US2208411A - Electrical switch - Google Patents

Description

July 16, 1940. H. J. cRABBs ELECTRICAL SWITCH Filed Dec. 17. 1937 5 Sheets-Sheet l w .www

INVENTOR /efber d @fabbri BY @21% Q/WL ATToR Y July '16, 1940. H. J. cRABBs ELECTRICAL SWITCH Filed Dec. 17. 1957 ATTORNE July 16, 1940.

vH. J. CRABBS ELECTRICAL SWITCH Filed Dec; 1'7. 1957 WITNESSES:

5 Sheets-Sheet 15 INVENTOR /ferert Crabb;

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H. J. cRABBs 2,208,411

ELECTRICAL SWITCH Filed Dec. 17, 19:57 s sheets-sheet 4 WITNEssEs; A v I u INVENTOR @25W ff/./WW #Hbf/1.x 04M@ H. J, CRABBS ELECTRICAL SWITCH July 16, 1940.

Filed Dec. 17, 19:57 5 sheets-sheet 5 INVENTOR Herbe/ l (/zfs. T B 2/ ATTORNE i Patented July 16, 1940 PATENT OFFICE ELECTRICAL SWITCH Herbert J. Grabbs, Wilkinsburg, Pa., assignor ,to Westinghouse Electric & Manufacturing Company, East Pittsburg-h. Pa., a corporation of Pennsylvania Appueeuen December 11, 1931, sei-1n Ne; 180,394 1s claims. (c1. zoo-1oz) The invention relates to electrical lswitches in general and more particularly to disconnecting switches oi the high contact pressure type for carrying relatively lhigh currents.

5 An object of the invention is the provision of an electrical switch embodying improved contact means for restrictingv the contact area between the relatively movable contact members of the switch. l

lo Another object of the invention is the provision of an electrical switch of the knife typ embodying an improved contact means for providing substantially line contacts between the relatively movable contact members of the l5 switch, which contact means have a low resistance under all conditions of operation.

Another object of the invention is the provision of an electrical switch embodying contact inserts to provide line contacts between the relatively movable contact members of the switch, at least the contacting surfaces of the inserts being of noble metal such as silver or the like.

.Another object of the invention is the provision of an'improved method of attaching contact area restricting inserts to the relatively movable contact members of an electrical switch.

Another object of the invention is the provision of an electrical switchof the knife type embodying an improved hinged contact construction consisting of cooperating annular rings attached to both the'hinge and blade members for providing silver to silver circular line contacts.

Another object of the invention is the provision of an electrical switch of the knife type embodying improved vcontact means for providlng line contacts between the break jaw and blade members, in which the actual contacting action takes place only when the blade member is relatively close to its final closed position.

vAnother Vobject of the invention is the provision of an electrical switch of the knife type embodying an improved break-v contact construction for providing one or more high pressure line contacts, in which the wear on the contacting portions is reduced to a minimum.

Another object of the invention is the provision of an electrical switch of the knife type embodying raised contact portions on either the blade member or break law member for providing a restricted contact area between the members, the raised portion being arranged so that they engage the other member only during theV final closing movement of the blade member and .following detailed description so that the lateral forces produced on the break jaw and its support are equal and opposite.

Another object of the invention is the provision of an electrical switch o f the knife type embodying an improved latch means for locking 5 the switch closed and a cooperating operating eye carried by the blade means which is operable to release the latch means and cooperate with a part of .the latch means to pry the blade means l l out of the break jaw before moving the blade lo means to open position.

Another object of the invention is the provision of an electrical switch of the knife type having high`unit pressure between restricted areas of the contact members, with an improved 16 latch means for locking the switch closed, and a cooperating operating eye pivoted intermediate its ends on the blade means which is operable to release the latch means and then fulcrum on a part of the latch means to pry the contact porzo tions of the blade means out of pressure engagement withthe break jaw before swinging the blade meansto open position.

-The novel features that are considered characteristic of the invention are set forth in par- 25 ticular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the bodlments thereof'when'read in connection with. the accompanying drawings, in which:

Figure 1 is a pian view of a double throw switch constructed in accordance with the invention, portions of the switch being broken away to reduce the length ofthe figure.

Fig. 2 is an enlarged sectional view of one of the hinge joints of the switchshown in Fig. 1, taken along the line lI--II of Fig'. 4.

Fig. 3 is a fragmentary view, partly in section. o of one of the break tongues and the break :and of the cooperating blades of the switch shown in` Fig. l, the section being taken substantially on the line III-III of Fig. 4.

Fig. 4 is a side elevational view of the switch a shown in Fig. 1.

Fig. 5 is a fragmentary sectional view of one of the tongues of the switch illustrating a part of the method of attaching a contact insert to the tongue; the insert being shown attached in u its recess before the pressing or swedging operation. Fig. 6 is a view similar to Fig. 5 showing the contact insert and adjacent portion of the tongue after the pressing or swedging operation.

of several em- 30 v tion.

Fig. 8 is a view similar to Fig. 7 showing thecontact insert and adjacent portion of the blade after the' pressing or s wedging operation.

Fig. 9 is a side elevational view of one part of the switch shown in Fig. 1, the blades being shown in partly open position illustrating the manner in which the operating eye fulcrums on the latch to pry the inserts of the blades 'out of engagement with the break tongues of the switch during an opening operation.

Fig. 10 is aplan view, partly in section, of a modified form of switch of greater current carrying capacity constructed in accordance with the invention.

Fig. 11 is a side elevational View of the switch shown in Fig. 10.

Fig. 12 is an enlarged sectional view taken substantially on the line XII-XII of Fig.'11 illustrating the contact means of the break end of the switch.

Fig. v13 is a side elevational view of another modified form of switch.

Fig. 14 is an enlarged fragmentary view, partly in section, of one of the hinge joints of the switch shown in Fig. 13 showing the contact means thereof, the section being taken on the line XIV- XIV of 13.

Fig. l5 is an enlarged fragmentary view, partly in section, of one of the break tongues and the break end of the cooperating blades of the switch shown inFig. 13, the section being taken on the line XV-XV of Fig. 13. Y

Fig, 16 is a fragmentary sectional view of the hinge end of one of the blades of the switch shown in Fig. 13 illustrating a part of the method of attaching the insert to the blade, Athe insert being shownattached in its recess before pressing or swedging operation.

Fig. 17 is aview similar to Fig. 1 6 showing-the insert and adjacent portion of the blade after the pressing or swedging operatic Fig. 18 is a fragmentary sectional view of the break end of-one of the blades of the switch shown in Fig. 13 illustrating a part of the method the of attaching a contact insert thereon, the insert Y being shown in its recess before the pressing or swedging operation, and

Fig. 19 is aview similar to Fig. 18 showing the insert and adjacent portion of the blade after the pressing or swedging operation.

Referring to Figs. 1 and 4 of thefdrawings, the

'switch illustrated is of the doublethrow multiple blade type and comprises, in general, a rigid supporting base 2|, a hinge terminal 23, two pairs of spaced parallel blades 25 pivoted on the hinge terminal for rotationr about a common axis, and two contact terminals 21 and 29 disposedfon opposite sides of the hinge terminal in positions to be 'engaged by the `blades 25 when ythey are rotated to either of theiritwo 'closed circuit positions. I

'I'he terminals 23, 21 and 29 are rigidly secured to the metal cap pieces of the insulating coluinnsl 3| which are preferably of vitreous insulating material such as porcelain or the like. The lower ends of the insulating columns 3| are rigidly boltedf=to the supporting base 2|.

. Each of the terminals 23, 21 and 29 are of suitable conducting material preferably copper or a copper alloy and are provided with terminal lugs or straps 33 for connecting electrical conductors to the terminals.

'Ihe hinge terminal 23 is provided withu a pair of spaced parallel hinge tongues 35 having the form of fiat plates or bars of suitable conducting material. The tongues 35 are either formed integral with the hinge terminal 23 or are welded thereto.

The pairs of blades 25 are pivotally mountedy lby the nuts 4|. rThus the spring washers 39 and the nuts 4| serve as a means for providing a high contact pressure between the contact means of the hinge joints of the switch.

I n order to restrict the contact varea between each pair of-blades 25 and the hinge tongues 35 to which they are pivoted, there is provided a contact means consisting of annular ring inserts 43 and 45 attached to the opposite faces of the 'hinge tongue 35, and the inner opposed surfaces of the blades 25 respectively. Referring to Figs. 2, 5 and 6 the inserts 43 for the hinge tongues 35 consist of at metal rings preferably formed of bimetallic material, thebody portion orv backing portion 41 of which is of a suitable conducting -material `such as copper or a copper alloy and the contact portion 49 of which is of a noble metal such as silver or the like. 'I'he bimetal portions 41 and 4 9 of the rings 43 are secured together in any suitable manner as, for example, by brazing or welding the engaging surfaces together. The opposite faces of each hinge tongue 35 are provided with annular grooves 5| for receiving the inserts 43. After being placed in the recesses 5|, the inserts 43 are soldered or brazed to the back wall of the recess as indicated yat 53 (Fig. 5). After the insertsr 43 havebeen attached in the recesses 5| provided therefor, the inserts and the portions of the material of the hinge blade. vThe soldering and swedging operations of the method of attaching the inserts 43 to the hinge tongue provide a good electrical joint between the insert and the tongue member, and also securely and rigidly position the inserts in the -faces of the tongue 35.

Referring to Figs. 2, 7 and 8, the annular inserts 45 which are attached to the hinge ends of the blades 25 comprise annular rings which have a semi-cylindrical cross section to provide a convex raised contact surface. The inserts 45 are preferably of bimetallic material similar to that of the inserts 43; that is, the inserts have a copper or copper alloy body portionv51 and a contact portion `59 of noble' metal such -as silver, the two portions being -brazed 'together to form theco'mposite insert.k Referring to Figs. 7 and 8, the ring inserts 45 are placed in annular recesses or grooves 6| provided Ltherefor ixr the inner opposed faces of the Vblades 25adjacent their hinged ends.

After being placed in the recesses 5I. the inserts 45 are rigidly secured in the recesses by brazing or soldering the back surface thereof to the back wall of the recess as indicated at 63. 'I'he inserts 45 and the portions of the material of the blades 25 adjacent the edges of the annular recesses 6| are subjected to a pressing or swedging operation to effect a cold flow of the material surrounding the inserts over and against the same. 'I'he soldering and swaging operationsrserve to provide a good electrical joint between the inserts 45 and the blades 25 and also rigidly secure the inserts to the blades.

The inserts 43 and'45 have the same diameter,

vscrthat their contact surfaces engage in all angu lar positions of the blades 25. The convex raised surfaces of the inserts 45 of the blades 25 provide substantially circular line contacts between the blades 25 and the hinge tongues 35, and the spring engagement washers 39 provide a high pressure of the line contacts.

The right hand contact terminal21 is provided with a pair of spaced parallel contact members or break tongues 61 which are disposed in the same planes as the hinge tongues 55. Each tongue 61 is adapted to be straddled by a corresponding pair of blade members 425 in the closed position of the switch. The break tongues 61 are of suitable conducting material and are either formed integral with the contact terminal 21 -or welded thereto.

Each of the pairs of blades 25 have the form of ilat elongated bars of suitable conducting material such as copper or the like andare of such length that their ends extend beyond the contact terminals 21 or 29. The ends of each pair of blades are spaced the proper distance apart by suitable spacer means. nected for rotation together by means of a bolt 59 which passes through openings provided therefor l in the blades and the ends of which are threaded for receiving the nuts 1 i A pair of spring washers 13 are mounted on the bolt 59 for yieldingly urging the contact portions of the blades 25 of each pair towards one another and against the break tongues 61 ,to provide a high contact pressure between the' blades and the break tongues in a well known manner. f

Each of the break tongues 51 are recessed as indicated at 15 for accommodating the bolts 59 in the closed position of the switc A contact means is provided for restricting the contact area between each pair of blades and its corresponding break contact tongue 51. Referring to Flg.3 the contact means for the break end of the switch comprises a pair of raised contact inserts 11 vcarried on the inner surface of each of the blades, 25 and projecting beyond the inner surface. The inserts 11are preferably of a bimetallic material similar to the inserts 45 at the hinge end of the blades and are attached in suitable recesses or grooves provided therefor in the blade members 25 and in the same manner as described inv connection with the inserts 45 at the hinge end of theblades. The inserts 11 instead of being annular as in the case of the inserts 45, are in the form of straight metal bars. There are two inserts 11 attached to the inner surface of each blade in the positions illustrated in Fig. 4,

the two inserts converging toward the outer lpn- The blades of each pair are conf to lle substantially cooperating with these silver contact portions the opposite faces of each of the break tongues" are provided with the contact inserts Il having contact surfaces level with the face of the' tongues and which are similar in construction and at- 5 tached in the same manner as the inserts 41 of the hinge tongue 35. The inserts Ii have the form of straight bars which are of the same length as the inserts 11 and which are attached to the break tongue 61 in the same relative positions as the inserts 11 of the blade members 25, so that they are alined with and engaged by the inserts 11 in the iinal closed position of the switch blades.

The edges of each of the break tongues 51 which are crossed over by the convex projecting contact surface of the inserts 11 o! the blade members as they are moved to closed position are cut oir-at angles as indicated at l5, so that these edges of the .break tongues lie substantially parallel to, and relatively close to, the' adjacent inserts 11 of the blades in the closed position of the switch as shown in Fig. 4. This construction of the break tongues cooperates with the arrangement of the raised inserts 11 of the blades 25 so that the raised inserts slide transversely over only a very 25 small portion of the faces of the break tongue 51 and this only during a small portion of the nnal closing movement of the blades. This reduces wear on the silver contact faces of the inserts .11 to a minimum.

The arrangement of the raised contact inserts 11 on the blades 25 so that they lie in opposed angular relation to each other, produces equal and opposite lateral forces on the contact terminal 21 and its supporting insulating column 3| `as well as the hinge terminal 2l and its supporting column 3 l thus eliminating any lateral or end thrust on the insulators" which would tend to break or crack the same.

The left hand contact terminal 29 is provided with a pair of spaced parallel contact members or break tongues 85 which correspond to and lie in the same planes as the break tongues 51 of the terminal 21 so that each is straddled by the corresponding pair of blades 25 when the blades are rotated in a counterclockwise direction to their lower closed position. The opposite faces of each of vthe break tongues 85 are provided with nat contact inserts 81 which are similar to and. attached in the same manner as the inserts 5i of so the break tongues 51. The inserts I1, however,

'are disposed in inverted relation with respect to theinserts 8i of the upper terminal member 21 in order to' make them aline with and be engaged by theraised inserts 11 at the break end of the Ami blades when the blades are rotated to their lower closed circuit position. Each of the tongues 55 is recessed as indicated at 85 to receive the through bolts 58 which connect the blade inembers 25. The edges of each ofthe break tongues so 85 which are crossed bythe raised inserts 11 of the blades when the blades are closed on the tongues 8.5 are cut away as indicated at 5I so as parallel and relatively close to the raised inserts 11 in the lower closed'circuit ,65 position of the blades. The edges 5l are cut away as indicated in orderto reduce the surfaces over which the raised inserts 11 must slide during closing ofthe blades to a minimum. It will be noted that the opposed angular relation of the raised inserts 11 produce equal and opposite lateral end thrusts or forces 'on thev lower contact terminal 25 andthe blades, when the blades are closed thereon, the same as in the case of the upper contact terminal 21. thus there is no lateral or end l with a pair of locking elements or latch members 93 which are adapted to engage cooperating locking elements 95 carried between each pair of blades 25 to lock the blades in either oftheir closed circuit positions. The latch members 93 of each contact terminal are pivotally mounted on the terminal by means of pivot pins 91 which are supported transversely between the spaced lugs or ears 99 (Fig. 9).` The latch members 93 are mounted in spaced relation on the terminals so that their outer ends enter in lthe spaces between the pairs of blades 25 when the blades are closed. The outer ends of the latchmembers 93 are provided with hooked noses |I which are adapted to engage over the locking elements 95 when the. blades are closed as shownin Fig. 4, and each of the latch members is biased to its latching position by means of a compression spring |03, the lower ends of which seat in recesses provided therefor in the terminal. Each of the latchmem-r bers 93 are provided with a pair of projections |05 and |01 Awhich lie on opposite sides of the pivot pin 91 for cooperating with the outer surface of the contact terminal for limiting the movement of the. latch member between its latched and released positions.

Each pair of blades 25 is provided with an operating lever |09 which is pivoted intermediate lits ends on a transverse pivot rpin extending transversely between the two blades 25. One end of the lever |09 is formed to provide an operating eye 3 adapted to receive a hook stick or other form of operating member for opening and closing the pair of blades. The arm ||5 of the lever |09 cooperates with the rounded nose'|0| of the latch member, so that when the operating lever |09 is pulled or pushed in'an opening direction bya hook stick, the arm ||5 of the lever cams the latch member 93 to its released position as shown in Fig. 9. When the latch 93 has been cammed or moved to its released position, the projection |01 thereof engages the outer surface of the terminal to stop any further movement of the latch member 93. The continued opening pull or thrust applied to the operating lever |09 in an opening direction causes the opf erating lever |09 to fulcrum on the end or nose of the latch 93 toexert a prying or multiplied leverage action on the blade members 25 as shown `in Fig. 9. The prying action of the lever |09 continues until the raised contact inserts 11 of the blade members 25 have substantiallydisengaged the break tongue of the contact terminal, thus disconnecting the high pressure line contacts. After the line pressure contacts are disengaged as described above, the blades 25 are lifted freely, being retarded only by the friction of the hinge joint. As the open pull or thrust is continued on the operating lever |09, the arm 5 of the lever engages the locking pin 95 which extends between the blades, so that continued pull or thrust on the operating lever swings the blades 25 to their open vertical position.

The above operation of the operating lever and latch has been described in connection with one pair of the blades 25 and one break tongue 'and understood that the erates in the same manner `to release the latch means and pry the blades out of engagement with the break tongue of either of the opposite terminal members. In closing the blades to either of their closed positions, the operating lever |09' is -rst moved until the arm ||5 engages the appropriate` pin 95 after which the operating lever |09 becomes rigid with respect to the blade members so that continued pull or thrust on the operating member swings the bladey members to their closed circuit position.

It will thus be seen that in opening the switch,

one continuous pull or thrust on the operating lever |09 serves to rst release the latch means,

then to pry the blades to disengage the line presleased position to clear the same as the blades are moved into engagement with either contact terminal. When the blades have reached their iinal closed position they springs |03 move the latches 93 to their latching position to lock the blades. n i

Fig. lrillustrates a modified form of switch of larger current carrying capacity. The switch is of the single throw multiple blade type and comprises in general a base (not shown) a hinge terminall23, two pairs of blades |25 pivoted on the hinge terminal for rotation about a common axis, and a contact terminaly |21.

- The terminals |23 and |21 are rigidly secured to the metal cap pieces of the insulating columns 3| which are preferably of vitreous insulating material. The lower ends of the columns 3| are bolted to the rigidfbase.`

Each of the terminals |23 and |21 are of suitable conducting material such as copper or a copper alloy and each is provided with appropriate terminal lugs or connecting straps 33 for connecting the switch in an electrical circuit. The'hing'e terminal |23 is provided with two sets of hinge members |33 (Fig. 10)', each of which comprises three contact members or jaws |35 in the form of spaced plates of suitable conducting material which are either formed integral with or welded to the hinge terminal |23.

`Each pair of blades |25 is pivoted` on its hinge member |33 by means of a bolt |31 which extends through suitable openings provided in the .blades |25 and jaws |35. The blades |25 of each blades and their hinge jaw members for restricting the contact areabetween the blades and the jaws. The contact meanscomprises raised annular inserts |43 on the bladesA |25' which cooperate with flat annular inserts |45 on the hinge contact members or jaws |35. 'Ihe inserts |43 and |45 are substantially identical to the ring inserts as shown and described in connection with ythe switch illustrated in Figs. 1 through 9 and are The inserts |43 attached in the same manner.

In closing, the Y locking pins 95 cam the latch members to reand |45 are of bimetallic material having copper c or copper alloy body portions or backs and contact portions of noble metal such as silver or the raised surface of the material having a copper .blades m and their like. The inserts are attached in vsuitable grooves provided therefor in the cooperating surfaces of the hinge jaws and the hinge ends of the blades |25 by a soldering operation to ensure a good electrical contact.- Following the soldering operation, the inserts and the surrounding portions of the jaws or blades, as the case may be, are subjected to a swaging operation to eect a cold ilow of the surrounding portion of the member over and against the inserts. The convexed inserts |43 engage the cooperating contact surface of the inserts |45 in all angular positions of the blades to provide a plurality of circular silver to silver line contacts between the hinge jaws and the blades. The line contacts are maintained in high pressure engagement by means of the spring washers |39 and the nuts |4i.

The blades |25 have the form of flat metal bars of suitable conducting material and are of a length to extend beyond thefcontact terminal |21 in the closed position of the switch. The blades are spacedat their outer ends by suitable spacer means.

The. contact terminal |21, which is of conductfing material, is provided with two sets ofcontact members |41 each consistingV of three spaced parallel break jaws |49 having the form of flat plates of conducting material. The break jaws 149 lie in the same planes as the corresponding hinge tongues |35, so that the blades |25 are adapted when rotated to enter in the spaces between the break jaws |49 as shown in Fig. 10.

A contact means is provided for each pair of corresponding break jaws |49 for restricting the contact area therebetween in the closed position of the blades. Referring to Figs. 11 and 12, these contact means comprise raised insertsv faces of the break jaws |49. The inserts |5|Jare substantially identical in construction' to the raised inserts 11 at the break ends of the blades ofthe switch shown and described in connection with Figs. l through 9, consisting of bimetallic body or back portion and a contact portion of noble metal such as sil'- ver. The inserts |5| have the form of straight metal bars and are attached in grooves provided therefor in the break jaws and disposed in parallel tandem relation at an angle to the line of motion ofthe break end of the blades |25 as they engage the contact terminal as shown in Fig. 11. The inserts |5| are attached in the grooves provided therefor by a lsoldering operation following which the portions of edges of the grooves and the inserts are subjected to a swaging operation in the same manner as has been previously described in connection with the of the switch illustrated in Fiss. 1 through 9.

For cooperating blades |25 which aline with the break jaws |49 areprovidedl with angularly disposed iiat bar inserts |53 of bimetallic material which .are adapted to aline with and be engaged by the raised inserts |5| in the closed position of the blade members. The inserts |53 'have contact portions of noble metal such as silver 'and are attached in suitable recesses provided therefore in the blades in the same manner and by the 4.saine method as described in connection with the |5I;l Each of the blades |25 is recessed as indicated at |55 for accommodating the through bolts |51 |5| attached to the opposed surthe jaws adiacent theA with the raised inserts Isl of the break jaws |49, the' opposite surfaces of thestructure of the switch has which extends through the break jaws |39 and supports the spring washers `|59 and nuts |4| which function to bias the break jaws |49 towards each other to ensure a high pressure engagement between the contact portions ofthe blades and break jaws in the closed position of the switch.

The edges of each blade raised inserts |5| of the jaw during closing of the blade are cut away as indicated at |63, so as to which cross over the lle parallel to and relatively close to the inserts |5| in the closed position of the switch, thus reducing the wear on the raised contact inserts |5| to a minimum in operation of the switch.

Theswitch is provided with latch means for locking the blades |25 in closed position and with cooperating operating levers 'for releasing the latch means and operating the blades, which are identical in structure and operation to the latch means and operating levers of the switch shown and described" in connection with Figs. l through 9 and hence have been given the" same reference characters. The latch members 93 are pivotally mounted in spaced relation on the pivot pins 91 supported by the contact terminal |21 so that. their upper ends extend in spaces between the pairs of blades |25. The latch members 93 'are biased to their latching positionsby means of springs |93, locking pins 95 carried by and extending Ltransversely between each pair of blades |95 to lock the blades in closed circuit position. The operating levers |99 are pivoted between the blades |25 of each pair and are provided with arms ||5 for cooperating with the latch members 93; and are also provided with operating eye portions ||3 kfor receiving a hook stick or other operating member.

To open the switch, an opening pull or thrustv from the contact terminal |21.

A further modified form of switch is illustrated in Fig. 13. This modified form of switch has the same general construction as the switch shown and described in connection with Figs. 1 through 9, with the exception of the contactterminals and thecontact tact area at, the hinge and break ends of the switch, and hence the same have been used to designate the corresponding parts wherever applicable. 'Since the general been previously described in connection with Figs. 1 through 9, the following description will be limited to the modiiled form of contact terminals and to the contact means for. restricting the contact area be tween the blades and 'the contact members. Referring to Fig. 14, the contact means for restricting the contact. area between the hinge tongues -35 and the hinge end of the blades 25 the opposed inner surfaces of the blade members |99 causes the arms ||5 of the levers.

The pull or thrust then swings thisv `blades |25 to their'open circuit position away reference charactersso that their noses |9| engage the means for restricting the con- 25 which aline with and engage dat annular in- A serts 43 attached to the] opposite faces of the hinge tongues 35. The inserts 43 are of the `saine construction and are attached to the hinge tongues in the same manner as the corresponding inserts on'fthe hinge tongues 35 of the switch shown and described in connection with Figs. 1 through 9,

The inserts |65 each have convexed raised contact portions |61 (Fig. 17) of noble metal such as silver which projects beyond the surface of the blades 25, and a body or back portionl |69 of copper or copper alloy whichis secured in a groove provided therefor in the blade 25. Referring to Fig. 16, the inserts |65 originally have the form of metal rings kwhich are secured by a soldering operation in annular grooves provided in the blades 25. Following the attachment of the ring inserts |65 in the grooves |110, as shown in Fig. I6, the rings and portions of the blades 25 surrounding `the recesses |1| are subjected to a swaging operation which presses the projecting portions of the ring into a convex shape, and which effects a cold flow of the material of the blades 25 surrounding the recesses |1| over and against the sides of the lower portlpnof the rings as shown in Fig. 17, so thatv a section rthrough the insert resembles the section through a mushroom or rivet. The method of attaching the insert |65 provides a good electrical joint between the insert andthe blade, rigidly secures it to the attached in the grooves by a soldering operation blade and provides the contact portion of the insert with a convex raised contact surface. The silver contact portions |61 of the inserts |65 engage the silver contact portions of the cooperating inserts 43 of the hinge tongues 35 in all angular positions of the blades 25, the spring washers 39 providing a highpressure engagement between the contact portions.

The blades k25 adjacent their break contact ends are each provided with raised contact inserts I 13 which are attached to the opposed inner surfaces of the blades for restricting the contact area between the break end of the blades and the contact terminals. Referring to Figs. 15, 18 and 19, the insets |13 for each blade comprise a pair of channel shapedbars of bimetallic materialr having a body portion |15 of rsuitable conducting material such as copper, anda contact portion |11 of noble metal such as silver. 'I'he inserts |13 are seated in grooves |19 provided therefor in the opposed surfaces of the blades 25, and are (see Fig. 18). Following the attachment of the inserts in the grooves, the inserts and portions ofthe blades adjacent the edges of the grooves |19 are subjected to a swaging operation to eifect a cold flow of the portions adjacent the edges.v

of the recess |19 over and against the sides of the inserts |.13 to rigidly secure them in position on the blades'as shown in Fig. 19. This method -of attaching the inserts is the same as disclosed in connection with the switch shown in Figs. 1-9. The two inserts |13 of each blade are arranged 1n spaced parallel relation at an angle to thek direction of movement of the blades as shown` in F18.- 13.

Each of the contact terminals I3| are providedl away as indicated at |31 so that these edges lie substantially parallel to andrelatively close to. the raised insertsv |11 of the blades 25 in the closed position thereof, thus reducing the amount of surface over which the raised inserts |11 must slide during closing and opening of the'blades and reducing wear on the silver contact portions of the inserts |13 to a minimum.

For cooperating with the raised inserts |11 of the blades 25, each of the break tongues |83 is provided on its opposite faces with inserts |89 in the form of at metal strips of bimetallic material having contact portions of noble metal such as silver. The inserts'lBQ are attached in suitable recesses vprovided therefor in the tongues |83 in the same manner as described in connection with the inserts of the break tongues of the switch `shown and described in Figs. 1 through 9. The inserts |29 are of the same length as the raised inserts` |11 on the blades 25 and are mounted in the same spaced angular relation, so as to align with and be engaged by the raised inserts |11 when the blades are in either of their closed positions. The inserts |11 of the blades 25 and the inserts |89 of the break tongues` |83 provide silver torsilver line contacts which are engaged with a high pressure by means of the spring washers -13 which'bias the blades 25 towards each other.

It will be noted that the constructionfand `shape of the hinge tongues |53 for each of the contact terminals |81 are identical thus enabling 'them to be manufactured in large quantities at a relatively low cost.

The switch illustrated in Fig. 13 is provided with latch means and,operating levers which are of the same construction and which function .in the same manner as the latch means and operating levers of the switch shown and described o in connection with Figs. 1 through 9.

The contact inserts in each of the switches shown and described are of bimetalllc material.

understood that either of the forms or constructions of inserts may be used with any one of the n three switch structures illustrated.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be `made without departingA from the spirit of the invention. It is desired therefore that' the` ap-- pended claims be given the broadest'reasonable construction permissible in the light of the prior art.

lclaim as my invention:

1. In a double throw electrical switch, a hinge member, a pair ci' stationary. contact members, a blade member pivoted onsaid hinge ymember for swinging movement into and out of engagement with either of said contact members. said blade member and said contacty members being provided with contact portions which engagev when the blade memberis-in, either of its closed tween the blade member and contact member,

'- Positions tol provide limited area contacts be'- said contact portions'having-.their lines of conf tactat an anglefto the longitudinal axis of the switch, and said contact members being identical in construction.

2'. In an electrical switch, a contact member, a blade member, one of said members being provided with raised contact .ribs to provide-line contacts between said members at an angle to the longitudinal axis of the blade member when the switch is closed, at least the contact surface of said ribs being composed of noble metal, the

other of said members being shaped so that the raised contact ribs slide transversely over only a relatively small portion of the surface of the opposite member during opening and closing of the switch.

3. In an electrical switch, a contact member. a blade member, one of said members being provided with raised contact, ribs to provide line contacts between said members at an angle to the longitudinal axis of the blade member when the switch is closed, at least the contact surface of said ribs being composed oi' silverfthe other of said members having its edges which are crossed by the raised contact ribs formed to lie substantially parallel to and relatively close to the raised ribs in the closed position of the switch.

4. In an electrical switch, a contact member, a blade member movable into and out of engagement with said contact member, one of said members being bifurcated to provide portions for cooperating with the opposite faces of the other member, one of said members being provided with raised contact portions to restrict the contact area between said members to less than that of the transversely aligned surfaces Aof the members when the switch is closed, said raised portions lying in lines which are at opposed angles to the line of `motion of the blade member as it engages the contact member so are to produce equal and vopposite end thrusts on the contact member and blade member during the iinal closing movement of the blade member.

5. In an electrical switch, an insulating column, a contact member rigidly supported on said column, a blade member movable into and out of engagement with Asaid contact member, one of said members being bifurcated to provide portions -for .cooperating with the opposite faces of the other member, one of said members being provided with raised contact portions to restrict the contact than that of the transversely aligned surfaces of the members when the switch is closed, means yieldingly urging the bifurcated branches oi' the v blfurcated member towards each other to provide tions lying in lines which are at opposed angles to the line of motion of the blade vmember as it engages the contact member so as to produce equal and opposite lateral forces on the stationary contact members and its supporting column during the closing movement of the switch member.

6. In an electrical switchl a switch jaw comprising spaced parallel contact members having opposed faces, a blade member having a contact 'v end movable into the space `between said mem--v bers, raised contact ribs `projecting from the opposed faces of said members to provide limited area contacts between the blade and jaw at an angle to the longitudinal axis of the blade in the closed position of the swit h, the contact end o f said blade being formed so that its edges which slide transversely across said ribs are substantially parallel to and relatively close to the ribs in the closed position of the blade.

-for said lever to pry area between said members to less said raised contact por,

'1. In an electrical switch, parallel blades having opposed surfaces, means mounting said blades for rotation about an axis, a tongue disposed in the path of said blades to be straddled thereby, a pair of raised contact ribs projecting from each of the opposed surfaces of the blades to provide limited area contacts between the blades and tongue, the ribs of each surface being in opposed angular relation so as to produce equal and opposite lateral forces on the tongue during closing of the blades on the tongue, said tongue having its edges which are crossed by the ribs formed to lie substantially closed position of the switch.

8. In an electrical switch, a fixed contact mem ber, a blade member movable into and out of engagement therewith, means providing pressure engagement of said members when the switch is closed, a latch pivotally mounted on said iixed contact member and a cooperating'locking element carried by said blade member for locking said blade member in closed position, an operating lever pvoted intermediate its ends on said bladel memberfor releasing said latch and operating said blade member, the latch carried by said fixed contact member serving as a fulcrum saidf blade -member out of pressure engagement with said contact member after said latch has been moved to a released position by said lever. 't

9. In an electrical switch, a fixed contact member, a blade member movable into engagement therewith, one of said members4 having raised contact portions to restrict the contact area between the members, means providing a high contact pressure engagement between said a pairA of spaced parallel to and relatively close to the ribs in the members in the closed position of the switch.

. pivotediintermediate its ends on said blade member operable to move said latch member to re leased position and said blade member to open position, said latch member in its released posltion serving as a fulcrum for said lever to pry said raised contact portion out oi engagement with the other member. 4

10. In an electrical switch, a contact member, a blade member movableinto and out of engagement with said contact member, said blade member having raised contact portions disposed-in lines which are at opposed angles to the line oi' ,motionof the blade member as it engages the contact member. said` raised contact portions Irestricting the contact area to an order less than that of the transversely aligned surfaces when 'the switch'is closed. It. In an electrical switch, a contact member, a blade member movable into and out of engagement with said contact member, said contact member being disposed perpendicular to the longitudinal axisof the'blade member in the closed position of the switch, one of said members being provided with 4an elongated raised contact portion disposed at an angle'to the linev of motion ofthe contact portion of the switch is closed, the other of said members being formed a stop for so that the raised contact portion slides transversely over only a relatively small portion ot the surface oi the opposite member and this only during the iinal closing movement and initial opening movement of the switch member.

12. In a double-throw electrical switch, a hinge member, a pair of stationary contact members. a blade member pivoted on said hinge member for swinging movement into and out of engagement with either of said contact members, said blade member having at least one elongated raised contact portion disposed at an angle to the longitudinal axis of the switch for restricting the raised contact portion when the switch member is in either closed position.

13. In an electrical switch, a contact member, a blade member movable into and out oi engagement therewith one of said members having an elongated raised contact portion disposed at an angle to the longitudinal axis of the blade member when the switch is closed for restricting the contact area, the other of said members being formed so that the raised contact portion slides transversely over only a relatively small portionv of the surface of the member which it engages and this only during the final closing movement and initial opening movement of the switch member, means iorproviding a high contact pressure when the switch is closed, a latch pivotally mounted on the contact member and a, cooperating locking element on the blade member for locking said blade member in closed position, an operating lever pivoted intermediate its ends on said blade member for releasing said latch and operating said blade member, the latch carried byy said contact member serving as a fulcrum for said operating lever to pry said blade member out of pressure engagement with said contact member after said latch has been moved to a released position by said operating lever.

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