US2096033A - Electric switch - Google Patents

Description

Oct. 19, 1937. F. FARRELL ELECTRIC SWITCH Filed Oct. 15, 1935 4 Sheets-Sheet l Imfen qr Fwd ZZIrrel/ a 2% .71. jam

Oct. 19, 1937.

Filed 'Oct. 15, 1935 4 Sheets-Sheet 2 7 r 0 0/ 6 M a w W m w w m m% 5 7 T m? 9 W v. 2 w mm F. FARRELL ELECTRIC SWITCH Oct. 19, 1937.

4 Sheets-Sheet 5 Filed Oct. 15, 1935 77 2a Eire/j i 'rngy Oct. 19, 1937. HR E 2,096,033

ELECTRIC SWITCH Filed 001:. 1935 4 Sheets-sheaf 4 I Ira/21x13? 7 /190 ZZZI'IPZ/ Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE Electrical Engineers E corporation of Illinois quipment Company, a

Application October 15, 1935, Serial No. 45,113

6 Claims.

The present invention relates to electric switches and has for its general object the production of an electric switch which shall be efficient and satisfactory in operation while being simple in construction, economical to manufacture, and of such design as to occupy a minimum of space relative to its electrical capacity.

More specifically, one object of the invention is to provide a switch wherein spring means are employed to apply heavy pressure to the switch contacts when contacting, and simultaneously therewith to hold the actuating mechanism in holding position.

Another object is to so construct and arrange the switch contacts that they will, when engaged, provide a novel application of balanced forces to thereby give the high contact pressure desired.

Another object is to construct the spring means by which the different toggle and contacting functions are performed, in a novel way such as to provide indications of the pressures upon the contacts, which are being exerted at any given time.

Another object is to utilize the spring means as couplings between the fixed and movable parts in such a way as to provide a floating construction for the movable parts and then to employ self-centering contacts, the two cooperating in the centering of the parts when the switch is moved into closed contact engaging position.

Another object is to so construct the main contacts of the switch that they will be related to each other somewhat after the manner of a ball and socket, whenever in engagement. By so doing there will be efiicient engagement whenever the switch is closed even though the contacts may not be in true axial alinement. Akin to this plug and socket, or ball and socket, feature, is that of providing substantially a line contact, 50- called, between the engaging contact surfaces of these ball and socket members in all the different positions they may occupy when in circuit closing position.

Still another object is to combine these various features in a structure wherein telescoping insulating tubes inclose the different switch contacts.

In this connection it may be pointed out, however, that the various features of the invention may be combined in various ways and still come within the scope of the invention. Thus, for example, the earlier objects may be attained without employing the particular insulation provided by telescoping insulating tubes.

Besides the various objects recited, other objects will appear as the invention is more fully set forth. To this end reference should be had to the following detailed description taken in connection with the accompanying drawings, while the scope of the invention will be more particularly set forth in the appended claims.

Before considering the drawings, it may be pointed out that by telescoping the switch contacts and by providing a plurality of line contacts for each pair of mating contacts, considerable saving of space for the switch structure may be obtained. Thus if a total length of line contact is required in any specific case to handle the energy of the circuit, then this length may be divided up among two or more sets of cooper ating contact surfaces and these sets may be arranged laterally of the aXis of the telescoping contacts with a great saving in space in the length of the contacts. A specific example is a sort of ball and socket structure wherein a pluglikering enters between two rows of spring fingers. The total length of required contact is here divided into two lengths, one provided by the outer surface of the ring engaging the outer spring fingers and the other by the inner surface of the ring engaging the inner spring fingers. This is one specific form of contacts herein disclosed. Obviously, the total length might be divided into more than two parts. The disclosed embodiment, however, illustrates the idea, which constitutes an important feature of the present invention.

It should also be noted that the contact arrangement mentioned provides a self-centering action and that by giving the meeting contact surfaces 2. suitable curvature, there may be considerable shifting of the contacts relative to their longitudinal alinement without decreasing the efficiency of the contact engagement as a conductor of electricity. The action of the engaging contacts is to a limited extent like that of a universal joint. The movements take place without the loss of efficiency in electrical conductivity through the joint.

Referring now to the drawings, Fig. l a front elevation of a three-phase switch constructed and arranged in accordance with the present invention, certain portions being cut away to show details of construction; Fig. 2 is an end elevation of the same, the view being taken from the right in Fig. 1 and showing the contacts in closed position; Fig. 3 is a similar view, with certain parts removed and other parts in section, illustrating the contacts in open position; Fig. 4 is a sectional plan view of a portion of the structure, the plane of section being indicated by the line 4.-4 of Fig. 2; Figs. 5 and 6 are detail views illustrating a stop employed in conjunction with the toggle mechanism; Fig. 7 is a vertical section through the switch parts of one phase, the plane of section being indicated by the lines 'i l of Fig. 1; Fig. 8 is a section of a portion of the toggle system, the section being taken along the arcuate section indicating line 8-8 of Fig. 2; Fig. 9 is a. vertical section illustrating one of the spring couplings by which the bridging contact lar sectional view illustrating a modified spring coupling; Fig. 13 is a similar view illustrating a further modified spring coupling; and. Fig. 14 is a similar View illustrating a third modified coupling.

Throughout these views like characters refer to like parts.

'As previously indicated, in the present'case a three-phase switch is shown. In brief, the same comprises a. main frame A, a shiftable frame B, and three contact carrying frames C, one for each phase, said frames C being connected to the frame B by three sets of spring couplings D. The result is that each frame C is yi-eldingly mounted upon the shiftable frame B. For each phase there is an upper insulator E, a lower insulator F, and any intermediate insulator G, telescopically arranged. The insulators E and F are both mounted on the frame A while the center insulated member G is mounted on the appropriate frame C. Associated with each set of insulators E, F, G, are corresponding contacts, H, J and K. A toggle system L serves to raise and lower the frame B together with all the parts carried by it. In open circuit position the contacts H and K are separated, while in closed circuit position they are in firm contact with each other, as clearly shown in Fig. '7.

The main frame A may be variously constructed but in the present case includes two flanged end frames 2i! united by upper angle bars 2| and lower angle bars 22. These bars are secured to the end frames in any suitable way as by means of bolts and nuts 23, 24, the former serving to connect the upper bars 2| and the latter the lower bars 22.

The end frames 23 are provided in their flanges with openings 25 through which securing bolts or the like may be passed into a suitable panel or other support, as will be obvious.

The frame B which is the shiftable frame of the structure, comprises angle bars 26 which extend along the front and rear of the structure in a manner similar to the bars 2|, 22 of the frame A and are connected at their ends to end frames 2'i. The latter are provided with horizontal flanges 28 which overlie the horizontal flanges of the angle bars 26 and are secured thereto by bolts 29 or the like. The latter are provided with nuts as usual and the parts of the frame are thus firmly secured together. In its up and down travel the frame B is guided by guide rods 32 which are firmly secured to the frame A. Connection is made by passing the rods through openings in the horizontal flanges near the tops and bottoms of the end members 20 and securing the same in place by suitable nuts 33 threaded on to the ends of the rods and screwed home against the flanges. The end members 21 of the shiftable frame B have guiding sleeves 4| through which the rods 32 extend. These sleeves are of considerable length and have a sliding fit on the rods. Hence a guided up and down movement is provided for the frame B in its operative travels.

The frames A and B are common to the three sets of insulators and their associated contacts.

When it comes to the frames C, we have one frame for each set of insulators and contacts. Each frame C thus constitutes a mounting for the intermediate insulator G and its associated bridging contact K, or modification of that contact. Each frame C takes the form of a web having an upstanding flange 3|. The latter has an outline conforming to the periphery of the insulator G which, in the present case, is circular. The horizontal web portion 3% is apertured near its four corners for the passage of the bolts of the coupling devices D. The latter provide the yielding connections between the shiftable frame B and the mounting plates or members C of the different phases. Viewedin another way, each flange 3! is a supporting frame which embraces the insulator G and the portions of the web 30 which extend outward from the frame 3| and contain the apertures for the retaining bolts of the coupling devices D, are lateral projections.

Turning now to a consideration of these coupling devices, We find the same may take quite different forms. The preferred form is that illustrated in the earlier figures of the drawings, and more in detail in Figs. 9, l0 and 11. In each of these couplings there is a central bolt 34 which is threaded into an opening in the horizontal web of the angle bar 25 of the shiftable frame B. Upon this same bolt 34 is a flanged sleeved member 35 which has the interior of its sleeve 36 threaded for engagement with the threads of the bolt 34 and at its lower end is provided with the horizontal flange 3?. By rotating the member 35, the same may be adjusted lengthwise of the bolt 3 The flange 3? forms a seat for the lower end of a coiled compression spring 38. The upper end of the spring bears against a flanged member 39 which has the outer surface of its sleeve til threaded through an opening in the web 38 of the associated contact-carrying member C. The flanged member 39 moves freely up and down over the member 35 and obviously carries with it the engaged portion of the Web 36. The member 39 is given an upward limiting position by means of a nut 52 which is likewise threaded upon the upper end of the bolt 3%. By adjusting the nut upon the bolt 3d, the position of the member as may be adjusted to give more or less compression to the spring 38. As clearly shown, the interior of the nut 42 is cut back on its under side, as indicated at 53, to enable the skirt of the nut to pass down over the exterior of the sleeve 36 of the member 85.

In Fig. 9 the parts are shown in the position they would occupy when first assembled and before any compression is given to the spring 38. It will be noted that the upper end of the bolt 34 is also provided with an extension 4 3 which passes out through an opening in the head of the nut 42. As clearly shown, this extension is provided with scale markings 45. are in the position illustrated in Fig. 9, the top of the projection 4% is flush with the top of the nut H2 and the markings 45 are intheir zero position.

Whenever the nut 42 is screwed down upon the bolt as so as to force the flanged member 39 downward to place the spring 38 under compression, then the parts assume some such position as illustrated in Fig. 10. It will be noted that in such case the projection id extends beyond the nut 42 and by reading that marking 35 which When the parts Lil Cal

her 39,

2,096,033 comes nearest to the top of the nut it will be pos sible to know from inspection the amount of compression which is given to the spring. Thus, indicating means are provided for knowing at once the set compression.

When the switch mechanism is assembled, the four springs 38 associated with each contact carrying member C are given preferably the same degree of compression. It will be seen that if each spring be given a compression of, say, 75 pounds, then the total of the four springs would be 300 pounds for the particular member C and its associated contact.

It will be apparent from what has been said that if the member B be forced upward by the toggle mechanism L, which constitutes the operating mechanism of the switch, then the different members C would be carried upward as a unit until some resistance was encountered to cause the springs to be compressed still further. As we shall see later, this occurs when the reciprocating bridging contacts carried by the frames C meet and effectively engage the upper terminal contacts of the switch.

When the switch parts are brought into final position, then the springs 38 are compressed beyond the amount at which they have been initially set and they assume some such position as illustrated in Fig. 11. There the parts are shown in a position corresponding to the fully 'closed position of the switch. In changing from the position of Fig. to the position of Fig. 11, the projection 44 will not be changed but it will be noted that the nut 42 will pass upward out of engagement with the member 39. The extent of this movement will show upon each coupling device that there is a pressure applied to the contacts in excess of that given the springs as an initial set. For the purpose of measuring the extent of this additional pressure, the exterior of the sleeve 36 is preferably provided with scale markings 46. By reading down upon these markings, a measured value for the extent of pressure applied by each coupling device D may be observed. If desired, these markings 46, and also the markings 45, may be carefully graduated to indicate the pressure in pounds or other convenient unit. Thus, indicating means for knowing the extent of contact pressure in addition to the set compression is provided.

Under the assumption, namely 75 pounds per spring, it will be apparent that as soon as any of the markings 46 appear by reason of the separation of the nut 42 from the sleeve 40 of the memthen more than 300 pounds pressure is being applied between the central contact and the upper contact, such being in the case of Fig. 7, the contacts K and H.

While on the subject of these spring coupling devices, it might be well to point out that the structure of the preferred spring means D may be modified and the modifications may be extended to include a very simple form.

Thus, in the case of the coupling D, shown in Fig. 12, the structure is the same as shown in Figs. 9, 10 and 11 except that the flanged member 39 is omitted and the upper end of the spring 38 acts directly against the under side of the web of the member C. Obviously, where the member 39 is employed, it is possible to adjust the position of the member C with respect to the flange of the member 39, and thus relatively position the frames B and C, without in any way changing the initial 'set given to the spring 38. Of course where the member 39 is omitted-this ad- However, in many not be desired. In

justment is not possible. cases this adjustment may the case of the coupling D, there are the same scale markings 45.and 46 and they serve in the same way exceptthat the reading of the markings 46 indicates the separation between the nut 42 and the web 30, instead of between the nut and the sleeve 40 of the member 39, as in the preferred form. The actions of the parts when pressure in excess of the set amount is applied are just the same .as before.

In the case of the modified coupling D we have advanced one more step toward simplification, with a resultant omission of function. In this case, the nut 42 is replaced by the nut 48, and the bolt 34 gives place to a similar bolt 49, which is threaded, as before, into the flange 26 of the ad- J'acent member 26 of the frame B, and which, as before, carries the flanged sleeve member 35. In

this case, the spring 38 is compressed between the flange 37 of the member the web 3|] of the frame C. By reason of substituting the bolt 49 for the bolt 34, there are nomarkings 45 to indicate the extent of initial set given to the spring 38. markings 46 which will indicate the extent of separation between the lower surface of the nut 48 and the upper surface of the web 30. The extent of separation as indicated by this reading, will show the amount of compression in to the set amount, that is being applied through that particular coupling to the associated contacts.

Going still further in the direction of simplifi- 35 and the under side of cation, we have the coupling structure D wherein the central bolt 50 has a head 51 at its lower end which bears against the under face of the flange 26 of the member B. A nut 52 is threaded on the upper end of the bolt 59 and is pressed home against a sleeve 53 which presses at its lower end against the upper face of the flange 26 and its upper end against the under face of the nut 52. When the nut is screwed down tight upon thebolt, then the parts 26, 56, 52 and 53 move together as a unit, and so long as the resistance to the movement of the frame does not exceed the amount of the set compression in the spring 38, said member will also move with the other parts. But, as soon as the resistance to the applied pressure is greater than said amount, the spring will begin to compress and the frame members B and C will be brought nearer together. In this case, scale markings 46 on the sleeve 53 may serve to indicate the amount of extra compression being applied through the associated spring.

Such markings will measure the extent of separation between the under face of the nut 52 and the upper face of the web 30 of the frame C.

These various forms of couplings maintain a loose connection between the frame B on the one hand and the several insulator and contact bearing frames C on the other hand. As a result, the mountings for the bridging contacts have a floating movement upon, or relative to, the frame B and in consequence thereof the contacts readily adjust themselves to each other forgood engagement.

It will also be noted that when. the operating frames C are moved into the closed position, and when the pressure in the springs exceeds the set amount, say '75 pounds per spring (300 pounds per phase), then the springs shift further, as before pointed out, and there is still reserve energy stored in the springs and available to compensate for any yielding which may occur by reason of the There are, however, 7

addition 7 parts remaining under pressure over along period of time or by reason of wear of the parts.

As previously indicated, there are three tubular telescoping insulators. The uppermost of these is the insulator E. It is the one of largest diameter and includes a skirt 56 and an apertured end iii. The outer surface of the insulator is corrugated to increase the exterior creeping surface. Near its lower end it is connected to a mounting member 54 having a vertical annular flange 55 and a web 58, said member being similar in shape and outline to the intermediate mounting member C, previously described. The four corners of the web 58 are apertured, as shown more particularly in Fig. 4, and suitable bolts 59 pass through these apertures and mating apertures in the horizontal flanges of the main frame members 21 and are provided with appropriate nuts. By screwing the latter home, themounting 5d of each insulator E may be firmly and fixedly secured. Suitable cement 65 positioned between the insulator and the flange 55 holds the insulator in place upon the main frame A.

The insulators F at the lower portion of the switch are similar to the insulators E but of considerably smaller diameter. Each such insulator comprises a skirt 6i and an apertured head Eil The outer surface of this insulator is also corrugated near its lower end so as to increase the creepage surface. Connection is made between each of these insulators and the lower members of the frame A through a member 62 similar in shape to the member 5%. The web portion of the member 62 is connected to flanges of the frame members 22 by suitable bolts 63 having appropriate nuts. In this instance cement 64 binds the insulator to the annular flange of the member 62 and the insulator is thus held firmly in place by attachment to the lower portion of the main frame A.

The intermediate insulators G are similarly secured by cement 65 to the vertical flanges 3i forming part of the intermediate frames C. The insulators G thus move with the frames C. As clearly shown, each of these insulators is of intermediate diameter and passes inwardly of the associated insulator E and outwardly of the associated insulator F. Each insulator G is also provided with an inwardly projecting flange 65 which serves as part of the connection with its contact K as hereinafter more fully pointed out.

When it comes to the contacts which are carried within these different insulators, different contact arrangement may be employed. In the preferred form of the invention, each of the terminal contacts I-I comprises a block 68 of copper or other good electric conducting material, which has a threaded shank 69 on the one side and a series of inner spring fingers l0 and outer spring fingers ii on the other side. The shank extends upward through the aperture in the head 51 of the insulator E and is firmly secured to the insulator by a nut '52, suitable washers l3, 14 being employed to perfect the connection. An additional nut 75 is threaded on the shank 69 and serves as a binder for the electric conductor that is connected to the shank. The fingers l0 and H are preferably provided by cutting away the block 68 so as to provide a central space 16 and an annular space ll and then splitting the resulting projections by 1ongitudinal cuts so as to give the several fingers, viz., the fingers ill on the inside and the fingers ll on the outside. These are also preferably curved so as to provide a bell-mouthed approach, as clearly illustrated in Fig. 7. A coiled outer spring 18 extends around the outer fingers H and tends to force them inward. A somewhat differently coiled spring 19 extends spirally around within the space '16 and engages the inner surfaces of the inner fingers 10 and by its action tends to force these fingers'outward. The spring pressed fingers l0 and H, however, are sufiiciently stiff, while yet laterally yielding, to provide the requisite space Tl for the entrance of the cooperating ring contact 95. Thus, a contact having a solid base portion and twoconcentric rows of contact fingers is provided. The spring fingers l0 and II cooperate with the space Tl between their respective rows to provide a socket for reception of the plug-like portion upon the associated bridging contact, presently to be described.

In the embodiment under consideration, each of the lower terminal contacts J is in the form of a rod 82 threaded at its lower portion and provided with retaining nuts 83, 8d, the former acting on the inside of the head St of the insulator F and the latter operating on the outside. Suitable washers 85, 86 are positioned between the nut 83 and the head 6 l on the one hand and the nut 85 and the head iii on the other hand. The extra nut 87 serves to bind the conductor, in whatever form it may be, to the terminal contact J. The latter is preferably composed of copper or other good conducting material.

Each of the intermediate contacts K is composed in this embodiment of a tube 88 which is reduced in diameter at an intermediate point and split so as to provide a series of spring fingers 89. The reduced diameter enables the spring fingers 89 to fit upon and make good contact with the lower terminal J. A series of coiled springs 96 surround the spring fingers 89 and press them inward against the surface of the rod 32 of the contact J. With this construction the tube 88 may be moved up and down upon the rod 82 and in all positions there will be good electrical engagement between the contacts.

The upper portion of the tube 89 is exteriorly threaded so as to be screwed into a contact head 91. The latter is provided with a lateral flange 92 and an auxiliary clamping ring 93. Between the flange 92 and the ring 83 is positioned the insulator flange 65. The ring 93 has threaded engagement with the outer portion of the head 9i and by screwing the ring 93 home against the flange 65, the head 91 and the tube 88, which is connected with it, are firmly secured to the intermediate insulator G. If desired, intervening washers 9d may be employed upon the upper and lower faces of the flange 85 in order to improve the mechanical connection. The upper part of the head 9! is shaped so as to provide a contact ring 95 which is solid and in cross-section has tapered surfaces similar to the surfaces of a gear tooth. This ring is adapted to pass into the annular space Tl between the spring contact fingers l9 and "H of the upper contact H. The ring 95 thus acts as a plug and the space H and the associated fingers i6 and H cooperate to provide a socket for receiving theplug-like portion 95.

The inclined bell-shaped walls of the socketlike space ll cooperate with the inclined walls of the plug-like ring contact 95 to provide a selfcentering action of the contacts. This action is permissible because of the loose mounting of the associated frame C upon the frame B'through the spring coupling means D, as before pointed out.

Besides obtaining the self-centering action, the engaging surfaces of the ring 95 and fingers l0 and H are such that a line contact is provided gr H on each side of the'ring when the switchis in closed position. Not only is this true, but it is. also true that such a line contact willexist even though the bridging contact be out ofexact axial alinement with the upper contact. In this way a certain floating of the bridging contact is possible without destroying the line engagement of the contact surfaces. One pair of lines, an. inner and an outer, will exist for each position of the parts, ranging from the central position where the axis of the intermediate contact isin exact alinementwith the axis of the upper contact, on through intermediate positions in all possible vertical planes, to the extreme positions in said planes wherein the axes of the two contacts intersect at the maximum possible angle.

Again, in these several positions of the contacts, the pressure exerted upon the ring contact 95 by the associated contact fingers l and II will be approximately equal and relatively high, the total pressure being divided among the several fingers. The pressures provided by the resiliency of the fingers i0 and II reinforced by the action of the springs 1'8 and 79 cooperate with the action of the springs 38 of the couplings D to maintain the contacts in proper position and thus insure the high pressure between the conducting parts while the switch is in closed position. In practice the contacts may be so firmly pressed together that the conductor formed thereby is in electrical effect practically a continuous solid conductor. Pressures upon the contact parts in excess of that required to produce this result need not be applied. By maintaining these high pressures for all line 1 contacts between the two conducting contacts,

there is no weakening of the conducting capacity even though exact alinement be not maintained. In this wayan eflicient and long lived switch is provided. The material of the tubular conducting member K is also copper or other good conducting metal.

In considering this matter tween switch parts, we find the central pluglike contact 95 and the associated spring finger contacts I53 and H good exampes. Thus, the outer surface of the ring 55 contacts with the inner surfaces of the several spring fingers H. Because of the curvature of the contacting surfaces of of these parts, clearly shownin Fig. 7, it follows that the portions of the surfaces thus engaging each other are in a practi'cally continuous line around the outside of the ring $5. This line-like engagement is what is meant by a line contact, although under pres-' of line contacts besure there might be some deformation of the parts along the contact line and thus the line might have infinitesimal width and so be a zone of infinitesimal wid h. The term line contact however is commonly used to describe this sort of engagement between switch'contacts. Similarly. because of the curvatures of the inner face of the ring and the outer surfaces of the fingers there is a similar line contact extending around on the inside of the ring and the outside of the spring fingers Iii. In this case, the sum of the lengths of these two line contacts determines the carrying capacity of the switch, as

before indicated.

The mechanism for moving the shifting frame B upward and downward is. found in the toggle mechanism L. This mechanism, or toggle leversystem as it may be called, applies the requisite high pressure to the engaging surfaces of the contacts K and H when the switch is in fully closed position. Such mechanism includes a longitudinalshaft 98 suitably journaled in the main frame A, crank arms 99 keyed to the opposite ends of the shaft 98, and cooperating links I00 acting between the ends of the crank arms 99 and the end members 2'? of the frame B, the connection with the latter being provided through suitablepivots I 0|. The construction is such that the members 99 and Edi] act as toggles, one at each end'of the switch s'ructure. The toggle arrangement is such that the central pivots I02 by which the arms 99 and links are connected move through and slightly beyond a dead center point existing between the centers of the shaft 98 and the pivots MI. The movement of the toggle members to this overenter point brings the contacts H and K into the requisite firm engagement, as aforesaid, and then the toggles lock the switch parts in closed position. In order to properly bring about this staying of the toggle movement each end member 2'! is preferably provided with a stop The stop I03 may take different forms but preferably an eccentric cam Hit is employed as illustrated more particularly in Fig. 6. This cam I04 may be held in any desired position by clamping it against the face of the adjacent member 21 by any suitable means, as, for example, the bolt I05. Where the latter is used, its head may press against the cam I5 4 and it may be held in permanent engagement by means of a nut I06 on the opposite side of the frame member 27, all as illustrated more particularly in Fig. 5.

Obviously, the actuating shaft may be rotated through the requisite angle in order to bring about proper opening and closing movements of the switch contacts by any suitable means. In the present instance, a lever 50 is keyed to one end of the shaft 98 in a position adjacent to one of the end members 2.? of the main frame A. This lever has a handle I It at its outer end by which an operator may move it to and fro between the closed position, illustrated in Fig. 2, and the open position, wherein the lever extends downward and forward from the shaft 93. The lever I09 is preferably provided with lugs Hi which are apertured and made to lie adjacent to a similarly apertured portion of the main frame, such as indicated at IE2, near the lower end of the member I I3, which is secured by bolts H4 to the adjacent portion of the main frame A, suitable spacing sleeves I55 surrounding the bolts and properly spacing the bracket member H3 from the end frame member 20. When in proper position the lever 05 may be held against interference by a padlock H5 which may have its hasp passed through alined openings in the lever I08 and the lugs H2 of the frame H3, either in the open or closed position of the switch, as desired.

The frame I I3 is provided with a grooved channel H8 which extends in an arouate path and provides a pathway for a retaining pin H9 carried by the lever I03. This is clearly illustrated in Fig. 8 which is a section along said arcuate pathway. A leaf spring I20 is secured at one end by pins I20 to the face of the lever I as and the pin H9 is secured to the free end of the spring I20 so that the same may be yieldingly moved with reference to the lever. A button I2! on the free end of the spring I20 and preferably in alinement with the pin H9 serves to draw the pin H9 out of one of two recesses I22 which it may occupy at the ends of its traverse. The

l and arrangement may lever' M39 is suitably recessed at l23' to provide for them and out movement of the pin H9.

From what has been said it will be clear that the various springs 38 of the coupling devices D serve two functions. One of these is to provide the requisite pressures between the electrical switch contacts, as, for example, contacts H and K, and the other is to hold the toggles in their locking positions after they have been moved to their holding positions beyond dead center, corresponding to the closed position of the switch. As previously indicated, the contact structure be considerably modified. What has been described in detail heretofore has included a solid lower contact and a tubular intermediate contact. In respect to modifications of these contacts it is clear that the shapes or the coacting contact surfaces may be greatly varied over those shown and still get the ball and socket action and the requisite line contacts and line contact lengths for the different positions of the engaged contacts relative to each other. The different shapes of the contacting portions of the cooperating contacts will be determined by the required current carrying capacity of the switch and other characteristics, such as the shape of the insulators required to permit the proper movements of the various switch parts and the like.

Obviously, then, in carrying out my invention many alterations and modifications may be made in the disclosed structure without departing from the spirit and scope of the invention. I therefore aim to cover by the terms of the appended claims all those alterations and modifications which rightly come within the scope of my invention.

I claim:

1. In an electric switch, cooperating electrical contacts, a relatively fixed insulating mounting for one of said contacts, a relatively movable insulating mounting for the other of said contacts, actuating mechanism for said movable mcunting, a set of compression springs acting between said actuating mechanism and said movable mounting to press said contacts together when brought into engagement, means for giving said springs a variable adjustment to suitably adjust the same with .a given compression whereby the movement of said actuating mechanism will compress said springs beyond said given compression only when the pressure between said contacts exceeds an amount corresponding to said given spring compression, and indicating means associated with each of said springs to show the extent of pressure being applied therethrough in excess of said given amount.

2. In an electric switch, cooperating electrical contacts, a relatively fixed insulating mounting for one of said contacts, a relatively movable insulating mounting for the other of said contacts, actuating mechanism for said movable mounting, a set of compression springs acting between said actuating mechanism and said movable mounting to press said contacts together when brought into engagement, means for adjusting the abutting ends of said springs relative to both said actuating mechanism. and said movable mounting, thereby to give said springs a set compression, and indicating means associated with each of said springs to indicate the pressure being applied the-rethrough in excess of said set amount.

3. In an electric switch, relatively fixed and movable suitably insulated contacts, suitable mountings for. said contacts, actuating mechanism for shifting said movable contact and mounting, a set of coiled compression springs each acting between said movable contact mounting and said mechanism, said movable contact and mechanism serving as abutment members for the spring, a bolt-like member secured at one end to one of said abutment members and movable freely through an opening in the other of said abutment members, a nut secured to the free end of said bolt-like member and serving through the intervening abutment member to limit its movement away from said spring, and means for limiting the inward movement of said nut on said bolt-like member to compress said spring with a given compression.

4. In a device of the class described, a contact carrying member, an actuating member for said carrying member, a plurality of spring mountings carried by one of said members and operating to transmit motion from one to .the other of said members, each said spring mounting comprising a coiled compression spring, a holding bolt secured to one of said members and passing freely through an opening in the other of said members, a nut on the free end of said bolt for limiting the movement of the adjacent member away from said spring and cooperating with said adjacent member to give said spring a definite set compression, and scale markings on said bolt for indicating two things, one the set compression of the spring, and the other the extent of movement of said members relative to each other whenever said spring is compressed beyond said set compression.

5. An electric switch comprising relatively fixed and movable self-centering electrical contacts, a movable mounting for saidmovable contact, said mounting having lateral projections, a movable supporting frame for said mounting having portions adjacent to said projections, a set of spring couplings uniting said projections and frame with yielding connections, each coupling including a bolt secured to said frame and extending loosely through an opening in the associated projection, a coiled spring around said bolt, means on said bolt for compressing said spring with an initial pressure, said couplings being peripherally spaced about said movable con tact and the springs and loose connections there a" of serving to provide a floating action such as to permit said contacts to center themselves when brought together, and means for moving said frame toward and from said fixed contact.

6. An electric switch comprising two end insulating tubes, an intermediate insulating tube in telescopic relation to said end tubes, terminal electric contacts within and mechanically connected to said end insulating tubes respectively, an intermediate electric contact within and mechanically connected to said intermediate in sulating tube and operative to electrically connect and disconnect said terminal contacts, a frame by which said end tubes are supported, an intermediate frame by which said intermediate tube is supported, all said tubes being in alinement, a toggle system for moving saidintermediate frame to make and break circuit, and spring means operating between said intermediate frame and associated tube to yieldingly hold the toggles of said system in contact closing position and simultane ously therewith to apply a yielding pressure to the engaged contacts.

- FRED FARRELL.

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