US2327533A - Relay - Google Patents

Description

Aug. 24, 1943. N. A. KURMAN 2,327,533

RELAY Filed April 13, 1942 3 Sheets-Sheet l INVENTOR.

ATTORNEYS Aug. 24,'1943. N. A. KURMAN RELAY Filed April 13, 1942 3 Sheets-Sheet 2 /l40 L zNvENToR.

(LWN/(Ulf AT ORNEYS Aug. 24, 1943. N.' A. KURMAN 2,327,533

RELAY Filed April 15, 19,42 3 sheets-sheet 3 INVENT OR. v

Y J" furman/ ATTORNEYS Patented Aug. 24, 1943 UNITED STATES PATENT OFFICE Application April 13, 1942, Serial No. 438 S95 (Cl. l7533$) 13 Claims.

rlhis invention relates to relays, and more particularly to sensitive relays intended for use in aircraft radio, and for keying, antenna changeover, and automatic controls of various kinds.

The primary object of my invention is to gcnerally improve sensitive relays.

The relay employs a U-shaped pole piece having a coil assembly around one arm of the pole piece. The armature extends across the ends of the pole piece, and fulcrurns cn the other or cutside arm of the pole piece. It is normally urged to open position by a restoring spring connected to an adjusting screw.

One specific object of my invention is to provide a simplified and sturdy mounting for the parts of the relay, and with this object in View, I provide a single sheet meta-l bracket, the base of which is secured to the insulation base of the relay, and the upper part of which functions, first, to hold the pc-le piece rigidly in position, second, to retain the armature at the ends of the pole piece, and third, to hold the adjusting screw f or the spring.

The relay of the present invention is not only sensitive, but has 'almost meter accuracy. For example, in a typical case, the operating specification may require the relay to act at 400 milliamperes and to drop out or release at 200 milliamperes. A small tolerance may be provided,

the four-hundred figure being given a range, for

example, of 380 to 420 milliampercs. In practice, I found that while many relays functioned satisfactorily, other relays of seemingly identical construction would tend to stick within the critical range of current, and so spoil the desired V accurate response. On careful study of this problem, I found that the effective adjustment of the restoring spring is sometimes altered during operation by a shift of the effective location of the fulcrum of the armature, and a consequent change in the leverage system on which the spring works. This shift is from one edge to the other of the pole piece end. It may be caused by a slight convexity of the armature toward the poles, o-r by slight inequality in the length of the poles, such that the ends, While square, do not lie in one plane, or may be caused by a slight langularity in an outward direction at the end of the fulcrum pole,

One object of the present invention is to overlll of the armature to make it slightly concave toward the poles. An alternative cure is to grind the end of the outside pole to make it slightly angular in an inward direction.

The adjustment of a sensitive relay is critical, and a shift in the location of the pole piece of only say, one-half of one-thousandth of an inch, may be sufficient to throw the relay out of adjustment. In accordance with a further feature and object of my invention, the mounting of the coil assembly on the base is preferably made independent of the mounting of the pole piece, a slight clearance is preferably provided between the side 'arm of the pole piece, and 1e coil assembly surrounding the same, so that any change in the location of the coil assembly will not affect the position of the pole piece and the adjustment of the relay.

The relay may be made in varying types to fit diiferent conditions. Sometimes an end pivot for the armature will be wanted, and at other times 'a center pivot. Sometimes the coil may be short, and at other times a greater number of turns may be wanted for a more powerful relay, thus leading to the use of a longer coil. Sometimes the entire armature is connected in the external or controlled circuit, but at other times the Contact end of the armature must be insulated. Some relays are intended for A. C. and some for D. C. operation.

A further object of the invention is to simplify the provision of these different types, and to make it possible to supply the same at reasonable cost. For `this purpose I have provideda single molde l insulation base, which .may be used in common for all types, the said base preferably being provided with a few eXtra holes which make it universally useful for the diierent relay types. Many of the metal parts are also usable for most or all of the relays.

To the accomplishment of the foregoing, and other objects which will hereinafter appear, my invention consists in the relay elements and their relation one to the other, as hereinafter are more particularly describe in the specification, and sought to be defined in the claims. The specification is accompanied by drawings in which Fig. l is a plan View of a typical relay enibodyn ing features of my invention;

Fig. 2 is an end elevation of the saine;

Fig. 2a is a detail;

Fig. 3 is a section taken approximately in the plane of the line 3 3 of Fig. l;

Fig. 3a is a detail;

Fig. 4 is a plan view of the molded insulation base with the parts of the relay removed;

Fig. 4a is a detail;

Fig. 5 is a perspective View showing a bracket forming a part of the relay;

Fig. 6 is a schematic drawing explanatory of one cause of fulcrum shift;

Fig. 7 schematically illustrates another cause of this dimculty;

Fig. 8 is a diagrammatic exaggerated showing of one way to avoid fulcrum shift;

Fig. 9 diagrammatically illustrates one method of grinding the ends of the pole piece;

Fig. l diagrammatically illustrates another method of avoiding fulcrum shift;

Fig. 11 is a plan view of a relay modified to use a center pivot;

Fig. 12 is an end elevation of a modified relay having an insulated armature;

Fig. 13 is a plan View of the same relay;

Fig. 13a is a detail drawn to enlarged scale;

Fig. 14 is a planview of a relay having a lengthened coil;

Fig. 15 is an end elevation vof the coil assembly;

Fig. 16 is an end View showing .a shading coil used when the relay is to be operated by alterhating current;

Fig. 17 is a side elevation of the end of the pole of such an A. C. relay;

Fig. 18 is a similar view of a pole intended for DfC. operation; and

Fig. 19 is a sectio-n through a part of the base taken approximately in the plane of the V-line ill-l 9 of Fig. 4.

Referring to the drawings, and more par- :is

ticularly to Figs. 1 through 5, the relay comprises a molded insulation base i2, a Ushaped pole piece iii, a coil assembly i disposed on the inside arm i5 of the pole piece, while the free end of the outside arm 2Q of the pole pieceacts as a fulcrum for the armature v22 extending across the ends of the pole piece. The pole piece is lpreferably made of a heat-treated nickel alloy. The working end of the armature carries appropriate contact surfaces 25 which cooperate with contact screws 25 and .28, threadedly received in contact posts 31) and 32. The armature is normally pulled to open position by .a pull spring 34, connected at one end to the armature, and at the other end to a threaded adjusting -screw or Abar 35.

A single sheet metal support bracket carries the pole piece, the armature, and the adjusting screw.y `The shape of this support bracket is best shown in Fig. 5, where it will be seen .that it comprises a base portion SS and an upright portion (it, the latter including an extension (i2 and an outwardly bent ear lid. rIhe bracket is rigidified by indented reenforccments (it. Auxiliary locating lugs it may be turned downwardly at the ends of the base 33. These are in addition to three holes 5i) for screws.

Referring now to Fig. 4, the molded insulation base l2 has four recesses 52 properly located to receive the lugs 48. It is further provided with three holes 5G to receive the screws which pass through the holes 5E! of the bracket. These Aholes 56 may be threaded to receive the screws, or the bottom of the base may have enlarged (countersunk) holes to receive nuts for the screws, or, as I prefer, small metallic bushings or inserts may be molded directly in the base, these inserts being internally threaded to receive the screws. The outside is preferably knurled to receive the insulation material molded thereabout. The top ends of these bushings do not project above the base. One of these flush bushings is shown in section in Fig. 4d of the drawings.

Reverting now to Figs. 1, 2 and 3, the outside arm of the pole piece is secured directly against the upright bracket wall it by means of screws 55. While not shown in the drawings, thin shakeproof washers are preferably inserted beneath the heads of the screws to guard against possible loosening of the same.

The armature 22 passes freely through the large opening 53 (see Fig. 5) of the bracket, and may then be moved into the stepped or reduced portion 5l. The armature is notched, as shown at 55 in Fig. 2a, to receive the stepped portion 5l. As a result the armature is retained at the end of the outside arm 2) of the pole piece. It is held against downward tilting by the action of the notches 55. However, these are loose enough not to interfere with the desired slight swinging action of the armature when viewed in plan. The arcuate projection il (Fig. 5) is what bears against the outside of the armature, and this permits. the yarmature to seat itself properly against the ends of the pole piece. The clearance or closeness of support of the armature against the outside pole is adjustable by reason of slots i3 (Fig. 5), the Dole piece being bodily moved relative to the bracket while the armature is already in position, following which the screws 56 (Fig. 1) are tightened. A shim may be placed between the armature and the fulcrum pole when securing screws 55. The shim may be a few, say two, thousandths of an inch in thickness. When the armature thus lies against the pole piece it cannot move from step 3l (Fig. 5) to the enlarged space 5t.

The spring adjusting bar passes freely through the outwardly bent ear 4d, previously referred to, the adjustment of this bar being fixed l.by oppositely tightened nuts The ear is preferably slotted, as shown at l5 in Fig. 5, thereby facilitating assembly and disassembly of the relay. The threaded bar '35 is Vpreferably flattened or squared on the outside, as is 'best shown in Fig. '3, the threads being vleft in full at the corners. This construction is yconvenient so that the bar maybe held against rotation while adjusting the nuts 55. The slot preferably fits the flat sides Vof the bar, thus itself preventing rotation of the bar.

The coil assembly l5 might be held in position by the pole piece. However, I prefer to provide at least a slight clearance between the inside arm of the pole piece and the inside of the coil assembly, Vso that any slight change in position of the coil assembly, as for example ii accidentally pushed or struck, will not be accompanied by a like movement of the pole piece, for that may throw the relay out of adjustment. l therefore mount the coil assembly independently on the base of the relay. Referring to Fig. 15, the end pieces 52 of the coil assembly are shaped as shown, andthe lower corners are provided with tiny metallic eyelets 54. One eyelet at each end is used for the end of the magnet wire coming out of the coil. These two eyelets are also used to locate the coil o-n the main base, as by soldering the same to metallic straps. A third` eyelet is additionally secured by soldering the same to the head of a locating screw, so that the coil assembly is held to the base at three points. 1t may, of course, be held at four points by usingv the fourth eyelet, and another locating screw. The slot 5E (Fig. 15) is slightly larger than the pole piece the coil assembly. This connection also serves as an electrical connection for one end of the coil. Another holding point is the point 12, where a longitudinally twisted metal strap 74 extends between one of the eyelets and a terminal screw 1B. This acts also as an electrical connection to the other end of the coil. It will be understood that the ends of the magnet wire pass from inside the end pieces of the coil assembly, through the eyelets, to the soldered connections. The third holding point is at the numeral 18, where a small selfthreading drive screw (such as a Parker-Kalou screw) is driven into a hole in the base. This is the hole 80 shown in. Fig. 4. It may be molded, or, being tiny, it may be drilled. If drilled its location is readily changed for a center pivot relay. Solder is owed at the point 'I8 between the head of the screw and the immediately adjacent eyelet on the end piece 62 of the coil assembly. If desired, a short bit of wire or metal may be laid between the head of screw 18 and the eyelet, thus guiding and supporting the ow of solder therebetween.

In the present relay (Fig. 1) the amature is not insulated. It is connected in circuit from terminal screw 82 by means of a strip of metal 84, which is folded at right angles, thus providing an extension 86 which extends parallel to and almost beneath the armature. Electrical connection is completed by means of a flexible pigtail wire 88, the lower end of which is soldered to strip 86, and the upper end of which is soldered to a tiny lug 90 which is eyeletted to the armature.

A conventional short upright soldering lugr 92 may be provided at each of the terminal screws T0, 1B, and 82. These soldering lugs are detachably held beneath the heads of the screws, the latter being threadedly received in metal inserts or bushings molded into the base. The upper ends of the bushings are anged or riveted to hold the connecting straps 68, 14, and 84 previously referred to, as is best shown in Fig. 3a., in

which the enlarged apertured end of a connecting strap is indicated at 84, while a. rectangular metal washer with upturned corners is shown at 96, the latter being useful when connecting a wire` directly beneath the head of the terminal screw. They are also useful to hold the free soldering lugs 92 against rotation. The rectangular washers are received in mating rectangular recesses in the base, four of which are clearlv shown in Fig. 4, and one of which is shown at 98 in Fig. 3. The section vthrough the latter is through insert |00, which is not used in the particular relay here shown, and which therefore has not been riveted over on top of any other parts. When the end is riveted over, it takes the form shown at |02 in Fig. 3a.

The contact posts 3D and 32 are formed integrally with sheet metal base portions |04 (Figs. 1 and 2), which are disposed on top of raised blocks of insulation |86. Each post is held by two screws |08 and I lil. Of the latter, the outer screw is also used for electrical connection to the relay, and for this purpose the corners are turned upwardly, as indicated at H2. In some variant forms of relay (double pole, in which two contact screws are wanted on one side of the armature),

I provide two contact posts, each of which is held in position by only one screw, instead of a single post being held by two screws, as here illustrated.

In order to increase the length of thread between the contact screw and the contact post, the metal of the latter is preferably extruded inwardly. for a. substantial distance, as is indicated at ||4 in Fig. 1. In this way the eiiective length of the thread may be increased to about twice the thickness of the metal used for the contact post, It will be understood that the ends of the contact screws are provided with special inserts or nonpitting'surfaces for 4long wear. Silver or other metal may be used, depending on the particular use of the relay. The same applies to the contact surfaces 24 on the end of the armature itself.

It will be understood that for any one adjustment, the eiect of the pull spring 34 on the armature 22 depends on the precise location of the fulcrum on which the armature is moved. The fulcrum should not shift. Under some conditions it may do so.

Thus, referring to Fig. 6, it will be seen that when the armature is in the closed position 22, the fulcrum is at the inside corner I |6 of the outside pole |4. When the armature is in the open position 22 the fulcrum is at the outside corner ||8 of the pole 28. Between these two positions the armature will lie iiat against the end of pole 20. There is evidently a distinct change in the leverage on which the pull spring operates when the fulcrum shifts between corners I |6 and ||8. In Fig. 6 the armature is straight, and the pole ends are square, but the fault arises because the pole ends do not lie in a common plane. The error is `greatly exaggerated in this and succeeding diagrams, for the sake of clarity.

The same difficulty may arise for other reasons, for example, because of the armature being bent convexly toward the poles. This is shown in Fig. 7, in which it will be seen that the convex armature |22, when in the closed position, turns on the inside corner |24 as a fulcrum, whereas, when in the open or broken line position |22, it turns on theoutside corner |25 as a fulcrum. This same diiculty may arise if the end of the outside pole 20 has a slight slope outwardly (upwardly toward the outside as viewed in Fig. 7), instead of being perfectly square.

One method of curing these difcultes is to intentionally bend the armature slightly concavely toward the poles, this being illustrated at |30 in Fig. l0. It will be evident that with this change, the armature can move between the solid and broken line positions |30 and |33', while at all times using the outside corner |3| of the pole |32 as a fulcrurn.

Another method is that illustrated in Fig. 8, in accordance with which the end |34 of the outside pole |36 is ground at an angle sloping inwardly. In such case the armature can move between the closed and open positions |38 and |38', while always using the outside corner |40 as a fulcrum. It is not necessary for the other lrubbed vagainst planar grinding surface |48. Einerypaper'securedlona-'steel disc lmay be used; After grinding theehuis, the spreader 'SIM is removed, permittin'g theipoles to spring Abackto originalparallelcondition. 'lhisprovides'v the desired slightangle at thef'ends.

1t 'should be -kept 'in mind "that the changes herer illustrated are veryvslight. `For example, with "a `pole piece about yan inch 'anda half in length, the ends are spread only'a'rmatter of .se of an inch. The angle should be keptislight, or, ii the armature is bent-as 4shown in Fig. 10,the concavity of the same shouldbe keptveryr'slight, in'order 'not vto appreciably increase the reluctance, or decrease the efli'ciency and power, of the relay.

' *Reierri'ng now to Fig. 11,`1 there shovvamodication in which the relay employs "a center pivot instead of anend pivot. For this purpose a bracket les is used, which is similar to that previously employed, except'that Iit is reversed aS to transverse dimension, that is, if 'the bracket of Fig. l5 is considered to be right-hand, vthen the bracket |54 lfor the center pivot relay Vis lefthand. V."Elpecii'cally,"the relative disposition of the ear '55 (Fig. 11) and the -base |58 is reversed compared `to ythe arrangement in Fig. 5. The shape of the brackets, before bending, is the same. A single cutting 'die may be used for both. Only the'bending dieis different. The pole piece 'is the same, Vand the same screws, inserts, and slots in the base vare used to mount the bracket 4l'al. The pole piece is inverted, the bracket being secured, as before, Yto the 'outside pole (meaning outside the coil), said outside pole having two tapped holes to receive the two screws shown. 'The location of the inserts in the'base is so selected, as will be seen by comparisonoiFigs. 1 and 11, that the coil 'is moved inwardly'in Fig. 1 to make roonrfo'r the 'pivot and adjusting spring mechanism at 'the outside of the coil, whereas in Fig. ll, the coil is moved outwardly, 'thus providing increased room for the pivot and adjusting spring mechanism von the other side of the coil. This desiredV result is obtained because the screws which hold the bracket to the base are displaced from the center line of the coil, and theamount of that'displacement is selected to obtain 'the desired shift Ain coil position. In the specinc example here illustrated, the screws are located halfway lbetween the arms "of the pole piece. v

In Fig. 1l the armature |55 'differs from that previously'desoribed in being shorter, and notched at the point |52 to fit in the bracket,'and in similarly changing the 'locationoic the loop 54 struck therefrom, which loop receives .one end of the restoring spring. Also the functions of the terminal screws |56 and |68 'are reversed, the screw |55 having aconnection |15 to theeyelet and coil endof the coil assembly, and the screw |63 having a connection |12 to a iieXible pigtail wire |74 leading to the armature, and connected thereto at its upper end by means of a small eyelet. The connection |16 between terminal |78 and the other end of the coil and its eyelet, is appropriately lengthened. The location of drive screw |19 for a soldered holding connection to a third cornerV eyelet of the coil assembly is also changed. In other respects the relay is unchanged. As before, the coil is mounted independently of the pole piece, and a slight clearance (say 20 thousandths of an inch) is provided therebetween.

Another modified relay is shown in Figs.v12 and 13. 'This relay resembles that shown in Fig.

11 `lin ihavin'g a center pivot, -butit diiers in insulating the armature vfrom the external circuits controlled by the relay.

Referring to Figs. '12, 13, and 13a, the armatureconsists'ofan inner portion lei), and an end portion |82, the latter being connected to the part |35 bythin fpieces `of mica |35, these being eyeletted -by 'means of four eyelets, two passing through the .part `|t3'as shown at |85 'in Fig.13a, and the other two passing through the part i322 as shown at E88 Vin Fig. 13a. Inthis way the'enfi portion |82 is `insulated frcm'the armature .ii'of the relay. There remains, however, the problem of connecting the end portion to an external circuit. This is done 'by 'means of a generally L- shaped'pieceof very thin, flexible, resilient material, best "shown at 19|) in Fig. 12. One end is connected tothe end portion |82 ofthe armature (within lthe mica) by means .of the eyelets ice previously referred to. The remote end |92 of the long arm of the L-sh'aped piece of metal is connected by means of a screw |94 to a connecting member |96 extending from terminal screw |98 to a point beneath the long-arm |22. It will be evident that because of the length and flexibility of the L-shaped connectingpart ''there is no appreciable resistance to movement at the contact end of the armature.

It will be understood 'that the 'relay of Fig. l may also be changed to use pieces of micato insulate the end of the armature, as shown 'in Fig. 13a, and that in such case the functions oi the terminal screws -19 and 82 in Fig. 1 will remain the Same as there shown, or the same as shown for theterminal Yscrews |98 and 2Min Fig. 13. This is reversed from the functions or the terminal screws I|66 and'l in Fig. l1.

Fig. 14 shows still another modilied form of relay using a coil'assem'bly 252 which is substantially longer than that used in the relays previously described.` The relay of Fig. ie happens to be a center pivot relay llike those shown in Figs. 11 and 13, the essential change being that the pole piece and vcoil assembly have been le'ngthened. The support bracket is unchanged. The reason the same support bracket may be used, may be'exqtlained with reference to Fig. 4 showing the insulation base. Referring to Fig. it will be noted that in vadditon to the kthree holes 54, va. fourth hole |55 is provided, the rspacing between all of the 'holes being equal; YMoreover, in yaddition vto 'the 'four rectangular recesses 52, four additional recesses |52 are provided, these being spaced from the recesses 52 by the same amount that Athe holes 'are spaced from one another. It will thus `b'e evident that the support bracket may be lmoved and secured to the base by means of the Ihole |58 and two of the holes 5ft, the 'right-hand hole 54 not being used. At the same time, the recesses |52 will receive the 'downwardly turned lugs 43 (Fig. 5) the other recesses 52 remaining idle.

Reverting now to Fig. 14, it will be seen that the 'base of the bracket, shown in dotted lines'at 38, is in the left-hand instead of the right-hand position. The coil vassembly 252 may therefore be lengthened by the 'amount of this leftward movement of vthe bracket. Inasmuch as the position of the contact posts and their screws 26 and 28 has not vbeen changed, the relative displacement of the parts of the relay vis taken care of by bending or offsetting the ends of the armature, as shown at 204.

As inthe case 'of Fig. 1l, the terminal screw 20S is connected to 'one end of the "coil, the terminal screw |08 is connected to the armature by means of a flexible pigtail wire 2l0, and the terminal screw 2l 2 is connected to the other end of the coil by means of connecting strap 2l4.

It should be understood that the lengthened coil may also be used with an end pivot instead of a center pivot. In other words, the bracket of Fig. 1 may be moved leftward in the saine manner as has just been described, in order to accommodate a longer coil assembly. The armature is then bent or offset, as described in conn nection with Fig. 14.

Any of the relays may be designed for either A. C. o1' D. C. operation. When designed for D. C. operation, it is unnecessary to employ shading coils such as are indicated at 2l6 in Fig. l, at 2|8 in Fig. 11, and at 220 in Fig. 14. These shade coils are simply stamped uloops of copper or other conductive metal, which are forced into slots 226 in the'end of thev pole piece, best shown in. elevation in Fig. 17. The shade coils are pressed into the slots, and may be generally rectangular in outline, asis indicated at 222 in Fig. 16. Fig. 16 is an end View of the pole, showing how the copper loop 222 is fitted into two slots in the end of the pole piece, so that they are held between three tenen-like projections 224. In the case of a D. C. relay, the end of the pole piece need not be slotted, it being left whole as shown in Fig. 18. f

Considering the molded insulation base itself, it may be pointed Iout that a raised wall 228 (Fig. l and Fig. 4) is disposed between one pair of terminals, whilea raised wall 230 is disposed between the other pair rof terminals, thereby guarding against accidental short circuit between the leads going to these terminals. Moreover, raised walls 232 are provided around the corner mounting screws, thereby protecting against accidental contact between a lead wire and the head of a mounting screw, which in turn might short circuit to the metal chassis on which the relay is mounted. There is also a wall 234 extending alongone edge, this being primarily to increase the strength and rigidity of the base.

A relatively large opening 236 is provided through the base in the space between the contact posts. As isbest shown in Fig. 19, this hole is initially blind, it being closed by a very thin iin 238 of insulation formed integrally with the base, The web or nn 238 is thin enough to be broken away, if it is desired to use the passage 236. yThe passage 236 is used in the event that the relay-is to. be fully covered by means of a dustproof cover. :In such casevthe lead wires are brought in from beneath the base, through the passage k236, and from there radiate outwardly to the different terminal screws. In most cases the relay is not enclosed, and there is no need to push the web 238 out of the base. The web is kept very thin, particularly at its connection to the base, so that the hole will be smooth r can be smoothed when the Web is broken awa-y.

The bottom of the base has feet at the, corners, as will be seen at 240 in Figs. 2 and 3. These prevent rocking of the base, and give it a firm foundation, despite possibility of slight warping of the chassis on which the base is` mounted. This in turn guards against distortion of the base when it is mounted in position, which in turn Will help prevent a change in the relation of the Working parts of the relay, with possible need for readjustment. The feet also make it possible for lead .wires to run beneath the base to the passage 236 previously referred to, in the event that the relay is covered.

The raised pedestals of insulation |06 for the contact posts 30 and 32 are desirable mechanically because they shorten a-nd therefore stiften and rigidity the contact posts, and are desirable electrically because they increase the length of surface path between the contact posts and the other terminals on the base, thereby improving the insulation therebetween.

It is believed that the construction and method of assembly and use of my improved relay, as well as the many advantages thereof, will be apparent from the foregoing detailed description thereof. It will also be apparent that, while I have shown and described my invention in several preferred forms, many changes and modications may be made in the structure disclosed, without departing from the spirit of the invention as sought to be defined in the following claims.

I claim:

l. A relay comprising an insulation base, a U-shaped pole piece, an armature extending across the ends of said pole piece, a coil on one arm of said pole piece, a spring and adjusting screw for normally pulling the armature away from the coil, and a single bracket bent out of sheet metal for supporting the pole piece and holding the adjusting screw, said bracket having a base portion secured to the insulation base, an upright portion secured to the outside arm of the pole piece, and an outwardly bent ear receiving the adjusting screw.

2. A relay comprising an insulation base, a U- shaped pole piece, an armature extending across the ends of said pole piece, a coil on one arm of said pole piece, a spring and adjustinfr screw for normally pulling the armature away from the coil, and a single bracket bent out of sheet metal for supporting the pole piece and holding the adjusting screw, said bracket having a base portion secured to the insulation base, an upright portion secured to the outside arm of the pole piece, and

. an outwardly bent ear receiving the adjusting screw, said adjusting screw being iiattened at opposite sides and having two nuts thereon, and said ear being slotted with an open ended slot dimensioned to non-rotatably receive said screw with the nuts on opposite sides cf the ear.

3. A relay comprising an insulation base, a L'- shaped pole piece, an armature extending across the ends of said pole piece, a coil on one arm of said pole piece, the end of the other arm of said pole piece acting as a fulcrum for the armature, and a single bracket bent out of sheet metal for supporting the pole piece and retaining the armature in position, said bracket having a base portion secured to the insulation base, and having an upright portion secured to the outside arm of the pole piece, the upright porticn including an extension With an opening therethrough for receiving the armature, said extension being immediately adjacent the fulcrum acting pole piece, said armature being notched to mate with the top and bottom edges of the aforesaid opening.

4. A relay comprising a molded insulation base, a U-shaped pole piece, an armature extending across the ends of said pole piece, the end of the other arm of said pole piece acting as a fulcrum for the armature, and a single bracket bent out of sheet metal for supporting the pole piece and the armature, said bracket having a base portion secured to the insulation base, and an upright base, a U-shaped pole piece, an annature extending across the ends of said pole piece, a coil on one arm of said pole piece, the end of the other arm of said pole piece acting as a fulcrum for the armature, a spring and adjusting screw for normally pulling the armature away from the coil, and a single bracket bent out of sheet metal for supporting the pole piece, the amature, and the adjusting screw, said bracket having a base portion secured to the insulation base, an upright portion secured to the outside arm of the pole piece, and an outwardly bent ear receiving the adjusting screw, the upright portion including an extension With an opening therethrough for receiving the armature in order to retain the same at the outside pole end, the passage through the coil assembly being slightly larger than the inside arm of the pole piece to provide a slight clearance therebetween permitting independent support; and positioning of the pole piece and the coil assembly, said coil assembly including end pieces which `extend downwardly to the base and which have small eyelets therethrough, said coil assembly being held on the base by means of connection straps soldered to said eyelets, two of said straps extending to terminal screws and acting as connections for the coil Winding.

NATHAN A. KURMAN.

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