US3239629A - Contact operator - Google Patents

Description

March 8, 1966 N. LESSER CONTACT OPERATOR 2 Sheets-Sheet 1 Filed Oct. 15, 1963 f R we m/ U .m f 0 N ATTX March 8, 1966 N. LESSER CONTACT OPERATOR 2 Sheets-Sheec 2 Filed Oct. 15, 1965 FIG 7 I N VENTOR. Norfon Lesser ATTY.

United States Patent 3,239,629 CONTACT OPERATOR Norton Lesser, 648 Burton Ave., Highland Park, Ill. Filed Oct. 15, 1963, Ser. No. 317,106 7 Claims. (Cl. 200104) This is a continuation in part of application Serial No. 98,699, filed March 27, 1961, now abandoned and pertains to an invention which has evolved from the consideration of a number of problems presented in the construction and operation of electrical contacts, These problems include:

(1) Contact erosion and/ or welding.

(2) Power requirements necessary to operate large numbers of contacts.

(3) Securing contact closure and/or opening within required time intervals.

(4) Enabling the sequential opening and/or closing of contacts simultaneously controlled from a common power source.

(5) Contact gap and spring adjustments.

By the use of a simple insulating card or sheet between respective contacts, the severity of the above problems and their economic consequences can be considerably reduced. In its simplest terms consider a pair of break contacts. The springs carrying such contacts are preformed or stressed so that when assembled the contacts are in engagement under a predetermined degree of spring pressure. Now if an insulating card be inserted between the contacts they will be held apart. If an aperture or notch is provided at a predetermined position in the card and the card moved to bring the aperture into alignment with contacts, the contacts close under their own spring pressure. They may therefore be separated by simply moving the card to bring the aperture out of alignment with the contacts. Thus the contacts may be made to serve as either normally open or normally closed contacts depending on the normal position of the aperture. The gap is determined by the thickness of the insulating card and requires no adjustment. With a card between each set of contacts it becomes a simple matter to move all simultaneously so that no special adjustment is required to compensate for the position of the springs in the pile up or other factors. Further by locating each aperture in a desired position in its card and/or controlling the aperture size both the operate and release time of the associated contacts may be easily controlled. Further by the location and size of the aperture the sequence of contact operation may be more easily controlled.

In relays or switches where the total movement of the card is limited to a predetermined small increment during which the card may clear the contacts but fail to clear the springs, a rigid card may prevent engagement between contacts. Thus if a rigid card is misaligned with respect to the plane of the contacts it may fail to disengage from one of the springs and thereby prevent movement of the spring to bring its contact into engagement with the contact of the other spring. This problem becomes more severe Where a plurality of contacts are arranged in a common plane in which the rigid insulator must be in the same plane as each of the contacts. Further a rigid card on engaging the projecting surface of the contacts is presented with an obstacle which directly resists its movement and therefore tends to obviate the power gain ordinarily derived from the sliding separation of the contacts.

It is therefore desirable to use a plastic or deformable insulator which yields to some extent to the contact surface and to the spring pressure and thereby avoid rigid engagement with the contact and also permits contact closure even it slightly misaligned. It has however steel and preferably soft iron.

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evidently been heretofore believed that such an insulator would contribute to contact contamination.

To reduce the frictional forces required to move the card especially in the case of intermittently operated devices such as relays or stepping switches, where the card is always slid from a rest position, it is desirable to lubricate the card. Lubrication however, has also evidently been considered as a source of contact contamination in addition to creating maintainence problems.

The present invention however, utilizes an insulator or card of a plastic or deformable character for operating the contacts and further utilizes an insulator having inherent lubricating characteristics derived from materials having an integrally formed lubricating surface such as provided by polytetnafluorethylene, commonly known as Teflon. Such an insulator is particularly valuable since it is easily shaped or worked and provides a low static coefiicient of friction with the static coefficient of friction falling with increasing load and does not result in contact contamination.

In many types of relays a stainless steel pin is used for pivotably mounting the armature at the end of the heelpiece with the pin being pivotably held in a yoke adapted to be fastened to the heelpiece. Both the pin and yoke are fabricated to extremely close tolerance and are expensive to manufacture and assemble. In addition the armature is usually provided with a nonmagnetic shim in the area where it engages the coil core to prevent magnetic sticking; and, in many relays using card actuated contacts the armature is returned to its normal position on coil de-energization by a special return spring.

Some attempts have been made in the past to provide an armature which is fixedly mounted on the end of the heelpiece for avoiding the pin and yoke construction referred to above. Such an armature would usually employ a spring material that is flexed on coil energization and whose resiliency would avoid the need for a separate return spring in the case of card actuated contacts. An

armature of spring material however has certain disadvantages for example, arising from the stresses set up therein if given a sharp bend adjacent the end of the heelpiece in order to maintain a short magnetic circuit. In addition high operating forces are required if the bend or point of flexure is comparatively close to the coil core.

It is therefore additionally proposed in the present invention to utilize a relay armature of mild or cold rolled steel and preferably of soft iron that is rigidly mounted on the heelpiece and which may be given a sharp bend at the end of the heelpiece in order to maintain a closely coupled magnetic circuit without danger of rupturing on repeated flexing.

A rigidly mounted armature which will flex under normal magnetic fields has to be of very thin cross section and therefore will not carry much flux. In order to render such an armature operable or flexible with a mini mum field and to render it sufficiently rigid, it is additionally proposed to increase the cross section of such an armature in the area adjacent the coil core and the end of the heelpiece by attaching thereto a plate of mild This increases the flux carried in the critical areas and rigidifies the armature while enabling flexure with a minimum of force.

Under certain circumstances where the armature is required to operate a large number of contacts, magnetic sticking may eventually overcome the normal return forces. To avoid this result the present invention also contemplates a spring of non-magnetic material mounted on the armature and interposed between armature and the core. The non-magnetic spring in this position serves the dual purpose of aiding the return of the armature and as a shim to prevent magnetic sticking.

It is also contemplated in the present invention to use an improved armature of the type just described for carrying an insulator of the type described in the previous paragraphs. For this purpose an improved arrangement for mounting the insulator on the armature is considered among the objects of this invention.

The foregoing having described certain advantages and objects of the present invention, these together with others will become more clearly apparent on reading the following specification, claims and drawings; wherein:

FIG. 1 is an illustration of a relay utilizing the principles of the invention,

FIG. 2 is a view taken along the line 22 in FIG. 1.

FIG. 3 is a perspective view of another manner of controlling the operation of contacts such as shown in FIG. 1.

FIG. 4 is a view of a bank contact portion of a stepping switch.

FIG. 5 is an illustration of one manner of controlling a make and break spring contact operation.

FIG. 6 is a side elevational view of a relay partially in cross section utilizing the improved armature construction.

FIG. 7 is a top elevational view of the relay shown in FIG. 6; and

FIG. 8 is a sectional view taken along the line 88 in FIG. 6.

In FIG. 1 a relay construction 10 is illustrated. That relay includes a coil 12 adapted to be energized in any well known manner over the leads 14 and 16. The coil 12 has a core 18 of appropriate material and is carried by the heelpiece 20. The bracket 22 is formed on or carried by the heelpiece 20 and in turn supports the contact or spring pile up 24.

When energized the coil 12 creates a magnetic circuit through the heelpiece 20 and the armature 21 pivotally carried at 19 on one end of the heelpiece to attract the I armature 21 to the core 18. The armature 21 pivots about 19 to move. its lever arm 23 counterclockwise. A residual screw 17 is provided on the armature 21. It limits the armature movement so as to provide an air gap between the armature 21 and core 18 to thereby prevent the armature from being delayed in returning to its normal position on de-energization of the coil 12.

The spring pile up 24 may comprise a plurality of make and/ or break contact sets or various combinations there- 26a and 27e are preformed or stressed so that the respective contacts 281 and 29a28e and 29e would normally be in engagement under a desired degree of pressure, in

other words-are formed as break contacts.

An insulating card or sheet 38, however, is inserted between the respective contacts 28a and 29a, 28b and 29b and 28c and 29c to maintain them normally separated so that they may act as make contacts on energization of the relays 10. The cards are provided with respective apertures 33, 34, 35, 36 and 37 for the respective contact sets. The apertures 36 and 37 are aligned with respective contacts 28d and 29d and 28a and 29:: respectively so that these contacts are normally break contacts. The other apertures 33-35 when aligned with their respective contacts permit the closure of those contacts under the tension of the respective springs. The cards 38 are supported in any well known manner by an appropriate bracket 40 to eliminate undesirable flexing. The design of the bracket 40 is of course subject to a number of factors so that its configuration and structure may vary over wide limits. Thus each card 38 may be provided with a separate bracket 40 and by suitable guide or stop arrangements each moved in a different manner.

The card 38 may comprise any one of a number of well known types of materials having desired characteristics. Plastics such as, for example, the saturated polyesters one of which is sold under the trade name Mylar: or others such as polytetrafluorethylene sold under the trade name Teflon may be used. Teflon evidently deposits a film on the surface with which it is in engagement and this film serves as a lubricant that provides a very low coefficient of friction. Such materials have excellent dimensional stability, tear or shear resistance, and desirable electrical and fabrication qualities. The rigidity of the sheet depends of course upon the quality of the material, its thickness and the unsupported area thereof. The desired normal separation between respective contacts 28a and 29a28c and 290 governs the thickness of the material. Normally in telephone circuits utilizing 48 volts, for example, a gap in the neighborhood of .006" would be provided between the contacts, and in other types the gap may be in the neighborhood of twice that amount. However, due to the high insulating qualities of the sheet 38 this may be lowered considerably if desired by simply using a thinner sheet, or if the gap is to be enlarged a thicker sheet is used.

The bracket 40 is movably supported on the bracket 22 by a pin such as 44 engaging a slot 46 in the bracket. The bracket 40 and sheets 38 are biased in one direction against the lever arm 23 by the spring 42, and the movement in one direction by the lever arm 21, bracket 40 and sheet 38 is limited by the stop 45.

The movement of bracket 40 on energization of the coil is guided by the pin 44 in the slot 46 and is limited by the residual screw 17. When the coil 12 is de-energized the spring 42 simply retracts the sheets 38 from their operated position.

If it is desired to operate the contacts as break contacts instead of make contacts, the position of the aperture is normally aligned with the contacts as shown, for example, at apertures 36 and 37. The aperture is moved out of alignment with contacts 36 and 37 when the coil is energized so that the card 38 opens the contacts. If the contacts are to be operated as make contacts the card is located between the contacts and on energization of the coil the apertures 33-35, for example, are moved into alignment with the respective contacts and they close under their own tension. If a large number of contact springs are to be operated in the pile up, this permits all springs to be preformed and assembled in the same manner whether operated as break or make contacts, thus minimizing assembly and spring adjustment and problems as to the gap size for each spring combination. It will be noted that the amount of force necessary to operate the springs need only overcome the bias of spring 42 and the inertia of bracket 40 and sheet 38, the frictional forces of the contacts against the sheet 38' and such force as necessary to initially pry the break contacts apart. The biasing spring in retracting the sheet 40 need only overcome the force involved in the described factors and the mass of the armature and lover arm plus any residual magnetism. Since the mass of the elements and the frictional and prying forces are comparatively nominal, little power is needed either by the biasing spring in overcoming those forces or by the energized coil, thus permitting a large number of springs to be simultaneously controlled by the coil. All springs may be of the same gauge and receive the same prestressing or forming.

The time interval at which the contacts are permitted to operate after the coil is energized is governed by the location or the size of the aperture and the velocity of the card. By locating the aperture at a desired point from the contacts it must travel x distance as shown for aperture 33 after the coil is energized before permitting contact closure between 28a and 29a. If the contacts are to open a certain time interval after energization the size of the aperture 36, for example, is dimensioned so that it travels y distance before the card 38 separates cont-acts 28d and 29d. Thus a simple expedient is available for governing the operating time of the contacts. The release time of the make contacts may be governed by the size of aperture 33. Thus by making the aperture large and having the sheet 38 travel some distance after the make contacts are closed the contacts 28a and 29a are located w distance from the aperture edge. Thus on de-energization of the coil 12 that distance must be traversed before the contacts open, thereby governing the release time of the contacts. For break contacts such as 28d and 29d the procedure for governing the release time after de-energization of the coil is simply reversed. Thus by moving the sheet 38 some distance z after the break contacts 280. and 29d are open, the release time of the break contacts is governed by the time period necessary to return the aperture 36 into alignment with the contacts. One set of contacts may be made to operate several times for one operation of another by simply providing spaced apertures each operating the one set of contacts in a desired sequence while another is operated by a single aperture or hole, for example, or in another sequence.

Inspection of FIG. 2 will also illustrate another facet of the invention. For example, consider the make contacts 28a and 29a-28c and 290. Since the edges 33, 34 and 35 are each spaced a different distance from the respective make contacts, those contacts will operate in a respective sequence on energization of coil 12. Thus the contacts 28a and 29a operates before contacts 28b and 29b and 280 and 290. Contacts 28c and 290 operate in a time interval after 28a and 29a determined by the distance between the respective aperture edges. Contacts 281) and 29b, of course, operate in another time interval determined by the distance between aperture 34 and contacts 28b and 2912. With respect to contacts 28d and 29d and contacts 28e and 29. it will be noted that contacts 28:; and 292 will operate or break before contacts 28d and 29d due to the spacing of the back edges of the apertures 36 and 37. Likewise the spacing of the back edge of aperture 36 with respect to the front edge of apertures 33 and 35, for example, enables contacts 28a and 29a and 280 and 29c to close before contacts 28d-and 29a open. Contacts 28e and 29:2, for example, open before contacts 28b and 29b close. Thus a large number of desired sequences of contact operation may be easily arranged. It will be noted that the use of an aperture in preference to complete disengagement of the card enables far superior support to be provided to edges disengaging the contacts and prevents buckling On de-energization of the coil 12 the cards 38 travel back to their original position. The location of the aperture edge with respect to the contacts will now control the time sequence of contact release. Thus contacts 28b and 29b open before contacts 28a and 29a. Contacts 28d and 29d close before contacts 282 and 29a close or before contacts 28a and 29a open, for example. The condition of contact release is therefore also easily susceptible to control. In addition if the cards 38 are to be separately guided or moved and/or the apertures given respective configurations and the cards guided accordingly, the time squence of contact operation may be varied in any one of a number of different manners.

The previous discussion has contemplated a spring pile up of a considerable number of springs in a single aligned array with a different sheet 38 between respective contacts. A plurality of such arrays or contact pile ups 50 as shown in FIG. 3 may be also used together with a simple sheet 52 for operating the respective contacts in each pile up. Each pile up 50 is mounted in respective spaced apart locations on a bracket 54 and the single sheet or card is adapted to traverse or engage with one of the contact sets in each pile up. This arrangement permits a plurality of contacts to be disposed laterally and operated simultaneously by a single insulator sheet or card controlled by a relay armature or lever.

The card 52 is moved in any one of a number of well known manners to the right, for example, as shown by the arrow. When this occurs one set of contacts in each pile up is operated. Thus the contacts 55 and 56 open as the aperture 57 moves out of alignment therewith. The contacts 60 and 61 on the other hand close as the aperture 63 moves into alignment therewith. The operative sequence may be controlled as already explained. In addition another feature is illustrated in FIG. 3. This is an additional arrangement for quench ing any tendency to arc. Thus a conductive coating 65 and 66 may be applied to respective sides of the sheet 52 adjacent the aperture 63, for example, and suitable spark supression means connected thereto.

The means for moving the sheet need not be limited to a relay, of course, but instead such devices as stepping switches of cams may also be used. Thus in FIG. 4 a portion of a multiple level switch 69 is shown having a series of sheets 70, 71 and 72 arranged to be given a rotary or similar movement. The sheets replace the conductive wipers normally used and are arranged to engage the respective bank contacts 74, 75 and 76 of a multiple level bank 77, for example. The contacts are arranged as normally closed contacts and the respective sheet maintains control of their position. In this type of operation usually the first contacts in each level are operated when the switch is in position 1, and the second and succeeding contacts of each level are operated when the switch is in position 2 or respective succeeding positions. The sheets 70, 71 and 72 are provided with respective apertures 81 and 82 and the ledge 83. The position of these is changed so that they successively engage the contacts of respective levels in positions 1, 2 and 3, etc. Thus as the cards 70, 71 and 72 rotate to their first position contacts 74 and 75 close while contacts 76 open and the ledge or projection 83 opens contacts 76. Due to the position of the edge of aperture 82 with respect to aperture 81, contacts 74 close before contacts 75. Also due to the position of ledge 83 with respect to aperture 82, the contacts 75 will close before contacts 76 open. The spacing of the edges may, of course, determine the time of contact operation with respect to card movement.

When the cards 79-72 are moved to the succeeding position, contacts 75 open after contacts 74, and contacts 76 close after contacts 75 open. This, of course, is due to the size of the apertures 81 and 82 and the ledge 83. Thus a number of control functions similar to those previously described for a relay may also be facily performed in a rotary switch in addition to other described advantages. If desired a common stationary wiper appropriately shaped may be used in place of one spring of each set and the appearance of an aperture between the wiper and spring will permit closure.

In FIG. 5 a simple arrangement for a set of make and/ or break contacts is shown. A bracket 87 holding a pair of insulating cards 88 and 89 having a respective aperture 90 and 91 is arranged to control the make contacts 92 and break contacts 93. Thus movement of the bracket 87 brings the card 89 into alignment with contacts 91 to open those contacts. The aperture 90 being brought into alignment with contacts 92 permits their closure. Spring 94 may be made to normally assume a neutral position with springs 95 and 96 biased towards spring 94. On the other hand card 88 may be omitted and card '89 can be used to move spring 94 for causing engagement of the contacts 92.

In FIGS. 6, 7 and 8 one practical version of the insulator described in the previous paragraphs is shown for use with a relay 100 having an improved armature 102 of a character described heretofore. The relay 100 comprises a conventional L shaped heelpiece 103 defining a vertical arm 104 and a horizontal arm 105. The arm 104 carried a contact bank 106 at its upper end.

The bank 106 includes an insulating structure 107 in which a plurality of rows of springs 108, 110 and 111 are fixed. The springs 108 of the upper row and 111 of the lower row engage a respective spring 110 of the center row to define four sets of respective contacts 113 and 114. The contacts 113 are normally closed to enable the completion of an electrical circuit through terminals 115 while contacts 114 are normally held open by one edge of a slot 116 in a Teflon insulator 117 carried at the upper end of armature 102.

A coil 118 having a core 119 is mounted on the heelpiece below a contact bank 106. When the coil is energized by an electrical circuit completed through terminals such as 110, the armature 102 is adapted to be attracted to the end of the core.

The armature 102 comprises a thin sheet 122 of soft iron carrying a soft iron plate 124 between the sheet and the core. The sheet preferably is less than .02 and should be approximately .01" for long continued nonstick operations with the four form C contacts illustrated in bank 106, while the plate 124 may be between .025" and .070. The sheet 122 is provided with a sharp bend 126 approximately 90 adjacent its lower end. The bend 126 serves as a point of flexure for the armature when attracted by the core 119. A horizontal leg 128 extends from the bend. The leg 128 is provided with a slot 130 whereby the armature may be adjustably mounted and fixed on the heelpiece leg 105 by means of a screw 132 and a clamp washer 134. The bend 126 is approximately .05" from the core while the gap between the plate 124 and the core is approximately .02" to .025 so that a short closely coupled magnetic path is provided.

Since the sheet 122 is quite thin it offers little resistance to flexure while the heavy plate 124 provides suflicient cross section to carry the flux between the heelpiece and core with the minimum distance possible provided between the end of the heelpiece leg 105 and plate 124. Since the weight of the plate 124 acts primarily along the longitudinal axis of the sheet 122 and transverse to the bend 126 there is little tendency for the sheet 126 to flex about the bend under the influence of the plate, while the plate in turn tends to rigidify the armature in areas other than the bend.

The upper end of the sheet 122 is also provided with a horizontal leg 136 that carries the insulator 117 of the type already described or of the type described in copending application Serial No. 98,699, now abandoned. The leading edge of the slot 116 in the insulator 117 is located between springs 110 and 111 to hold contacts 114 open while the opposite edge of the slot 116 is adapted to be moved between normally engaged contacts 113 for opening the same on attraction of the armature to the core. The leg 136 is provided with a depending tang 13 8. The tang 138 is extended through an alperture in the insulator and bent over after the edges of the slot 116 are aligned as desired with the contacts 113 and 114 to clamp the insulator in position. Actually a number of such tangs or tines may be provided and they may simply pierce the insulator and be bent over to clamp the insulator. Additional adjustment may be provided by flexing the sheet 122 between the upper end of plate 124 and the leg 136. An epoxy may cement the tang to encapsulate the insulator.

It will be noted that backstops are not provided for limiting the return movement of the armature 102. This :is another advantage since repeated blows by the armature against the backstop may throw the armature out of adjustment. In the relay 100 on the other hand, the angle of the bend 126 or any other bend provided in the vertical leg of the armature together with the resiliency of the armature and the pressure of the springs cooperate to return the armature to the same position on each operation.

When the coil 118 is energized the armature 102 is attracted thereto to simultaneously move the leading edge of slot 116 from between the contacts 114 to permit them to engage while the opposite edge of the slot separates contact 113. On tie-energization of the coil, the normal resiliency of the soft iron sheet 122 serves to return the armature and insulator to normal thereby returning the contacts to normal. With the arrangement shown four or five form C contacts are operable on approximately milliwatts. Under certain circumstances such as when more than five contacts 113 and 114 are provided, the normal resiliency of the sheet 122 may be insufiicient to return the armature after many cycles of operation.

To overcome this situation an elongate spring 144 approximately .005 thick and of non-magnetic material is provided. One end of the spring is fastened to the plate 124 at rivet 146 and the other end is located between the core 119 and the plate 124 so that when the armature is attracted to the core the spring is placed under tension as the armature approaches the core while the thickness of the spring serves to space the armature from the core to reduce the danger of sticking.

The foregoing is a description of a number of concepts for achieving improved results in the operation of electrical contacts, and whose inventive concepts are believed set forth in the accompanying claims.

What I claim is:

1. A switch construction comprising an electromagnetic actuator, one contact carried by a cantilever spring, another contact carried by a cantilever spring for mating with said one contact under the biasing tension of one of the respective springs, and an insulating member having an integral lubricating surface for sliding between said contacts in response to either the energization or deenergization of said actuator.

2. A spring pile up for use as a switch comprising a plurality of cantilever springs having a support at one end and arranged in pairs with each pair engaging at a respective point lying on an axis transverse to the longitudinal axis of said springs and on a common line having a constant distance from said support and at a substantially irrelevant position with respect to each other for extending a respective electrical circuit therethrough, and an electrically insulating structure of deformable material material mounted for sliding movement between said springs of only a predetermined increment substantially perpendicular to each transverse axis for separating the springs of each pair during said movement.

3. A switch construction in which an electromagnetic actuator is arranged to be successively energized for selecting a different pair of contacts for operation on each successive energization of said actuator, the improvement comprising an arrangement for biasing one contact of each pair towards engagement with the other contact, and a plastic insulating member having an integral lubricating surface arranged to be moved successively a predetermined increment only in response to each energization of said actuator to disengage each pair of contacts successively.

4. For use in a stepping switch wherein a coil is periodically energized for selecting one of a plurality of positions dependent on the order of the energization, a spring individual to each position biased for movement in one direction to engage with another spring, and a plastic deformable sheet insulating member always maintained between the springs at each position and moved only a predetermined increment responsive to each successive energization of said coil, said member arranged to permit one spring in the position corresponding to the order of the energization to engage with the other spring while still maintained between said engaged springs.

5. A relay comprising a coil adapted to be energized by an electrical current, a plurality of spring pairs with the springs of each pair adjusted to normally engage at a respective point adjacent common plane to form sets of contacts lying along a common straight line transverse to the longitudinal aXis of each spring pair, a deformable insulating sheet adapted to be moved in said plane for simultaneously operating all of said spring pairs regardless of the position of said spring pairs with respect to each other, and means for moving said sheet one predetermined increment only for simultaneously operating all of said spring pairs responsive to each energization of said coil.

6. A relay comprising a coil adapted to be energized by an electrical current, a plurality of spring pairs with each pair having a supported end and adjusted to normally engage at a respective point lying along a common straight line equidistant from said supported end of each spring transverse to the longitudinal axis of each pair, and an insulator of polytetrafluorethylene for each pair adapted to be moved a predetermined increment only between said spring pairs and substantially parallel to the longitudinal axis of each pair responsive to the energization of said coil for operating all of said spring pairs irrespective of the position of said spring pairs with respect to each other.

7. A relay comprising an electrically insulating deformable sheet material having an integral lubricating surface and normally held in one position, a coil energized for moving said material from said one position to only one other position on each energization of said coil, and a plurality of contacts each carried by a respective cantilever spring biased to bring said contacts into engagement, said material being always disposed between said springs and moved between said contacts alternatively when said materizl is either in said one or in said other position.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A. GILHEANY, Primray Examiner.

ROBERT K. SCHAEFER, Examiner.

R. N. ENVALL, 111., Assistant Examiner.

Claims (1)

1. A SWITCH CONSTRUCTION COMPRISING AN ELECTROMAGNETIC ACTUATOR, ONE CONTACT CARRIED BY A CANTILEVER SPRING, ANOTHER CONTACT CARRIED BY A CANTILEVER SPRING FOR MATING WITH SAID ONE CONTACT UNDER THE BIASING TENSION OF ONE OF THE RESPECTIVE SPRINGS, AND AN INSULATING MEMBER HAVING AN INTEGRAL LUBRICATING SURFACE FOR SLIDING BETWEEN SAID CONTACTS IN RESPONSE TO EITHER THE ENERGIZATION OR DEENERGIZATION OF SAID ACTUATOR.

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