 upwardly to close the switch or downwardly to open the switch, a verticallymovable operating rod 20 of insulatingmaterial is pro d vided. This operating rod 20 is rigidly secured at its lower end to the bridging member 15 and is pivotally connected at its upper end to anvarm 21, which is pivotally mounted at 21a on the cover 11. The operating rod 20 is guided for substantially straight-line vertical motion by a suitable guide member 23 having an appropriate guide opening therethrough. As shown in Fig. 2, the guide member 23 is supported upon an insulating plate 24 which is bolted to suitable support rods 25 projecting downwardly into the tank from the cover 11.

For imparting motion to the operating-rod 21, a contact-actuating lever 30 is provided. This lever 30 is pivotally joined at one of its ends to the arm 21 by a pin 31 located intermediate the ends of the arm 21. At

Vits other end, the lever 30 is mounted for angular movement upon a rock shaft 32 and is so mounted that it is free to move angularly relative to the rock shaft 32. Preferably, the lever 30 is of the U-shaped configuration shown in the drawings, with its bight portion 30a located at the right-hand end of the lever, as shown in Fig. 2.

For operating the lever 30 clockwise from its position of Fig. 2 in order to produce upward closing motion of the contacts 16, a toggle mechanism 35 is provided. This toggle mechanism includes a toggle link, or arm, 36 keyed, or otherwise secured, to the rock shaft 32 and a pivoted `eXpansble toggle link 37 comprising a heavy compression spring 38 tending to lengthen the link 37. The link 37 further comprises a threaded rod 39 pivotally joined to the toggle link 36 by means of a pin 40 forming a knee for the toggle. The compression spring 38 surrounds the rod 39 and bears at its upper end against a plate 41 which, in turn, hears against a stop nut 42 threaded and fixed on the rod 39. The lower end of the compression spring 38 is supported on a pivot block 43 having trunnions 44 laterally-projecting therefrom to pivotally support the block 43. As shown in Fig. l, these trunnions 44 are journaled in suitable supporting plates 45 rigidly attached to the cover 11 at laterally-spaced locations. For suitably guiding the rod 39, a centrally disposed guide passage 46 is provided in the pivot block 43 toslidably receive the rod 39.

As shown in Figs. 2 and 3, the toggle link 36 has a recessed portion at its right hand side for receiving the bight portion 30a of the U-shaped lever 30. At opposite edges of this recessed portion are a pair of abutments 50a and 50b for transmitting switch-operating forces to the lever 30, as will soon be described. When the switch is in the open position of Fig. 2, the upper abutment 50a is spaced a considerable distance from the bight portion 30a, and when the switch is in the closed position of Fig. 3, the lower abutment 50b is spaced a considerable distance from the bight portion 30a.

When the rock shaft 32 together with the toggle link 36 are driven clockwise from the position of Fig. 2, the spring 38 is compressed until the toggle passes through an in-line, or center, position. When this occurs (i.e., when the toggle knee 40 moves across a reference line interconnecting the axis of pins 44 and rock shaft 32), the spring 38 rapidly discharges and drives the toggle link 36 further in a clockwise direction. The recessed portion of toggle link 36 is so proportioned that the upper abutment 50a does not contact the bight portion 30a of the lever 30 until the toggle link is well past its center position. As a result, when the spring 38 begins discharging immediately after the toggle is driven overcenter, it accelerates the toggle link 36 at a relatively high rate without initially being impeded by the lever 30 and the mechanism 21, 20, 15, 16 connected thereto. After a relatively high velocity is attained, the abutment 50a impacts against the bight portion 30a, driving the lever 30 rapidly clockwise, thus transmitting contact-closing forces through the parts 21, 20 and 15 to the contacts 16. The spring 38 continues to expand, following-up the initial impact and imparting additional contact-closing forces.

4 At the end of the contact-closing stroke, the parts are positioned as shown in Fig. 3.

After the switch has been closed, switch opening can be produced by rotating the rock shaft 32 in an opposite or counterclockwise direction from the position of Fig. 3. This again compresses the spring 38 until the toggle link 36 moves counterclockwise overcenter. The spring then discharges and drives the lower abutment 50b into impacting engagement with the lower side of the bight portion 30a, thus transmitting switch-opening forces to the contacts 16 through the parts 30, 21, 20 and 16. This action, coupled with the spring-discharge which follows, returns the parts of the switch to the open position shown in Fig. 2. The abutment 50b is so located that during this opening stroke, the toggle 37 was allowed to move considerably past its center position before the abutment 50b impacted the bight portion.

The above-described impacting action serves highly desirable functions both during the opening and closing strokes. In this regard, during either of these strokes, the impact action provides considerably higher contactoperating speeds than would be otherwise obtainable. Increasing the contact-opening speeds desirably tends to provide reduced arcing intervals and, hence, reduced contact erosion. Increasing the contact-closing speeds desirably tends to increase the inertia forces available to drive the movable contacts into their closed position against opposing magnetic forces which would be produced by high inrush currents. In addition, increased contact-closing speeds desirably tend to reduce the time interval required for closing. In capacitor-switching applications, it is desirable to minimize this interval so as to make the capacitors available when they are most needed.

Another advantage of the impacting action during an opening stroke is that it is most effective in overcoming any contact welding which might have occurred. The hammer blow imparted by the impact tends to break any welds which might have developed between the contacts, thus freeing the movable contacts 16 to separate from the stationary contacts 14.

For manually oscillating the rock shaft 32 to produce the above-described switch-opening and switch-closing actions, a handle 55 is provided. This handle 55, which is best shown in Fig. 5, is connected to the shaft 32 by a lost-motion connection 56 permitting a limited amount of angular motion of the handle 55 relative to the shaft 32. For opening the switch, the handle 55 is operated in a counterclockwise direction from its position of Fig. 5. In response to such motion, the right-hand end wall of a slot 56 formed in the hub of the handle 55 immediately engages a pin 57 integral with the shaft 32, thus immediately driving the shaft 32 counterclockwise. When the overcenter spring 38 discharges to produce the above-described switch opening after being driven overcenter, it tends to continue counterclockwise motion of 'the rock shaft 32 at a substantially higher speed than the handle is normally being moved. The slot 56 allows the rock shaft 32 to overrun the handle 55 during this interval, thus assuring that the handle will not interfere with the desired high speed switch-opening operation. Upon completion of the opening operation, the pin is positioned adjacent the left-hand end wall of the slot S6.

For closing the switch, the handle 55 is simply returned in a clockwise direction to its position of Fig. 5. During this return motion, the slot 56 allows the rock shaft 32 to overrun the handle 55 during the time the spring 38 is rapidly discharging to produce high speed clc-sing.

Preferably, the handle 55 is provided at its outer end with a ring portion 55a, which is adapted to receive a 'suitable hook stick (not shown) for imparting counterclockwise switch-opening motion to the handle 55. Clockwise closing-motion can be imparted to the handle S5 by e@ lforcingthe hook stickupwa'rdlyagainst arrecessedportion SSb formed at the lower side of the handle 55. y During a switch-opening operation, it will be apparent that the overcenter spring 38 initially is being compressed by counterclockwise rotation of the toggle link 36 and therefore is then exerting` no force on the contacts 16. To assure that the contacts 16 do not fall open or are not otherwise accidentally opened during this short interval, a latch 90 is provided. 'I'his latch 90 is pivoted at 91 on the cover 11 and is biased in a counterclockwise direction by a suitable biasing spring 92. When the switch is in its closed position of Fig. 3, a latching surface 94 formed on the latch is disposed in latching relationship beneath a pin 95 iiXed tothe: actuating lever 30. In such position, the latch 90 positively holds the contacts 16 in their closed position.

When the toggle link, or arm, 36 is moved counterclockwise to open the switch, as previously-described, a projection 96 carried by the link 36 engages a cam surface 97 formed on the latch 90. This forces the latch 90 to the left thus releasing the pin 95 and allowing the contacts 16 to be driven open.r The projection 96 on toggle link 36 is so located that release of the latch 90 takes place only after the toggle 35 has been driven past center. Latch release occurs, however, priorrto the instant that abutment Stib impacts the bight portion 36a of the lever 3i), thus assuring that the latch 90 does not interfere with the desired high speed contact-opening.

Since the latch 90 positively locks the contacts 16 in closed position when the switch is in its fully closed position of Fig. 3, it will be apparent that the latch serves during such intervals to preventv the contacts from being forced open by any abnormal magnetic forces which might be capable of overcoming the biasing force of over'- center spring 3S.

It will be noted that the arm 21 is pivoted on the cover 1I by means of a pin 21a sldably mounted in a slotted bracket 2lb secured to the cover 11. A leaf spring 21C bears against this pin 21a urging it to the right. As a result of this action, the spring 21e tends to hold the contacts 16 open when they are in the open position and tends to hold the contacts 16 closed when they are in the closed position. In certain applications large magnetic forces tending to open the contacts are not encountered after the contacts have been moved into closed position. In such applications, the latch Si@ can be omitted and the leaf spring will serve to prevent a premature slow opening of the contacts during the time the overcenter spring is being driven up to its dead center position during a switch-opening operation.

Opening and closing of the switch can also be initiated by the action of a suitably-controlled, unidirectional electric motor 66, which is capable of oscillating the rock shaft 32 in generally the same manner as the manuallyoperable handle S5. In this connection, the motor 60, when energized, acts through a suitable speed reducer 61 to effect rotary motion of the power shaft 62 as is shown in Fig. l. A cam 63 is keyed or otherwise secured to the power shaft 62 and is thus rotated by operation of the motor 66. Coacting with the carn 63 is a V-shaped crank 65 that is secured to the rock shaft 32'. As best shown in Fig. 4, this crank 65 carries a pair of cam followers 66 and 67 at the outer end of eachof its angularlyspaced arms. Each of these followers 66 and 67 is preferably a roller which is journaled on a pin 63 secured to the crank. The axis of the rock shaft 32, it will be noted from Fig. 4, is laterally offset from the axis of the power snaft 62. When it is desired to utilize the motorV 64) for closing the breaker, the motor is energized to rotate the cam 63 counterciockwise from its solid line position of Fig. 4. This acts to lift the follower 66 thereby driving the rock shaft 32 in a clockwise switch-closing direction. When this action has continued to the point where the rock shaft'32 has driven the spring 3S slightly overcenter, the spring 38 discharges to close the switch, as previousgestaag S 1y described, and, in so doing, lifts the followerV 66 from the outer surface 'of the carn 63 and into the dotted line position shown in Figure 4. The motor continues roftating the cam 63 until the cam reaches the dottedline position of Fig. 4, whereupon motor-operation is terminated.

To open the switch, the motor rotates the cam 63 clockwise from its dotted line position of Fig. 4. This lifts the lower follower 67, thereby driving the rock shaft 32 in a counterclockwise switch-opening direction. When this action has continued to the point where the overcenter spring 3S begins discharging to open the switch, the spring acts to lift the roller 67 from the outer surface of the cam, ultimately Vreturning the follower to its solid line position of Fig. 4. The motor continues rotating the cam 63 until the cam has returned to its solid line position of Fig. 4, whereupon motor operation is terminated.

It will be apparent that manual operation of the switch can be readily effected without interference from the motor means 6ft-63 inasmuch as the V-shaped crank 65 is free to oscillate between its solid-line and dottedline line positions of Fig. 4 independently of the cam 63. Thus, the manually-operable handle 55 can be operated between its switch-open and switch-closed positions completely without interference from the motor means 6th-6.3. i

For controlling the operation of the motor 60, a controlling disc 70 is secured to the rotary power shaft 62.

As shown in Fig. 6, this disc 70 has a conductive sun face except for two spaced-apart insulating areas '7. 2 and 73. Pour conductivefingers 74, 75, 76 and 77 bear against the disc and are` adapted to be connected in circuit With the motor 60 as shown diagrammatically in Fig. 6. Connected in circuit with the disc 60 is a suitable conventional control switch 78, which can be operated either manually or in response to predetermined conditions. One terminal of this switch 78 is connected to a supply bus 80 and its other terminal can be'shifted from the neutral position of Fig. 6 into engagement with either a switch-opening contact 82 or a switch-closing contact 83.

In Fig, 6, the controlling disc 70 is shown in the position it occupies when the main switch is open.Y Ciosing is effected by transferring the control switch 78 to the switch-opening contact 83. This completes an energizing circuit through the nger 77, the conductive disc 70 and the finger 74 to the motor 60. The motor responds by rotating the shaft 62 counterclockwise to close the main switch. The disc 7G, being coupled to the shaft 62, rotates therewith, and rotation continues until the insulating area 72 of the disc aligns with the iingers 77 and 76. This interrupts the energizing circuit for the motor 60, thus terminating motor-operation. The disc 70 will thenoccupy the position shown in Fig. 5 of the drawings.

The main switch may thereafter be opened by transl ferring the control switch 78 over tothe switch-opening contact 2. As will be apparent from Figs. 5 and 6, this will complete an energizing circuit for the motor 60 through the finger '75, the conductive disc 70, and the finger 74. The motor responds by rotating the shaft 62. ciockwise to produce switch-closing. Motor operation continues until the insulated area 73 aligns with the fingers and 76, as shown in Fig. 6, whereupon the energizing circuit for the motor 66 is interrupted, thereby terminating motor-operation.

The purpose of the conductive finger 76 is to provide a seal-in circuit bypassing the control switch 7S once motor operation has been initiated, thus assuring a complete switch operation even though the control switch 7S is only momentarily closed. Y

Fig. 7 shows how the cam mechanism of Fig. 4 can be modified to render the switch capable of closing against still larger inrush currents. Those parts of Fig. 7 which correspond to similar parts in Fig. 4 are assigned corre;

aesnsee toggle 35 of the switch has just been driven overcenter. A

At this instant, the overcenter spring 3S of the toggle begins discharging to produce switch-closing forces, and, in so doing, drives the follower 66 away from the outer periphery of cam 63 into the dotted line position of Fig. 7.

' The mechanism of Fig. 7 differs from that of Fig. 4 in that' it comprises an additional or auxiliary cam 100 which is mounted on but is freely Vrotatable with respect Vto the cam shaft 62. This auxiliary cam 100 is spring coupled to the main cam 63 by means of a suitable torsion spring 101 urging the auxiliary cam 100 into engagement with a pin 102 projecting laterally from the main cam.

During a switch-closing operation, when the main cam 63 is rotated counterclockwise from a position corresponding to that indicated by solid-lines in Fig. 4 to its position of Fig. 7, it drives the follower 66 up its outer peripheral surface. In so moving, the follower 66 contacts the left hand surface of the auxiliary cam 100, which is then projecting above the outer surface of the main cam 63. This temporarily prevents the auxiliary cam from following along with the main cam, with the result being that continued counterclockwise movement of the main cam charges the torsion spring 101.

When the follower 66 leaves the surface of cam 63 and approaches its dotted line position of Fig. 7, the torsion spring 101 becomes free to discharge. In discharging, the spring 101 quickly drives the auxiliary cam counterclockwise into a position underneath the follower 66. The surface 100a of the auxiliary cam in passing beneath the follower 66, provides a wedging action which supplements the closing forces provided by the overcenter spring 38. The top surface 1001: of the auxiliary cam 100 has an axis of curvature coinciding with the axis of cam shaft 62 and thus acts to block return movement of the follower 66 and the connected contacts 16 until the motor has driven the auxiliary cam counterclockwise clear of the follower 66.

The particular auxiliary cam arrangement shown in Fig. 7 is not a part of my invention but is claimed in application S.N. 705,331, Heintz, filed December 26, 1957, and issued as Patent No. 2,905,787, assigned to the assignee of the present invention. The purpose of describing this auxiliary arrangement in the present application is to illustrate how the operating mechanism of the present invention readily allows the closing action of an overcenter spring to be supplemented by closing power delivered to the contacts independently of the overcenter spring. In this regard, when the contacts 16 near their closed position shown in Fig. 3, the abutment 50a is bearing against the lever 30 and, thus, a substantially nonyielding power path by-passing the overcenter spring 38 is available for the transmission of supplementary closing forces to the contacts. This non-yielding path extends through the successive parts 65, 32, 36, 50a, 30, 21, 20 and 16. Thus, when the auxiliary cam 100 is driven beneath the follower 66, as above-described, power is transmitted to the contacts through a substantial non-yielding path. This path bypasses the overcenter spring 38, thus assuring that the supplementary closing forces are applied quickly and positively to the contacts 16 rather than being cushioned or absorbed by the overcenter spring, as would be the case if it were necessary to deliver these supplementary forces through the spring.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, intend in the appended claims to cover all such changes and 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 Unietd States is:

1. In an electric switch, a pair of separable contacts, a rock shaft, a switch-actuating lever coupled to one of said contacts and pivotally mounted on said rock shaft for angular movement relative to said rock shaft, a toggle link secured to said rock shaft, an overcenter spring coacting with said toggle link to form a toggle, means for rotating said rock shaft in one direction to charge said spring and drive said toggle link into an overcenter position relative to said spring whereupon said spring discharges and continues motion of said link, abutment means carried by said link for impacting against said lever after said link has been driven a substantial distance overcenter thereby to actuate said one contact, said abutment means being spaced from said lever during initial overcenter movement for allowing the discharging spring to accelerate said toggle link before impact occurs, the forces produced Lby discharge of said spring being transmitted through said abutment means from said link to said actuating lever to produce continued actuation of said contact as said spring continues to discharge after impact occurs.

2. In an electric switch, a pair of separable contacts, a rock shaft, a toggle link secured to said rock shaft, an overcenter spring coacting with said toggle link to form a toggle, a switch actuating member coupled to one of said contacts, means for rotating said rock shaft in one direction to charge said vspring and drive said toggle link into an overcenter position relative to said spring whereupon said spring discharges and continues motion of said link, abutment means positively connected to said link for impacting against said switch actuating member after said link has been driven a substantial distance overcenter thereby to actuate said one contact, said abutment means being spaced from said actuating member during initial overcenter movement for allowing the discharging spring to accelerate said toggle link before impact occurs, the forces produced by discharge of said spring being transmitted through said abutment means from said link to said actuating member to produce continued actuation of said contact as said spring continues to discharge after impact occurs.

3. In an electric switch, a pair of separable contacts, a rock shaft movable in one angular direction to effect contact-closing and in an opposite angular direction to effect contact-opening, a toggle link secured to said rock shaft, an overcenter spring coacting with said toggle link to form a toggle, a switch-actuating member coupled to one of said contacts, means for rotating said rock shaft in either of said directions to charge said spring and drive said toggle link into an overcenter position relative to said spring whereupon said spring discharges and continues motion of said link, first abutment means positively connected to said link for impacting against said switchactuating member after said link has been driven in one direction a substantial distance overcenter thereby to drive said contact in an opening direction, second abutment means positively connected to said link for impacting against said switch-actuating member after said link has been driven in an opposite direction a substantial distance overcenter thereby to drive said contact in a closing direction, each of said abutment means being so located that for operation of said toggle link in either direction said overcenter spring is allowed to discharge and accelerate said toggle link before said impact occurs, the forces produced by discharge of said spring during opening and closing operations being transmitted through said first and second abutment means respectively to produce continued actuation of said contact as said spring continues to discharge after impact occurs.

4. In an electric switch, a pair of separable contacts, a rock shaft movable in one angular direction to elect contact-closing and in an opposite angular direction to effect contact-opening, actuating means for said rock shaft comprising a motor and a rotatable cam adapted to be driven unidirectionally by said motor about a predetermined axis of rotation, an oscillatable crank coupled to said rock shaft and oscillatable about a predetermined pivot axis laterally offsetfrom said axis of rotation, said crank carrying iirst and second cam followers at angularly spaced locations about said pivot axis, said first follower coacting with the outer periphery of said cam to drive said rock shaft in one direction in response to partial rotation of said cam, and said second follower coacting with the outer periphery of said cam to drive said rock shaft in an opposite direction in response to added rotation of said cam, a toggle link secured to said rock shaft, an overcenter spring coacting with said toggle link to form a toggle, rotation of said rock shaft in either of said directions acting to charge said spring and drive said toggle link into an overcenter position relative to said spring whereupon said spring discharges andrcontinues motion of said link, and force- I transmitting means connected between said contacts and said link for transmitting opening forces from said spring to said contacts in response to motion of said link in one angular direction and for supplying closing forces from said spring to said contacts in response to motion of said link in an opposite angular direction.

5. The switch of claim 4 in combination with a handle coupled to said rock shaft, said handle being movable in one angular direction to open said switch and in an opposite direction to close said switch.

6. The switch of claim 4 in combination with a handle coupled to said rock shaft, said handle being movable in one angular direction to open said switch and in an opposite angular direction to close said switch, one of said followers departing from the outer surface of said cam and the other of said followers approaching the outer surface of said cam in response to operation of said rock shaft in one direction, said other follower departing from said cam surface and said one follower approaching said cam surface in response to operation of said rock shaft in an opposite direction.

7. In an electric switch, a pair of separable contacts, a rock shaft, a toggle link secured to said rock shaft, an overcenter spring coactng with said toggle link to form a toggle, a switch-actuating member coupled to one of said contacts, releasable latch means for positively holding said one contact in closed position, means for rotating said rock shaft in a switch-opening direction to charge said spring and drive said toggle link into an overcenter position relative to said spring whereupon said spring discharges and continues motion of said link, abutment means carried by said link for impacting against said switch-actuating member after said link has been driven a substantial distance overcenter thereby to drive said one contact toward open position, said abutment means being spaced from said switch-actuating member during initial overcenter movement and thereby allowing the discharging spring to accelerate said toggle link before impact occurs, and means responsive to movement of said toggle link for releasing said latch means after said toggle link has been driven overcenter but before said impact has occurred.

8. The combination of claim 2 in which the forces transmitted through said abutment means act to drive said one contact into closed position.

References Cited in the le of this patent UNITED STATES PATENTS 2,534,007 Dietrich Dec. l2, 1950

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