US2211161A

US2211161A - Switch

Info

Publication number: US2211161A
Application number: US115693A
Authority: US
Inventors: Ramsey Allan
Original assignee: Schweitzer & Conrad Inc
Current assignee: Schweitzer & Conrad Inc
Priority date: 1936-12-14
Filing date: 1936-12-14
Publication date: 1940-08-13
Anticipated expiration: 1957-08-13

Description

A. RAMSEY Aug. 13, 1940.

SWITCH Filed Dec. 14, 1936 '7 Sheets-Sheet l Aug 13,1940- A. RAMSI-:Y 2,211,161

SWITCH Filed Dec. 14, 1936 7 Sheets-Sheet 2 A. AMsEY Aug. 13, 1940.

SWITCH Filed Deo. 14, 1956 7 Sheets-Sheet 3 Ww ,Ww mm W Km ff m ZM Aug. 13, 1940. A. RAMsEY 2,211,151

- SWITCH Filed Deo. 14, 1956 '7 sheets-sheet 4 -A. RAMSEY Aug. 13, 1940.

SWITCH Filed Dec. 14. 1956 'T Sheets-Sheet 5 A. RAMSEY SWITCH Aug. 13, 1940.

7 Sheets-Sheet 6 Filed Dec. 14, 1956 ried by the other insulator.

Patented ug. 13, 1940 PATENT VOFFICE.

2,211,161 swl'rcn.

Allan Ramsey, Evanston, Ill., assignor to Schweitzerev Conrad, Inc., Chicago, Ill., a corporation'of Delaware Application December 14,1936, serial 10,115,693

18 Claims.

My invention relates, generally; to electric switches, and it has particular relation to disconnecting switches for "electric power transmission lines.

It is customary to provide disconnecting switches in electric power transmission lines for the purpose of sectionalizing them or for the purpose of disconnecting a feeder circuit from .the line. Ordinarily such switches are of the air break type, and they are mounted out of doors on one of the transmission line poles or towers. In the construction of such a switch, care must be taken to provide a suitable electrical clearance between the relatively movable switch members when they are in the open1 position in order to prevent ashover.

For this purpose various types of disconnecting switches have been provided. One of these types comprises a pair of pillar typeinsulators,

one of which is stationarily mounted andcarries a contact assembly that is connected to one of the line conductors, the other being mounted-for rotation in the plane'of its axis and carrying a switch arm that is movable into and out of contact engagementwith the contact members car- The switch arm is electrically connected to the other line conductor. It is to improvements in the construction of. this type of switch that my invention is directed.

It has been the practice in the past to employ flexible shunt connectors between the movable switch arm and the line conductor associatedv therewith. These shunts deteriorate when exposed to the weather, and require periodic replacement. f

Another diiiiculty that hasbeen encountered inthis type of switch lies in the requirement of accurate alignment of the relatively movable 4 switch members, constructed in accordance with the teaching of the prior art, which calls for'a high degree of accuracy-in the installation of the switch and frequent inspections and adjust ments to maintain vthe accurate alignment. TheA problem becomes particularly acute 'when two or more disconnecting switches are mounted for' simultaneous operation by a single operating mechanism. These difficulties will be more readily appreciated when it is recalled that the complete insulator and associated switch arm are moved to open or close the switch. The in sulator is ordinarily relatively heavy, and with the switch arm mounted on one end it presents an unwieldly mechanism to be moved with any degree of-accuracy.

(Cl. 20G-48) When only the two insulators are employed, one for the stationary switch member and one for the switch arm, difiiculty is encountered in connecting the switch arm to its associated line conductor unless careful alignment is maintained 5 between the switch and the conductor. The difficulty is increased when a direct connection is provided by relatively inflexible connectors. It is `often not.possib1e to provide the desired alignment between the line conductor and the switch, and, even if it is provided, the line conductor will sway because of the effects of the wind or vibrations that may be set up therein. Unless provision is made for taking care of this misalignment, the necessary movement of thev switch arm to properly engage the stationary contact member will be interfered with.

An important object of the present invention is to provide a disconnecting switch for transmission line conductors in which a highly accu- 2o rate alignment of the relatively movable switch members is not required.

Another important object of my invention is to incorporate in a transmission line disconnecting switch individually flexible and resilient prestressed contact fingers, each. of winch lhas a small area high pressure contact engaging surface for contact engagement with-a relatively movable switch member having like contact surfaces which do not require accurate positioning either' to make or maintain efiicient contact engagement therebetween.

Still another important object of my invention is to provide for connecting the movable switch arm of a disconnecting switch directly to a line conductor by an iniiexible connecting link in such manner as not to interfere with its operation despite a hunted movement of the line conductor.

An object of my invention is to provide a simple ,m means for connecting a common operating membento the movable insulator of each of several poles of transmission line disconnecting switches to permit simultaneous operation of all of the poles. A l 4 Another object of my invention is to provide an improved base for a transmission line disconnecting switch to which the strain insulators supporting the line conductors may be directly fastened.

A further object of my invention is to provide silver contact engaging surfaces between the relatively vmovable switch members of a disconnecting switch.

A still further object of my inventionl is to increase the resistance to torsional stressof alight sectionA sheet metal operating shaft used for-A simultaneously operating two or more poles of a disconnecting switch.

Other objects of my invention will, in part, be obvious and in part appear hereinafter.

My invention, accordingly, is disclosed in the embodiments hereof shown in the accompanying drawings, and it comprises the features of construction, combination of elements, and arrangement of parts which will-be exemplified in the constructions hereinafter set forth, and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, references may be had to the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a view, in sideelevation, of a transmission line disconnecting switch constructed in accordance with the present invention;

Figure 2 is a view, in top plan, of the bases for two transmission line disconnecting switches arranged for simultaneous operation, the switches lthemselves being omitted;

Figure 3 is a detail sectional view taken along the line 3-3 of Figure 2;

Figure 4 is a detail sectional View taken along the line 4 4 of Figure 3;

Figure 5 is a detail sectional view taken along the line 5 5 of Figure 2;

Figure 6 is a view, similar to Figure 5, and showing a different type of loperating shaft;

Figure 'l is a view at an enlarged scale, partly in side elevation and partly in section, showing the arrangement and construction of the switch members shown in Figure 1;

Figure 8 is a view, in top plan, of the switch members shown in Figure 7, the sleet hood being omitted;

Figure 9 is a detail sectional view taken along the line 9-9 of Figure 7;

Figure 10 is a detail sectional view taken along the line lll-l0 of Figure 7;

Figure llis a perspective view of the line connector to which the switch arm ,is connected, and showing the construction of one of the universal joints;

`Figure 12 is a perspective view of another of the universal joints; Y

Figure 13 isa view, in side elevation, of a modified form of the disconnecting switch in which three, in place of two, insulators are employedj Figure 14 is a view, similar to that shown in i' Figure 9, illustrating a modified form ot contact construction;

Figure 15 is a view, in top plan, of an improved form of operating shaft; and

Figure 16 is an end view of the operating shaft shown in Figure 15.

Referring particularly to Figures 1 .and 2 of therlrawings, it will be observed that the referenoer character I5 designates, generally, a twopoled disconnecting switch for opening the circuit in the two conductors of a two wire transmission line. It will be understood that onLv a single pole unit may be employed, or that three or four poles may be employed,as required, without departing from the scope of my invention.

Each pole' of the switch I5 is .provided with a switch base, shown generally at I6, that may be mounted on cross' arms l1 which may be secured to the upper end of a pole I8. Each switch base I6 comprises a pair of frame members |9 in the form of angles having suitable apertures in the lower flanges to permit mounting on the cross arms L-'shaped bracket 20 is welded between the lefthand ends of the frame members |9, and an insulator support bracket 2| is welded between the right hand ends, as illustrated. The outwardly extending ends of the brackets 20 and 2| are provided with transverse apertures to permit connection thereto of strain insulators 22 and 23 to which

line conductors

24 and 25 are fastened. Generally, the conductors 25 will be normally energized, and conductors 24 will be energized only when the switch I5 is in the closed position.

The insulator support bracket 2| is provided with an inclined intermediate section 29 on which may be bolted a pillar type insulator 30. Stationarily mounted on the upper end of the insulator 3i) is a contact assembly, shown generally at 3|, the details of construction of which will be illustrated and described hereinafter. A conductor 32 is provided for electrically interconnecting the switch member 3| and the line conductor 25.

Rotatablymounted intermediate the ends of the switch base I6 isa yoke, shown generally at 33, that is generally rectangular in shape and on which is mounted a pillar type insulator 34. At its upper end the insulator 34 carries a switch arm support bracket 35 for rotatably mounting a switch arm, designated generally by the reference character 36. A guide member 31, wedge-shaped at its upper end, is carried by the support bracket 35 to guide the switch arm in its movement relative thereto.

A link, shown generally at 31a, is provided for interconnecting the switch arm 36 and a line clamp 38, both electrically and mechanically. Universal joints, shown generally'at 39 and 40, are provided at each end of the link 31a for furnishing the required mechanical and electrical connection with the switch arm 36 and line clamp 38. The left hand end of the bracket 35 is turned upwardly to provide a stop for the switch blade 36 to insure that the line clamp 38 will not be positioned too far away from the switch l5 on installation. In this manner proper alignment of the switch blade 36 with the contact assembly 3| will be assured. The details of construction of the

universal joints

39 and 40 will be set forth hereinafter. Arcing horns 4| and 42 are carried by the support bracket 35 and the switch member 3|, respectively, to cause the arc to be formed therebetween when the switch l5 is opened under load.

With a viewto mechanically interconnecting the rectangular yokes 33 to permit simultaneous that may be variably spaced. An`

rotation of the insulators 34 and the switch arms 36. carried thereby, an operating shaft 44 in the form of a Z-shapedstructural section is positioned therein and clamped by means that will be presently described. An operating lever 45 is secured to the connecting shaft 44, having at its outer end an operating rod 46 connected thereto. As shown, theoperating rod 46 extends downwardly, and at its lower end it 1s pvotally mounted on a. pin 41 carried by an arm 48 forming a part of a handle 49. The arm 48 is rotatably mounted on a suitable bracket' 50 that may be fastened to the pole I8. When the handle 49 is rotated in the direction indicated by the broken line Il,

Athe pin 41 moves in the path indicated by the broken line 52 to operate the switch I5 to the open position. The relative positions of the various movable parts of the switch II in the open 7l drawings, to which reference will now be had. As

there shown, the yoke 33 comprises a pair of interfltting generally

U-shaped 4members

55 and 58 that may be bent to the desired shape from steel plate-likematerial. The member 55 maybe secured, as by rivets 51, to a pair of bearing brackets 59 lthat are secured to a shaft 59, extending through suitable apertures in the frame members.

|9, by means of pins 68. One end 6| of the member 56 is bent outwardly to form a stop for movement of the switch to the open position by engagement with the upper edges of the frame members I9. The other end 62 of the member 56 serves as a stop for movement of the switch to the closed position by like engagement with the upper edges of the frame members I9.

The pin of the insulator 34 is secured to the yoke 33 by suitable cap screws v63 that are positioned in suitable threaded holes in the

members

55 and 56.

With a view to securing the connecting shaft 44 in the yoke 33, a clamp plate 64 is provided within the rectangle formed by the members 55 .and 56, and its ends are turned upwardly as shown in Figure 3. Set screws 65, that are threaded in suitable threaded holes in the-

members

55 and 56, bear against the upper surface of the clamp plate 64 and, when tightened, serve to fasten the connecting shaft 44 securely in place. It will be understood that the pin of the insulator 34 is provided with four clearance holes,

only two of which are used by the cap screws 63 for holding it in position. The set screws 65 are positioned in the remaining two holes for the purpose of bearing against the clampplate 64 as described.

The manner in which the operating lever 45 is fastened to the connecting shaft 44 is shown more clearly in Figure 5 of the drawings. It will be understood that the operating lever 45 is positioned suitably on the connecting shaft 44 intermediate the two switch bases I6 to properly align it with the pin 41 carried by the arm 48. Bolts 61, extending through suitable clearance holes in the operating lever 45 and in aplate 68 underneath `theconnecting shaft 44, serve to secure the operating lever 45 in position. Instead lof employingthe Z-shaped connecting member or shaft'44, it is also possible to employ a channel-shaped member Aor an I-shapedl member therefor.

It may be undesirable to employ a 'metallicmember-for the connecting shaft 44 where it is required that the switch bases I6 be fully insulated from each other; For this purpose a wood connecting shaft 69 may be employed, as shownin Figure 6 of the drawings, instead of .the metal connecting shaft 44 shown in Figure 5. Pointed projections 18 are provided underneath vthe operating lever 45, as illustrated, for penetrating the upper 'surface of the wood connecting shaft .to more securely connect it thereto. It will 'now be lapparent that metal or wood connecting shafts may be employed as desired, without requiring any special parts for either ty'pe of shaft.

The construction of the switch members mounted on top of the

insulators

30 and 34 is more clearlyillustratedfin Figures -'7, 8,-9 and l0,

to which reference now'will be had. It will be noted that the right hand end of the support bracket 35 is bifurcated and that the sections 12 thus formed are bent upwardly and lgivena -ninety-degree twist through which a pin 13 may be positioned for rotatably supporting the switcha light weight and inflexible construction. Thebearing points on the p in 13 and between the sections 12 are, therefore, widely spaced and insure accuracy`of alignment with the contact assembly 3|.

The switch blades 14 and 15 are provided,

respectively, with exible switch ngers 16 and 11 that may be suitably secured thereto as by the rivets illustrated and having the free. ends curved as indicated at 18 and 19. Figure 9, to form convex contact surfaces for contact engagement with correspondingly-shaped contact surfaces and 8| of

flexible contact fingers

82 and 83. The switch fingers 16 and 11 and the

contact fingers

82 and 83 are formed preferably y of strap copper, and they are subjected to forming dies to provide the desired shapes. The

contact fingers

82 and 83 are mounted by means of bolts 84 which extend through a terminal block 85 composed preferably of copper. lower ends of the

contact fingers

82 and 83 have

bosses

86 and 81 integrally formed therewith by a suitable upsetting` operation for lnterflttingwith recesses 88 and 89 in the block.85 to prevent them from turning about the bolts 84. The copper block the form of 'a copper strap which is bolted, as illustrated, to the upper end of the insulator 38.

With a view to providing a relatively high contact pressure between the curved ends 1 8 and 85 is'mounted on a bracket 90 in 19 of ythe switch fingers 16 and 11 and the correspondingly shaped surfaces 80 and 8| of the contact fingers '182 and 83, compression springs 9| are interposed between the outer ends of the

contact fingers

82 and 83, t hereby serving to bias them apart. Stop members 92 in the form of rivets are loosely mounted in suitable apertures near the ends of the contact fingers 82 and 83 'for limiting the movement apart thereof under the influence of the compression springs 9|. The distance between the headed ends of the rivets 92 is suchvas to permit a slight movement apart of the contact iingers 82 and 83 when the switch vngers 16 and 11-are moved out of1 contactengagement therewith. The contact surfaces I9 and 8| are then positioned slightly within the path of relative movement of the curved ends 18and 19 of the switch fingers 16 and 11. AIt will then be apparent that it is only necessary to compress the springs 9| slightly whenl the switch is operated to the closed position to obtain the effect of its resiliency, this eect being the same as if the contact lingers 82 and 83 were moved to provide a relatively high contact pressure between the mutually engaging contact surfaces of relatively movable switch members and, at the Same time, provide a simple form of switch' construction as illustrated herein. Tubular members` 93 are positioned around the springs 9| to protect the latter and to improve the general appearance of the switch. A guide bracket 94 is mounted, as |illustrated, on the block 85, and its upper end is bent into a horizontal position and tapered to guide the switch fingers 16 and 11 into proper engagement with contact lingers 82 and 83.

With a view to further increasing the contact pressure between the contact engaging surfaces, to increase the number of contact-engaging surfaces and to generally improve the eiiciency of the switch, a reenforcing member 96 is mounted on the upturned right hand end of the bracket 90 so that it extends horizontally in the plane of the switch arm 36 when it is in the closed position. Stantially U-'shape, is formed preferably of relatively thick strap copper, and it has a reenforcing member 91 in the form of a rivet extending therethrough, as illustrated, to prevent lateral displacement of the arms thereof; Rivets having spherical shaped

heads

98 and 99 are secured near the outer ends of the switch ngers 16' and 11, and they are adapted to engage the inner surfaces of the arms of the U-shaped reenforcing member 96. The outer ends of the arms are ared outwardly in order to readily permit the movement of the rivet heads 98 and 99 into the switch closed position.

It will be observed that the curved ends 18 and 19 of the switch ngers 16 and 11 engage the correspondingly shaped surfaces and 8| of the contact ngers 82 and 83 substantially at right angles. In this manner substantially point contact engagement takes place therebetween. In addition, a similar point contact engagement takes place between the rivet heads 98 and 99, which are preferably'formed of copper, and the inner surfaces of the arms of the reenforcing member 96. In effect, then, there are six points at which contact engagement takes'place in the particular embodimentvof the switchdisclosed herein. The combination of the action of the compression springs 9| and of the reinforcing member 96 insures that a relatively high contact pressure is available between the relatively movable switch members and, since the contact engagement therebetween takes place Within relatively small areas, a high unit Contact pressure is` applied. Moreover, because of the individual exibility and resiliency of the switch lingers 16 and 11 and of the contact ngers 82 and 83, contact engagement under substantial pressure is obtained at all six contact points.

Since the switch fingers 16 and 11 move transversely with respect to the contact fingers 82 and from and to the switch closed position, any 'oxide coating or other lm that might tend to increase the contact resistance is removed by the scraping action which ensues. The scraping action provides a clean contact surface, and the relatively high contact pressure insures that a minimum of heating will result at the contact surfaces.

The reenfoi'cing member 96 is of sub- Aterminal bracket |00, in the form of an L- shaped strap, is secured to the bracket and is provided with suitable apertures for connection of the conductor 32 (Figure l), thereto.

It is desirable to protect the contact fingers 82 5 and 83 from the weather as much as possible, and for this purpose a sleet hood |0|, formed preferably of sheet metal, is mounted on the bracket 90, as illustrated. The sleet hood |0| opens downwardly, and, since the switch arm 36 moves horizontally and downwardly when operated to the open position, it does not interfere with the functioning of the switch.

The particular manner in which the tiltable insulator 34 is rotatably mounted, together with the positioning of the switch blade 36 thereon, makes possible the provision of the sleet hood |0| in a position where it fully protects the contact assembly 3| from the weather. It will be observed that the insulator 34 is mounted in a vertical position when the switch |5 is closed. A line drawn through the centers of the shaft 59 and the pin 13 is inclined slightly from the vertical axis of the insulator 34. As soon as the handle 49 is operated to open the switch the pin 13 moves about the shaft 59 as an axis and initially moves upwardly. At the same time, because of the provision of the inflexible link 31a, theleft-handend of the switch blade 36 is elevated so that it rotates slightly about the'pin 13 and the right-hand end is moved 4slightly downwardly at the same time that it is withdrawn from the contact assembly 3|. The sleet hood |0| may then be of ample length to fully cover the contact assembly. At the same time, in the open position of the switch I5, as illustrated by the broken lines, the required electrical clearance distance is provided between the right-hand end of the switch blade 36 and the contact assembly 3|. In this manner a compact and sturdy construction is provided in a minimum of space and with a minimum of cost and the parts that are likely to get out of adjustment are fully protected from the weather.

As indicated hereinbefore, it may not be practical or convenient to exactly align the line conductor 24 with the switch arm 36 that is electrically and mechanically connected thereto. Moreover, even if exact alignment is initially provided, the chances are that it will not remain, because of the swaying of the line conductor 24 in the wind, or because of slight movement of the pole I8 relative thereto. While it is desirable to provide a substantially rigid mechanical and electrical connection between the conductor 24 and the switch arm 36, the connection must be such that the movement of the conductor 24 out of its initial alignment will not alect the operation of the switch arm 36 in moving to and rom the switch closedposition. It is for this purpose that the link 31a, formed by a pair of copper straps |04 and |05, is provided, Figures 11 and I2, with the

universal joints

39 and 40 at each end. The universal joint 39 comprises a rectangular block |01, preferably formed of copper, having a pin |08 extending through it and through the switch blades 14 and 15 of the switch arm 36. In like manner, a pin |09 also extends through the block |01 in a plane at, right angles to that in which the pin |08 is N positioned, and it extends through the straps |04 and |05 forming the link 31a. Spring washers ||0 are positionedunder the headed-ends of the pins |08 and |09 in order to bias the switch blades 14 and 15 and the straps |04 u ing the straps formingthe link |25 into Vcontact engagement with the sides ofthe block |26'. A'

and |05 into contact engagement with the vadjacentl surfaces of the block |01 under considerable pressure. At the same time, the switch blades 14 and 15 and the straps |04 and |05 are permitted to rotate relative to the block |01 in planes at right angles `to each other while still maintaining said contact engagement therewith. In like manner the other Auniversal joint 40 com- .prlses a block v| through which extends a pin I2. The pin i i2 also` extends through the straps |04 and |05. A similar pin ||3extends through the upstanding arms of a U-shapedyoke |14 and throughthe block ill. Spring washers ||5 are positioned underneath the headed ends of the pins ||2 and ||3 to bias the straps |04 and |05 and the arms of the yoke H4 into contact engagement with the block lil. At its lower end, the yoke lill is rotatably mounted by means of a-rivet HB on an integrally formed raised portion ||1 of the upper section of the connector clamp 38. A spring washer IIB is positioned under one end `of the rivet ||6 and a similar washer is lo-y cated under the'other end beneath the raised portion ||1 for securing the desired contact engagement under pressure. l

It will now be apparent that the provision of the

universal joints

39 and 40,"constructed as just described, permits considerable latitude in the positioning of the conductor 24 with respect to the switch arm '36 without interfering in the slightest with the satisfactory operation of the latter. Not only is this true,l but also any swaying of the conductor 2 4 relative to the switch will I notbe translated to movement of the aswitch arm 35.

In some installations it may be undesirable to connect the switch arm 36 directly to the conductor 34, the latter being mounted so that it may move relative to the switchl arm. If it is desiredl to stationarily position the end of the conductor 24 to which the switch arm 36 is to be connected, the switch construction shown generally at |20 in Figure 13 of the drawings may be employed. As thereshown, in addition to the two insulators 30and 34, a third insulator |2| is provided and mounted on a bracket |22 that is positionedbetween the frame members forming the switch base |23. The switch base |23 may be identical in construction with that of the switch base I6 except that the frame members are slightly longer, and the bracket |22 is provided not only for supporting the insulator |2I but also for providing a support for the strain insulator 22.

A terminal member |24 is mounted on top of .the insulatorl 12| foi` connection thereto of the conductor 24. The terminal member |24 is electrically and mechanically connected to the left` hand end of the' switch arm 36 by a link |25 that may be formed of a pair of copper straps. At itslower end the link |25 is mounted on a block |26 that is riveted on its underside to the terminal member |24. A pin |21 extends -through the straps forming thevlink 5 'andthrough the 'block |26. The ends of the pin |21 are headed over, and spring washers |28 are positioned underneath (only one of which is showni) for bias- I are positioned under the headed ends of the pin |30 for biasing kthe blades forming the switch arm 36 into contact engagement'with the vstraps forming the link |25. If desired, suitable grease fittings |32 may be mounted on the block |20 and on the spacer |29 4to permit greasing ofthe. relatively movable parts located thereat.

Since the left hand end of the switch arm 35 is guided by the link |25 in a more substantial manner than it is guided in the' switch construction shown in Figure 1 of the drawings, it is unnecessary to use the guide member 31 carried by the support bracket 35, and, therefore, it is omitted. The third insulator 12| provides this aligned support; and therefore it is unnecessary to utilize the

universal joints

39 and 40 previously described. The wood'connector shaft 39,

shown rin Figure 6 of the drawings, may be employed in the yoke 33 for permitting simultaneous constructed as illustrated in Figure 13 and described hereinbefore may be provided and simultaneously operated by a single operating mechanism. It will be understood that the mounting for such an assembly .would be similar to that shown in Figure 2 of the' drawings, and, since it will be readily understood, it will not be described in detail herein.

In Figure 14 of the drawings I have illustrated a modified form of construction for the switch and contact iingers that are shown in Figure 3 of the drawings and described hereinbefore. As indicated in my copending application, Serial No.

115,694, filed December 14, 1936, and assigned to.

the assigneeof this application, it is pointed out that it is desirable to employ silver contact engaging-surfaces forthe relatively movable members of a switch in order to provide low resistance contact engaging surfaces that will not changed throughout the life of the switch. In Figure 14 of the drawings the manner lin which the silver contact engaging surfaces maybe applied to the transmission line disconnecting switch i5 is illustrated. As there shown, theswitch flngers'18' and 19 are provided with silver inserts |38 and |39, while the contact fingers 82' and 83' are provided with similar silver inserts The manner in which the silver inserts are positioned in the switch and contact fingers is described in my copending application,

'be appreciablyv aiected or their characteristics form" them of v,copper strips "or strap in which the silver inserts are positioned throughout the entire length thereof. The original stock for these members would be purchased in strips of indefinite length and the necessary lengths cut therefrom as required. The switch and contact lingers would then be 'upset and machinedas required to provide the cylindrical contact engaging surfaces for providing substantially point contact engagement therebetween.

Since the silver inserts in the switch and contact flngers form parts of oppositely curved cylin- 'drical surfaces that engage substantially at right angles, a point contact engagement therebetween is provided .over a wide range of relative positioning of the switch and contact lingers, either longitudinally or transversely. Therefore, it is unnecessary to provide a highly accurate operating mechanism which would cause the contact engagement to take place at positions in which accurate alignment would be required.

With a view to providing silver contact engaging surfaces between the remaining contact points, the arms of the reinforcing member 96" are provided with silver inserts |46 that are formed preferably by a circular copper member overlaid with a layer of solid silver, as described in my copending application, Serial No. 115,694, hereinbefore referred to. v'Ihe copper rivets 98 and 99' carried by the switch fingers 'i8' and '19V' are drilled and countersunk for receiving silver rivets |48 to formthe contact engaging surface with the inserts |46. It will be understood that the inserts |46 are large in diameter as comparedA to the rivets |48 for the purpose of securing the desired silver to silver contact without requiring an accurate positioning of the switch fingers 18 When the foregoing construction is employed, low resistance contact engaging surfaces will be provided at all six contact points. Moreover, the contact engagement will take place within small areas, approaching point contact, and because of the individual flexibility and resiliency of the switch and contact fingers. each will carry its share of the current, with the result that no one of them will be overloaded.

When the individual units forming the switch I5 are spaced relatively far apart and the Z- shaped operating sh'aft 44 is employed, there is a tendency for it to twist since it is formed of relatively light sheet metal that has been bent to the shape indicated. In order to increase the resistance of the operating shaft to torsional stress, the construction shown at 44' in Figures 15 and 16 of the drawings may be employed. For the purpose of increasing the resistance of the operating shaft 44' to torsional stress, a reinforcing member |50, in the form of a steel rod is formed into the shape indicated and welded at the points |5| where it engages the surface of the connecting shaft 44. A reinforcing member |50 is provided on each side of the connecting shaft 44', as shown in Figure 16. This construction provides a relatively simple and economical manner in which the light-weight operating shaft 44 may be braced. It is unnecessary to position the reinforcing members |50 with a high degree of accuracy and therefore this construction lends itself readily to manufacture and assembly. Ordinarily the connecting shaft 44' will be formed of 1/8" thick hot-rolled steel and shaped to a rectangular outline approximately 2" x 4". The reinforcing members |50 may be of 1A" steel rod material that is readily bent and welded as illustrated and described.

vSince certain further changes may be made in the above constructions and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A switch comprising, in' combination, a pair of relatively movable switch members, a first pair of spaced apart flexible contact fingers carried by one of said switch members and each having a convex longitudinal contact surface, a second pair of spaced apartfiexible contact f ingers carried by the other of said switch members and each having a convex longitudinal contact surface for individual contact engagement with the corresponding contact surfaces of said first pair of contact fingers, and a pair of substantially inflexible contact fingers disposed adjacent one of said pairs of iiexible contact fingers in such manner as to be engaged by the other of said pairs of flexible contact fingers when said contact engagement takes place.

2. A switch comprising, in combination, a pair of relatively movable switch members, a first pair of spaced apartI flexible contact fingers carried by one of said switch members and each having a convex longitudinal contact surface, a second pair of spaced apart fiexible contact fingers carried by the other of said switch members and each having a convex longitudinal contact surface for individual contact engagement with the corresponding contact surfaces of said rst pair of contact fingers, means biasing the contact fingers of/ one of said pairs of contact fingers relative to each other, means limiting the relati've movement of said biased contact fingers to position their contact surfaces slightly within the path of relative movement with the contact surfaces of the other pair of contact fingers, and a pair of substantially infiexible contact fingers disposed adjacent one of said pairsY of fiexible contact fingers in such manner as to be engaged by the other of said pairs of flexible contact fingers when said contact engagement takes place.

3. A switch comprising, in combination, a pair of relatively movable switch members, a rst pair of spaced apart flexible contact fingers carried by one of said switch members and each having a convex longitudinal contact surface, a second pair of spaced apart fiexible contact fingers carried by the other of said switch members and each having a convex longitudinal contact l surface for individual contact engagement with the corresponding contact surfaces of said first pair of contact fingers, means biasing the contact fingers of one of said pairs of contact fingers relative to each other, means limiting the relative movement of said biased contact fingers to position their contact surfaces slightly within the path of relative movement with the contact surfaces of the other pair of contact fingers, a pair of substantially infiexiblelcontact fingers disposed adjacent one of said pairs of flexible contact fingers in such manner as to' be engaged by the other of said pairs of flexible contact fingers when said contact engagement takes place, and a small radius projection carried by each of the iiexible contact fingers engageable with said infiexible contact fingers and constituting the contact engaging portion therebetween.

4. In a switch for interconnecting Va pair of high voltage transmission line conductors, in

, combination,.a pair of spaced apart switch blades rotatably mounted intermediate the ends thereof, a first block of conducting material rotatably pair of spaced apart link members rotatably mounted at one end on said first block, a second block of conducting material rotatably mounted between the other 'ends ,of said link members, a connector securedto one of said conductors, and a U-shaped member rotatably mounted on said connector and rotatably mounting said second block.

5. A base for adswitch for interconnecting a pair of high voltage transmission line conductors comprising, in combination, a pair of spaced apart frame members, a first insulator support bracket secured between said frame members at mounted between said switch blades at one end, a

l rone end and having an apertured portion extend- Tao ing therefrom for connection to a strain insulator to which one of said conductors is fastened, a second insulator support bracket rotatably mounted intermediate the ends of said frame members;

and an apertured bracket secured between said frame members at the other end for connection to a strain insulator to which the other of said conductors is fastened.

6. A switch comprising,v in combination, a pair lof relatively movable switch members, a first pair' of spaced apart iiexible contact fingers carried by one of said switch members and each having a convex longitudinal contact surface, a second pair of spaced apart iiexible contact fingers carried by the other of said switch members and each having a convex longitudinal contact surface for individual contact engagement with the.

corresponding contact surfaces of said first pair of contact fingers, means biasing the contact fingers of one of said pairs of contact fingers relative to each other, means limiting the relative movement of said biased contact fingers to position their contact surfaces slightly within the /path of relative movement with the contact survarying degrees of misalignment comprising, in

combination, a stationary switch member for connection to one of said conductors, a rotatable 4support member, a switch arm rotatably mounted on said support member for movement into and out of contact engagement with said switch member, a connector clamp for mounting on the other conductor, an iniiexible link electrically and mechanically interconnecting said clamp and said switch arm, and stop means carried by said support member limiting the position of said clamp on said conductor to insure proper contact en-A gagement between said switch arm and said switch member.

8. A light weight base for a disconnecting switch adapted to be mounted on a pole comprising, in combination, apair of spaced apart structural frame members, a bracket formed of -plate-like material and secured between said frame members at each end to rigidly brace them relative to each other, one of saidbrackets being arranged and adapted to support an insulator, and an insulator support bracket rotatably mounted between said frame members intermediate the ends thereof.

9. A light weight base for a disconnecting switch adapted to be mounted on a ple for opening the circuit between a pair of transmission line conductors comprising, in combination, a|l

pair of spaced apart structural frame members, a bracket formed of plate-like material and sevcured -between said frame members at each end to rigidly brace them relative to each other, each of said brackets including means for connection thereto of a strain insulator to each of which one of said conductors isv fastened and one of said brackets vbeing arranged and adapted to support .facing toward eachy other, a

an insulator, and an insulator support bracket rotatably mounted between said frame members intermediate the ends thereof.

10. A light Weight base for a disconnecting switch adapted to be mounted on a pole f'or interconnecting a pair of transmission line conductors comprising, in combination, a pair of L- shaped spaced apart structural frame members with the outer surfaces of the upstanding legs bracket-formed of plate-like material and welded to the opposite faces of said frame membersat each end to rigidly brace them relative to each other, each of said brackets including means for connection thereto of a strain insulator to each of which one of said conductors is fastened and one of said brackets being arranged and adapted to support an insulator, a shaft extending transversely through said upstanding legs of said frame membersintermediate their ends, a pair of inverted L-shaped hinge members carried by said shaft between said upstanding legs, and. an insulator support bracket .carried by said hinge members having a generally'rectangular opening for receiving a lcorrespondingly shaped operating member. Y

11. A-combined support bracket and yoke for a tiltable insulator of a disconnecting switch disposed to be rotatably mounted on a base comprising, in combination, a pair of interiitting gen,- erally U-shaped members formed of plate-like material in such manner as to form a generally rectangular opening for receiving a correspondingly shaped operating shaft, clamp means for securing said operating shaft in said opening, and means for securing said insulatoron the upper side of said members, the end of one of said members cooperating with said base to limit the movement ofv said insulator in one direction.

12. Ajcombined support bracket and yoke for a tiltable insulator of a disconnecting switch disposed to berotatably mounted on a base comprising, in combination, a pair of interfitting generally U-shaped members formed 'of plate-like material in such manner as to form a generally rectangular opening for receiving a correspondingly shaped operating shaft, a clamp plate in said opening, means extending from the upper side of said membersv into said opening and cooperating with said clampplate to secure saidl operating shaft in position, and means extending intothe upper side of said members for securing said insulator thereon, the ends of one of said members cooperating with said base to limit the movement of said insulator toward the open and closed positions of said switch.

13. A shaft to which a torsional force-is applied for simultaneously operating a plurality of widely spaced apart transmission line disconnecting switches or the like, comprising, in combination, a Z-shaped metal member formed of relatively thin plate-like material, and reenforcing means 3 of zig-zag construction secured at spaced pointsr to the web and one iiange of saidZ-shaped member for bracing it against the stress set up'therin on vapplication of said torsional force.

14. A shaft to which a torsnal force isf/applied for simultaneously operating aplurality ,of `widely spaced apart transmission line disconnecting switches or the likgT comprising, in combination, a Z-shaped metal member formed of relatively thin plate-like material, and a pair of continuous reenforcing 'members of zig-zag construction welded at spaced points on opposite sides of the web of said Z-shaped member and-to the adjacent fianges for bracing it against the stress set up .therein on application of said torsional force.

15. A switch comprising, in combination, a switch blade having a longitudinally convex contact surface along one side and a small radius projection on the other side, and a cooperating contact assembly including a pair of contact members having contact surfaces facing in opposite directions, one of said contact surfaces being longitudinally convex for substantially point contact engagement with said longitudinally convex surface of said switch blade and the other being substantially plane for substantially point contact engagement with said small radius projection, said contact members being biased toward each other, and means limiting the movement of said contact members toward each other to position the contact surfaces thereof slightly within the path of relative movement of the Contact surfaces of said switch blade.

16. Aswitch comprising, in combination, a pair of spaced apart switch blades each having on adjacent sides a longitudinally convex contact surface and on the other sides a small radius projection,l and a cooperating contact assembly including a pair of biased apart contact ngers having longitudinally convex contact surfaces facing outwardly for substantially point contact engagement with the longitudinally convex surfaces of said switch blades, and a pair of platelike contact members for substantially point contact engagement with the small radius projections on said yswitch blades.

17. A switch comprising, in combinationa pair contact fingers.

of relatively movable switch members, a first pair l of spaced apart flexible contact fingers carried by one switch member each having a convex longitudinal contact surface, a pair of substantially infiexible contact fingers also carried by said one switch member and disposed adjacent said first pair of contact fingers, and a second pair of flexible spaced apart contact fingers carried by the other switch member each having convex contact surfaces on opposite sides for engagement on one side with the corresponding one of said first pair of contact fingers and on the other sidewith the corresponding one of said infiexible contact fingers.

18. A switch comprising, in combination, a pair of relatively movable switch members, a first pair of spaced apart flexible contact fingers carried by one switch member each having a convex Alongitudinal contact surface facing outwardly, a

pair of Vsubstantially inflexible contact fingers also carried by said one switch member each being individual to' one of said first pair of contact fingers and spaced outwardly from the contact surface thereof, means biasing said first pair of contact fingers apart, and a second pair of flexible spaced apart contact fingers carried by the other switch member each having convex contact surfaces on opposite sides for engagement on one side with the corresponding one of said first pair of contact fingers and on the other side with the corresponding one of said inflexible ALLAN RAMSEY.