US3597560A

US3597560A - Electric switch with releasable screw-threaded spring charging means

Info

Publication number: US3597560A
Application number: US843613A
Authority: US
Inventors: Alexander R Norden
Original assignee: Empire Switchboard Co Inc
Current assignee: Siemens Energy and Automation Inc; Empire Switchboard Co Inc
Priority date: 1969-07-22
Filing date: 1969-07-22
Publication date: 1971-08-03
Anticipated expiration: 1988-08-03

Abstract

A normally manually operable electric switch is provided with stored energy mechanism which can be remotely controlled to open the switch without interfering with the direct manual operation to open or close the switch. The stored energy mechanism consists of a threaded rod portion and releasable screw-threaded means engaging said rod portion and allowing a spring to be compressed; upon release of the releasable screw-threaded means, the spring discharges. The stored energy mechanism is manually operable to render it potentially operable to open the switch automatically by remote control and provision is made to render said mechanism inoperable when said remote control is not desired.

Description

United States Patent Inventor Appl. No. Filed Patented Assignee ELECTRIC SWITCH WITH RELEASABLESCREW- THREADED SPRING CHARGING MEANS 11 Claims, 12 Drawing Figs.

11.5. c1 200/153 sc,

. 74/239151, 185/39 lnt.Cl 110111 3/30, 110111 21/40,l-l01h 3/40 Field oiSeerch ..200/-153.23; 337/8, 7; 335/171; 173, 23; 185/37, 39; 74/59, 89.15, 127, 509

References Cited UNITED STATES PATENTS 7/1958 Dickson Primary Examiner- Robert K. Schaefer Assislan! Examiner Robert A. Vanderhye a a m-Jerry o en ABSTRACT: A normally manually operable electric switch is provided with stored energy mechanism which can be remote- 1y controlled to open the switch without interfering with the direct manual operation toopen or close the switch. The stored energy mechanism consists of a threaded rod portion and releasable screw-threaded means engaging said rod portion and allowing a spring to be compressed; upon release of the releasable screw-threaded means, the spring discharges. The stored energy mechanism is manually operable to render it potentially operable to open the switch automatically by remote control and provision is made to render said mechanism inoperable when said remote control is not desired.

SHEET 2 0F 6 PATENTEI] AUG 3 I371 PATENTEH AUG 3l97l 3, 597,560

PATENIEUAUI; 31971 3597560 sum 5 UF 6 F/G./O

This is a continuation-in-part of my Application Ser. No. 599,904 filed Dec. 7, I966, now US. Pat. No. 3,496,3l9, issued Feb. l7, I970.

BACKGROUND OF THE INVENTION This invention relates to a high current quick make and quick break switch which is normally manually operable to effect rapid closing and rapid opening of the switch. In the invention described in the above identified application, an arc chute is provided for each of a plurality of lines which are connected by main and auxiliary contacts and there is an interlock between the movable companion main and auxiliary contacts which prevents engagement of the main movable contact with the companion stationary contact if the companion arc chute is not in place, said interlock being released to permit closing of the companion maincontacts if the arc chute is in place.

OBJECTS OF THE INVENTION One object is to provide a simple and rugged stored energy mechanism to effect rapid opening movement of the switch without requiring operation of the normal manually operable handle.

Another important object is to provide a mechanism as above stated and which will not interfere with the operation of the normal switch actuating mechanism and will not affect the normal electrical and mechanical functions of the switch.

Another object is to provide a normally manually operable switch with a stored energy mechanism which can be conditioned to open the switch by either remote or manual control without actuation of the normally manually operable handle.

These and other objects, features and advantages of the invention will become apparent from the following description considered in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of this invention, showing the switch in its open position, and with one arc chute removed for the purpose of illustration;

FIG. 2 is a right side detail view of the contact assemblies, showing the contacts in their fully open disposition;

FIG. 3 is a left side detail view of the contact assemblies, showing the auxiliary arcing contacts in closed dispositionand the main contacts still open, all with the left half of the arc chute removed for the purpose of illustration;

FIG. 4 is a left side detail view of the contact assemblies in their fully closed positions, with the left half of the arc chute removed for the purpose of illustration;

FIG. 5 is a front detail view of the switch operating mechanism;

FIG. 6 is a front detail view of the switch operating mechanism in the switch closed position;

FIG. 7 is a cross-sectional view of FIG. 6 taken along the plane FIG. 6-6;

FIG. 8. is a view taken on the line 8-8 of FIG. 1;

FIG. 9 is a view taken on the line 9-9 of FIG. 8;

FIG. 10 is a view taken on the line 10-10 ofFIG. 9;

FIG. 11 is a view taken on the line 11-11 of FIG. 10; and

FIG. 12 is a view taken on the line 12-12 of FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION The switch which is shown in FIG. I is supported on a frame provided by two rear

upstanding angles

12 and 14, a front plate 16, and two sideplates l8 and20. An upper dielectric back panel 33 is mounted to and between the

angles

12 and 14, as by a plurality of bolts and nuts 24. A lower dielectric back panel 26 is mounted to and between the

angles

12 and 14, as by a plurality of bolts and nuts 28.

Three lines or phases are here shown as being simultaneously'switched. Each phase includes: A line terminal 30 which is secured to and between two

angles

32, 32, as by nuts and bolts 34, and which angles are secured to the upper dielectric panel 22, as by a plurality of nuts and bolts 36. An upper fuse terminal 38, which is secured to and between two

angles

40, 40, as by a plurality of nuts and bolts 42, and which angles are secured to the upper dielectric panel 22, as by a plurality of nuts and bolts 44. A lower fuse and load terminal 46, which is secured to and between two angles 48, 48, as by a plurality of nuts and bolts 50, and which angles are secured to the lower dielectric panel 26, as by a plurality of nuts and bolts 52. A fuse 54 has an upper terminal 56 which is secured to the upper fuse terminal 38, as by a plurality of nuts and bolts 58, and a lower terminal 60 which is secured to the lower fuse terminal 46, as by a plurality of nuts and bolts 62. The

various angles

32, 40 and 48 each have a plurality of fins 64 formed thereon for rapid heat radiation.

As best seen in FIGS. 2, 3, and 4, a main moving contact 66 comprises a pair of bars 68 which are pivotallymounted to and astride the upper fuse terminal by a lower cross-shaft 70. The pair of bars 68 is also provided with an upper cross-shaft 72 and a cross-rod 74. The right end of the lower cross-shaft 70 is integral with a crank 76, exterior to the right bar, having a short arm 78 and a long arm 80. The distal end of the long arm 80 terminates in a right angle 82 which is secured, as by a plurality of nuts and bolts 84, to a dielectric crossbar 86. The left end of the lower cross-shaft 70 is threaded into a nut 88, exterior to the left bar, which is fixed to the left bar, as by a machine screw 89. The right end of the upper cross-shaft 72 is integral with a crank 90, exterior to the right bar, having a short arm 92. The left end of the cross-shaft is threaded into a nut 94, exterior to the left bar, which is fixed to the left bar, as by a machine screw 95. The distal ends of the short arms 78 and 92 are interconnected by a connecting rod 96. Downward movement of the connecting rod, and associated rotation of the cranks 76 and and their respective cross-shafts 70 and 72 draws the pair of bars closer to each other.

In the main contact-open position, shown in FIG. 2, the connecting rod 96 is in its upper position. In the intermediate position, shown in FIG. 3, the bars 68 are swung upwardly about the lower cross-shaft 70. The lower corner 98 of the terminal 30 is cut away to clear the bars in the intermediate position. The connecting rod remains in its upper position. In the fully closed position, shown in FIG. 4, the bars 68 are swung upwardly further to overlap the terminal 30. A notch 100 is cut into the terminal 30to receive the upper cross-shaft 72. The connecting rod is in its lower position, and the bars 68 are clamped onto the terminal 30 and a terminal 38.

A relatively movable, auxiliary arcing contact assembly 102 is carried by each main moving contact 66. A fixed, auxiliary arcing contact assembly 104 is secured to each line terminal 30. The assembly 104 includes a pair of spring blades 106 which are respectively secured to each side of the terminal 30, as by a plurality of nuts and bolts 108. The distal ends of the blades each have a reflex bend 110 therein to form a female contact. The assembly 102 has an outline which approximates a question mark. The upper end 112, which serves as the male contact, is advantageously made of a solid bar. The lower end 114 is bifurcated, and is advantageously made of a pair of bars secured to the upper end, as by a plurality of nuts and bolts 116. The lower end 114 is pivotally mounted between the bars 68 by the cross-rod 74 passing through a journal 118 mounted through the bars. A second dielectric crossbar 120 is secured to each of the pair of bars 68, as by a plurality of machine screws 122. A compression spring 124 is mounted on one leg of a U-shaped guide 126. The reflexed end of the guide and the lower end of the spring are disposed in a blind bore in the crossbar 120. The upper end of the spring is disposed in a notch 132 out into both bars 114, while the upper ends of the guide pass beyond the notch between the pair of bars 114. The spring is thus captured.

A pair of latches 134 are respectively mounted to the upper ends of the bars 68. Each latch 134 is pivoted to the bar 68, as

by a machine screw 136. An elongated hole 138 is cut into the latch to pass the shank ofa machine screw 140, while the head of the screw 140 precludes lateral movement of the latch. The upper portion 142 of the latch is bent over to form a camming surface. A hairpin spring 144 is disposed with its reflex portion under the head of the screw 136, and its legs between the cam 142 and the screw 140, to bias the latch upwardly. A cross-pin 146 is secured through the upper part of the lower end portion 114 of the movable arcing contact assembly 102. A hook 148 is formed into each latch 134 and this hook is normally biased upwardly by the spring 144 when the switch is in its open position to engage behind the cross-pin 146. When the latch is so engaged, the main contact bars 68 cannot swing upwardly without similar movement of the movable arcing contact assembly 102. The compression spring 124 biases the moving auxiliary arcing contact 114 into abutment with the shaft 72 of the crank 90.

An arc chute assembly 150 is secured to each line terminal 30. A U-shaped bracket 152 is secured to the edge of the terminal 30, as by a plurality of machine screws 154. A pair of chute halves 156 are secured to the bracket, as by a plurality of machine screws 158, and to each other, as by a plurality of nuts and bolts 160. The pair of chute halves together form a hollow enclosure in which the making and breaking of the auxiliary arcing contact is performed. The halves have mutually abutting surfaces at

portions

162, 164, 166 and 168. The female contact 104 projects into the enclosure between the portions 166 and 168. The male contact 102 is movable into this enclosure between the

portions

164 and 168. A plurality of grooves are formed into the inner walls of the chute halves to support a plurality of V-notched arc extinguishing plates 170. The portion 168 projects downwardly and serves as a cam which rides against the camming surface 142 of the latch 134 when the moving

contacts

66 and 102 are swung upwardly from the open position of FIG. 2 to the intermediate position of FIG. 3. The male contact 102 passes into the enclosure, between the bifurcations of the V-notched plates 170 above the portion 168 into the female contact 110 until it abuts the edge of the terminal 30. Normally, each portion 168 will cam its respective latch 134 downwardly releasing the movable main contact assembly 66 for movement independently of the auxiliary arcing contact assembly 102. However, should any one of the arc chute halves 156 be missing from any of the terminals 30, then none of the contact assemblies 66 will move beyond the intermediate position of FIG. 3, since all of the main contacts are secured to the second dielectric crossbar 120.

Any arcing between the

auxiliary arcing contacts

104 and 102 as they make or break will be blocked by the respective portions 168 of the arc chute from the main contact assembly 66. Any ionized gas will be drawn up between the plates 170 and will be blown out the top of the arc chute between the projections 162 and 164. On break motion particularly, when the arcing contacts first separate, the portion 168 ensures that the lowest potential path for the arc is between the arcing contacts, rather than between one arcing contact and the and the other main contact.

The first and second

dielectric crossbars

86 and 120 are interconnected by a pair of toggle assemblies 172. Each toggle assembly includes a cam 174 which is pivotally mounted at its lower end, as by a capped machine screw 176, to the crossbar 86, and which has a notch 178 at its upper end. An arm 180 is pivotally mounted at its upper end, as by a capped machine screw 182, to the crossbar 120, and is pivotally mounted at its lower end, as by a spooled rod 184, to the middle of the cam 174. A tension spring 186 is secured to and between the screws 182 and 176, and around the spooled rod 184. ln the locked position of the toggle assemblies shown in FIGS. 2 and 3, the notch 178 ofthe cam sits on the cap ofthe screw 182. A pair of striker assemblies 188 are secured to the upper dielectric back panel 22 in line with the respective toggle assemblies. Each striker assembly includes a bolt 190 secured to the panel 22 and a cap 192. When the moving main contact assembly 66 moves from the intermediate position of FIG. 3 to the closed position of FIG. 4, the cap 192 of the striker assembly abuts the edge of the cam 174, moving the pivot 184 over center against the bias of the spring 186, breaking the toggle, and permitting the crossbar 86 to move upwardly towards the crossbar 120. Upward movement of the crossbar 86 swings the crank arm upwardly and the connecting arm 96 downwardly; rotating both cranks 76 and to clamp the bars 68 tightly against the terminal 30 and the terminal 38.

Quick make and break operation of the switch is provided by an operator assembly 200. The operator assembly includes a shaft 202 which is journaled through the front plate 16 to an intermediate plate 204 and which plate is secured to the sideplate 18, as by nuts and bolts 206.

in accordance with the present invention, when the switch is provided with stored energy remote control mechanism for the opening operation of the switch, as hereinafter described, there is a releasable connection 209 between operating handle 208 and shaft 202. For this purpose shaft 202 extends forwardly of front plate 16 and has a rotary bearing in member 211 secured to said plate, handle 208 being releasably connectable to shaft 202 by engagement of the pin 213, fixed to shaft 202, in the slot 215 of handle 208 in opposition to the compression spring 217 which normally holds handle 208 in retracted position against the stop 219 on the forward end of shaft 202, which extends in a slot 219a in handle 208. When operating handle 208 is out of operating engagement with shaft 202 it pivots on said shaft into engagement with the stop 221 on front plate 16. It will be understood that slot 219a is wide enough to permit turning of shaft 202 for opening of the switch under remote control without rotation of the handle 208.

A charging spring assembly couples rotation of the shaft 202 to movement of the dielectric crossbar 86. The charging spring assembly includes a bracket 212 which is secured at one end to the crossbar 86, as by a plurality of nuts and bolts 214, and at its other end is adapted to interlock with a hook 216 on the end of a detent 218. The bracket is pivotally secured to a clevis 220, as by a pin 222. The clevis is integral with a cap 224 and a stud 226. The cap is secured to the top of a tube 228, as by a pin 230 through the stud and the tube. The bottom of the tube 228 rests on a shoulder 232 of a spool 234 and is secured thereto, as by two pins 236. A cup shaped washer 238 also sits on the shoulder 232. A helical compression spring 240 is disposed on the tube 228 and is captured between the plate 224 and the washer 238. A rod 242 is disposed through a longitudinal bore 244 in the spool. The lower end of the rod is threaded and is secured to a convoluted washer 246 by a washer 248 and a nut 250. A helical compression spring 252 is disposed on the rod 242 and is captured between the top of the spool 234 and a washer 254 and a cross-pin 256 through the top of the rod. A cup 258, having a longitudinal bore 260 which clears the spool and a shoulder 262 which engages the washer 238, is supported on the convoluted washer 246. Two crank

arms

264 and 266 are secured to the shaft 202, as by welding, and are pivotally secured to the cup 258, as by pins 268 and 270 respectively.

The detent 218 is pivotally mounted to the front plate 16, as by a nut and bolt 272, and is limited in its swing by a pin 274 fixed to said detent and projecting through a relatively larger hole 276 in the front plate. An arm 278 is pivotally secured at one end to the detent 218, as by a nut and bolt 280, and at its other end to one end of an arm 282 by a roller, a stud and a C spring 284. The other end of the arm 282 is pivotally secured to the front plate 16, as by a nut and bolt 288. A tension spring 290 is connected to and between the arm 282 and the front plate 16 to bias the detent 218 towards the bracket 212. A right angle 292 is secured to the arm 266, as by a plurality of machine screws 294 and has a foot portion 296 which is disposed under the roller 284.

When the switch is in its normal open position, the end of the bracket 212 is under the hook 216 of the detent 218. Upward rotation of the handle 208, towards the closed position, swings the

brackets

266 and 264 upwardly and slides the cup 258, the washer 262, the spring 240, the clevis220 and the bracket 212 upwardly to abut the bracket against the hook 216. Further rotation of the handle compresses the spring 240 against the clevis, and when the spring is fully compressed providing a direct drive, until the foot portion 296 engages the roller 284 to swing the detent 218 away from the bracket 216, thereby releasing the bracket from the hook. The now released compressed spring fires the bracket 212, the dielectric crossbar 86, the toggled locked thereto dielectric crossbar 120, the main moving contact assemblies 66 and the auxiliary arcing moving contact assemblies 102 upwardly. On normal operation, sequentially, the auxiliary male contact 112 will mate with the auxiliary female contact 110, the arc chute portion 168 will strike open the latches 134, the main contact bars 68 will overlap the terminal 30, the striker 192 will break the toggle 172, and the dielectric bar 86 will rotate the cranks 76 and 90 to clamp the bars 68 on the terminal and the terminal 38.

If one or more of the arc chute halves 56 is missing, the respective latch 134 will not be opened and the switch will halt in the intermediate open position of FIG. 3.

If a short circuit condition should exist at the instant of closing of the arcing contacts 112 and 110, the flow of current creates electrodynamic forces having a direction which opposes the closing force of the spring 240 and the momentum of the high inertial mass of the moving contacts.

In the case of a relatively less severe short circuit, these electrodynamic forces are insufficient to prevent the normal closing sequence of the switch. The moving arcing contacts. 112 will be driven into engagement with the respective stationary arcing contacts 110 by the respective latches 134 engaged with their respective cross-pins 146. Subsequently, the latches will be disengaged from the cross-pins by the respective camming portions 168 of the arc chutes and the main. moving contacts will close onto the main stationary contacts. In due course, depending on the current and the fuse ratings, the fuses will blow.

In the case of a very severe short circuit, these electrodynamic forces will equal or exceed the closing force of the. spring 240 and the momentum of the high inertia mass of the moving contacts. Under such conditions, the fuses will blow within one-half cycle, while more than one-half cycle will be required to either drive the moving arcing contacts in their closing direction from the commencement of mating with the. stationary arcing contacts to the point of disengagement of the latches 136 from their respective cross-pins, or to arrest andp reverse the direction of movement of the high inertia mass of.

the moving contacts driven by the spring 240. Therefore, within this one-half cycle the fuses will blow; and the light springs 124 will be compressed and the moving contacts will be arrested by the cross-pins pushing against the latch hooks 148 so that the latches 136 will not reach the camming portions 168 and will not be disengaged from their respective cross-pins, and the main moving contacts will not mate with the main stationary contacts. Should the electrodynamic forces exceed the driving force, and the moving contacts be thrown back, such forces will be shock-absorbed and cushioned by the compression of the spring 240, and will not be directly transmitted to the handle.

When the switch is in its normal closed position, downward rotation of the handle 208 towards the open position, swings the

brackets

266 and 264 downwardly and slides thecup 258,

the convoluted washer 246, and the rod 242 downwardly,

compressing the inner spring 252, when the spring 252 is fully compressed, the handle 208 is in direct drive with the clevis 220 and swings the bracket 212 downwardly, swinging the dielectric crossbar 86 downwardly and locking the toggles 172. This releases the compressed spring 252 which now fires the bracket 212 and the moving

contact assemblies

66 and 102 downwardly. A ramp 298 is formed on the corner of the detent'above the hook 216 so that the bracket 212 cams the detent aside as it moves downwardly to the open position. It should be noted that when the'dielectric crossbar 86 is swung downwardly, it rotates the crank 76 and 90 to unclamp the bars 68 from the terminal 30. At this time the end 112 of the moving auxiliary arcing contact is abutting the edge of the terminal 30, and the compression spring 124 biases the dielectric crossbar and the main moving contact bars 68 away from the terminal 30. In the event that a chute is missing and the moving contact is halted in the intermediate position of FIG. 3 with the toggle unbroken, on opening movement the handle will swing the moving contact bars downwardly without any compression of the spring 252.

Referring now to the provision for remote control of the switch opening operation the mechanisms illustrated more particularly by FIGS. 8 to 10 will now be described.

' A screw-threaded rod 300 is releasably engaged by a split nut 301 which comprises parts 302'and 304 carried by

arms

306 and 308 pivotally mounted on shouldered

screws

310 and 312 for movement into and out of engagement with the threaded portion of rod 300 in frame 314 which is secured to plate 16. A handle 316 is provided at the front of plate 16 (FIGS. 1 and 8) for rotating rod 300 which extends through an opening 318 in said plate. When said split nut 301 engages rod 300, the latter is longitudinally movable in one direction, pursuant to rotation of the handle, to compress,'i.e..to charge, spring 320 which is captured between the end 322 of frame 314 and a collar 324 fixed to said rod. When nut 301 is released from rod 300 the latter is movable longitudinally by the charged spring 320, without rotation of said rod, toward v panel22.

Rod 300 is coupled operatively to bar 86'by mechanism including bellcrank lever 326 which is pivotally mounted on stationary bracket 328 and is pivotally connected at one end to collar 324 and at its other end to the lower end of link 330. A stop 331 limits the movement of bellcrank 326 in a clockwise direction viewing FIG. 8 and thereby limits the longitudinal movement of rod 30010 the right. Said link 330 is pivotally connected at its upper end to bellcrank lever 332 which is pivotally mounted on stationary bracket 334. The upper arm of lever 332 carries an adjustable member 335 which bears against bar 86 for moving said bar 86 to open the switch when split nut 301 releases rod 300.

It will be noted that the rib-defining grooves of rod 300 are such that the confronting sides 334' of each groove define an obtuse angle therebetween so that the discharging force of spring 320, when latch arm 336 (FIGS. 9 and 10) which is pivotally mounted nut part 302by the pivot 338 is disengaged from nut part 304, is effective to release the nut 301 from rod 300 so that the latter can move longitudinally without rotation. More particularly, latch arm 336 carries a roller 340 which engages nut part 304 when nut 301 is in threaded engagement with rod 300. Spring 341 is connected at one end to plate 16 as indicated at 342 (FIG. 9) and at its opposite end to pin 344 on arm 308. Nut part 304 has an inclined portion 345 over which roller 340 can move to and from the two positions shown in FIG. 9, the position of said roller at the left being in the latching position of arm 336 and the position of said roller at the right being in the unlatched position of said arm.

A solenoid 346 is mounted on a bracket 347 secured to casing 314. The solenoid plunger 348 is connected to arm 350 of latch arm 336 so that when the solenoid in energized, which can be done by closing a switch at any selected location, roller 340 is retracted and nut 301 is moved out of operative engagement with rod 300. A manually operable pin 352 accessible atarrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of the invention within the scope of the appended claims.

What I claim is:

1. An electric switch comprising, a stationary contact member, a companion movable contact member, a fuse associated with one of said contact members, mechanism coupled to said movable contact member for opening and closing the switch manually operable means for normally actuating said mechanism to open and close the switch releasably coupled to said mechanism and means operable independently of said manually operable means to actuate said mechanism to open said switch after it is closed by actuation of said mechanism by said manually operable means said independently operable means comprising rotary screw-threaded means, spring means which is stressed by rotation induced longitudinal movement of said screw-threaded means in one direction coupled to said mechanism for rendering it potentially operable to actuate said switch opening mechanism, said spring means being coupled to said screw-threaded means for biasing said screw-threaded means for longitudinal movement in a direction opposite to said one direction, and means coupled to said screw-threaded means for releasably preventing nonrotary longitudinal movement of the screw-threaded means in said opposite direction and permitting said longitudinal movement of said screw-threaded means in said opposite direction by said spring means for actuation of said switch opening mechanism.

2. An electric switch comprising switch closing mechanism and switch opening mechanism, means to actuate said switch opening mechanism comprising rotary screw-threaded means, spring means which is stressed by rotation-induced longitudinal movement of said screw-threaded means in one direction coupled to said mechanism for rendering it potentially operable to actuate said switch opening mechanism, said spring means being coupled to said screw-threaded means for biasing said screw-threaded means for longitudinal movement in a direction opposite to said one direction, and means coupled to said screw-threaded means for releasably preventing nonrotary longitudinal movement of the screw-threaded means in said opposite direction and permitting said longitudinal movement of said screw-threaded means in said opposite direction by said spring means for actuation of said switch opening mechanism.

3. An electric switch according to claim 2, wherein said screw-threaded means comprises a screw-threaded rod, the companion confronting sides of rib-defining grooves of the threads defining an obtuse angle therebetween, a split nut coupled to said threaded rod and releasable therefrom to permit said nonrotary longitudinal movement of said rod.

4. An electric switch according to claim 1 wherein said screw-threaded means comprises a screw-threaded rod, the companion confronting sides of rib-defining grooves of the threads defining an obtuse angle therebetween, a split nut coupled to said threaded rod and releasable therefrom to permit said nonrotary longitudinal movement of said rod.

5. An electric switch according to claim 3, wherein said split nut comprises two parts, a pivot on which said parts are pivotally mounted for engagement with and disengagement from said rod, and means for moving said parts of the nut into and out of engagement with said rod.

6. An electric switch according to claim 5 wherein the means for moving said parts of the nut into engagement with said rod comprising manually movable means releasably coupled to said parts of the nut and movable to a projected position and to a retracted position.

7. An electric switch according to claim 5 wherein the means for moving said parts of the nut into engagement with said rod comprises camming means releasably coupled to one of said parts of the nut and comprising a manually operable means for actuating said camming means.

8. An electric switch according to claim 5, wherein the means for moving the split nut out of engagement with said rod comprises said stressed spring acting on said rod when said movable means which is releasably coupled to the nut is moved to a retracted position.

9. Stored energy mechanism comprising, longitudinally movable screw means, spring means stressed by rotation-induced longitudinal movement of said screw means in one direction, said spring means being coupled to said screw means for biasing said screw means for longitudinal movement in a direction opposite to said one direction, and releasable means coupled to said screw means for releasably preventing nonrotary longitudinal movement of the screw means in said opposite direction and permitting said longitudinal movement of said screw means in said opposite direction by said spring means.

10. Stored energy mechanism according to claim 9, wherein said screw-threaded means comprises a screw-threaded rod and said releasable means comprising a split nut having separable parts disengageable from said rod to permit said longitudinal movement ofsaid rod.

11. Stored energy mechanism according to claim 10 wherein the companion confronting sides of rib-defining grooves of the threads of said rod define an obtuse angle therebetween.

Claims

10. Stored energy mechanism according to claim 9, wherein said screw-threaded means comprises a screw-threaded rod and said releasable means comprising a split nut having separable parts disengageable from said rod to permit said longitudinal movement of said rod.