US2558524A - Relay construction - Google Patents

Description

R. K. MGBERTY ETAL RELAY CONSTRUCTION ow hm. mw

June 26, 1951 Fned oct 4, 194e June 26, 1951 R. K. McBl-:RTY ETAL. 2,558,524

RELAY CONSTRUCTION Filed OCb. 4, 1946 5 Sheets-Sheet 2 anczld 5.5aker.

June 25, 1951 R. K. MGBERTY ETAL 2,558,524

RELAY CONSTRUCTION Filed oct. 4, 194e 5 sheets-sheet s ma) E R. K. MGBERTY ETAL RELAY CONSTRUCTION June 26, 195] Filed oct. 4, 1946 June 26, '1951 R. K. MCBERTY ET AL 2,558,524

RELAY CONSTRUCTION Filed oct. 4, 194e 5 sheets-sheet 5 hama im ze. 1951 RELAY CONSTRUCTION Robert K. McBerty, Galion, and Donald S. Baker, Iberia, Ohio, udgnors to The North Electric Manufactum; Company, Galion, Ohio, a ecrporation of Ohio Application October 4, 1946, Serial No. 701,810

18 Claims. (Cl. 20G-103) Our invention relates, generally, to relays. and it has particular relation to relays for use in switching communication circuits, such as telephone circuits and the like.

Our invention constitutes an improvement over the relay construction disclosed in Patent No. 2,396,332 to F. R. McBerty and the relay construction in which our invention is incorporated is particularly adapted for use in the all relay automatic system for telephone exchanges, such as described in Chapter VI of Telephone Theory and Practice by Kempster B. Miller, ilrst edition, 1933.

It is desirable, in certain instances, to obtain diilerential action between the contacts of a relay in the same magnetic circuit. For example. for the cut-off relay of the all relay telephone exchange system, it is desirable that a ciruit be completed through a back or break contact before another circuit is opened at a front or make contact on deenergization of the operating winding. That is, the contact, which is to close the circuit, must move from its energized position to its deenergized position before the other contact begins to move. The reverse function often is required. In such a case, on energization of the operating winding, a circuit is completed through the front or make contact before the circuit is opened at another back or break contact.

Accordingly, an object of our invention is to provide selective or differential operating characteristics for the contacts of a relay by difierences in individual armature sensitivity to the magnetic circuit.

Another object is to cause the contacts to move from the deenergized position to the energized measured from time that the operating winding is energized.

A further object is to cause the contacts to move from the energized position to the deenergized position during ditl'erent length time intervals measured from the time that the operating winding is deenergized.

Another object is to accomplish the foregoing 'objects by employing diierent sizes of armatures for operating the contacts.

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

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

For a more complete understanding of the nature and scope of our invention reference can be had to the following detailed description. taken together with the accompanying drawings, in which:

Figure 1 is a view. in side elevation. of the left hand side of a relay construction in which our invention is embodied;

Figure 2 is a view, in side elevation, of the right hand side of the relay shown in Figure 1;

Figure 3 is top plan view of the relay shown in Figure '1;

Figures 4 and 5 are detailed sectional views taken, respectively, on the lines I-I and l-I of Figure 3;

Figure 6 is a perspective view, on an enlarged scale, of the make'and break contacts together with the movable contact which is operated therebetween;

Figure '7 is a top plan view, at an enlarged scale, of the contacts and of the movable contact having the large size armature associated therewith;

Figure 8 is a view similar to Figure 7, but show--l ing the small size armature for the moving contact;

Figure 9 is a view, in side elevation. of the lett hand side of another type of relay in which our invention is incorporated;

Figure 10 is a view, in side elevation, of the right hand side of the relay shown in Figure 9;

Figure 11 is a top plan view, of the relay shown in Figure 9; and

Figure 12 is a detail sectional view, taken along the line I2-I2 of Figure 11.

Referring now particularly to Figures 1 through 5 of the drawings, it will be observed that the magnetic circuit for the relay comprises a core I0 which may be secured at its lower end. as by welding, to a web or back plate I I on the edges of which side plates I2 extend upwardly parallel to the core I0. A number of cores I0 is secured to the web I I, the number depending upon the number of winding assemblies which are to be used. At its upper end each core III has a pole piece Il which extends transversely thereof and the ends of which are spaced from the upper edges of the side plates I2 so as to provide air gaps I l therebetween. For illustrative purposes the core Il and side plates I2 are shown as extending upwardly from the web II which is shown in a horizontal position. However, it will be understood that the relay ,construction disclosed herein can be positioned in any desired plane and that the functioning thereof is entirely independent oi the i'orce of gravity.

With a view to retarding the change in the flux in the magnetic circuit just described, the core I0, as illustrated in Figure 4, can be surrounded with a sleeve I1 of conducting material such as copper. The sleeve I 1 functions as a shading winding or coil to retard the change in ilux, as is readily understood.

For energizing the individual cores I0, windings having diierent numbers of turns may be employed and the windings may be single or double. As shown in Figure 4, a winding I8 surrounds the sleeve I1 and has terminals I8 to which appropriate connections can be made. as will be described hereinafter. In Figure 5,-two windings 20 and 2I are illustrated. These windings 20 and 2I may have different numbers of turns. One ofthem may act as the energizing winding for its associated core I9 and the other may be employed as a resistance winding to perform certain control functions. It may also be arranged to be energized, if so desired, to

vprovide for energizing the associated magnetic circuit at a diierent energy level than is provided by the other winding. Terminals 22 and 23 may be provided for the windings 20 and 2| respectively, and the connections thereto will be described hereinafter.

As illustrated in Figure 1, coils 24 may be provided on the two left hand cores and they may have different numbers of turns as compared to the operating winding I8. for example. Terminals 25 are employed to permit connection to the windings 24.

At its upper end each core I has a threaded stud 28 which projects through the pole piece I3` and which has a nut 29 threaded thereon for holding the pole piece I3 in place. The pole pieces I3, four of which are employed in the relay construction here described, are held in alignment by a pole piece alignment -bracket 30, which may be a die casting, and which has end portions 3|, provided with notches 32 on the under-sides for registering with the adjacent upper edges of the side plates I2.

Extending along the pole pieces I3 is a stationary or make contact molding 32', formed of a suitable plastic, such as polystyrene. Make or stationary contacts 33, in the form of strips of conducting material having reentrant intermediate portions 34, are molded along the edges of the molding 32 and are held thereby in place thereon. The contacts 33 have extensions 35 above the surface of the molding 32' to permit.

connection thereto as will appear hereinafter. The contact surface of the contact 33 is provided by an insert 3B of suitable arc and wear resisting material such as a gold alloy. The insert 36 is longitudinally slotted, indicated at 31. -for the `purpose of providing two contact engaging surfaces. The molding 32' with the contacts 33 integrally molded therein, may be held in place by screws 38 which are threaded into the alignment bracket 39.

Extending along the lower portion of each of the side plates I2 is a transfer reed molding 40 of suitable insulating material such as polystyrene. The molding 49 has reeds 4I integrally molded therein and they carry at their upper ends armatures 42 and 43 of different sizes which, as will appear hereinafter, provide the differential operation which is desired.

As shown more clearly in Figure 6 of the drawings, the armatures, such as the armature 43,

l carry a transverse contact 44 near the upper end of each for engaging the stationary makecontact' 33 at the surface of the insert 36. The contact 44 may be formed oi' gold alloy wire. On the rear side of the armature 43 a similar contact 45 is provided. the contacts 44 and 45 being secured to the armature 43 by welding. The contact 45 is arranged to engage a pair of contacts 48 which are carried by a metallic support member 41 which forms a part of a stationary or break or back contact. The support member 41 is carried on the upper end of a metallic reed 48.

As disclosed in McBerty Patent No. 2,396,332, the armature 43 and the support member 41 may be secured to the upper ends oi the reeds 4I and 48, respectively, by having longitudinal slots therein which interflt with the reeds and having the armature 43 or support member 41 deformed laterally thereof to hold the same in place. If desired spot welding may also be used.

The reeds 48, which carry the support member 41 of the break contacts, are molded in break reed moldings 49 which, as illustrated more clearly in Figures 4 and 5, are superimposed on the moldings 49. .A metal reed clamping strip 59 also extends along the moldings 40 and 49 and screws 5I project there through into the side plates I2 to serve to hold the same in place.

The lower ends of the reeds 4I and 4B, which project below the moldings 49 and 49 are held ln insulated spaced relation by beads 52 of suitable insulating material, such as polystyrene, that are molded around these projecting end portions as will be readily understood.

The inherent resiliency of the reeds 48 is such as to bias them away from the pole pieces I3 and into engagement with a back stop 53, preferably in the form of la round glass rod. In this manner the break contacts 46 and the support 41 therefore are held in alignment in an accurate manner with respect to the associated air gaps I4. The back stops 53 extend between the end portions 3| of the alignment bracket 30 and are held in place thereon by clamping springs 54.

As illustrated in Figures 1 and 2 of the drawings, connections to the coil terminals I9, 22, 23 and 25 are provided by wire reeds 55 which may be molded in the break reed molding 49 along with the break reeds 48. In addition, reeds 56 may also be molded in the break reed moldings 49 for connection to the extensions 35 of the make or stationary contacts 33. The connections between the reeds 55 and 56 and the coil `terminals and contact extensions are made preferably by spot welding.

As we have indicated heretofore. the use of different sizes of armatures 42 and 43 provides different times for the movement thereof and thereby movement of the contacts 45 and 44 out of and into contact engagement with their respective break and make contacts 46 and 33. This differential action may be obtained by employing a single operating winding, such as the winding I8. to establish the desired energy level in the magnetic circuit. One commercial type winding conventionally used in such type structure comprises a winding of 5700 times of #38 B @a S wire on a winding spool length 13%". Upon energization of the operating winding I8 with direct current, the armatures 42 and 43 are attracted toward the pole piece I3 to bridge the associated air gap I4 which is in the nature of .375 inch. The construction is such that assasas s. the armatures 42 and 4I do not physically engage either the pole piece Il or the adjacent sides of the side plates I2 with movement of the armature theretowards. the average residual air gap between the amature and the adjacent edge of the pole piece being of from .010 to .015 inch. The average travel distance of the armatures is in the approximate nature of .010 inch.

Reeds 4I of stainless steel were used having 'a diameterof 0.020" and a length above the molding 4l of 121,64". As taught hereinbefore, the reed members 4I are normally bent or tensioned so as to bias the armatures outwardly into engagement with the back contacts 4l. Therefore, in moving the reeds 4I to their inward position. whereby contacts 44 engage make contacts 33, the amount of force requiredto move the armature will be determined by the force required to overcome the imposed reed tension. It is apparent that with diderent tension settings for diiferent reed carrying armatures controlled by a common winding. inconsistent armature operations may result.

It is customary in the manufacture of releval of this type, therefore, to adjust or bias each of the reeds so that a predetermined value of force is required to move each of the armatures toits secondary or attracted position. The particular value of tension applied to the reeds will, of course, vary with the type of work and the nature of the installation in which the relay is to be used, the practical limits of reed tensions values for this general type of relay being from 3 to 13 grams.

In the relay of Figures 1-8, inclusive, reeds 4I, which support the large armatures 42 and the small armatures 43, are adjusted to equal tensions in the manner of the conventional practice, the recommended tension values again varying with the nature of the installation. Differential action of the armatures is attained as a result of the armature differential sizes, However a slight variation in the degree of the differential action may result with the imposition of equal tensions of diierent values selected from the accepted range. For instance, the differential action eflected between the armatures when tensioned at three grams will vary slightly in duration from the differential action effected when the armatures are tensioned at thirteen grams.

The large armature 42 was formed of nickel iron magnetic alloy, weighed 535 mg., and measured V8 by 0.120" by 0.043". The small armature 43 was formed of the same material, weighed 296 mg., and measured H" by 0.080" by 0.043". The sleeve I1, as illustrated in Figure 4 was used in obtaining the following data. The winding I was energized with direct current of the type conventionally existent in automatic telephony exchanges (normally a source in the order of from 44-56 volts) On energization of operating winding II by asource which is equivalent to that conventionallyused -in an automatic telephone exchange. contact 44, carried by the large armature 42, engaged its make contact 33 before the contact 45, carried by the small armature 43, disengaged its break contacts 46. Also, upon deenergization of the operating winding Il, the contact 45, carried by the small armature 43, engaged its break contacts 46 before the contact 44, carried by the large armature 42, disengaged its make contact 33. Additionally, this dierential action is of suilicient length to eiiect an overlap circuit controlling operation involvingtbe completion of certain circuits before opening of other circuits on energization of-the winding Il and to likewise permit completion of certain other circuits before still other circuits are opened on deenergization of the winding II. Therefore, it is unnecessary to employ a series of relays having din'erent operating characteristics to provide the desired differential action. In accordance with our invention, the diiTerential action is provided by employing different sizes of arma tures 42 and 43. It is obvious that the differential time increment between operations may -be fur-ther altered by suitable adjustment of other of the relay variables, such as for example, by changing the relative air gap widths or by applying different tensions to the reedg of contemporaneously Operated armatures.

When the sleeve I1 is omitted, the relay is considered to be a fast relay as distinguished from a slow relay.

Upon removal of the sleeve I1 from the previously described relay structure and with energization oi' the operating winding I8 by a power supply source which is similar to that conventionally used in an automatic telephone exchange, contact 44, carried by the large armature 42, engaged the make contact I3 before the contact 45, carried by the small armature 43, disengaged the break contacts 48. However, on deenergization of the operating winding I0, there was no overlap, i. e., contact 44, carried by the large armature, disengaged the make contact ll before contact 45, carried by the small armature 43, engaged the break contacts 46.

It will bernoted that we have illustrated in Figures 1 and 2 of the drawings two large armatures 42 on one side of the operating winding I8 and two small armatures 43 on the opposite side. The desired differential action can be obtained by employing a large armature 42 and one small armature 43 adjacent each other on the same side of the operating winding I 8. That is,A it is not necessary in practicing our invention to place all of the armatures of the same size on one side of the operating winding Il. Rather, they can be individually controlled, as described hereinbefore, regardless of whether they are all located on the same side of the operating winding I8 or some of them are located on one side and the balance on the other.

By employing either of the two operating windings 20 or 2|, shown in Figure 5, which are formed of different numbers of turns, it is possible to energize the associated magnetic circuit at different energy levels by separately ener# gizing these windings. As aforesaid, the windings can be combined or connected in seriesor parallel to obtain still other levels of energy in the magnetic circuit. When they are connected in series, they may be either cumulative or differentially connected.

Various combinations of the windings 2l and 2i acn be employed. One of them can be an inductive winding and the other can be a resistance winding. the two windings being connected in series. 'Ihis will etlect attraction of the armatures 42 and 43 at diierent flux levels.

Both windings 20 and 2i may be inductive windings and arranged, when energized with direct current, to generate balanced opposed uxes. 'I'his arrangement permits magnetic ileld control of the armatures 42 and 43 and thereby control of the associated contacts.

'I'he windings 20 and 2l both may be inductive windings arranged, when energized with direct current, to generate unbalanced opposed fluxes. By this ymeans differential operation and release of the contacts can be effected by magnetic field control. With the unbalanced uxes the large armatures 42 only 'may be attracted, leaving the small armatures unattracted. Both large and small armatures 42 and 43 can be attracted using either of the windings 26 or 2| alone. The small armatures 4,3 can only be released by opposing the fluxes while holding the large armatures 42 in their attracted positions.

Instead of locating the windings 20 and 2| coaxially, as illustrated in Figure 5, they may be mounted adjacent each other in a common magnetic circuit having a common pole piece. This arrangement permits the use of a larger number of armatures and greater field strength.

In Figures 9, 10, l1 and l2 of the drawings we have disclosed an extra-slow type of relay in which our present invention has been incorporated. The principal difference between the relay construction shown in these figures and the relay construction disclosed -in the preceding iigures and described hereinbefore resides in the modification of the magnetic circuit so that the change in flux is retarded to a substantially greater degree. This provides a longer time for operation of the contacts after energization and deenergization of the operating windings and also provides a greater differential time eiect between successive operation of contacts, thereby providing a greater margin in the opening and closing of various circuits on a single energization or deenergization of the operating winding.

The magnetic circuit for the relay is substantially the same as that described hereinbefore but modified to accommodate the additional flux retarding means. A round core 60 is secured, as by welding, to a web 6| which is common to the three cores 69 that are employed in this particular relay construction. Side plates 62, of magnetic material are secured, as by Welding, to the web 6| and extend therealong and also upwardly, parallel to the core 60. At the upper end of the core 68 there is a pole piece 63 between which and the upper edges of the side plates 62 air. gaps 64 are provided.

'Ihe ux delay means comprises a relatively thick sleeve 61 of conducting material such as copper. around the core 68 together with a larger sleeve or slug 68 of copper which is located, as shown, around the lower end of the core 60. The effect of the relatively large current capacity and low resistance conducting paths around the core 68 provided by the sleeve 61 and slug 68 is to delay the change of the flux in the magnetic circuit formed by the core 60, web 6|, the side plate 62 and pole piece 63 on energization or deenergization of the operating winding 69, which surrounds the sleeve 61. Terminals 10 are provided for the operating winding 69.

At its upper end the core 60 has a, threaded stud 1| which projects through pole pieces 63 and which has a nut 12 threaded thereon for holding the pole pieces 63 in place. In addition the pole pieces 63 are held in alignmentl on the core 60 by an alignment bracket 13 the ends 14 of which are positioned substantially parallel to the core 60. The alignment bracket 13 may be a die casting.

Extending along the pole pieces 63 is a stationary or make contact molding 15 that is formed of suitable insulating material, such as polystyrene. 'I'he molding 15 carries stationary or make contacts 18 which are similar in construction to the make contacts 33, described hereinbefore. They have extensions 11 which permit the making of circuit connections thereto.

Extending along the side plates 62 are transfer reed moldings 88, preferably formed of polystyrene, which carry reeds 8| which in turn'. support relatively small armatures 83 or relatively large armatures 82 at their upper ends;

For the left hand coil, as viewed in Figure 1l, a relatively large armature 82 is provided on one side and a relatively small armature 83 is provided on the other side. Two relatively small armatures 83 are provided on opposite sides of the centrally located coil of the relay construction shown in this figure. For the right hand assembly a relatively large armature 82 is provided on each side. The reasons for using different sizes of armatures in the instant relay construction are the same as set forth in detail hereinbefore' for using different sizes of armatures for the relay construction shown in Figures 1 through 8 of the drawings.

Each of the armatures 82 or 83 carries a contact 84 near its upper end for engagement with make contacts 16. They also carry contacts 85 for engagement'with stationary or break con-4 ends of the reeds 8| and 88 are held in insulated spaced relation by beads 92 of thermoplastic material such as polystyrene, molded along the same.

The reeds 88, which carry the contact supports 81, are initially arranged so that vthey are biased outwardly. They are limited in their movement outwardly by back stops 93 in the form of glass rods which extend between the ends 14 of the alignment bracket 13 and are held in place thereon by clamping springs 94.

As shown in Figures 9 and l0, reeds 95 are molded in the break reed molding 89 and serve to make connection to the coil terminals 10.

`Similar connections are made by wire reeds 86 to the extensions 11 of the stationary or make contacts 16, by being connected to the extensions 11 thereof. The connections vof the reeds 95 and 96 to the coil terminals 18 and the contact extensions 11 may be made by spot welding.

Using the relay construction shown in Figures 9, 10, 11 and l2 of the drawings with large and small armatures 82 and 83 having the weights and sizes of the large and small armatures 42 and 43, reeds 8| having like tension values, and energizing the operating winding 69 with direct current in the manner heretofore described.

Contact 84, carried by large armature 82, engages its make contact 16 before the contact 85, carried by the small armature 83, disengages the break contacts 86, the time diiferential between these operations being greater than that effected in the operation of the first and second relay modification described herein. On deenergization of the operating winding 69 there is an overlap between the time thatcontact 85, carried by the small armature 83, engaged its break contacts 86 and the time that contact 84, carried by the large armature 82, disengaged its make contact 16 which overlap is at least several times greater than the overlap effectedin the de-enerattac i gizationoftheflrstandsecondreiaymodiiications described hereinbefore.

Since certain further changes can be made in the foregoing constructions and different embodiments of the invention can vbe made without departing from the spirit and scope thereof.

it is intended that all matters shown on the accompanying drawings and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. In a relay for switching communication circuits and the like the combination of vertically disposed magnet core means, magnetizing means thereon, pole pieces means extending laterally from the upper end of said core means, a magnetic plate lying. substantially parallel to and spaced from said magnet core means and from said pole piece means to provide an air gap therebetween, magnetic extension means from the lower end of said magnet core means to said magnetic plate, a transverse bar of insulation extending along said magnetic plate and clamped thereto, a plurality of substantially parallel wire reeds fixed in and extending above and below lsaid bar substantially parallel to said plate, magnetic bars constituting armatures fixed to the upper ends of said reeds in bridging relation to said air gap, certain of said armatures having effective areas of one size and others of said armatures havi-ng effective areas of diii'erent sizes, which several armature sizes are rproportioned to effect with a single application of a given potential to said magnetizing means and with the removal of said given potential therefrom, the intersection of a proportionally different number of lines oi' flux and a corresponding given differential'in the time of movement of the armatures to and from their attached positions,

said given differential comprising with at least' one of said change of conditions of said magnetizing means, an overlap circuit controlling operation involving the completion of the movement of said certain armatures to their attracted position prior to initiation of movement of said others of said armatures; contacts moved with operation of said armatures, and stationary contacts carried by said relay structure and disposed for engagement by said movable contacts with operation of their associated armatures.

2. The invention, as set forth in claim 1, wherein time delay means cooperate with the magnetic circuit formed by the core means, pole piece means.. magnetic plate and magnetic extension means to delay the decay of magnetic flux therein responsive to occurrence of the other change of condition of said magnetizing means to eiiect an overlap circuit controlling operation by said armatures with occurrence of said other condition, said armature operation with said other change of condition being converse to that eil'ected with occurrence of said one condition.

3. The invention, as set forth in claim 2 wherein said time delay means comprise a sleeve of conducting material around said core means and within said magnetizing means.

4. The invention, asset forth in claim 2. wherein said time delay means com-prise a slug of conducting material around said core means and between the magnetizing means and said magnetic extension means.

5. The invention, as set forth in claim 1, wherein means are provided for varying the amount of magnetic flux generated by the magnetizing means, comprising a plurality of windings around l0 the core means having different numbers .of turns.

6. The invention, as set forth in claim l, wherein said other armatures have about one-half the eective surface area of said certain armatures.

7. The invention, as set forth in claim l, wherein said stationary contacts comprise a 'set of engageable front contacts and a set of engageable back contacts and the connections to said back stationary contacts comprise wire reeds fixed in and extending above and below the transverse bar of insulation.

8. The invention, as set forth in claim 1, wherein said stationary contacts comprise a set of engageable front contacts and a set of engageable back contacts and wherein the connections to the magnetizing means and said back stationary contacts comprise wire reeds ilxed in and extending above and below a second transverse bar of insulation coextensive with the transverse bar carrying the armature bearing wire reeds.

9. In a relay for switching communication circuits and the like the combination of a vertically disposed magnet core, a magnetizing coil on said core, a 'pole piece extending laterally from the upper end of said core, a pair of magnetic plates on opposite sides of said coil substantially parallel lto said core and spaced from the respective ends of said pole piece to provide air gaps therebetween, magnetic extension means from the lower end of said magnet core to said magnetic plates, a transverse bar of insulation extending along each of said magnetic plates and.

clamped thereto, at least one wire reed fixed in and extending above and below each of said transverse bars substantially parallel to the adjacent plate, a magnetic bar constituting an armature fixed to the upper end of each reed in bridging relation to the adjacent air gap, said armatures having effective areas of different sizes which are proportioned to eiect with each single application of a given potential to said magnetic coil and with each interruption thereof, the intersection of a proportionately different number of lines of flux and a corresponding given differential in the time of movement of the armatures to and from their attracted positions; said given differential comprising for at least one of said changes of conditions of said magnetizing means, an overlap circuit controlling operation involving the completion of the movement of one of the armatures to its attracted position prior to initiation of movement of the other of said armatures, contacts moved by each armature, an insulating contact support on said pole piece, and front stationary contacts carried by said contact support for engagement by certain of said movable contacts with said one change of condition oi' said magnetizing means, and stationary back contacts for engagement by others of said movable contacts responsive to said other change of condition of said magnetizing means.

10. The invention, as set forth in claim 9, wherein time delay means cooperate with the magnetic circuit formed by the magnet core, pole piece, magnetic plates and magnetic extension means to delay the decay of magnetic flux therein responsive to occurrences of the other change of condition of said magnetizing coil to effect an overlap circuit controlling operation by said armatures with occurrence of said other condition, said armature operation with said other change of condition being converse to that effected with occurrence of said one change oi' condition.

11 11. The invention, as set forth in claim 10, wherein said time delay means comprise a sleeve oil conducting material around said core and within said coil.

12. 'I'he invention, as set forth in claim 10 wherein said time' delay means comprise a slug of conducting material around said core and between said coil and said magnetic extension means.

13. The invention, as set forth in claim 9, wherein said other armature has about one-haif the effective surface area of said one armature.

14. The invention, as set forth in claim 9, wherein the connections to said back stationary contacts comprise wire reeds fixed in and vextending above and below the transverse bargof insulation.

`15. The invention, as set forth in claim 9, wherein the connection to the magnetizing coil and stationary back contacts comprise wire reeds xed in and extending above and below a second transverse bar of insulation coextensive with the transverse bar carrying the armature bearing wire reeds.

16. In a relay for switching communication circuits and the like, the combination of at least two associated armatures, each having multiple contacts associated therewith, a magnetic circuit for each of said armatures, common winding means for said magnetic circuits for placing said magnetic circuits alternatively in the energized and in the deenergized conditions to operate each of said armatures and their attached contacts between two positions, said armatures having differentially-proportioned effective areas to eect, with each change of condition of said winding means, the intersection of a different number of lines of flux and a corresponding diiferential in the time of movement of the armatures and their associated multiple contacts, said differential comprising for at least one of said changes of condition, the completion of movement of the armature of one said areas to its new position prior to initiation of movement of the armature having the other of said areas to its new position, whereby an overlap in the respective circuit or circuits controlled by the associated contacts is established.

17. In a relay for switching communication circuits andthe like, the combination of a plurality of movable armatures each having a set of multiple contacts individual thereto, eachof said armatures having an associated break contact engageable by one of its multiple contacts anda stationary make contact engageable by the other oi its multiple contacts, a plurality of similar magnetic circuits for attracting said armatures and moving said multiple contacts between said make and break contacts, winding means in said magnetic circuits for energizing and deenergizing same to operate all oi the associated armatures responsive to each single energization and each single deenergization of said winding means, each of said winding means being common to several of saidmagnetic circuits and their associated armatures. certain of said armatures comprising effective areas whch are smaller than those of other of said armatures, certain of said common winding means being operative to control armatures of both sizes and others` of said common winding means being operative to control armatures of the same size, said certain common winding means being eifective responsive to one of said changes of circuit condition to effect an overlap circuit controlling operation comprising movement of the larger size armatures to theirvnew position prior to movement of said smaller sized armatures from their previous position. v

18. In a relay for switching communication circuits and the like, the combination of at least two armatures having multiple contacts associated therewith, a magnetic circuit for each of said armatures including an air gap, winding means on said magnetic circuit for alternatively energizing and deenergizing the same to operate said armatures and attached contacts, said arma-` tures being positioned to be controlled by said magnetic circuit for bridging said air gap and having effective surface areas of diierentially proportioned sizes to eiect intersection of a proportionately different number of lines of ux and a corresponding differential in operation of said armatures responsive to a single application of a given potential to said winding means and responsive to interruption of said given potential supply thereto, said differential operation comprising an overlap circuit controlling operation involving completion of movement of one of said armatures on energization of said winding means prior to initiation of movement of the other armature, and differential control means for effecting a differential operation of said armatures on deenergization of said winding means which involves an overlap circuit controlling operation comprising completion of movement of said other armature to its return movement prior to initiation of movement of said one armature.

aonrrr K. MCBERTY. DONALD s. BAKER.

nEFEnENcEs crrEn UNITED STATES PATENTS Number Name Date 928,104 Brodton July 13, 1909 1,128,562 Webster Feb. 16, 1915 1,272,317 Reed July 9, 1918 1,324,452 Kasiling Dec. 9, 1919 1,475,166 Beall et a1. Nov. 27, 1923 1,646,956 Erickson Oct. 25,1927 1,681,473 Erickson Aug. 2l, 1928 1,800,256 Keller Apr. 14, 1931 1,974,852 Menzel et al. Sept. 25, 1934 2,396,332 McBerty Mar. 12, 1946 FOREIGN PATENTS Number Country Date 748,050 France Apr. 10, 1933

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