US2317118A - Quick-break disconnect switch - Google Patents

Description

Ap 20, 1943. w. o. SCHULTZ ETAL QUICK-BREAK DISCONNEC'I' SWITCH Filed June 16, 1959 4 Shets-Sheet 2 Patented Apr. 20, 1943 Line Material Company,

QUICK-BREAK DISCONNECT SWITCH William C. Schultz, South Milwaukee, and Alwin G. Steinmayer, Milwaukee, Wis., assignors to South Milwaukee,

Wis., a corporation of Delaware Application June 16, 1939, Serial No. 279,414

16 Claims.

This invention relates to quick-break disconnect switches.

In electrical distribution circuits operating on comparatively high voltages and amperages, it is customary to provide a manually-operable switch for sectionalizing and interconnecting distribution feeder lines. When these switches are opened under load and where no provisions are made for obtaining instant wide separation of contacts, arcing which is destructive to the contacts occurs between the contacts.

Various provisions have heretofore been made in disconnect switches for obtaining quick, wide separation of switch contacts, but is has been found that the speed of separation and the arrangement of the parts have permitted some arcing-between the separating contacts with the result that such contacts are frequently damaged.

Therefore, it is the principal object of this invention to provide for a disconnect switch, an auxiliary switch which will maintain closed-circuit conditions until the disconnect switch has opened sufficiently to avoid arcing between its contacts and which will thereafter break the circuit in a minimum interval of time without any arcing to the contacts of the disconnect switch.

More specifically, it is an object to provide for disconnect switches, an auxiliary switch including an inherently resilient switch member adapted to be flexed when the disconnect switch is moving to open position, thereby biasing the switch member to open position and to be released for such movement during movement of the disconnect switch after the circuit there through is opened.

Another object is to provide improved camaction means facilitating operation of the disconnect switch to open-circuit position. This feature is the subject matter of our divisional application, Serial No. 337,194, filed May 25, 1940.

A further object is to provide full-floating and self-aligning contacts adapted to insure efficient and smooth operation of the switch. This feature is also the subject matter of the above identified divisional application.

In the drawings:

Fig. 1 is a view in side elevation, partly in section, showing a housed disconnect switch embodying this invention.

Fig. 2 is a view similar to Fig, 1 showing the switch moved toward open position.

Fig. 3 is a view in front elevation with the housing door substantially removed.

Fig. 4 is a sectional View taken on the line 4-4 of Fig. 1.

Fig. 5 is a detail view of a part of the switch structure.

Fig. 6 is a front view of the switch housing with the door removed and a fragmentary part of the switch in open position.

Fig. '7 is a front view of a fragmentary portion of the housing with the switch in open position.

Like parts are identified by the same reference characters throughout the several views.

The housing for the switch comprises insulating material, such as wet process porcelain, which is moulded to form a relatively thick rear wall I, a top wall 2, side walls 3, and bottom wall 4 having a recess 5.

A door 6, made of insulating material such as Bakelite, is pivotally mounted at its upper end adjacent the top wall 2 within the recessed portion 1. The pivot for th door may comprise a pin 8 extending through the walls 3 and the hub portion 9 on the door. Disposed on the pin 8, at each end of the hub portion 9, are a resilient friction plate It and pressure member H coacting to resist pivotal movement of the door and thus providing means for retaining the door in open position extending horizontally from the housing as indicated in Fig. 2. The means for retaining the door in elevated position has not been shown in great detail, since any suitable means may be provided for obtaining the intended result. I The rear wall I of the housing is provided with spaced terminal supports and I6 anchored in the recesses I! by means of cement or other desirable material [8 and with a pivot plate or blade l9 spaced from the support 16 and anchored in the recess 20 by means of cement 2i. Secured tothe outer face of the rear wall I by any desirabl means, such as bolts 22 anchored in the wall, is a pivot plate 23 having its ends 24 bent angularly to coact with similar ends on the mounting strap 25. The correspondingencls of the plate 23 and strap 25 are pivotally connected by means of bolts 26 and are normally held against relative pivotal movement by means of the nuts 21. The strap 25 is provided with bolts 28 cooperating with other parts, not shown for attaching the housing to a crossarm, not shown. Disposed between the terminal supports l5 and I6, is a barrier 29 which increases the leakage distance between the supports.

The side walls 3 of the housing are each provided with spaced holes 30 adjacent the terminal members 3| and 32 for the insertion of line wires, not shown, to be connected with the terminals in the manner hereafter more fully disclosed. Each of the holes 30 is provided with a hood 33 on the outer face of the respective walls 3 adapted to prevent rain and sleet from entering the housmg.

The terminal members 3| and 32 are identical and, as may be clearly seen in Figs. 2 and'G, each comprises a base 34 having a contact plate or blade 35 normal thereto and extending along a central portion thereof, Wing portions 36 at opposite'sides of the plate 35 and each having an aperture 31, clamping jaws 38 disposed on opposite sides of the plate 35 and spaced. from adjacent wing portions 35, and spaced legs39. Asimay be clearly seen in Figs. 2 and 6, the contact plate 35 is L-shaped to provide a narrower portion 4|] which serves as a camming surface more fully described hereafter.

The terminal members 3|. and- 32 are loosely mounted on the terminal supports [5 and I6, respectively, to obtain a full-fioatingjeiiect permitting lateral and angular alignment thereof.

relative to the supports and with the. switch.

blades subsequently more fully described. This mounting is secured by means of the sleeves. 4| which fit loosely in the apertures 31 in the terminal members. The sleeves are rigidly retained on the supports and I6 by means of bolts 42 which extend through the sleevesand are threaded into the supports.

The upper terminal member 31 is retained" on the sleeves by means of auxiliary L-shapedjcontacts 43 in which the bases 44 serve as washers confined between the sleeves 4| and the heads of the bolts 42. The length of the. sleeves 4| is greater than the distance between the base ofthe legs 39 andfa'ce of the wing portions 35. on terminal member 3!, thereby permitting movement of the member between the contact bases 44 and the support I5. The outer ends of the L-shaped contacts 43 are each provided with a deflection or wedge-like portion 45 which terminates in a rearwardly-extendinghook 46, more fully disclosed in Fig. 4. V

The lower terminal member 32 is secured'to the support It in a similar manner withthe exception that a washer 4'! replaces the base 44 on the L.-shaped contact 43. Disposed betweentheterminal members 3| and 32 and the supports l5 and I6 are plate springs 48, shown in detail in Fig. 5, which serve to hold the'members outwardly of the supports and in contact with the bases 44 and washers 41, respectively.

Mounted on each of the. clamping. jaws 38 is a movableclamp having an elongated opening 5i receiving the jaw 38 andprovidedwith a clampactuating bolt 52 extending into and lengthwise of the opening 51 for actuating engagement with the jaw 38. The bared ends of conductors, not shown, may be passed through the holes 30 in the sides 3 of the housing and inserted between the cooperative clamping surfaceson the jaws 38 and clamps 50 and clamped thereby upon appropriate manipulation of the bolts 52.

The switch blade comprises a pair of spaced, parallel, flat bars 53 and 54 which are pivotally mounted at the lower end of the housing on, the pivot bolt 55 which extends through the bars 53 and 54 and the pivot plate is and is secured in such position by means of the nut 56 and: lock nut 57. The upper ends of thebars53 and 54, as viewed in Figs. 1, 2 and 3', or the lower end, as viewed in Fig. 7, are connectedby a bolt 59 which extends through the bars and is held in position by means of a nut 60. Preferably, the nut 60 is secured in' position by mutilating the threads on the bolt, and cupped washers Bl are provided to give a degree of resiliency and for maintaining the bars in firm frictional engagement withthe contact 35 on upper terminal member-3|.

The upperportion of the bars 53 and 54x intermediate theenols thereof is providedv with abolt 62- which. extends through the bars andis secured in position by means of. a nut 63. This bolt in Fig. 1 is positioned below contact 35'on the upper terminal 3| and serves with the cupped washers 64 to hold the bars in firm contact with the contact 35.

Below the bolt 62, as viewed in Figs. 1 through 3 and above the contact 35 on the lower terminal member 32, is a bolt 65 which extends through the bars 53 and. 54. Mounted on this bolt are a pair of tubesfifi, apair of cupped washers 61 and a pair oflstandard. washers 68. A nut 69 retains the bolt 65 in position. This bolt also serves to hold the bars in firm frictional engagement with the contact 35 on the lower terminal member 32.

Pivotallymounted on the bolt 65 and between the-bars53 and 54, is switch-operating lever 10 of the first class having at its upper end a pull-push ring 'H extending from between the bars, a cam finger l2, and stop finger 13 engageable with the pin 14 which extends through the bars 53' and 54 and'is retained-in position by means of a washer 15 and'cotter pin 16. V

A coil spring 18 positioned between the bars; 53' and 54 is engaged-at one end with the pin 14' and atthe-other end with the apertured lug'lfl'on' the lever 10. lever 15 in the position shown in Figs. 1 and 2 and against the bolt 62.

When it is desired to'move the switch from the closed position shown in Fig. 1, the door 6, which is provided with a recess BA forreceiving the pull ring H, will be first moved to the position indicated in Fig. 2". Then the pull ring H onthe lever 10 will be engaged by a suitableoperatlng stick, not shown, and thereby pulled from. between the bars 53 and 54. As the lever 10 is pulled in the manner indicated, the cam finger 12 at'the lower end thereof will engage theportion 40 on the lower terminal member 32; Pressure thus applied to the member 32 will first cause the-member'to'assume substantially the position shown in Fig. 2, and therafter cause' the switch blade to move outwardly about the pivot bolt. to the position shown in Fig. 2 where the switch is out of contact with the contact 35 on the upper terminal member 3i. When the switch has reached substantially the position shown in Fig. 2, thestop finger 13 on the lever 10 will engage the pin; 14 and thereafter the switch will be moved directly by means of the lever'to' the position indicated in Fig. 7 whereit will be insulated from the terminal members 3| and32.

In order to maintain the circuitfor a predetermined period of time while the switch is being moved from the position indicated in Fig. 2 to the position shown in Fig. 7, resilient spring wire contacts are provided. When the switch is in closed position, the upper ends of the spring wire contacts are in contact with the L-shaped contacts 43 at the upper end of the housing and are positioned as indicated in Fig. 4 within the bights of hooks 46.

The lower ends of the wire contacts 80 are each loosely coiled at 8| about a tube on the bolt 65 and extended therefrom to the pin 14 where they are anchored by hooked. portions 82. Intermediate the ends of the wire contacts 80, are guide plates 83 secured to the bars 53jand 54. Each of these plates is L-shaped and has the horizontal portion provided with an elongated slot 84 through which the corresponding wire contact 80 extends.

When the switch is in the positionsh'own in Fig. l, the wire contacts 80 normally rest against the outer end of the slot 84 as maybe seen in Fig. 1. Adjacent the upper end of each of the wire contacts 80 and below the L-shapedcon- This spring normally maintains" the" tacts 43, is a stop plate 85 secured in any suitable manner, such as riveting, to one of the bars 53 and 54. These stop plates serve to limit the movement of the wire contacts 80 relative to the switch after the wire contacts have disengaged from the contacts 43 as will more fully appear hereafter.

Operation of the switch bars 53 and 54 from closed to open position has been previously described. In Fig. 2, the switch bars are shown in a position just after they have been disconnected from the upper terminal member 3!. In this position, the wire contacts 80 are still in engagement with the L-shaped contacts 43 and consequently the circuit is still closed. As the switch bars 53 and 54 move further from the terminal member 3|, the wire contacts 80 will be flexed until the upper ends pass beneath the wedgelike portions 45 on the L-shaped contacts 43 and are released for unobstructed movement toward the stop plates 85, whereupon the wire contacts will assume the position relative to the switch bars 53 and 54 shown in Fig. 1.

In a circuit which is opened under load in the manner described, an arc may be drawn between the upper ends of the wire contacts 80 and the L-shaped contacts 43 when the wire contacts leave the contacts 43. However, the duration of the arc will be very short because of the rapid movement of the wire contacts away from the contacts 43 and such contacts will not be appreciably damaged.

It will also be noted that by drawing the are between the wire contacts and the contacts 43, the main parts of the switch, such as the bars 53 and 54 and the contact 35 on the upper terminal 3|, will not be subjected to destructive arcs which might cause pitting of the main portions of the switch.

As switch bars 53 and 54 are moved to closed position the upper end portions of contact wires 80 engage the angular cam surfaces on the wedge-like portions 45 of hooks 46 and are thereby caused to flex laterally of the plane of movement of said bars until they clear the tips of the hooks, whereupon they snap back into the bights of the respective hooks and finally occupy approximately the position in which they are shown in Fig. 4.

As previously noted, the terminal members 31 and 32 are in effect floating on the terminal supports I5 and 16, respectively. lhis permits the members 3| and32 to assume various positions during closing and opening movements of the switch bars 53 and 54 and thereby affords eflicient and smooth operation of the switch.

When the switch is in the open position shown in Fig. '7, the door 6 may be closed to prevent accidental contact with the live portions in the housing and to prevent small birds from attempting to rest on such portions.

From the foregoing description, it will be obvious that a disconnect switch has been provided in which arcing between the main portions of the switch has been eliminated and pitting thereof avoided when the switch is opened under load, in which a maximum mechanical advantage is available for manual operation of the switch during movement of the switch blade to its initial disconnect position, and in which a maximum efliciency and smoothness of operation of the switch is obtainable.

We claim:

1, In a quick-break disconnect switch the combination with a main switch comprising a pair of spaced terminals and a pivotally-mounted switch bar connecting said terminals, of an auxiliary switch electrically connecting said terminals and including a catch associated with one of said terminals and a resilient member engageable at one end with said catch and secured at the other end on said bar, said member comprising a wire having a coiled portion intermediate its ends and relatively in closer proximity to the last-mentioned end than the other, and a pin on said bar about which said portion is coiled, said catch comprising a hook-like wedge portion normal to the plane of movement of said bar, whereby upon movement of said bar to open position said memher will be withdrawn from said catch subsequent to the opening of a circuit through said bar.

2. In a quick-break disconnect switch the combination with a main switch comprising a pair of spaced terminals and a pivotally-mounted switch bar connecting said terminals, of an auxiliary switch electrically connecting said terminals and including a catch associated with one of said terminals, a resilient wire contact engageable at one end with said catch and secured at the other end on said bar, said wire having a coiled por tion intermediate its ends and relatively in closer proximity to the last-mentioned end than the other, and means on said switch bar holding said coil in a substantially fixed position relative to said bar, said catch comprising a hook-like wedge portion normal to the plane of movement of said bar.

3. In a quick-break disconnect switch the combination with a pair of spaced terminals and a pivotally-mounted switch bar frictionally engaging said terminals, of a pivot pin carried by said bar, a bar-actuating member for actuating said bar to open-circuit position, and aresilient wire having one end releasably latched with one of said terminals and its other end anchored on said bar, said wire having a portion loosely coiled about said pin, said one of said terminals including a latch adapted to flex said wire laterally of the plane of movement of said bar in one direction of movement thereof and to flex' said wire in a plane paralleling the plane of movement of said bar in the direction opposite to said one direction.

4. In a disconnect switch the combination with a support having a pair of spaced terminal supports and a pivot in insulated relation thereto, of a pair of terminals each loosely mounted on one of said terminal supports for lateral and angular movement thereon, a switch bar frictionally engaging said terminals and pivotally mounted on said pivot, a bar-operating member for actuating said switch bar toward open-circuit position, and a resilient wire electrically connecting said terminals and releasably'latched at its upper end, the'other end of said wire being anchored on said bar, the terminal adjacent said upper end including a latch adapted to flex said wire laterally of the plane of movement of said bar in one direction of movement thereof and to flex said wire in a plane paralleling the plane of movement of said bar in the direction opposite to said one direction.

5. In a disconnect switch the combination with an insulating support, a pair of terminals carried by said support in insnlatedrel'ation, a pivot carried by said support in insulated relation to said terminals, a switch bar pivotally mounted on said pivot and frictionally' engaging said terminals, a pivot pin carried by said bar, and a bar-operating means foractuating said bar to open-circuit position, and a resilient member having one end riele'a s'ab'ly latched with one ofsaid terminals and secured at the other end on saidpivot pin, said one of said terminals including a latch adapted to flex said wire laterally'of the plane of move= ment of said her in one direction of movement thereof and to flex said wire in a plane paralleling the plane of movement of said bar in the direction opposite to said one direction, whereby uponmovement of said bar to open position said member will be withdrawn from the last-mentioned terminal subsequent to the opening of a circuit through said bar.

6. In a disconnect switch the combination with an insulating support, a pair of terminals carried by said support, a switch bar pivotally mounted on said support, and a pivot pin carried by said bar, abar-operating means supported by said pivot pin for actuating said bar to open circuit position, of an auxiliary switch electrically connecting said terminals and including a catch associated with one of said terminals, a resilient wire contact having a coiled portion intermediate its ends slidably engaged with said pivot pin and in contact at the other end with said catch, said catch comprising a hook-like wedge portion adapted to move said wire laterally of said bar in one direction of movement thereof and in parallel relation to the bar in the other direction of movement thereof, whereby upon movement of said bar to open position said member will be withdrawn from said catch subsequent to the opening of a circuit through said bar,

'7. In a disconnect switch including an insulating support, a pair of terminals carried by said support in insulated relation and each including a blade-like contact, a pivot support carried by said insulating support in insulated relation to said terminals and including a blade-like portion,

and a pair of substantially parallel fiat bars 'frictionally engagingsaid contacts and said portion and pivotally mounted on said portion, the combination with said switch, of an operating lever mounted on said bars, an auxiliary switch electrically connecting said terminals during a portion of the movement of said bars to open positions, and means inter-engaging said auxiliary switch and bars for withdrawing said auxiliary switch from circuit-closing position following'the opening of the circuit through said bars, said auxiliary switch comprising a pair of resilient wires each secured at one end to one of said bars and having its other end releasably held in electrical connection with one of said terminals, said one of said terminals including latching means adapted to flex said wires laterally of the plane of movement in one direction of movement thereof and to flex said wires in a plane paralleling the plane of movement of said bar in the opposite direction, whereby said wires will be flexed during movement of said bars to open position.

8. In a disconnect switch the combination with an insulating support, a pair of terminals carried by said support in insulated relation, a switch blade pivotally mounted on said support for engagement with said terminals, a blade-operating means for actuating said blade to open-circuit position, of a resilient wire contact carried by said blade and operable thereby, and a latching means associated with one of said terminals for said contact, said means including a deflection portion and a contact seat disposed in a plane normal to a plane including said wire contact, said wire contact being movable laterally relative to said main blade by means of said deflection portioniinto saidiconta'ct seatsubsequent to the closing of the circuit by said blade through said terminals, and withdrawn from said seat and circuit-closing position in a direction substantially normal to its lateral direction of closing movement subsequent to the withdrawal of said blade from one of said terminals.

9. The combination in a disconnect switch of a terminal, a main switch blade and an inherently resilient auxiliary switch blade, both said blades being operable to engage and disengage said terminal, said auxiliary blade being mechanically connected with said main blade and movable in response to opening and closing movements of said main blade, latching means operative to retain said auxiliary blade in electrical connection with said terminal during a predetermined initial portion of each opening movement of said main blade and further operative abruptly to release said auxiliary blade and thus abruptly break said connection when said main blade has completed each aforementioned predetermined initial portion of an opening movement, said latching means having a deflector port" n enga'geable by said auxiliary blade and operative to flex said auxiliary blade laterally of its normal plane of movement during each closing movement thereof, whereby to effect a latching engagement between said latching means and said auxiliary blade, said latching means being operative to release said auxiliary blade in response to an opening movement of said main blade without substantially flexing said auxiliary blade laterally of its normal plane of movement.

10. The combination in a disconnect switch of a terminal, a main switch blade and an auxiliary switch blade resilient in all directions lateral to its longitudinal axis, both said blades'being oper able to engage and disengage said terminal, said auxiliary blade being mechanically connected with said main blade and movable in response to opening and closing movements of said main blade, latching means operative to retain said auxiliary blade in electrical connection with said terminal during a predetermined initial. portion of each opening movement of said main blade, and further operative abruptly to release said auxiliary blade and thus abruptly break said con nection when said main blade has completed each aforementioned predetermined initial portion or an opening movement, said latching means hay-- ing a deflector portion engageable by'said auxiliary blade and operative to flex said auxiliary lade laterally of its normal plane of movement during each closing movement thereof whereby to effect a latching engagement between said latching means and said auxiliary blade, said latching means being operative to release said auxiliary blade in response to an opening movement of said main blade without substantially flexing said auxiliary blade laterally of its normal plane of movement. I 11. The combination in a disconnect switch of a terminal, a main switch blade pivoted at a point remote from said terminal and operative to make and break contact with said terminal, an auxiliary blade having a free end operative to make and break contact with said terminal, said auxiliary blade being operable by and coincidentally with the operation of said main blade, said auxiliary blade being supported at a point remote from said terminal and having a looped portion adjacent its point of support, said looped portion being operative to render said auxiliary blade susceptible-of being readily flexed, at least in the plane of movement of said main blade about its pivot, and a latch operative to engage and retain the free end of said auxiliary blade in contact with said terminal during a predetermined initial portion of each switch-opening movement of said main blade, thereby causing said auxiliary blade to flex and thus store up energy within itself for effecting an abrupt break of contact with said terminal, said latch being operative to release said auxiliary blade in conse quence of a predetermined degree of flexing thereof in the manner previously recited, the arrangement being distinguished in that said auxiliary blade abruptly breaks contact with said terminal only after said main blade has broken contact therewith.

12. The combination in a disconnect switch of a terminal, a main switch blade pivoted at a point remote from said terminal and operative to make and break contact with said terminal, an auxiliary blade carried by said main blade and having a free end operative to make and break contact with said terminal, said auxiliary blade being operable by and coincidentally with the operation of said main blade and attached to said main blade at a point remote from said terminal, said auxiliary blade having a looped portion remote from its free end and adjacent its point of attachment to said main blade, said looped portion being operative to render said auxiliary blade susceptible of being readily flexed, at least in the plane of movement of said main blade about its pivot, and a latch operative to engage and retain the free end of said auxiliary blade in contact with said terminal during a predetermined initial portion of each switch-opening movement of said main blade, thereby causing said auxiliary blade to flex and thus store up energy within itself for effecting an abrupt break of contact with said terminal, said latch being operative to release said auxiliary blade in consequence of a predetermined degree of flexing thereof in the manner previously recited, the ar rangement being distinguished in that said auxiliary blade abruptly breaks contact with said terminal only after said main blade has broken contact therewith.

13. The combination in a disconnect switch of a terminal, a main switch blade pivoted at a point remote from said terminal and operative to make and break contact with said terminal, an auxiliary blade consisting of a wire and having a free end operative to make and break contact with said terminal, said auxiliary blade being operable by and coincidentally with the operation of said main blade, said auxiliary blade being supported at a point remote from said terminal and having a looped portion adjacent its point of support, said looped portion being operative to render said auxiliary blade susceptible of being readily flexed at least in the plane of movement of said main blade about its pivot, and a latch operative to engage and retain the free end of said auxiliary blade in contact with said terminal during a predetermined initial portion of each switch-opening movement of said main blade, thereby causing said auxiliary blade to flex and thus store up energy within itself for efiecting an abrupt break of contact with said terminal, said latch being operative to release said auxiliary blade in consequence of a predetermined degree of flexing thereof in the manner previously recited, the arrangement being distinguished in that said auxiliary blade abruptly breaks contact with said terminal only after said main blade has broken contact therewith.

14. The combination in a disconnect switch of a terminal, a main switch blade pivoted at a point remote from said terminal and operative to make and break contact with said terminal, an auxiliary blade carried by said main blade and consisting of a wire having a free end operative to make and break contact with said terminal, said auxiliary blade being operable by and coincidentally with the operation of said main blade and attached to said main blade at a point remote from said terminal, said auxiliary blade having a looped portion remote from its free end and adjacent its point of attachment to said main blade, said looped portion being operative to render said auxiliary blade susceptible of being readily flexed at least in the plane of movement of said main blade about its pivot, and a latch operative to engage and retain the free end of said auxiliary blade in contact with said terminal during a predetermined initial portion of each switch-opening movement of said main blade, thereby causing said auxiliary blade to flex and thus store energy within itself for effecting an abrupt break of contact with said terminal, said latch being operative to release said auxiliary blade in consequence of a predetermined degree of flexing thereof in the manner previously recited, the arrangement being distinguished in that said auxiliary blade abruptly breaks contact with said terminal only after said main blade has broken contact therewith.

15. A switch comprising a first and a second stationary contact, a main switch blade pivotally mounted on said first stationary contact and movable into and out of engagement with said second stationary contact, a flexible auxiliary switch blade structure rigidly secured to said main switch blade and having a free end portion, latch means forming a portion of said second stationary contact for engaging and latching the free end portion of said auxiliary switch blade structure during closing of said switch, said latch means resisting outward motion of said auxiliary switch blade structure during opening movement of said main switch blade, said auxiliary switch blade structure flexing during opening movement of said main switch blade and withdrawing its end portion from said latch means solely by relative sliding motion due to flexing of said auxiliary switch blade structure.

16. A switch comprising a first and a second stationary contact, a main switch blade pivotally mounted on said first stationary contact and movable into and out of engagement with said second stationary contact, a flexible auxiliary switch blade structure rigidly secured to said main switch blade and having a free end portion, said auxiliary switch blade structure being composed of wire, latch means forming a portion of said second stationary contact for engaging and latching the free end portion of said auxiliary switch blade structure during closing of said switch, said latch means resisting outward motion of said auxiliary switch blade structure during opening movement of said main switch blade, said auxiliary switch blade structure flexing during opening movement of said main switch blade and withdrawing its end portion from said latch means solely by relative sliding motion due to flexing of said auxiliary switch blade structure.

WILLIAM O. SCHULTZ. ALWIN G. STEINMAYER.

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