US2800547A

US2800547A - Front operated disconnect switch mechanism

Info

Publication number: US2800547A
Application number: US460746A
Authority: US
Inventors: David W Johnson
Original assignee: Arrow Hart and Hegeman Electric Co
Current assignee: Arrow Hart and Hegeman Electric Co
Priority date: 1954-10-06
Filing date: 1954-10-06
Publication date: 1957-07-23
Anticipated expiration: 1974-07-23

Description

July 23, 1957 D. w. JOHNSON- FRONT OPERATED DISCONNECT SWITCH MECHANISM Filed Oct. 6, 1954 4 Sheets-Sheet 1 //71/e/7/0r Dav/'0 M/ Ja/mson By his af/omeys "'6 M 9%M.

FRONT OPERATED DISCONNECT SWITCH MECHANISM Filed 00$. 6, 1954 July 23, 1957 D. w. JOHNSON 4 SheetsSheet 2 //7 van/0r Dav/d 14 Johnson By his af/omeys FRONT OPERATED DISCONNECT SWITCH MECHANISM Filed Oct. 1954 July 23, 1957 D. w. JOHNSON 4 Sheets-Sheet 3 //7 yen/0r Dav/d 14 Johnson By his af/omeys FRONT OPERATED DISCONNECT swrrcn MECHANISM Filed Oct. 6, 1954 July 23, 1957 D. w. JOHNSON 4 Sheets-Sheet 4 United States Patent FRONT OPERATED DISCONNECT SWITCH MECHANISM David W. Johnson, Newington, Conn., assignor to The Arrow-Hart & Hegeman Electric Company, Hartford, Conn., a corporation of Connecticut Application October 6, 1954, Serial No. 460,746

31 Claims. (Cl. 200-77) This invention relates to electric switches. More particularly, it relates to switches for alternating current work especially useful as disconnect switches operable from the front; but the invention is not limited to such use. In this type of switch, it is difficult and expensive to use =bafiles or other arc quenching means to extinguish the arcs that develop on contact separation. Therefore, it is frequently desirable to cause the contacts to separate initially with a slow motion for a short distance and thereafter to snap into fully open or oil position. By such action, the arc extinguishes itself during the slow break while the current is in the low part of the cycle. In that way, the capacity of the switch and its eifectiveness in quenching arcs is enhanced and the life of the switch is increased in a relatively inexpensive manner.

Although switches for the above mentioned purpose and to accomplish the above mentioned function have been previously devised and have been put on the market and met with some success, their life has not been as great as it is desired and as is possible by the improvement which constitutes the present invention.

In view of the foregoing, it is an object of the invention to provide an improved electric switch structure preferably operable from the front and having provision for slow separation of the contacts-initially followed by a rapid break in the same direction, the rapid break not being subject to control the operator after the snapping action starts.

Another'object of the invention is to provide a switch of the aforesaid type which may be economically manufactured and will stand longer use than switches for similar purpose as heretoforemade and which will have a higher rating than switches normally used in disconnecting electric circuits with-a snapping action.

Another object of the invention is to incorporate in the improved switch structure a provision for positively moving the contacts to open circuit position in the event that the contacts should become stuck or the switch snapping mechanism otherwise disabled.

Other objects and advantages of the invention will appear as itis described in connection with the accompanying drawings.

In the drawings:

Fig. 1 is a top plan view of a switch embodying the invention.

Fig. 2 is a side elevation view partly broken away and partly in section with the section taken along line 2-2 of Fig. 1.

Fig. 3 is a bottom plan view of the operating mechanism of the switch with the bottom mounting plate removed and wit-h the parts in the switch-on position.

Fig. 4 is a view similar to Fig. 3 but with the parts in the switch-0E position.

Fig. 5 is a View similar to Figs. 3 and 4 but with the parts in a third or cover-open position.

Fig. 6 is a detail of the contact operating member.

s Fig. 7 is a detail view of the shifter member.

2,800,547 Patented July 23, 1957 "ice Fig. 8 is an enlarged side elevation view of the operating mechanism.

Fig. 9 is a plan view of electric switch to which another form ofthe invention may be applied, the switch handle being broken away for clarity.

Fig. 10 is a fragmentary elevational section view taken along line 10--10 of Fig. 9.

Fig. 11 is a fragmentary elevational View partly in section of one end of the switch illustrated in Fig. 9.

Fig. 12 is a bottom plan view of the switch operating mechanism with the bottom mounting plate removed.

Fig. 13 is a diagrammatic view of the parts of the operating mechanism illustrated in Fig. 12 shown in switch-on position.

Fig. 14 is a diagrammatic view of parts of the operating mechanism of Fig. 12 in switch-oil position.

Fig. 15 is a diagrammatic view of parts of the operating mechanism of Fig. 12 in an extreme or cover-releasing position.

Fig. 16 is a detail plan view of the contact-operatingslide member.

Fig. 17 is a detail plan view of the shifter member.

Referring to the drawings, the switch may be mounted in a base 10 made of insulating material and provided with three connected central recesses 12 positioned transversely along the base and running from front to back. Connected with the'three recesses 12 are three recesses 13 on each side of the switch base containing terminal members '14, connected with which are pairs of fixed contact members such as 15 and 16 extending from the terminal recesses into the central contact recesses 12. The terminal and contact members may be stamped as one part from sheet metal.

F-or engaging and disengaging the three pairs of stationary cont-

acts

15 and 16, three

similar bridging contacts

25, 26 and 27 stamped from sheet metal in bar form are mounted upon a contact carrier 20. The contact carrier may'conveniently be molded from insulating material with a central rectangular spine from the opposite sides of which extend

arms

22 and 23 lying within the recesses 12. In order to mount the movable contacts resiliently upon the carrier, contact receiving recesses or passages 24 are formed transversely through the carrier, through which passages may extend the

bridging contacts

25, 26 and 27. Pressing the bridging contacts toward the fixed contacts are coiled compression springs 28, one end of each of which presses upon the back of the movable contact member while the other end presses against the carrier so that 'when the carrier is moved into switch-closed position, the bridging contacts will engage and automatically adjust themselves against the fixed contact pair-s.

In order to move the contact carrier 20, a small round metal pin 21 is molded into the bottom thereof and extends through a rectangular recess 10a in the floor of the insulating base 10 in position to be engaged by certain parts of the operating mechanism, as will more fully appear presently.

The mechanism operating the switch to cause separation of the fixed and movable contacts at first with a slow break and finally with a snap action comprises a switch operating shaft 30 extending through the switch base 10 from front to back. The shaft may be operated directly by a handle 31 on its outer end or in any suitable fashion.

The operating mechanism is mainly mounted between two spaced parallel sheet

metal mounting plates

80, 81 which are secured'to the bottom of the insulating base, the inner plate being secured flush against the bottom of the base preferably in a recessed portion thereof. The bottom or inner end of the operating shaft extends through the mounting plate 80.

Fixedly mounted upon the bottom or end of the spindle St) is an actuator 32 formed from a flat disc like sheet metal stamping which has mounted thereon and extending from the surface thereof a short actuating pin 34 parallel to the spindle axis. The actuator 32 is notched as at 33 for about a quarter of its periphery in order to permit the rotation thereof and of the shaft through an angle of approximately 90. A stop' pin 38 mounted in and extending between the frame plates and located in the notch 33 limits the movement of the actuator 32.

Also extending from the actuator in the same direction as the actuating pin 34 is a release pin .36 which is spaced from the actuating pin but is otherwise similar thereto. The purpose and function of the releasing pin 36 will be described hereinafter.

Both the actuating pin 34 and the releasing pin 36 are adapted to engage the surface of a cam member designated generally by the numeral 40. This cam member may be stamped from sheet metal into the form illustrated with a recess 44 extending inwardly within which the actuating pin 34 works. The cam is mounted rotatably about a fixed pivot 42 comprising a pin mounted in and extending between the

frame plates

80, 81. On the periphery of the cam member 40 at a point opposite the recess 44 is a peaked cam-surface46 which is :adapted to engage with a cam roller or follower 51 on an axle pin 52 which is mounted on a shifter member, designated generally by the numeral 50. Formed on the cam 40 in a position substantially diametrically opposite to the peak cam .46, there is a substantially circular protuberance or cam surface 49, one side of which is adapted to be engaged by the releasing pin 36 when the switch shaft is moved into a certain position. The position referred to is an extreme position of the switch shaft beyond the normal open-circuit position and is provided so that theshaft may be moved for the purpose of releasing the coverof the switch box (not shown) by known mechanism which, per se, forms no part of the present invention. In this extreme cover-open position, the switch shaft may cause movement of a shutter plate to uncover the switch contacts by mechanism described in detail and claimed in my copending application Serial No. 455,879, entitled Sliding Shutter for Electric Switches.

Rotation of the switch shaft between the open-circuit position of Fig. 4 and the closed-circuit position of Fig. 3 is accompanied by movement of the actuating pin 34 within the recess 44 of the cam 40 and engagement with opposite sides of that recess to cause movement of the cam clockwise and counterclockwise for the purpose of actuating the switch mechanism.

The cam roller 51 is adapted to roll up and down the sides of the cam peak 46 as the cam moves in clockwise and counterclockwise directions under command of the actuator. In order to exert a bias upon the cam roller 51 and cam member 40 and to exert an over-center action, a coiled compression spring 62 is wound. around a spring holder or strut 60 which, extends parallel to and between the

mounting plates

80, 81 and has one end slidably mounted in a slot in the transverse portion of a U-bracket 63 which is secured to the

mounting plates

80, 81 with its transverse portion perpendicular to the mounting plates. The spring holder may be of any suitable form or construction, but preferably is formed of two like stamped sheet metal members having enlarged ends; the plane of those ends 64 being offset fromthe remainder so that when the two members are put back to back, a space is provided between the two offset portions, in between which the cam roller may be inserted. The enlarged end of the spring holder is apertured and pivotally mounted upon the cam roller axle pin 52 on the shifter member 50. One endv of the spring 62presses against the U-bracket and the other against the offset portion of the spring strut.

From the foregoing, it will be observed that as the cam 40 pivots about its axis .42, the peak 46 acting'against the cam roller will cause the strut to move longitudinally compressing the switch spring. Upon the roller reaching the peak of the cam, the roller will roll suddenly down the opposite side with a snap action as the spring expands.

The movement of the roller is transmitted to the shifter member 50 through the roller axle pin. The shifter member may be stamped conveniently from sheet metal and may comprise two parallel plates which are spaced apart and between which the enlarged end of the spring strut may be located. At the opposite ends of the shifter member are

transverse pins

54 and 56 which connect the top and bottom plates of the shifter member. The pin 54, which may be enlarged between the top and bottom shifter plates as at 54c, is adapted to slide in, and is guided by, fixed registering slots 84 in the mounting plates, the pin ends extending beyond the surface of the shifter member so as to enter and to be guided by said slots. Thus, lengthwise movement may be imparted to the shifter member, such movement being guided by said slots 84.

When the parts are in the switch-on position of Fig. 3, the effort of the switch spring is to move the cam 40 counterclockwise. Simultaneously, the effort of the spring transmitted through the cam roller urges the shifter longitudinally in upward direction (in Fig. 3) causing the pin 54 to seat in the inner or upper end of the slots 84. That pin stays in that position during the movement of the cam in counterclockwise direction during the initial movement of the switch parts from the switch-on to the switch-off position of Fig. 4. As the cam peak 46 reaches the over-center position, the etfort of the switch spring is suddenly shifted to the opposite direction and the parts snap in the position of Fig. 4. This causes longitudinal movement of the shifter member and causes its pin 54 to slide to the other end of the slots 84.

During the foregoing movement of the shifter, the upper end of the shifter has moved differently than the lower end. The pin 56 in the upper end has one end extending into an opening 82 in the inner frame plate 80, which opening is of such size and shape as to permit the movement of the shifter pin 56 without restriction within that opening.

Since the first movement of the switch cam in a counterclockwise direction from Fig. 3 will tend to cause the roller to ride up toward the peak of the cam 40 and the spring to be compressed, the shifter is caused to pivot in the clockwise direction about the pin 54. A similar pivotal motion takes place when the switch is moved from switch-off to switch-on position, but in that instance, the pin 54 is at the outer or bottom end of the slot 84.

In. a. manner as will now 'be described, the movement of the shifter member is utilized to cause movement of the switch contacts between open and closed positions through the agency of a contact operating lever generally designated by the numeral 7 0. This lever or member may be stamped from sheet metal into the form illustrated. Although illustrated as a plate, it functions as a :bellcrank lever with lost motion provision at both of its movable pivots. The member pivots about a fixed pivot pin 72 extending between the mounting

plates

80, 81. Near one corner is a small slot 74 through which passes the contact-moving pin 21 which, it will be recalled, extends down from the movable contact carrier 20. This contact-moving pin also extends through the inner mounting plate 80, an elongated slot 83 being provided therein to permit longitudinal motion of the pin as the contact carrier moves.

As previously indicated, it is desirable to have the initial movement of the contacts from switch-on position to switch-off position take place slowly to provide a slow break, and thereafter to be followed with a snap action to the final switch-off position. This is accomplished by shaping the shifter member 50 or at least the inner plate thereof so that a surface or edge of it is adjacent the contact moving pin 21 when the switch parts are in switch-on position of Fig. 3. As the cam moves from the position of Fig. 3 in counterclockwise direction, it causes pivoting of the shifter initially about the pin 54 in clockwise direction while that pin is in the upper end of the slot and until the roller has moved up the side of the peak of the cam to its apex. That clockwise pivotal motion of the shifter member causes the edge thereof to engage the contact moving pin 21 and to move it (and the contact-carrier 20 on which it is mounted) slowly to the right as shown in Fig. 3, i. e., toward open-circuit position. This causes the slow separation of the movable from the fixed contacts.

After the cam roller is passed over the peak of the cam, the changed effort of the switch spring causes the shifter to move longitudinally until the pin 54 reaches the other end of the slot 84. This longitudinal movement of the shifter is transmitted to the contact operating member 70 in the following manner. The pin 56 passes through an aperture 76 in the contact operating member, the aperture having the shape as illustrated (see Fig. 6) in order that the initial pivotal movement of the shifter shall not cause any movement of the contact operating lever. One edge 76a therefore is arcuate. When the operating cam or actuating cam and the cam roller have reached over-center position, the pin 56 will have moved from one end (the left end as illustrated in Fig. 3) toward the other end of the slot 76. Now upon passing the dead-center position, the shifter and its pin 56 tend .to move both clockwise and longitudinally. The clockwise motion is due to the tendency of the shifter to be moved about thepivot 4 by expanding spring 62 while the longitudinal movement is due to the tendency of the pin 54 to move to the other end of the slot. Thus, the shifter pin 56 exerts a force upon the opposite side 76b of the slot '76 in the contact operating member and tends to move that member in the opposite or counterclockwise direction. 'This movement is with a snap action because of the freedom of the spring to expand as the roller rides down the opposite side of the peak 46.

During the slow opening movement of the contacts and the movement of .the contact-moving pin 21 along the slot 83 in the inner mounting plate 80, there was necessarily some pivotal motion of the contact operating lever member, 70 about its pivot 72 because as the edge of the shifter acts upon the contact moving pin, that pin also presses against the side of the slot 74 in the contact operating member through which that pin passed. Hence, any movement of the contact-moving pin 21 was imparted to some degree to the contact-operating member. On movement of the switch from the switch-off to the switch-on position, that is from the position of Fig. 4 the position of Fig. 3, the action is just opposite of that just described. In this instance, the pin 54 of the shifter is in the lower end or outer end of the slot 84 in the mounting plate; and as the cam roller 51 passes over the peak 46 of the cam, the contact-operating member 70 is moved in a clockwise direction to cause the contactcarrier 20 and contact-moving pin 21 to move to the left in Figs. 3 and 4 to cause closing of the switch contacts.

It is possible and desirable for the switch operating spindle to move into a position beyond the normal switchopen position of Fig. 4. This is necessary when there is a lock provided upon the cover in which the switch is normally housed which can only be disabled by movement of the handle past normal off position into coveropen or unlocking position. It is also desirable to be able to move the switch lever into that position when a slide plate is provided over the switch contact, as may sometimes be necessary. This cover-open position is illustrated in Fig. 5. In that position, the switch shaft has been moved clockwise beyond the switch-open position. .In so doing, the actuator 32 has caused its pin 34 to engage the circular enlarged portion 49 of the cam. But, since that hascaused clockwise motion of the cam from the position of Fig. 4 wherein the contacts are already open, no further action takes place in the switch operating mechanism to cause change of condition of the contacts.

In case the main spring 62 should break, provision is made for opening the contacts and for keeping them from vibrating back into switch closed position again. To that end, a coiled hair pin spring 90 is mounted upon a pivot or anchor pin 91 passing transversely between, and mounted in, the mounting plates and 81. One end a of this spring extends toward the edge of the mounting plates and is anchored by an anchor pin 92. The other end 90b of the spring extends in the opposite direction and normally presses against a stop pin 93. Both the anchor pin 92 and the stop pin 93 are mounted in the mounting plates with their axes parallel to the spring carrying pin 91. When the switch parts are in switchopen position and the pin 54 is in the lower end of the guide slot 84, the end 90b of the hair pin spring presses against the stop pin 93. When the switch parts are in switch-on position, as illustrated in Fig. 3, the end 90b of the hair pin spring presses against the pin 54 which is then in the upper end of the guide slot 84.

It is possible with the main spring broken to move the switch operating shaft into the cover-open position of Fig. 5 and in so doing, the contacts will be manually forced open, even though they may have become stuck or Welded together. Separation of the contacts will not be as great, however, as in normal switch operation, but will be sufiicient .to break the circuit.

Assuming that the switch main spring 62 breaks, the end 90b of the hair pin spring pressing upon the guide pin 54 will move the shifter downwardly in the guide slot 84 and at the same time carry the contact operating member 70 rotatably about its pivot 72 upon any rotation of the switch shaft from the switch-on toward the switchoif position. The contacts will thus be caused to separate slowly. There will be no final snap opening action. When the parts are in this emergency switch-open position, they will remain there in spite of any vibration of the switch which might otherwise tend to cause the contact carrier to move back toward switch-on position. The pressure of the hair pin spring overcomes any such tendency.

In Figs. 911, there is shown another form of the invention, for switches carrying high amperage, but not limited in that respect. The insulating base which carries all of the parts may be similar to, but need not be identical with, the base of the previously described form. The base has contact receiving recesses 112 in which are located the fixed and movable contacts. The terminals 114 have fixed

contacts

115 and 116 formed integrally therewith as before. The bridging

contacts

125, 126, 127 may be mounted upon a sliding contact carrier 120 of insulation, similar but not identical to the previously described modification. The bridging contacts pass through openings or passageways 124 and are pressed by springs 128 as in the previous form.

In order to move the contact carrier 120, a small notch or recess is formed in the bottom surface thereof to receive a lug 171 bent up at right angles from the end of a slidable contact-moving member designated generally by the numeral 170. The lug 171 extends through an aperture 110a in the floor of the base in order that the lug may move freely as the slider is actuated by the operating mechanism as will hereinafter appear. The slider 170 may be stamped from sheet metal in the form illustrated in Fig. 16 and may be located beneath the floor of the base in a recess or channel in the bottom of the base and may be guided for rectilinear movement by the channel. The slider 170 slides upon the inner or upper surface of a mounting plate 180. The mounting plate is parallel to and spaced from a bottom or outer mounting plate 182 and both mounting plates are secured to the bottom of the switch base, as in the modification 7 previously described. The operating mechanism in this case, as in the previous form, is mounted mainly between these parallel mounting plates.

- In the form of Figs. 917, an operating shaft 130 extends through theswitch base from front to back and is operated by a handle. Fixedly mounted upon the bottom or inner end of the shaft 130 which extends through the mounting plate 180 is a sheet metal disc or actuator 132 which has mounted thereon and extending from its surface a short actuating pin 134. The actuating pin works in a recess in a stamped sheet metal cam member (designated generally by the numeral 140) to cause rotation of the cam member about a fixed pivotpin 142 in the mounting

plates

180 and 182 on which pin the cam member is mounted. The cam has a peak 146 which is adapted to engage with a cam roller or follower 151. The roller is mounted on an axle pin 152 which in turn is mounted on a shifter member, designated generally by the numeral 151 The cam roller is spring pressed by an over-center coil compression spring 162 wound around a strut 160,. one end of which is slidably mounted in a slot in the transverse portion of a U-bracket 163 while the opposite end carries the axle pin 152 on which the roller 151 is mounted in a manner similar to the previously described form. Rotation of the switch shaft clockwise or counterclockwise will cause the actuating pin 134 working within the recess 144 to move the cam counterclockwise or clockwise for the purpose of actuating the switch mechanism.

From the foregoing, it will be observed that as the earn 140 pivots about its axes 142, the roller will be caused to suddenly shift from one. side to the other of the peak with a snap action due to the switch spring.

The movement of the switch spring and roller is transmitted to the shifter member 150 through the roller axle 152, one end of which is reduced and extended through a recess (not visible) in the floor of the switch base. The shifter member may be stamped conveniently from sheet metal and may comprise two

parallel plates

153, 155 which are spaced apart and between which the enlarged ends of the spring strut and cam roller are located. The plate 153 may be in the form of a link; and the plate 155 may be similarly formed but may have an extension or leg 157 laterally extending from one end for a purpose to be hereinafter described. At the opposite end of the link portions from the end in which the roller axle is located is a transverse pin 154 which connects the top and bottom 'plates of the shifter member. The pin 154 may be enlarged between the top and bottom'plates. Its

ends extend into parallel oblong aligned guide slots in I the fixed mounting

plates

180, 182.

In order to cause the slow initial separation of the contacts, the contact moving member or slider 170 is provided near one end with an oblique slot 176 running in a generally crosswise direction of the slider. The end of the cam roller axle 152 is reduced and extended through the floor of the switch base into this slot 176. In the at-rest positions of the switch, as illustrated in Figs. 13 and 14, the axle pin extension 152 will be located in one end 176' of the slot 176. In the switch-on position of the parts, as illustrated in Fig. 13, the cam roller 151 is on the left side of the peak 146 of the actuating cam and hence, the end of the roller axle pin 152 holds the slider 170 to the left. In that position, the transverse pin 154 at the other end of the shifter member 150 is situated in the left end of the guide slot 184 in the mounting

plates

18 and 182.

Now on rotation of the switch operating shaft 130 in clockwise direction, the actuating cam 140 will be rotated counterclockwise and the cam roller 151 will roll upward on the peak 146. Such movement of the axle pin of the roller will do two things. It will ride up in the slot 176 of the shifter until it engages the surface of the angulated or oblique portion 176a whereupon it will push the slider 170 to the right. This action, through the agency of the contact moving lug 121 acting upon the contact carrier 120, will slowly separate the movable from the fixed contacts. While the cam roller is riding up upon the peak of thecam, the shifter member is pivoting about the transverse pin 154, such pin being pressed against the left end of the slot 184 in the mounting plates. The pin 154 will continue to press against that end of the slot 184 until the roller pa'ssesover the peak 146 of the actuating cam. Then, as the effort of the spring 162 is suddenly shifted to the other side of the cam peak, the roller will roll down that side of the cam. Such action will urge the transverse pin 154 to the right along the fixed slot 184 in the mounting plates. The transverse pin 154 also passes through a slot 174 in the slider 170. The slider 170 has moved a fraction of an inch from the pin 154 during the slow-breaking action, but as the pin 154 moves to the right, it will engage the left end of the slot 174 in the slider. At that instant, the pin is rapidly moving. Hence as soon as that engagement takes place, the slider moves with the transverse pin 184 with a sudden or snap motion which continues into the positionof Fig. 14 wherein the parts are all in switchopen position.

It is desirable to provide means for positively moving the parts from the switch-on to the switch-off position in the event that the switch spring should break. For this purpose, a radially extending shoulder 139 is provided upon the periphery of the actuator 132 in position to engage the end of the laterally extending arm 157 of the shifter member.

As will be observed by reference to Fig. 12, even if the switch spring should be broken, the movement of the switch operating shaft in clockwise direction from Fig. 13 would cause the rotation of the cam member and the pivotal action of the shifter as above described by the rolling up of the cam roller 151 onto the peak 146 of the cam. The contacts would have slowly separated. At this point, if the spring were broken, there would be no further tendency of the cam roller to roll down the opposite side of the peak 146. However, by continued rotation of the switch shaft in clockwise direction, it will eventually come into the position of Fig. 14. At that point, the shoulder 139 would be about to engage the end of the lateral arm 157 of the shifter member, which would be about in the position of Fig. 12. By continuing the clockwise rotation of the switch shaft and actuator 132, the shoulder 139 will actually engage the extending arm 157. This engagement will at one time cause not only a tendency of the shifter member to pivot about the pin 154 in a counterclockwise direction and thus tend to cause the cam roller to move down the opposite side of the cam peak 146, but at the sametime the shifter member and pin 154 will tend to move to the right, or in other words, to move the slider toward switch-off position.

When the invention is mounted in a box in which it is necessary to move the handle past the normal switch-off position further in the same direction in order to disable the box lock, or so that a shutter plate over the switch base may uncover the switch contacts, it is possible to do so with the mechanism of Figs. 917.

Continued rotation of the switch operating shaft past off position of Fig. 14 to the extreme position of Fig. 15 causes a radial pin 194 extending from the shaft to engage a shutter actuating member 195 which in turn engages a shutter plate 196 slidably mounted on top of the switch base as described in my copending application Serial No. 455,879. Since the details of the shutter and its operating mechanism are fully described in that application, they need not be more fully described herein, the utility of the ability to position the parts as illustrated in Fig. 15 being fully apparent from the illustration and disclosure herein given.

In order that the handle shall be maintained in switchopen position when the parts of the operating mechanism are in that position, a centering member may be provided. This member may conveniently be stamped fromsheet metal into the form best illustrated in Fig. 15. It comprises in general an elongated plate having at one end a deep notch 191 extending longitudinally and near the other or inner end of a slot 193 through which extends the end of the pivot 142 of the cam member 140. The end of the switch operating shaft 130 may be reduced and extended to fit into the notch 191 and thus, in conjunction with the extended end of the shaft 130 in the slot 193 to guide the movement of the member 190 rectilinearly. The innerend of the centering member is extended in position to be engaged by the lower or inner end 164 of the outer plate of the spring supporting strut 160.

Extending laterally from one side of the centering member 190 near the end in which the notch 191 is located is a projection cut back to form a shoulder 195. That shoulder is adapted to engage a lug 137 struck up at right angles to the plane of the actuator 132 on the opposite side of the actuator pivot from the pin 134. In the normally expanded position of the switch spring 162, the parts will be in the positions of Figs. 13 and 14. In both of these positions, the end 164 of the spring supporting strut will press against the upper end of the centering member, just as it does in Fig. 15. But in Figs. 13 and 14, the effort of the spring exerted upon the centering member forces that member longitudinally until the end of the slot 193 engages the fixed pivot pin 142, and the inner end of the notch 191 engages the extension 130e of the switch shaft. In that position, the shoulder 195 will have caused the actuator plate 132 and the switch shaft, which is affixed thereto, to be held in the position of Fig. 14, i. e. the switch-open position. The engagement of the pin 134 on the actuator 132 in this slot 144 of the cam member 140 prevents movement of the switch shaft toward switch-closed position until additional manual force is exercised.

The switch shaft can be rotated further in the switch opening direction from Fig. 14 to Fig. 15. In so doing, the lug 137 engaging the shoulder 195 moves the centering member longitudinally into the position of Fig. 15 against the stress of the switch spring exerted through the strut 164 pressing upon the upper end of the centering member. The parts can only remain in the position of Fig. 15, i. e., in the cover-opening and shutter-opening position, while manually held there. As soon as the hand of the operator is removed from the switch handle and shaft, the parts will resume the position of Fig. 14 because of the action of the switch spring exerted upon the centering member and, in turn, upon the lug 137 and the actuator 132 and the switch shaft 130.

From the foregoing, it will be observed that in both forms, the peaked cam is used together with the cam roller and shifter member and through their cooperatlon with the other parts of the operating mechanism to accomplish two functions. The first function is to cause slow separation of the contacts, and the second function is to cause final movement to switch-open position with a snap motion. The invention thus differs from the commonly known over-center or hill and valley cam actions of prior switches in which only a snap action contact separation was possible.

Many modifications will become apparent to those skilled in the art. Therefore, I do not limit the invention to the specific form of the modifications illustrated and described.

What is claimed is:

1. An electric switch comprising fixed and movable contacts, a carrier movable rectilinearly carrying said movable contacts, a contact operating member and a shifter member cooperating therewith adapted to cause movement of said carrier, manually operable actuating means, over center snapping mechanism operated by said actuating means and causing said carrier, said contact operating member and said shifter member to move between a switch-cit and a switch-on position with a snap action, and means for causing a slow initial contact separation prior to said snapping mechanism reaching overcenter position.

2. An electric switch as claimed in claim 1 in which said means for causing slow break includes means moving with said shifter member and acting on said contact moving member during the portion of the movement of said manual actuating means prior to snap action.

3. An electric switch as claimed in claim 2 wherein said manual actuating means is movable into a third position past switch-off position, and means operable by said manual actuating means upon movement into said third position to positively separate said fixed and movable contacts on disablement of said snap action means.

4. An electric switch comprising fixed and movable contacts, a carrier movable rectilinearly carrying said movable contacts, a contact operating member and a shifter member cooperating therewith adapted to cause movement of said carrier, manually operable actuating means, snapping mechanism operated by said actuating means and causing said carrier, said contact operating member and said shifter member to move between a switch-off and a switchon position with a snap action, and means for causing a slow initial contact separation prior to said snapping mechanism reaching over-center position, said means for causing the slow break including means moving with said shifter member and acting on said contact moving member during the first portion of the movement of said manual actuating means.

5. An electric switch as claimed in claim 4 wherein said manual actuatingmeans is movable into a third position pa-st'switch-ofi position, and means operable by said manual actuating means upon movement into said third position to positively separate said fixed and movable contacts on disablement of said snap action means.

6. An electric switch comprising separable contacts, a contact carrier movable to cause separation and engagement of said contacts, a carrier-operating member and a shifter member cooperating therewith adapted to cause movement of said carrier, spring biasing means acting on said shifter, manually operated means adapted to change said bias from one direction to the opposite while said manually operated means continues to be moved in one direction, and means to cause slow initial separation of the contacts prior to the changing of said bias, said slow separation being followed by snap-action completion by said biasing means.

7. An electric switch as claimed in claim 6 having a pivotal connection of said shifter to said biasing means.

8. An electric switch as claimed in claim 6 in which the shifter is bodily movable.

9. An electric switch as claimed in claim 6 in which the shifter is pivotally connected to said carrier operating member but is bodily shiftable.

10. An electric switch as claimed in claim 6 having pivotal mounting means about which the shifter pivots during initial movement, said pivot being shifted when said bias changes.

11. An electric switch as claimed in claim 10, having means operated by said manually operative means for positively separating the contacts in case the biasing means should become disabled.

12. An electric switch as claimed in claim 11 in which said positive contact separation is caused by engagement of said manually operable means with said shifter.

13. An electric switch as claimed in claim 6 having a pivotal connection between said shifter and said carrier operating member, said biasing means comprising a spring whose force is exerted at said pivotal connection.

14. An electric switch as claimed in claim 13 having a member acting on said pivotal connection to move the line of action of said spring over-center and change its bias.

15. An electric switch as claimed in claim 6 having 9 11 means to .hold the contactsapart after their separation, in caseof .disab'lernent ofsaid biasing means.

16. An electric switch as claimed in claim '6 wherein said carrier-movingmember is mounted forim'ovement about .a fixed pivot.

17. An electric switch as claimed in-claim .6 having a member integral with said carrier and engaged by said shifter to cause said slow initial separation.

18. An electric switch as claimed in claim l7 wherein said carrier-moving member engages Isaid carrier-integral member to impart the snap action to-the final carrier movement.

'19. An electric switch as claimed in claim '6 having pivotal mounting means about which .the shifter pivots during initial movement, said pivot being shiftedwhen said bias changes, and a member integral withsaid carrier and engaged by said shifter to. cause said islow initial separation.

20. An electric switch as claimed :in claim l9 wherein said carrier-moving member engages said carrier-integral memberto impart the snap action to the final carrier movement.

21. An electric switch as claimed in claim 20, having means operated bysaid manually operative means for positively separating the contacts in case the biasing means should become disabled.

22. An electric switch as claimed in claim 21 having means to hold the contacts apart after their separation, in case of disablement of said biasing means.

23. An electric switch as claimed in claim 6 having a pivotal connection between said shifter and said biasing means, a second pivot about which said shifter pivots during initial switch operating movement, said second pivot being shiftable, and mounting means in which said second pivot is supported and guided during its shifting.

24. An electric switch as claimed in claim 23 having a member on said shifter acting. upon said carrier-moving member to impart the final snap action to said carrier movement.

25. An electric switch as claimed in claim 6 having a pivotal connection between said biasing means and shifter, said connection acting on said carrier-operating member to cause said slow initial contact separation.

,26. .An-"electric switch as claimed in claim 25 wherein said pivotal connection of the biasing means with the shifter exerts a camming action on said carrier-moving member.

27. An electric switch as claimed in claim 6 having a pivotal connection between said biasing means and said shifter, and having a member acting on said pivotal connection to move the line of action of said spring overcenter-and change its bias.

28. An electric switch as claimed in claim 6 having a pivotal connection betweensaid shifter and said biasing means, said shifter having a second pivotal connection which is shiftable as said bias changes, and mounting means in which said second pivotal connection is supported and guided.

29. An electric switch as claimed in claim 6 having a pivotal connection between said biasing means and shifter, said connection acting on said carrier-operating member to cause said-slow initial contact separation, and having means for positively separating the contacts in case the biasing means should become disabled.

30. A11 electric switch as claimed in claim 6 having means to guide said carrier-moving member for rectilinear motion.

31. An--electric switch as claimed in claim 6 having a centering member biased by said biasing means to hold said manually operated means in a certain position when the contacts are separated.

References Cited in the file of this patent UNITED STATES PATENTS 2,163,919 Siegel June 27, 1939 2,251,830 Holmes Aug. 5, 1941 2,281,544 Beeman et a1 May 5, 1942 2,289,643 Furnas et a1. July 14, 1942 2,318,227 Jackson May 4, 1943 2,481,141 'MQIT'I'SOI1 Sept. 6, 1949 2,490,523 Kneisley Dec. 6, 1949 2,515,449 Hammerly July 18, 1950 2,605,367 Cochran July 29, 1952