US1868460A - Electric switch - Google Patents

Description

3 Sheets-Sheet l S. S. GREEN ELECTRIC SWITCH Filed Aug. l, 1929 Y 5 fr di @6' fz 07".' KZ zlyj, $746673 July 19, 1932.

July 19, 1932. s. s. GREEN ELECTRIC SWITCH Filed Aug. l, 1929 3 Sheets-Sheet 2 i @za-Zeg a. Gree'z ff/XM M July i9, 1932. s. s. GREEN 1,863,450

ELECTRIC SWITCH Filed Aug. l, 1929 3 Sheets-Sheet 3 Q 45 /l /7 /Z :i: i :g NM f f 'ff w n u l'l u /5 l f4 '35 Patented July 19, 1932 parrait,

istantsr'res PATENT rieles STANLEY S. GREEN, OF LA FAYETTE, lNIDIANA., ASSIGNOIR T0 DUNCAN` ELECTRIC Iannurnornnrns- ILLINOIS COMPANY, 0F 'LA FAYETTE, VNDIANTAQ .A VC'QBPORATI01N' ELECTRIC SWITCH application, ined august 1, 1929. serian No. 382,644.

My invention relates to electric switches andhas a number of objects and advantages in view.

The invention, in one of its embodiments, relates particularly to an electric switch which is inclusive of a turning member having a contacting blade 'thereon anda stationary member having two contactingblades thereon positioned to Vhave one end of each engageable by the first mentioned-contacting blade 'that is receivable between the other blades. Instead of relatively positioningfthe two contacting' blades -upon thestationary member, as hitherto, I employ clamping means for securing the mounted'ends of the blades together, with suitable spacing means therebetween. In the preferred embodiment of the invention the clamping means is in the form of a metallic rod passing through said mounted blade/ends and through the spacer therebetween.y this spacer being preferably in the form of a metallic washer. The rod Vis pressed into clamping or holding relation with these two blades andthe Ainterposed washer by lhaving its ends upset or riveted. The rod is desirably provided with a threaded bore for the reception of a. binding screw. This bore desirably passes throughout the length of the rod, so that Va binding screw may be applied at each end, a construction which is advantageous 'where one conductor is to be permanently connected with one end of the rod and another yconductor is to be separablv connected with the other end of the rod. My invention finds a very useful embodiment in a switch structure which associated with the line and load Vcircuits of an electric current consumption system. Vfhen switch is made for this association7 the turning member has two contacting blades thereon and a plurality of pairs of stationary contactingblades arev provided, the blades of each pair being spaced apart to enable thecomplemental blade upon the turnmember to besnugly received therebetween. There are four such pairs of stationary'blades whose anchoring' rods or other anchorages are the corners of a quadrilateral. the axis of the turning member dee sirably intersecting the intersection of the diagonale of the quadrilateral. The stationary 'blades that Vare securedby these four anohorages extend to the turning member where theyare engageable bythe bla'de'supjon the turning member. The'switch may :be provided with a fifthl stationary pair Vf blades located 'abreast of one of the other pairs of blades and held inplace, preferably, by thesameanchorag'e. v I

Generally speaking, suoli a switch is of a grid or grating formation with its parts of such simple construction thatthey may be cheaply made andureadily assembled. A

switch vthus organized preferably has 'two c oplanar pairs of contacts Vwhich are relatively disposed to have one of the blades upon the turning member complemental to both, all the blades'being so 'proportioned `and relativelydisposed .that the blade'upon vthe turning member is adapted to have lsimultaneous engagement with the blades of both pairs at the same time. The blade upon the turning member and the blades of both pairs are always in such relation as to `receive axial thrusts upon the turning member, making it unnecessary to provide any additional means for receiving such thrusts. When such a switch employs a plurality of contactingvblades upon the turning member, there are preferably 4at least two pairs of stations ary blades which areso related to eachother and to the blades upon the turning member that some one of 'these latter blades isreceived between the contacting blades ofthe pair individual to lit in all positionsjof the turning member, whereby axial movement of `th turning member is further guarded.`

are held in assembly -by the 'anchorages at the` corners of the switch structure, fbeii'i'g preferably clamped between the rivetedends of the rods and the switch structure Vportions that intervene between 'these 'rod ends, where anchoragesinthe fori-n of rods -are employedV These end plates may, if desired, serve as bearings by being provided with circular adjustment of the switch may be readily determined the stationary and turning members thereof are provided with lines thereon, these lines being preferably provided upon the'turning member and guard in such rela- 'tion that when the switch is closed the lines are consecutive and when the switch is open the-lines are separated. Thus an animated diagram is provided whereby the circuit adjusting condition of the switch is revealed without the necessity of observing the relationship of the switch contacts.

The switch structure of my invention, in another of its characteristics, is provided with a support, preferably a casing, having one Aormore contact terminals therein, according to the number of stationary contacts or pairs of stationary contacts which are automatically brought into connection with said stationary contact or contacts when the switch structure is fully received within the casing. I also provide a holder for the turning member to secure it in contact making position. This holder is desirably a cover for the casing. The holder and turning member have interengaging holding formations, eccentric to the axis of the lturning member, which secure the turning member' in circuit closing position when the holder is in position. The holding formation upon the turning member is desirably a pin and the holding formation upon the cover is then a socket that receives the pin.

The invention will be more fully explained in connection with the accompanying drawings in which Fig. 1 is a perspective view illustrating the preferred form of switching mechanism of my invention and a container therefore, these structures being shown in separated relation; Fig. 2 is a front sectional view taken through a mid-portion of the casing shown, it being assumed that the switch is within the container, in this ligure; Fig. 3 is a sectional view on line 3-3 of Fig. 2; Fig. 4 is a sectional'view on line 4 4 of Fig. 5;` Fig. 5 is a sectional view on line 5--5 of Fig. 4; Fig. 6 is a sectional view on line 6-6 of Fig. 5; Fig. 7 is a sectional view on line 7-7 of Fig. 4; Fig. 8 is a circuit diagram illustrating one of the uses to which the switch of my invention may be put; Fig.

9 is a face view of the switch within its container, the container cover being removed; and Fig. 10 illustrates a slight modification.

The switch illustrated includes a stationary member having live pairs of contacting blades 1, 2; 3, 4; 5, 6; 7, 8; and 9,10. The blades of each pair are provided with spacing means therebetween, such spacing means being preferably separately formed from the blades and assembled therebetween. ln the preferred embodiment of the invention, the spacing means are in the form of metallic washers 11 and the means for anchoring the mounted ends of the blades are in the form of metallic rods 12 of equal length that pass through the aforesaid blades and washers. These rods have reduced end portions which pass through quadrilateral or rectangular insulating plates 13 and 14. The rods are rivet ended, as indicated at 15 and 16, against the plates, the rivet ends of the rods exerting clamping pressure upon the aforesaid blades and washers through the intermediation of said plates. The washers 11 that are alternated with the blades 7, 8, 9 and 10 fill the space between said plates 13 and 14 suficiently to enable these plates to exert clamping pressure upon said washers and plates with sufficient firmness to hold these four blades in xed relation with each other and with said plates'. Other washers 17 are employed in conjunction with the remaining blades to enable said plates to clamp these blades in place. The rivet- ed ends 15, 16 of the rods thus serve to exert clamping pressure upon the plates 13 and 14, this pressure being transmitted to the washers and blades interposed between the plates. The pairs of blades 3, 4; 5, 6; 7, 8 are coplanar, the spaces between the blades of these three pairs being, therefore, coplanar. The pairs of blades 7, 8 and 9, 10 are abreast of each other on the same anchorage 12. The pairs of blades 1,2 and 9, 10 are also coplanar, the spaces between the blades of these two pairs being, therefore, also coplanar.v The blades are desirably parallel with the long sides of the insulating plates 13 and 14 and terminate slightly short of the plane which contains the median transverse lines or axes of said plates. These plates are desirably just in fullr lapping relation with the aforesaid blades that are between them, thereby serving as guards for these blades and the contacting blades, later to bek mentioned, that are complemental thereto.

The turning member of the switch is preferably inclusive of a cylindrical body portion of insulation 18 which is desirably molded about the anchored sides of the blades 19 and 20. Themember 18 is preferably journaled in the plates 13 and 14, being received within circular holes that snugly fit it. A

knob 18 issuitably assembled with the front end of the body portion 18, as by means of the nate portions of the adjacent vstationary blades'beingsmall. Therblades 19 and`20 upon the turning member extend radiallybeyond the gaps between the member portion 18 and the stationary blades and are ofA sufiicient width to reach the outer longitudinal` sides of the stationary blades as the turning member is operated. A withdrawable metallic post 21 is-screwed into the'plate 14`to'coA operate with an insulating tongue 22 upon the turning member to limit the turning movement ofthe turningfmember'in one di rection, the movement of this member in the other direction being limited bythe cooperation of this tongue with the inner long side of the blades'9 and 10. The elements 21 and 9 and 10 confine theturning member of the switch to `movement through an angle of ninety degrees. .The blades-19 and 2O are nearly, but not quite, half circles,`the inner or adjacent straight edges oftheseblades being slightly spaced apart from a plane that is inclusive of the axis ofthe turningmember. Whenthe tongue 22 engages thepost 21 said straight edges of theblades 19 and 2O are parallel with the long sides of the stationary blades and are substantiallyf'flush with the inner long sides of the'stationary blades with Arespect to which they "are complemental. In this adjustment of the turning member, the pair of blades 3 and 4 receives the blade 19 as does also the pair `of blades 5 and 6 that'are coplanar vwith the blades 3 and 4, equal portions of the blade 19 being received between both blades of each of these pairs. The blade 20is similarly received between the blades of the ' coplanar pairs 1, 2; and 9, 10, and iswitlidrawn `from between the blades 9, 10. The blade 2O thus remains in constant engagement with the i blades -1 and 2. Y When the tongue 22 engages the blades 9 and 10 the blade 19 is received between the blades 5, 6.and 7, Sand the blade 20 is received between the blades 1, 2. lVhen the post 21 is withdrawn to bring its inner end flush with the insulating plate 14 the turning member has its rangeof rotation inv creased to one hundred and eighty degrees, the stationary blades 1 and 2 then serving as a motion limiting stop in place of the post 21. Vhen the tongue 22 engages the blades 1 and 2, the blade 19 is engaged only between the blades 3, 4 and the blade 20 is engaged only between the blades 9,:10. =Each setof Aeoplanar pairs-of stationaryblades enables theemployment ofthe plates 13 and Y 14 =merely as `lateral ybearings for the `tu rningfmember. Theseplateswould permit the turning `member to'be axiallymovable were itnot for the described interrelation'offthe contacting blades. `Diagonally opposite pairs ofstationary contacting blades that 4are'nt coplanaralso cooperate withboth blades upon the turning memberito achieve the same result, one or the other of-these `pairs of blades cooperating with the complemental blade upon the turning member to receive end thrusts upon this member.

' The anchoring rods 12 are desirably formed withthreaded boresfor the reception of metalli'c binding screws'23 and 24. The bind-V ing-screws 23 serve to clamp circuit continuingA conductors 25,-26, 27 and 28'into engagement with'theinnerriveted ends ofthe rods 12 l that lrespectively 'assemble the blades 1, 2; 3,4; 5, `6; and 7,8,9and 10. Vhen the switch is employed in connection withelectricity meters, the binding screws 24 do not normally lserve `to connect any conductors with the rods A12 and the stationary contacting blades respectively pertaining thereto. When ameteris to be tested'thesescrews are backed 0H sutliciently to `enable i conductors tobe clamped between saidrods and the heads ofV these screws. p

Other distance preserving devices 28 vare also desirably interposed between the plates y13 and 14, beinggpreferably'in the lform of shouldered ftubes of insulation, whose shoulders have :abutting engagement with the plates andwhose ends are snugly received within holes that are formed `in the plates. The headsiof `the 'mounting screws 29 have clamping `engagement with the insulating plate `l4'and the stems of these screws pass through 'the :tubes 28 into threaded engagement withthe'portions 30 of a support, which is desirablyalsoinclusive of a mounting body 31 of Airsulation in which the parte 30, that are preferably-metallic, are desirably molded. The mounting body 31 desirably also carries U-shaped contact terminals 32, 33, 34 and 35 chattare respectively complementalto the circuit continuing contacts 25, 26, 27 and V28. rlhese circuit lcontinuing contacts Iare desirably in the form of resilient bars orarms whose unmounted ends yare engageable with the aforesaid U-shapedcontacts and cooper- A ate therewith to firmly fix the entire switching mechanism upon its support 31. The contacting ends of the circuit continuing contacts 25, 26, 27, 28 are sufficiently spaced apart from the inner insulating plate 13 and iiexed away therefrom as to enable the same to have firm mechanical and electrical connection with the aforesaid complemental U-shaped terminal contacts, when the assembling screws 29 are screwed sufficiently home.

The switching mechanism is desirably placed within a casing, in which event the insulating supporting body 31 is desirably the back wall of the casing body, the top, bottom and side walls of the casing body being continued far enough forward to extend slightly in front of the knob 18. The Casing is provided with a cover 36, also preferably of insulation. This cover is provided with an opening 37 which receives the pin 182, that is eccentric with respect to the turning member 18, when the switch is adjusted to its normal working position. The shank of a bolt 38 is screwed into the pin 182, the head of the bolt clamping upon the cover to hold it in place, the cover having suitable formations 36 which prevent it from turning. The bolt 38 may have a perforated eX- tension 38 which cooperates with a perforated lug 39 for holding a sealed wire which `guards against the undetectable rotation of said bolt. The cover 36 is thus a holder for the turning member and the pin 182 and the cover portion at 37 .areinterengaging holding formations, eccentric to the 'axis of theV turning member which serve to secure this turning member in its contact making position. i

The circuit conductors may be led through the slots'40 in opposite sides of the boX, or the circuit wires may be clamped into electrical connection with metallic rods 41 by means of Vthe clamping nuts 42, Fig. 10. These rods are desirably also screwed into the inner ends of thebores of the rods 12 tok bring these rods and the contacting blades in electrical connection therewith into electrical connection with said circuit conductors. llVhen the construction of Fig. 10 is employed, the U-shaped members 43 are of slightly different shape from the U-shaped members 32 etc. and are placed reversely with respect to the latter U-shaped members to accommodate the rods 41. In the structure of Fig. 10 the circuit continuing conductors 25 etc. need not be employed since the inner riveted ends of the rods 12 are in direct engagement with the parts 43. The rear walls of the casing that contains the switch may be channeled as indicated at 44 for the reception of assembling bars and other parts that are employed when a number of these casings are assembled in a set, as set forth more particularly in my copending application Serial No.

382,645 filed August V11, 1929. f

yThe insulating plate or guard 14 so effectively covers the contacts of the switch, particularly when the switch is enclosed in a casing,'that the positions of the switch contacts cannot be observed, even though the j cover 36 is removed, to determine the circuit adjustment effected by theswitch.r In order that the circuit'adjustment effected by the switch may be known by mere observation, I provide the characteristics shown in Fig. 9. In this figure, the stationary member of the switch has lines 45, 46, 47 and 48 thereon, these lines being desirably routed in the plate or guard 14. Said lines extend from the regions of the binding screws 24 and the rods 12 toward'the turningv member of the switch. This turning member has lines 49 and 50 routed on the insulating body portion 18 thereof. When the switch is in normal position the line 49 iills'thev gap between the lines and46, being in consecutive relation with each line. The line 50 is then, also similarly related to the lin-es 4 7 and 48. When the switch is not in working position the lines 49 and 50 are separated from the lines related thereto. The user of the switch can instantly tell whether or not it is in its normal position by the relationship of the lines upon the moving and stationary members of the switch.

The switch of my invention may be put to many'uses. Fig. l8 is a diagrammatic illustration of the switch of my invention as it may be employed in connection wth an electric current consumptioncircuit the service meter in connection with such circuit and a rotating standard test meter when such is brought into connection kwith the system for the purpose of testing a service meter.A In this figure,I have illustrated a single phase alternating current generator 51, though generators of other current may be employed, this generator being in Ycircuit with a primary 52 of a transformer whose secondary 53 is included between the sides 54 and 55 of a'load circuit. The load may be of any suitable sort, incandescent lamps 56 being illustrated in bridge of said load sides. The service meter illustrated is inclusive of a core 57 surrounded by a pressure winding 58 that is in bridge between the load sides and a core 59, which is surrounded by the current winding 60, which is normally included in circuit with the secondary 61 of a current transformer whose low woundprimary 62 is serially in.- l

eluded in the load side 54. The switch of my invention di agrammatically illustrated in Fig. 8 normally includes the current winding in circuit with the transformer winding 61. The other parts of the service meter which are diagrammatically illustrated being so well known to those skilled in the art need not be described. The rotating standard test meter illustrated is in many respects similar to the'service meter similar parts being given similar characters of reference with prime eX- ponents added. The service meter is provided with switches 63, whereby its pressure winding 58 may be excluded from circuit. The pressure winding 58" ofthe test meter has its terminals supplied withclips 64, whereby this winding may be includedin bridge .between the load sides. The currentwinding 60 has its terminals supplied ywith clips 65 which may be clamped inzelectrical connection by means of the binding screws 24..' The test meter has an artiiicialload, such as a bank of lamps 66, in circuit with its current winding 60. F ig. 8 illustrates the test meter in testing relation with the service meter. TvVhen the test meter employed as illustrated a jumper 67 with clips 68 may be included in circuit with the -current winding of the service meter.

Changes maybe made without departing from the invention.

Having thus described my inventi'oml claim: i

l. An electric switch includingia turning member and a stationary member, one of said members having thereon-a plurality of metallic contacting blades; a plurality of pairs of metallic contacting blades upon the other member with the blades -thereof spaced apart to receive the first aforesaid blades therebetween, each of the first aforesaid blades having a pair of contacting blades individual thereto, the contacting blades upon' both members of the switch being Vso proportioned and related thatscme one of the Vfirst aforesaid blades is received between the contacting Iblades of the pair individualto it inall positions ofv the turning member, whereby axial movement of the turning Amember-is guarded against; and a support in which the turning member is journaled and formed to permitv the turning member to be axially movable were it not for the interrelation of the contacting blades. .y K

2. An electric switchincluding a turning member and a stationary member, one-of said members having a metallic contactingblade thereon; a plurality of coplanar pairs of stationary blades upon the other member, the blades of each pair being spaced apart to receive the first aforesaid blade therebetween, the contacting blades upon Vboth members of the switch being so proportioned and related that the blade upon the rst member is received between the contacting blades of-some pair in all positions of the turning member, whereby axial movement ofthe turning mem'- ber is guarded against; and a support in which the turning member is journaled and formed to permit the turning member to be axially movable were it notfor the' interrelation of the contacting blades.

3. An electric switch including a turning member and a stationary member,.onefof1said members having thereon a plurality ofmetallic contacting blades; and a plurality of pairs all positions'of `the turning member, whereby Y axial movement of the turningmember is gimrded against, the interengaging blades receiving axial thrusts of the turning memberto hold this member against axial movement. i

l. An electric switch including a turning member and a stationarymember, one of said members having a metallic contacting blade thereon; and a plurality of coplanar pairs of stationary blades upon the other member, the blades of each pair being spaced apart'to receive the first aforesaid blade therebetween, the contacting blades upon both members of the switch being so proportioned and related that the blade upon the' first member is receivedbetweenY the contacting blades of some pair in all positions of the turning member, whereby laxial movement of the turning member is guarded against, the interengaging blades receiving axial thrusts ofthe turning member to hold this meinberfagainst axial movement.

5. An electric switchincluding a turning member havingthereon a plurality of contacting blades gland a stationary member having four pairs of contacting blades thereon, the blades of the pairs beingspaoed apart to receive the other blades therebetween, each of the latter blades havinga pair of contacting blades complemental thereto, said pairs of blades having four metallic anchorages which are distributed about the turning member, each anchorage being formedfand accessible vfor `circuit connection therewith externally of the switch andincluding a rod passing through ,the related blades and rivet ended to clamp said blades together.

6. An electric switch including a turning member having Vthereon two contacting blades; and a stationary memberhaving four pairs ofcontactingblades thereon, the blades of the pairs being spaced apart to receive the other blades therebetween, each of the latter blades havingtwo pairs .of contacting blades complemental thereto, said pairsvof blades having four` vmetallic anchorages which are distributed about the turning member, each anchorage being formed and accessible for circuit connection therewith externally offthe switch and including a rod passing throughthe related blades, said rod being rivetendedto clampthe blades together and being provided with a threaded ybore to receive a binding screw.` f

enY

7. An electric switch including a turning member having thereon two contacting blades; and a stationary member having four pairs of contacting blades thereon, the blades of the pairs being spaced apart to receive the other blades therebetween, each ot the latter blades having two pairs of contacting blades complemental thereto, said stationary member having a fifth pair of contacting blades which is also oomplemental to one of the complemental blades upon the turning member, this fifth pair of contacting blades being locatedabreast of one of the aforesaid pairs of contacting blades, said pairs of blades having tour metallic anchora ges formed and accessible iior circuit connection therewith externally of the switch.

8. The structure of claim 7 wherein the anchorages are in the form of rods wl. ich p ass through the blades to which they relate and are rivet ended to clamp these blades together.

9. The structure of claim 7 wherein the anchorages are in the form ofrods which pass through the blades to which they relate andl are rivet ended to clamp these blades toA gether and are provided with threaded bores to receive binding screws.

10. An electric switch including a turning member having thereon two contacting blades; a stationary member having tour pairs of contacting blades thereon, the blades of the pairs being spaced apart to receive the other blades therebetween, each of the latter blades having two pairs of contacting blades complemental thereto; and adjustable means for varying the range of movement oi" the rotatable member and serving, in one adjustment, to maintain a blade upon the turning member permanently in engagement with one of the pairs of contacting blades complemental to this contacting blade and in another adjustment permitting this contacting blade to move into and out of engagement with both of the pairs of contacting blades complemental thereto.

11. An electric switch including a turning member having a contacting blade thereon; a stationary member having two contacting blades thereon positioned to have one end ot' each engageable by the first mentioned contacting blade that is receivable between the blades of the stationary member, there being spacing means between the other ends of the blades of the stationary member; and clamping means for securing these other blade ends together with the spacing means therebetween.

12. An electric switch including a turning member having a. contacting blade thereon; aV stationary member having two contacting blades thereon positioned to have one end of each engageable by the first mentioned con'-Y tacting blade that is receivable between the blades of the stationary member, there being i Labelled metallic rod passing through said other ends of the blades upon the stationary member and serving to clamp these other blade ends, with the spacing means therebetween, in assembly, said rod being Jformed with a threaded bore for the reception of a binding screwA 14. An electric switch including a turning member having two contacting blades thereon and spaced apart longitudinally of the aXis of the turning member; a stationary member having two pairs oit contacting blades thereon, each blade upon the turning member having such a pair individual thereto, and being engageable with both blades ot such pair, there being spacing means between the blades of each pair; and clamping means for securing the blades of each pair, together with the spacing means therebetween, in assembly.

15. An electric switch including a turning member having two contacting blades thereon and spaced apart longitudinally of the axis of the turning member; a stationary member having two pairs of contacting blades thereon, each blade upon the turning member hav- 'roo ing such a pair individual thereto, and being ,A

engageable with both blades of such pair, there being spacing means between the blades of each pair; and a rod passing through said other ends of the blades upon the stationary member andserving to clamp these other v,

blade ends, with the spacing means therebetween, vin assembly.

16. An' electric switch including a turning member having two contacting blades thereon and spaced apart longitudinally of the axis of the turning member; a stationary member having' two pairs of contacting blades thereon, each blade upon the turning member having such a pair individual thereto, and being engageable with both blades of such pair,

there being spacing means between the blades 'of each pair; and a metallic rod passing through' said'other'ends'ot the blades upon the stationary member and serving to clamp these other blade ends, with thek spacing means therebetween, in assembly and provided with threaded bores to receive binding screws.

17. An electric switch including a rotating VmemberhavingV contacting blades thereon;

a stationary memberrhaving a plurality of sets of contacting blades thereon that are complemental to the aforesaid blades and an anchorage for the blades of each set comprising a rod passing through -the blades of such set and washers through which the rod also passes and which are alternated with the blades, said rod being pressed into holding relation with the associated blades and washl ers.

18. An electric switch including a movable member having a contact thereon; and a stationary member having a contact thereon, the first Contact being movable into and out of engagement with the second, in combination with a casing for the switch having a cover portion, said movable switch member andV cover po-rtion having interengaging holding formations which serve to secure this switch member in one of its adjustments when the cover is applied.

19. An electric switch including a turning member having a contact thereon; and a stationary member having a contact thereon, the lirst contact being movable into and out of engagement with the second, in combina-tion with a casing for the switch having a cover portion, said turning switch member and cover portion having interengaging holding formations eccentric to the axis of the turning member and which serve to secure this switch member in its circuit closing adjustment when the cover is applied.

20. The structure of claim 19 in which the holding formation upon the turning member is a pin and the holding formation upon the cover is a socket adapted to receive said pin.

21. The structure of claim 18, wherein the' switch is secured to the body of the casing and a cover retaining device is assembled with the holding formation upon the movable switch member.

22. The structure of claim 19, wherein the switch is secured to the body of the casing and a cover retaining device is assembled with the holding formation upon the turning switch member.

23. The structure of claim 19 wherein the holding formation upon the turning member is a pin and the holding formation upon the cover is a socket adapted to receive said pin, and wherein the switch is secured to the body of the casing and a cover retaining device is assembled with the holding formation upon the turning switch member. y

24. An electric switch including a movable member having a contact thereon, and a stationary member having a plurality of contacts thereon which are adapted to be bridged by the first contact, said stationary member having visual indications Corresponding to the stationary contacts and bot-h ofsaid members having lines thereon which mate, when stationary contacts are bridged by the movable contact to form a continuous line visibly connecting the indications of the bridged contacts.

25'. An electric switch including a movable member having a Contact thereon, a stationary member having' a plurality .of contacts thereon which areconnectible in pairs by the first contact, anda visible terminal for each contact on the stationary member, said members each'having lines thereon which mate, when Va pair of contacts on the stationary member are connected 'by the contact on the movable member, to form a continuous line visibly connecting the terminals of the connected pair of contacts on the stationary member. Y

26. An electric switch comprising a rotate able contact, a plurality of stationary contacts arranged about said rotatable contact and connectible in pairs by the latter, a face plate, a terminal for each stationary contact extending through the face plate and visible on the front of the latter, and an operator for the rotatable contact also extending through the face plate, said operator and face plate having linesthereon which, when a pair of stationary contacts are connected by the rotary contact form a visible continuous line connecting the terminals of the connected stationary contacts. i

In witness whereof I hereunto subscribe my name.

STANLEY S. GREEN.

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