US2411730A

US2411730A - Electric switch

Info

Publication number: US2411730A
Application number: US551645A
Authority: US
Inventors: Orlondo A Huntsman
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1944-08-29
Filing date: 1944-08-29
Publication date: 1946-11-26
Anticipated expiration: 1963-11-26

Description

Nov. 26, 1 946.

O. A. HUNTSMA N ELECTRIC SWITCH Filed Aug. 29, 1944 4 Sheets-Sheet l Inven to:-

Orlando A. Huntsman H i' l it Abtor-neg.

1946- 0. A. HUNTSMAN 2,411,730

' ELECTRIC SWITCH Fil ed Aug. 29, 1944 4 Sheets-Sheet 2 V I Y M 11 L'm-umi'iu- HL: f 1/ -i-i 577 Z a! 46 t' 86 )1 43' U40 Inventor: Orlohdo A. H unosman,

His Attorheg.

Nov. 26, 1946. O.A.HUNTSMAN ELECTRIC SWITCH Filed Aug. 29, 1944 4 Sheets-Sheet 3 Inventor- Or-l-ondo AHuhtsrnan,

His Attorney.

N o. A. HUNTSMAN ELECTRIC SWITCH Filed Aug. 29, 1944 4 Sheets-Sheet 4 kNkNbRk a wQm m W vAO a u gm Invent or- Orlondo A. Huntsman,

His Attorne g.

Patented Nov. 26, 1946 ELECTRIC SWITCH Orlondo A. Huntsman, Arlington, Va., assignor to General Electric Company, a corporation of New York Application August 29, 1944, Serial No. 551,645

23 Claims. 1

My invention relates to improvements in electric switches and more particularly to improvements in multistage, multiposition control and instrument switches.

For so-called control and instrument switching purposes, the variation in the number of circuits and switching sequences is such that economic reasons dictate a switch structure of such adaptability as to be usable for any probable circuit combination and sequence and yet so simple as to be capable of ready assembly from a relatively small number of parts. Moreover, to be in keeping with the trend of the times, the switch should be adaptable to flush mounting with certain vital parts of the switch structure readily removable from the front of the switchboard and other vital parts removable from the back for inspection, maintenance, renewals, and operational changes without hazard to apparatus or personnel in consequence of failure of the human element involved. Also, it is important from the standpoint of space economy that the switch structure be compact even when a large number of circuits is involved. Inasmuch as multistage, multiposition control and instrument switches are more usually manually operated, the structure should be such as to require the minimum of physical effort not only for circuit controlling operations but also withdrawal and insertion of the removable or drawout parts of the switch structure. Furthermore, in order to minimize contact damage, circuit closing and opening operations should be accomplished with contact closing and opening independent of the control of the operator.

An object of my invention is to pwcvide an improved switch which can be readily assembled into a compact structure from a relatively few different parts to provide a wide variety of switching combinations and sequences. Another object of my invention is to provide an improved multistage, multiposition control and instrument switch which is particularly adapted for flush mounting with certain vital parts of the switch structure readily and easily inserted and Withdrawn from the front of the switchboard or mounting panel without danger to personnel and apparatus and also without risk of false circuit controlling operations. Still another object of my invention is to provide an improved control and instrument switch with a structural part of the switch withdrawable from the back of the switchboard and arranged to control circuits which must be left in a predetermined condition when the part of the switch, which is withdrawable from the front of the switchboard, is removed. A further object of my invention is so to interlock the withdrawable parts as to avoid hazard to personnel and apparatus and false circuit controlling operations. A still further object of my invention is to provide an improved control and instrument switch with a simple yet positive actuating means which is easy to operate and by which a quick make and break of the contacts is assured independently of the control of the operator. These and other objects of my invention will appear in more detail hereinafter.

In accordance with my invention, I provide an electric switch comprising a relatively stationary terminal mounting structure on which is supported, for movement from one end of the structure to a predetermined operating position thereon, a contact mounting structure. On this contact structure, I mount rela.ively stationary spaced contacts for conductive register with the terminals on the terminal structure when the contact structure is in its predetermined position on the terminal structure. On the contact structure are mounted cooperating movable contacts for respective engagement with the stationary contacts and means adapted to be operated to actuate the movable contacts. Also in accordance with my invention, I provide a second contact mounting structure which is supported for movement from the other end of the terminal mounting structure to a predetermined operating position thereon. This second contact structur is supplied with relatively stationary and cooperating movable contacts in a manner similar to the first contact mounting structure. Further in accordance with my invention, the two contact supporting structures are respectively removable from opposite ends of the terminal structure, but these two contact structures are so interlocked that when either is removed the other cannot be removed and neither can be removed until the cooperating contacts on the other or both are in predetermined positions. Still further in accordance with my invention, I provide a sectionalized switch structure which can be assembled from a relatively few component parts to provide an unlimited number of switching stages and a wide range of contact operations for each stage. Again in accordance with my invention, I provide a positive contact operating means wherein the required operating effort is dependent only on the number of contacts which have to be operated at any one time and not on the total number of contacts in the switch, and wherein a, positive quick make and break is assured independently of the operator.

My invention will be better understood from the following description when considered in connection with the accompanying four sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying four sheets of drawings, Fig. 1 is a vertical longitudinal sectional elevation of a multistage, multiposition switch embodying my invention; Fig. 2 is a horizontal longitudinal sectional view on the line 2-2 of Fig. 1; Fig. 3 is a part sectional view similar to Fig. 2,.showing the interlocks and coupling between the two removable contact structures with one of these structures partially withdrawn; Fig. 4 is an elevation on the line id of Fig. 1; Fig. 5 is an exploded perspective of the rear withdrawable contact structure; Fig. 6 is an exploded perspective of the front end of the front Withdrawable contact structure with some parts omitted; Fig. 7 is a diagrammatic View in one plane of the contact mechanism as positioned for withdrawal of the front contact structure; Fig. 8 is a circuit diagram illustrating an application of the embodiment of my invention chosen for illustration thereof; Fig. 9 is a partial perspective of a terminal supporting spacer section or barrier; and Fig. 10 is a perspective of a part of a key interlock mechanism. I

For the purpose of describing my invention, I have shown an embodiment thereof in a multistage multiposition control switch comprising a supporting structure i on which two other structures 2 and 3 are supported for movement toward each other from the opposite ends respectively of the supporting structure to predetermined positions thereon as shown in Figs. 1 and 2. In other words, the structures 2 and 3 are insertable in the structure i from the opposite ends thereof to an operating position from which they can be withdrawn but only under predetermined conditions, as will hereinafter appear. For diversity of application and also economic reasons, the structures I, 2 and S are preferably sectionalized, as shown. Thus, for example, the multistage supporting structure i includes a base or front section Ll, one or more intermediate sections 5, a front spacer section 6, a rear spacer section I and a rear section 8. For purposes of alignment and rigidity, these sections are provided with interlocking bosses 9 and recesses It and the sections are fastened together in a unitary assembly by suitable means, such as bolts ll passing through holes 52 in the sections and threaded into the base section 4, as shown in Fig. 2. Also, as shown in Fig. 2, this supporting structure assembly is mounted on a panel or switchboard structure l3 by suitable fastening means, such as countersunk screws l4. As illustrated, the sections d, 5, ii, i and 8 are of suitable insulating material, preferably molded, in a generally rectangular outline. Also they are provided with generally rectangular central openings for admitting the movable or drawout structures 2 and 3.

For circuit controlling purposes, suitable terminals l5 are mounted in pairs at the top and bottom of and between adjacent sections 45, 5-5, 55 and 'l8 of the stationary supporting structure I in registering recesses I6 of these sections, as shown in Figs. 4 and 6, so as to be rigidly secured in position when the sections are clamped together by the bolts H. Each of the terminals [5 is provided with a clip I! and also with a contact engaging edge is extending into the central openings in the respectively associated sections of the supporting structure 1. The terminals 55 are made of suitable resilient electric current conducting material, examples of which are well known to the art.

The front drawout multistage contact structure 2 comprises a rear contact carrying section I9, one or more intermediate contact carrying sections or barriers 2i} and a front contact carrying section 2!. Also, as shown, the rear drawout contact structure 3 is single stage and comprises only a rear contact mounting section 22 and a front contact mounting section 23. Obviously, for multistage purposes, the rear drawout structure may include intermediate contact mounting sections like the sections 23 of the front drawout structure 2. As illustrated, the sections i9, 29, 2E, 22 and 23 are of suitable insulating material, preferably molded, in a generally rectangular outline shaped to conform with the openings in the

sections

5, 5, l and 8 of the stationary supporting structure l.

For circuit controlling purposes, suitable rela tively stationary contacts 2% are mounted in pairs at the top and bottom of and between adjacent contact carrying sections Lib, 2fl2ii and 211-2! of the front drawout structure 2 and the contact carrying sections 22-23 of the rear drawout structure 3. For this purpose, the con tacts 2 8 may, for example, be mounted on suitable resilient conducting elements 25 which are set in registering recesses 26 in the opposing faces of the adjacent sections in question. For conductive registry with the terminals l5 when the drawout structures 2 and 3 are in the fuily inserted position, each of the contact supporting elements 25 is provided with a suitable contacting portion 27 so shaped as to provide a good fulcruming action on and good conducting engagement with the edges Id of the terminals I5. The corners of the terminal edges l8 are suitably finished as by slightly rounding them, for example, so that during insertion or withdrawal a smooth engaging action is possible. For holding the contacts 24 in contact engaging position and the bearing portion 27 of each supporting element 25 in good conductive relationship with its respectively associated terminal edge, I pro vide suitable means such as a compression spring 28 seated in the registering recesses 26 between a wall of the recessed portion and the tail of the element, as shown more clearly in Fig. 4.

For bridging the upper and lower pairs of contacts 24 I provide

movable contacts

29 and 30, respectively. Longer contact life and less movement of the contact is obtained by making these contacts in the form of star wheels with four arms spaced as shown. For some applications, as will be obvious to those skilled in the art, the

bridging contacts

29 and 35 may have a difierent number of arms, such as two or six for example. The ends of these arms may be tipped with silver, silver plated or otherwise modified to insure good conductivity and satisfactory interrupting performance. Each of the movable contacts 29 and 383 is supported by a shaft 35. These shafts are rotatably mounted in suitably bossed openings 32 in opposing faces of adjacent contact carrying sections, as shown mor clearly in Fig. 1.

For rotating the bridging

contacts

29 and 30, I provide a positive intermittent driving mechanism such that the torque required for operation is dependent on the number of contacts that have to be operated at any one time and not on the total number of contacts in the switch. The

intermittent mechanism chosen to illustrate my invention is of the Geneva type and comprises for each stage two drive gears 33 and 34 which are respectively operativeiy associated with upper and lower contact gears 35 and 35. For simplicity and economy, these contact gears are preferably made of suitable insulating material which, as shown, is shaped to include the shaft portions 3|, an alignment spacing boss portion 3i and a square hub portion 38 for positioning the star Wheel contacts to turn with their respectively associated contact gears. For yieldingly maintaining the star wheel contacts 29 and 3t in position on the square hub portion 33 and against the boss portion 3? of their respective gears, I provide suitable resilient means such as dished spring washers 39.

The drive gears 33 and 34. of the front drawout structure 2 are mounted between opposing faces of adjacent contact carrying sections on a square shaft 40 so as to turn therewith. As shown, this shaft passes through suitably bossed openings 4! in the

contact carrying sections

49 and 20 large enough to permit free rotation of the shaft and through openings 52 in the drive gears 33 and 3d so shaped that these gears can be assembled on the shaft '40 in different angular positions relatively to their tooth profiles. The drive gears 33 and 34 of the rear drawout structure 3 are similarly mounted on a square shaft 43 which passes through suitably bossed openings Ml and 45 in the contact carrying sections 23 and 22, respectively. For greater strength and wear, the opening 45 may be provided with a suitable metallic bushing 66. Bosses 41 on the drive gears 33 and 34 provide clearance space for the star wheel contacts 29 and 3E) and also serve to stiffen th gears and to increase the shaft bearing area. By suitable choice of the number of teeth on the contact gears 35 and 35 and the pitch ratio of the contact and drive gears, the number of circuit controlling operations per stage per shaft revolution can be materially varied within practical limits. As shown, the contact gears have eight teeth and the pitch ratio is 11 In other words, the drive gears 33 and 34 may have a maximum of twelve teeth, thus providing twelve operations of the star wheel contacts 29 and 38 of a stage during one revolution of the shaft Mi. Obviously by increasing the ratio, more operations per revolution can be obtained. Broadly speaking, the drive gears 33 and as will be provided with spaced teeth $8 in such numbers and at such intervals as to actuate the contact gears 35 and 36 and their associated contacts 29 and 3E! at desired intervals. It will be apparent that, since no pressure appears between a contact gear and a drive gear except when operation of the star wheel contact is desired, the effort required to turn the shaft 40 is dependent only on the number of star wheel contacts to be operated at any one time.

For supporting the front end of the shaft 48 and so turning it as to insure at the rotating contacts 29 and 3D and the cooperating stationary contacts 24 a quick make and break action with which the operator cannot interfere, either deliberately or otherwise, I provide an energy storing quick release mechanism, shown more clearly in Figs. 1 and 6. As illustrated, this mechanism comprises an operating handle 49 which, as illustrated, is of the removable type so as to provide interlocking between a plurality of switches whereby only one switch can be operated at a time. .For this purpose, I provide a key Hi3 having, as shown in Fig. 10, a square shaft portion I94 to which the handle 19 can be suitably secured. This key Hi3 has a head portion H35 which fits into a recess let in a base section 53. In order that the key H33 may be inserted or withdrawn only when the switch is in predetermined positions and for changing the combination, I provide in the recessed portion it's of the base section one or more headed pins it? which permit entry and withdrawal of the key only when notches i623 therein register with the heads of the ins 16''. By varying the angular spacing of the pins and the notches, different keying combinations are obtained. The head portion of the key W3 is recessed at I99 to receive an o erating stub shaft 56. This is rigidly secured to an operating element 5| which has a hub portion 52 rotatably positioned in the base section of the drawout structure 2. Bigidly secured to the front end of the shaft ii! is a coupling element 54 which has a cylindrical bearing portion rotatably positioned in a suitably shaped retainer and bearing plate 5%. The front end of the coupling element 5a is notched to provide guides bl, as shown in Fig. 6, between the opposed edges of which a trigger member 235 is slidably mounted. The trigger member 58 is provided with notched flanges 553 conforming to and slidable in the notched guides 5'! of the coupling t-i so as to permit linear movement of the trigger member relatively to the coupling 54 also to insure simultaneous angular movement of both when the trigger member is turned. It will be apparent to those skilled in the art that if the removable handle feature is unnecessary the stub shaft may be continued clear through and beyond the base section sufficiently to receive the handle directly.

For positioning the shaft 4% to secure the desired circuit controlling arrangements, the trigger member 58 carries between its flanges 59 a resilient member 69 which has two teeth 68'. These are arranged to project through an opening 59' in the upper flange 59 so as to engage I notches which are formed by two identically notched positioning plates 82 and 62 assembled with their teeth in reverse order. The front plate 62 and the rear plate 52 respectively have their teeth arranged to hold the shaft to against clockwise and counterclockwise rotations until the handle 89 is turned sufficiently in one or the other of these directions to release the teeth 59 from the notches ti. The positioning plates 52 and 6'2 are mounted between the retainer plate 56 and the base The retainer plate 55, the positioning plates "52 an t2, the base 53 and an escutcheon 63 are secured together by any suitable means such as bolts 64, In the inserted position, the drawout structure 2 is secured to the panel i3 by suitable means such as screws 65.

For maintaining the trigger member 53 with its resilient teeth 6b in one of the notches 6| formed by the positioning plates 62 and 52 and for effecting the turning of the shaft so from one position to another free of the operators control, I provide energy storing means such as a torsional spring '56 which is mounted on the hub portion 6! of the operating element 5!. This spring has two arms 68 which project under lugs 69 on the trigger member 58 and the spring is so stressed as to tend to maintain the trigger member 58 with its resilient teeth 68' in one of the notches iii of the positioning plates 52 and 62'. Before the shaft 48 can be turned, the trigger member 58 must be moved linearly with respect to the guide 57 to withdraw the teeth 69 from their registering notch 6!. For this purpose, the operating element is provided with two camlike portions 70 which are on opposite sides of the lugs 69 from the spring arms 98. Thus when the handle 49 is turned sufliciently in either direction, one of the earn-like pOItiOns ill engages one of the lugs 69 to release the teeth 69' on the trigger member 58 from their registering notch 6|. At the same time, sufficient energy is stored in the spring 86 to turn the shaft 49 quickly in the same direction the handle was turned immediately after the teeth 99' clear their registering notch 6|. When the spring 69 actuates the shaft 49 in the direction the handle 49 Was turned, the spring 66 also ffects linear movement of the trigger member 58 in a direction to move the teeth 60 into the next notch thereby positioning the shaft 48. During this movement, one of the resilient teeth 50 has to flex enough to permit it to ride over the tooth in its respective positioning plate as the trigger moves linearly to force the teeth 99' into the next notch (ii.

For controlling the number of positions to which the shaft d9 may be operated, I provide means for limiting the angular range of movement of the shaft. As shown in Fig. 6, this means comprises a stop arm H on the operator 5|. This arm is arranged to engage stops such as the heads of screws 72 which may be positioned as desired in holes '33 in the positioning plates 62 and 62. As shown, these holes 13 are spaced between the notches Si in a circle whose center is on the axis of rotation of the shaft 49. For visually indicating the position of the shaft 49, I provide, as shown in Fig. 1, suitable means such as an indicator disk it positioned on the key shaft I04 between the hub 75 of the handle 49 and the base section 53 and provided with a pointer portion 7'6 which moves over suitable markings on the escutcheon 63.

In order simultaneously to rotate both the front drawout structure shaft 49 and the rear drawout structure shaft 43 and yet permit the withdrawal and insertion of only one of the drawout structures 2 or 3 at a time and then only when both of the shafts it and E3 are in predetermined circuit controlling positions, I provide suitable shaft coupling and interlocking means which, as shown in Figs. 1, 2, 3 and 5, is positioned in the portion of the operating structure I defined by the spacer sections 6 and i. As shown, this means comprises a rear coupler ll mounted on the shaft 43 so as to rotate therewith and provided with looking lugs 13 which project into recesses 79 in a flanged front coupler 89 mounted on the shaft 9 so as to turn therewith. The lugs 78 and the recesses '59 are so spaced as to permit registry in only one way, thus insuring a coordinated relation between the relative positions of the two shafts 99 and In order snugly to hold the parts which are slidable lengthwise on the shafts 39 and 93, I provide suitable means such as cushioning springs 8i and 82 respectively mounted on the

shafts

49 and 43 and retained thereon by pins 93. These springs are conveniently mounted in a recessed portion 89 in each coupler, as shown more clearly in Fig. 5. For withdrawing the rear drawout structure 3 and also holding it in the inserted position, I provide a locking bar 85 which is rotatably mounted on the outer end of the rear shaft 93 and maintained in place thereon by suitable means shown as a cotter pin 86. As shown, the bar 85 is provided near its endswith reversed hook portions which are arranged to engage the clamping bolts ll under their heads to hold the rear drawout structure in place.

Although the sections of the drawout structures 2 and 3 are of such outline as to fit snugly and yet slidably within the sections of the supporting structure I, I provide further aligning means in order to secure nicety of alignment and also to provide for indexing and interlocking and to prevent error in assembly and in insertion of the drawout structures. As shown, this means comprises a key 81 on an inner wall of each of the supporting

structure sections

4, 5, 6, 1 and 8 and a registering slot 88 in each of the drawout sections l9, 29, 2|, 22 and 23 and also the operating assembly plates 56 and 62 and the base 53. For clearance of the terminal edges IS, the

drawout sections l

9, 29, 2i and 23 are suitably notched as shown at 89.

For interlocking the drawout structures 2 and 3 so that only one can be removed at a time and then only when both are in predetermined circuit controlling positions, I provide on the rear coupler ll a lug 99 and on the front coupler a flange 9! which is notched at 92 to slide over the keys 8?. Further, I provide notches 93 and 99 in the keys 8! on the spacers 6 and i, respectively. Thus, the rear drawout structure 3 cannot be removed while the lug 99 on the rear coupler ll is positioned in the notch 93 of the key 8? on the rear spacer I, as shown in Fig. 3, and the front drawout structure 2 can be removed only when the notch 92 in the flange 9| registers with the key 87 on the front spacer section 6.

In order to prevent rotation of the

shafts

40 and 43 as on or the other of the drawout structures 2 and 3 is withdrawn or inserted, I provide suitable rotation preventing means which, for the sake of simplicity, I have incorporated in the cushioning springs 8| and 82. As shown, this means includes on each of these springs BI and 32 a resilient arm 95 which springs out, when the pressure between the springs is released by withdrawal movement of either drawout structure and while either drawout structure is in the drawout position, to straddle the key or keys 8! in the diiferent sections and thereby to prevent rotation of the

shafts

30 and 43. Thus, as shown in Fig. 3, the front drawout structure has been partially withdrawn, but its operating shaft 40 cannot be turned and the rear drawout structure is in position and blocked against linear move-' ment by the lug 99 and key 81 on the spacer section i and cannot be rotated since the arm 95 of the spring 82 straddles the adjacent portions of the keys 87 on the two spacer sections. Similarly, in order to withdraw the rear drawout structure 3, the shafts 9i] and 43 must be turned until the lug 99 on the rear coupler 7'! does not register with the aligned key 87 in the sections 2?. and 23 of the supporting structure. In so doing, the notch 92 in the flange 9| of the front coupler 80 is turned out of registry with the aligned keys 81 in the

sections

4, 5 and 6 of the supporting structure i. In other words, the front drawout structure 2 can be withdrawn only when each drawout structure is in a predetermined circuit controlling position, and the rear drawout structure 3 can be withdrawn in any position except that corresponding to the drawout position of the front drawout structure 2 and the nextintermediate position. Thus when the front drawout structure 2 is withdrawn, the rear drawout structure 3 cannot be withdrawn or rotated. Also when the rear drawout structure 3 is withdrawn, the front drawout structure 2 cannot be withdrawn, but it can be rotated to any position except the drawout position.

Openings are provided between sections 4-5, 5-5, 56 and 1-8 for test and inspection of the contacts. For some applications, the switch may be constructed without these openings. In order to keep dust, dirt and other foreign articles from entering the switch, particularly between the sections of the supporting structure I, a box-like cover may be used to enclose the part of the switch back of the panel, as will be apparent to those skilled in the art. I have, however, shown an enclosing arrangement embodying two flat relatively thin mem ers such as slides 96 which are insertable in recesses 91 in the supporting structure sections t, 5, t, i and 8. These slides may be of suitable insulating material, as illustrated in the drawings. In addition to closing the open places, these slides also help to maintain the alignment of the supporting structure sections t, 5, 6, l and 8.

While switches embodying my invention can be assembled in almost innumerable ways to provide different circuit combinations and switching sequences, I have shown, for the purpose of illustrating my invention, a relatively simple switching arrangement for transferring a voltmeter 98 and an ammeter as from one alterhating current source A to another alternating current source 13, as diagrammatically indicated in Fig. 8. The sources A and B are respectively provided with current transformers i551 and HM. For this switching arrangement, the illustrated embodiment of my invention is shown as a sixposition switch having six main switching stages in the front drawout structure 2 and one by-pass switching stage in the rear drawout structure 3 used in the illustrated example to keep the current transformers its and Hit from becoming open circuited. The positions are in sequence the voltmeter and the ammeter connected to source A; intermediate positions I1 and Is; the

voltmeter and the ammeter connected to source B; intermediate position 13 and position D, the drawout position for the structure 2. The structure 3 may be withdrawn in any position except positions 13 and D. In Fig. 7, these are respectively indicated as they would be on the escutcheon 63 by the letters A, I1, I2, 13, I3 and D, over which operates the pointer it on the stub shaft. In Fi l, the shafts Ail, a3, and 56 and the key shaft H34- are indicated by a dash-dot line. Also, for the sake of simplicity in illustration, I have shown the two drive gears 33 and 134 of each stage as a single gear 3B-3 l carrying the teeth of both drive gears of the stage. The movable contacts 29 and 3d are designated respectively by stages from the panel end of the switch as 29!, 292, 7:93, 296, 285, and 2%, and 3st, 382, 55b3, 3M, 3135, and 3%. These same numbers are used to indicate the contacts in Fig. 8.

As shown in Fig. 7, all of the contacts in the five main stages are open, but the contacts 256 and 396 in the single by-pass switching stage in the rear drawout structure 3 are closed. This is the drawout position for the front drawout structure 2 and the position illustrated in Figs. 1, 2 and 3. In this position, as will be apparent from Fig. 8, each of the current transformers its and I!!! is short circuited, and neither the voltmeter nor the ammeter is connected to either of the sources A and B. In this drawout position, the

rear drawout structure 3 cannot be withdrawn since the lug 99 on the rear coupler fl is in the notch 93 of the key Bl and abuts the key 81 on the rear spacer section l. If the front drawout structure 2 is withdrawn, the by-pass stage cannot be operated to open the current transformer circuit since the notch in the spring arm 95 of the spring 82 straddles the adjacent portions of the aligned keys 8'1 on the two spacer sections 6 and 1.

Assuming the two drawout structures 2 and 3 positioned as shown in Figs. 1, 2 and 3 and that it is desired to connect the voltmeter 98 and the ammeter 99 to the source B, the operating handle 39 is turned counterclockwise from the position D to the position I3. By this operation, the contacts 293, 2514 and are turned to the closed position and the contacts 2% and 3% remain closed. The operating handle is then turned counterclockwise from the position Is to the position 13. By this operation, the contacts Edi and 2&2 are turned to the closed position, the contacts 2&3, 23 i and 3% remain closed and the contacts 2% and 385 are turned to the open position. The structure 3 may be withdrawn in the B position because the lug 510 has been turned clear of the key 8'5. If it is desired to connect the voltmeter and the ammeter to the source A, the operating handle id is turned counterclockwise to the intermediate position I2. By this operation the contacts 2.)! and 292 are turned to the open position, the contacts 2%, 294 and 8% remain in the closed position and the contact 295 is moved to the closed position. The operating handle 39 is then turned counterclockwise to the position I1. By this operation, the contacts 2&3 and 2% are turned to the open position, the

contacts 363 and set are turned to the closed position, and the contacts 2% and remain closed. Finally, the operating handle is turned counterclockwise to the position A. By this operation, the contacts 3i. and 362 are turned to the closed position, the contacts 33 i and 295 remain closed and contact 335 is turned to the open position. This connects both the voltmeter and the ammeter to the source A. From the foregoing, it will be observed that at no time has either current transformer been open circuited. Structure 2 can be withdrawn only in the D position, and structure 3 can be withdrawn in any position except the position I3 and the position D.

In cases where a finer angula adjustment in contact operation is desired than that afforded by the hexagonally notched opening or bore 32 in the main drive gears 33 and 3 2-, these gears may be provided with a micrometer bushing variation arrangement similar to that disclosed, for example, in United States Letters Patent 1,797,960, dated March 24, 1931.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my inven-- tion.

What I claim as new and desire to secure Letters Patent of the United States is:

1. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a second structure supported by said supporting structure and movable relatively thereto, relatively stationary spaced contacts mounted on said second structure for conductive register with said terminals when said second structure is in a predetermined position relatively to said supporting structure, cooperating movable contacts mounted on said second structure for respective engagement with said stationary contacts, and means for actuating said movable contacts.

2. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a second structure supported by said supporting structure and movable relatively thereto, relatively stationary spaced contacts mounted on said second structure for conductive register with said terminals when said second structure is in a predetermined position relatively to said supporting structure, cooperating movable contacts mounted on said second structure for respective engagement with said stationary contacts, means for actuating said movable contacts, and means for preventing movement of said second structure relatively to said supporting structure except when at least one of said movable contacts is in a predetermined circuit controlling position.

3. An electric switch comprising a first structure having a longitudinal chamber, terminals mounted on said first structure, a second structure insertable in and withdrawable from said chamber, relatively stationary contacts mounted on said second structure and respectively conductively engageable with said terminals when the second structure is fully inserted in said chamber, cooperating movable contacts mounted on said second structure for respective engagement with said stationary contacts, and means for actuating said movable contacts in a predetermined se quence.

4. An electric switch comprising a first structure having a longitudinal chamber, terminals mounted on said first structure, a second structure insertable in and withdrawable from said chamber, relatively stationary contacts mounted on said second structure and respectively con ductively engageable with said terminals when the second structure i fully inserted in said chamber, cooperating movable contacts mounted on said second structure for respective engagement with said stationary contacts, means for actuating said movable contacts in a predetermined sequence, and means for preventing the actuation'of said contacts during insertion and withdrawal of said second structure.

5. A multistage multiposition electric switch comprising a first sectional structure having a I longitudinal central chamber, a plurality of spaced pairs of oppositely disposed terminals mounted on said first structure, a second sectional structure insertable in and withdrawable from said chamber as a unit, a plurality of spaced pairs of oppositely disposed relatively stationary contacts mounted on said second structure and respectively conductively engageable with predetermined pairs of oppositely disposed terminals when the second structure is fully inserted in said chamber, a plurality of movable contacts mounted on said second structure for respectively connecting said pairs of stationary contacts, and means for actuating said movable contacts in a predetermined sequence.

6. An electric switch comprising a supporting structure, a plurality of paced terminals mounted on said supporting structure, a structure movable on said supporting structure to a predetermined position thereon from one end thereof, another structure movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductive register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with the stationary contacts thereon, and means for actuating the movable contacts on said movable structures when both are in their respective predetermined positions on the operating structure.

7. An electric switch comprising a first structure having a longitudinal chamber, terminals mounted on said first structure, a second structure insertable in and withdrawable from said chamber at one end thereof, a third structure insertable in and withdrawable from said chamber at the other end thereof, relatively stationary contacts mounted on said second and third structures and respectively conductively engageable with said terminals when the second and third structures are fully inserted in said chamber, movable contacts mounted on said second and third structures for respective engagement with the stationary contacts thereon, and means adapted to be operated to actuate the movable contacts on said second and third structures.

8. An electric switch comprising a first structure having a longitudinal chamber, terminals mounted on said first structure, a second structure insertable in and withdrawable from said chamber at one end thereof, a third structure insertable in and withdrawable from said chamber at the other end thereof, relatively stationary contacts mounted on said second and third structures and respectively conductively engageable,

with said terminals when the second and third structures are fully inserted in said chamber, movable contacts mounted on said second and third structures for respective engagement with the stationary contacts thereon, means adapted to be operated to actuate the movable contacts on said second and third structures, and means for preventing the withdrawal of one of said second and third structures after withdrawal of the other is started.

9. An electric switch comprising a first structure having a longitudinal chamber, terminals mounted on said first structure, a second structure insertable in and withdrawable from said chamber at one end thereof, a third structure insertable in and withdrawable from said chamber at the other end thereof, relatively stationary contacts mounted on said second and third structures and respectively conductively engageable with said terminals when the second and third structures are fully inserted in said chamber, movable contacts mounted on said second and third structures for respective engagement with the stationary contacts thereon, means adapted to be operated to actuate the movable contacts on said second structure, means adapted to be operated to actuate the contacts on said third structure, and means interconnecting said actuating means for simultaneous operation.

10. An electric switch comprising a first structure having a longitudinal chamber, terminals mounted on said first structure, a second structure insertable in and withdrawable from said chamber at one end thereof, a third structure insertable in and withdrawable from said chamber at the other end thereof, relatively stationary contacts mounted on said second and third struc tures and respectively conductively engageable with said terminals when the second and third structures are fully inserted in said chamber, movable Contacts mounted on said second and third structures for respective engagement with the stationary contacts thereon, means adapted to be operated to actuate the movable contacts on said second and third structures, and means for preventing the withdrawal of one of said second and third structures unless a movable contact of the other of said second and third structures is in a predetermined position.

11. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a structure movabl on said supporting structure to a predetermined position thereon from one end thereof, another structure movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductive register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with the stationary contacts thereon, an actuator for the movable contacts of each of said movable structures, and means interconnecting said actuators for common operation only when each of said movable structures is in its respective predetermined position.

12. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a structure movable on said supporting structure to a predetermined position thereon from one end thereof, another structur movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductive register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with th stationary contacts thereon, means for actuating the movable contacts on said movable structures, and means operative upon movement of one of said movable structures from its respective predetermined position on said supporting struture whil the other of said movable structures is in its predetermined position for preventing movement of said other movable structure and actuation of the movable contacts thereon.

13. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a structure movable on said supporting structure to a predetermined position thereon from one end thereof, another structure movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductiv register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with the stationary contacts thereon, means for actuating the movable contacts on said movable structures, and interlocking means on said structures for preventing movement of either of said movable structures from its predetermined position except when the movable contacts on the structure are in predetermined circuit controlling positions-and all of the contacts on the other 14 structure are in predetermined circuit controlling positions.

14. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a structure movable on said support ing structure to a predetermined position thereon from one end thereof, another structure movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductive register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with the stationary contacts thereon, means for actuating the movable contacts on said movable structures, and interlocking means on s id structures for preventing movement of either of said movable structures from its predetermined position except when the movable contacts on the structure are in predetermined circuit controlling positions and all or the contacts on the other structure are in predetermined circuit controlling positions and for preventing linear movement of the remaining structure while the one structure is out of its predetermined posi tion. I

15. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a structure movable on said supporting structure to a predetermined position thereon from one end thereof, another structure movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductive register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with the stationary contacts thereon, means for actuating the movable contacts on said movable structures, and interlocking means on said structures for preventing movement of one of said movable structures from its predetermined position except when all the movable contacts on the structure are in the open circuit position and all the movable contacts on the other structure are in the closed circuit position and for preventing movement of the remaining structure and the movable contacts thereon while the one structure is out of its predetermined position.

16. An electric switch comprising a relatively stationary supporting structure, a plurality of spaced terminals mounted on said supporting structure, a structure movable on said supporting structure to a predetermined position thereon from one end thereof, another structure movable on said supporting structure to a predetermined position thereon from the other end thereof, relatively stationary spaced contacts mounted on said two movable structures for conductive register with said terminals when the two movable structures are in their respective predetermined positions, cooperating movable contacts mounted on said two movable structures for respective engagement with the stationary contacts thereon, in eans for actuating the movable contacts on said movable structures, interlocking means on said structures for preventing movement of either of said movable structures from its predetermined position except when the movable contacts on the structure are in predetermined circuit controlling positions and all of the contacts on the other structure are in predetermined circuit controlling positions and for preventing linear movement of the remaining structure while the one structure is out of its predetermined position, and means for preventing a change in the circuit controlling positions of the contacts on either of said movable structures while it is being moved to and from its predetermined position on the supporting structure.

17. A multistage multiposition electric switch comprising two electrically and mechanically independent movable contacts in at least one stage, an intermittent driving mechanism for actuating said contacts, and a quick make and break centering mechanism for positioning said contacts independently of the force applied to actuate said driving mechanism.

18. A multistage multiposition electric switch comprising relatively movable cooperating contacts in each stage, a driving mechanism for actuating said contacts comprising two rotatable members, a quick make and break centering mechanism between said rotatable members, a base in which one end of one of said rotatable members is supported, a removable operating member adapted for engagement with said one of the rotatable members, and means on said base cooperating with said operating member to tire vent the removal or application thereof except when said one of the rotatable members is in a predetermined position.

19. A multistage multiposition electric switch comprising two electrically and mechanically independent movable contacts in each stage, an intermittent driving mechanism for actuating said contacts, and a centering mechanism for positioning said contacts independently of the force applied to actuate said driving mechanism.

20. In an electric switch, a supporting structure, two rotatable contact carrying members mounted on said structure and normally interconnected for simultaneous rotation, means permitting rectilinear movement of one of said members when the members are in a predetermined position to effect the separation of said members and the removal of said one of said members from said structure, and means for preventing rotation of the other of said members from said predetermined position when the members are separated.

21. In an electric switch, a supporting structure, two rotatable contact carrying members mounted on said structure and normally interconnected for simultaneous rotation, means for permitting rectilinear movement of one of said members when the members are in a predetermined position to efiect separation of the members, and means efiective on a predetermined separation of the members to prevent both rotary and rectilinear movements of the other member.

22. In an electric switch, a supporting structure, two rotatable contact carrying members mounted on said structure and normally interconnected for simultaneous rotation, means for permitting rectilinear movement of one of said members when the members are in a predetermined position to effect separation of the members, and means for permitting rectilinear movement of the other of said members when the members are in a difierent predetermined position to efiect separation of the members.

23. In an electric switch, a supporting structure, two rotatable contact carrying members mounted on said structure and normally interconnected for simultaneous rotation, means for permitting rectilinear movement of one of said members when the members are in a predetermined position to effect separation of the members, means for permitting rectilinear movement of the other of said members when the members are in a different predetermined position to effect separation of the members, and means effective on a predetermined rectilinear separating movement of one of said members to prevent both rotary and rectilinear movements of the other member.

ORLONDO A. HUNTSMAN.