US1886629A - Electrical switch arrangement - Google Patents

Description

Nov. 8, 1932. E. J. BLAKE ELECTRICAL SWITCH ARRANGEMENT Filed Nov- 2 1924 3 Sheets-Sheet 1 awwwntoz 951 a alum I W M Nov. 8, 1932. E. J. BLAKE 1,886,629

ELECTRICAL SWITCH ARRANGEMENT File NOV- 1924 5 Sheets-Sheet 2 anvemtoz 1% 2.6% A I b WZM NOV. 8, E. J. BLAKE I ELECTRICAL SWITCH ARRANGEMENT Filed Nov. 25 1924 5 Sheets-Sheet 3 amvemtoz Patented Nov. 8, 19 32 UNITED STATES PATENT OFFICE ELI J. BLAKE, OF BUFFALO, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO SIM- PLEX EQUIPMENT COMPANY, INC, OF NEW YORK, N. Y., A CORPORATION OF DELA- WARE ELECTRICAL SWITCH ARRANGEMENT Application filed November 25, 1924. Serial No. 752,173.

My invention relates to improvements in electric switch arrangements. The main object of the invention is to provide a construction and arrangement of parts which is easily assembled, in which certain of the parts may be easily adjusted as required and an arrangement which is easily disassembled for repair and replacement of parts. A further obj eot of the invention is to provide an improved form of relay controlled main switch. F urther and more specific objects, features and advantages will more clearly appear from the detail description given below taken in connection with the accompanying drawings which form a part of this specification. The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the drawings Fig. 1 is a front view of a switch arrangement embodying my improvements in the preferred form thereof, the front cover plate being removed. Fig. 2 is a transverse section taken on the line 22 of Fig. 1. Fig. 3 is a section taken on the line 3-3 of Fig. 2. Fig. 1 is a section taken on the line l% of Fig. 2, and Fig. 5 is a bottom View of the switch arrangement with the bottom member and parts attached thereto removed. Fig. 6 is a detail perspective showing the knife edge mounting for one of the armatures. Fig. 7 is an end view illustrating the method of connecting the same armature with its contact member and Fig. 8 is a diagram illustratin a system in which the switch arrangement is particularly useful.

Referring to Figs. 1 to 5, 9 represents an iron box like structure having an insulating plate 10 screwed to the top thereof as by screws 11, and secured upon the insulating plate 10 by screw 12 is a bracket 13. A plate of insulating material 14- closes the bottom of the box like structure and is secured thereto as by screws 15, and secured to this insulating bottom member 14 are brackets 16 and 16 The brackets 13 and 16 and 16 may be bolted to any suitable support or insulating panel in upright position as by bolts 17 in order to secure the arrangement in place. These bolts and brackets serve as the only terminals required for external connection and by removing the nuts on the three bolts 17 the whole switch arrangement may be bodily removed. The front of the box-like structure is preferably closed by brass plate 18 secured thereto by screws 19. Depending within the boxlike structiiire from the top part thereof is a magnetic core 20, the same being held in place by locking screw 21. In front of this core 20 there also depend from the top part of the box like structure three magnetic cores 22, 23 and 2 1 arranged in a row and each held in place as by locking screws 25. The core 23 carries the combined magnetic flux of the core 22 and 24: and is therefore preferably of larger cross section than the latter cores. The iron box structure serves as a magnetic yoke for all said cores. There is placed about the core 20 an electro-magnetic winding 26, the same being held in place on the core by an iron washer 27 which is screwed to the core and serves also as an extended pole piece. The winding is prevented from jarring by means of a bent spring washer 28 inserted between the top of the winding and the top of the box like structure 9. The rear portion of the box structure has a bottom portion 97 having a circular hole 98 therethrough which permits the coil 26 to be easily assembled on its core 20 before the insulating plate 14 is attached. Located just below the core 20 is a suitable arn'iature 29 for the electro-magnet 26. The armature 29 is provided with a stud 30, rigidly attached thereto, which stud extends loosely through an opening in the bottom insulating member 14 and also through a laminated spring leaf main switch member 31 and is provided with a removable ball shaped head 32, which engages the switch member 31 at the bottom side thereof preferably seating within a socket there provided (see Figure 2). A spiral compression spring inserted between the switch member 31 and the bottom member 14: tends to force the switch member 31 away from its cooperating fixed contact 34; which is formed as partof the bracket 16. hen the electroanagnet 26 is properly energized, it attracts the armature 29 toward the core 20 and so causes the switch 31 to be raised against the action of the spring 33 and make contact with contact 34-. One end of the main switch member 31 is secured as by screw 37 to a block 36 which is attached to the insulating plate 14 so that this end of the switch member 31 is substantially fixed. The switch member 31 however, is preferably of, the leaf type so that its flexibility permits the opposite end thereof to be drawn into contact with cont act 34, upon the energization or the electro-magnet 26. A

bolt 37 passes through the brachet'member' 15 and through the bottom member 14. The block 36 is provided with a binding post screw 38 whereby electrical connection may bem ade between the switch member 31 and strap conductor 93. 'The cores 22 and 24 have iron washers 39 screwed to the bottom ends thereof for the purpose of holding in place windings 40 and 41 respectively on said cores and providing extended pole pieces for the cores. Likewise the core 23 is provided with a washer 42 on the bottom thereof for holding in place thereon winding 43 and providing an extended pole. Curved spring plates 44 are inserted between the tops or these electro-magnetic windings and the top of the box like structure in order to hold the coils resiliently in place and prevent jarring thereof. Secured to the bottom of the washer 42 is aplate- 45 provided with two downwardly turned portions 46 proyid'ed with knife edges at 47. The parts 45 and42 are securedto the'core 23 by means of :l'sci'ew 48 provided with a suitable collar to space the head of the screw at some distance fromthe'plate 45. 49 represents an armature haying a' central aperture through which passes loosely the screw'48 and the said bushing and the armature is also cut away on its side edges to r ceive the bent-down portions 46 whereby it may be properly pivoted upon the linii'e edges 4'7. The armature will normally be'attracted by the magnet 43 and hence will be kept in contact with the knife edges 47, and so spaced slig itly from the head of the scre'w'4 -3, One end of the rmature extends under the pole of electro-magnet 41 while the other end of the armatureextends under the pole of electro m'agnet 40. Secured tothe insulating base 14 by the bolt 87 is a spacing block 50 to which is secured by the same bolt one end of a spring support 51, the other end an electrical contact 52.

of which carries Securedrigidly to the support 51 as by screw but. insulated from the support 51 is a sprin orfresilient contact-carrying member 54 having an electrical contact at 55 adapted to cooperate with the contact 5 Electrical connection may be made to the contact 55 through theresilient or spring" supporting member '54 and plate 56 and binding screw -at 5'. ','and to wires leading to one end of coil-26 and one end of the shunt resistance 70. The other ends of the resistance 70 and coil 26 connected to binding post 94 and thence to the generator as hereinafter explained. Electrical connection may be made with the contact 52 through support 51 by means of binding screw 58. The contact 52 is also connected'through the support 51 and the bolt 8? to the bracket 16?, which is recessed as indicated in Fig. 3 topass the block 36without making contact therewith. Riveted to; the end of the armature 49 is a member of insulating material 60 and secured on the end of the member 54 is a metal member 61 stamped upwardly at its center in order to hold thereon a compression spring 62 the other end of which engages the insulating member 60L Pivot-ed to the armature 49 is a bail 63, its lower portion extending through a lower insulating roller 64 (see also Fig. 7), the bail i eld inplace underneath the contact pporting arm 54 by slipping the 1 wer part the bail with the roller under the member 6 where it is held in place by bent down projections on the member 61, the spring 62 tendtoforce the sametightly against the roller 64. The strenoth of compression spring 62 is sullicient to prevent yielding thereof under the maximum downward force ever exerted by the armature In this way an easily detachable connection is made between the end o'tthe armature 49 and the end of the contact member 54. Secured adjacent the end of the support 51 are two posts65 and extend ing between the upper ends of these posts is an insulating member 66 whi h prevents the s aration of the members 51 and 5 more than a predetermined amount and thus prevents the contacts 52 and 55'being separated more than a predetermined amount. A headless set screw 67 extends trough the insulating base member 14 and is adapted to make contact with the member 51 whereby the height of the resilient member 51; and fixed contact 52 may be adjusted. As the same is pushed upwardly there ,willbe carried upwardly to a corresponding extent the post 65 and member 66 and also the contact-carrying member 54 so that when the contact-carrying member 51 i thus aC 'usted upwardly no material change is made in the separation of the con tacts 52 and 55. Likewise when the members 51" and are thus adjusted upwardly the corresponding end of thearmature 49 is adjusted upwardly and the opposite end of the armature adjusted downwardly so that in this manner the air gaps between the ends of the armature andthe respective poles of cores 22 and 24 may be adjusted as desired and a small resultant magnetizing force in either direction will suilice to move the armature 49 to opener close contacts 52 and 55 as the case may be. lVhatever adjustment is thus made the space between the contacts 52 and 55 constant, and the connection between the armature 49 and the contacts is such that the parts are always under spring stress and therefore are free of lost motion. This is important because the pull exerted by the magnets varies greatly as the air-gap varies and if considerable lostmotion were permitted in the armature, the pull through the air gap, which was diminished by lost motion would be very much increased and a relatively large reversing force would be required.

represents a suitable fixed resistance car ried by rod 71, the lower end of which rod is located in an aperture in'the base of the box like structure and the upper end of which extends into a hole '72 in the top of the structure. Rod '71 is provided with a washer 73 fixed thereon and above which is placed a compression spring 74 which bears between the washer 7 3 and the top of the box like structure so that the resistance member is held securely in place. It may, however, be easily removed by forcing the rod upwardly against the action of the spring 74 until the lower end thereof is removed from the bottom part when it may be tilted and pulled out through the front of the box structure. A binding post screw 99 (see Fig. 1) is provided on the connector strap 93 whereby there is connected thereto one end of the coils 40, 43 and 41.

Referring to Fig. 8 I there illustrate diagrammatically a method of connecting such a switch arrangement in an electrical system of distribution where it is particularly useful. In Fig. 8 I have illustrated a generator at 80 connected to supply a storage battery at 81 and a work circuit at 82 in parallel, any suitable automatic variable resistance or regulator 83 being connected between the battery and the work circuit 82. 31 represents the main switch shown in the other figures, 26 its operating winding and 7 0 the fixed resistance in shunt thereto. The three cores 22, 23 and 24 are illustrated in Fig. 8 by similar reference characters and the corresponding windings are shown thereon at 40, 43 and 41. The resiliency of the contact support 54 tends to maintain the contacts 55 and 52 separated. This action is illustrated in Fig. 8 by the spring 84 which tends to pull the armature 49 in a direction to separate the contact end of the armature at 85 from the fixed contact 36. The coil 41 is connected in series between the generator and battery and in series with the main switch 31. The coil 40 is connected in series between the generator and the battery and in shunt to the main switch 31. The coil 43 is connected directly across the circuit, i. e., across the battery so that it is constantly energized in the same direction and serves to polarize the relay switch. The coil 26 is adapted to be connected across the circuit so as to become energized when the armature 49 is repelled sufiiciently by coil 40 or attracted by core 24 so as to close the circuit at 86.

With the main switch closed and the generator running at sufficient speed to charge the battery, the coil 40 is practically deenergized by reason of its being short-circuited by main switch 31, but current passes through coil 41 in a direction to attract the armature 49 so that the circuit through coil 26 is maintained closed and, therefore, the main switch is maintained closed. However, when the generator speed drops and its voltage is reduced to a. point where the battery tends to send current back through the generator, this energizes the coil 41 in the opposite direction whereupon it repells the armature 49 and so opens the circuit of coil 26 causing the main switch 31 to open under the action of spring 33. The opening of the main switch 31 again permits current to flow through coil 40 from the battery to the generator but in a direction to attract its end of the armature 49 so as to maintain the circuit of coil 26 open. If, now, the generator speed increases to a point where its voltage is above that of the battery, current will flow through coil 40 in the opposite direction whereupon it will repell the armature 49 and close the circuit through the main switch coil 26 and permit current to flow to the battery through coil 41, which acts to maintain the relay switch closed at 86, since the closing of the main switch 31 short-circuits the coil 40.

I have shown in Fig. 1 the gonnections of the battery and generator to the switch arrangement, the field of the generator being indicated at 90. The generator field in such system may be regulated by any suitable automatic regulating apparatus (not shown) to maintain the voltage at the desired value during certain variations in speed. The main circuit from the generator to the battery enters the switch at the bracket 16 and passes through the fixed contact 34, the resilient switch contact 31, block 36, strap 93, coil 41 and strap 91 to the bracket 13, and thence to the battery, the strap 93 passing through openings in the bracket 16" and insulating plate 14. Connection of the operating circuits to the opposite pole of the battery and generator is made through the bracket 16 and bolt 37 Thus all of the external connections to the switch may be made through the three bolts 17 by which it is supported and no other electrical connections to the system are required. For connecting one side of coils 40 and 26 to one side of the generator a binding post is provided at 94 which is connected to the bracket 16 through strap 95 and screw 96.

It will thus be seen that there has been provided in this invention an apparatus in which the various objects hereinabove pointed out,

' scope thereof in its broader aspects. Hence I desire to cover all modifications and forms comingwithin the language and scope of any one or more of the following claims.

What I claim and desire to secure by Let- I ters Patent. is

' 1-.. In apparatus of the character described, in combination,a winding, a movable member of magnetic material adapted to be moved by saidcoil, a device, adapted to be moved by said movable member, and: means connecting said device to said movable member, said means including a device for limiting movement in one direction between said movable member and said first-mentioned device and spring I means exerting a force greater than the force exerted by said movable member and. opposing movement between said two parts in the other direction.

2. In apparatus of the character described, in combination, a winding, a movable member of magnetic material adapted to be moved by said coil, a device adapted to be moved by said movable member, and means connecting said device to said movable member, said means including a rigid loop engaging both said device and said movable member and spring means, exerting a greater force than the force exerted by said movable member, for forcing said two parts away-from each other.

3.. In apparatus of the. character described, in combination, a box-like structure having one end and two side portions of iron and having its opposite endsubstantially closed only by a member of non-magnetic materiaha core projecting from: said first-mentioned end and toward said member of. non-magnetic material, a Winding about, said core, an armature interposed between said member and the free end of said core and adapted for movement toward or away from said core, a movable switch member pivotally mounted adjacent the outside face of'said' end member to swing toward or away from the latter, and? means passing through said member for connecting said armature and said movable switch memher, said means being rigidly'connected to said armature and looselyconnected to said switch member.

4,. In apparatus ofthe character-described", in combination, a box-like structure having one end andi'two-side portions-of iron andhaving its opposite end substantially closed only by a member of'non -magnetio and non-conducting material, a; core projecting from. said first-mentionedend' and toward said member of non-magnetic material, a winding about said core, a movable circuit-controlling device extraneous of saidbox-like structure, an armature interposed between the end of said core and said non-magnetic member, means passing through said non-magnetic member for connecting said device and said armature, and means biasing said armature in a direction away from said core and toward said non-magnetic member, the latter limiting ,movement of said armature in a direction away from said core said biasingmeans being in the form of a spring interposed between said device and said non-magnetic member.

5. In apparatus of the character described, in combination, a box-lil1e structure having one end and two side portions of iron and having its opposite end substantially closed by a member of non-magnetic material, a core projecting from said first-mentioned end and toward said member of non-magnetic material, a winding about said core, said member being also anon-conductor, a switch device carried exteriorly of and insulated by said non-conducting member, an armature extending crosswise of said structure and being thereby magnetically related to the. ends of said sides and to the free end of said core, and means having a universal connection between said armature and said device for actuating said switch device and passing throughsaid non-conducting member.

6. In apparatus of the character described, in combination, a fixed support, a box-like structure having one end and two. side portions of iron and having its opposite end substantially closed by a: member of non-magnetic material, a core projecting from said first-mentioned end and toward said. member of non-metallic material, a winding about said core, an armature interposed between said member and the free end of said core, a movable switch member mounted adjacent the outside face ofsai'd member of non-magnetic material, means passing through said. member for connectingsaidarmature and said movable switch= member, terminal means electri cally connected to said winding and said switch member for making electrical'connection thereto and mechanically constructed and related. to said fixed support and to said box-like structure to secure the latter to said fixed support, and means insulatingly securingsaid terminal means to said box-like structure, whereby conductors of an outside circuit may be electrically and mechanically connected to said terminal means as said struc-' ture" is secured to said fixed support.

7; In apparatus of the character described, in combination, a fixed support, supporting means carrying switching means, acoil carried bysaid supportin means for operating said switching means, electromagnetic means carried'by said supporting means and having contact means operated thereby for controlling the circuit of said coil, terminal means electrically connected to said electromagnetic means and said switching means mechanically constructed and related to said fixed support and to said supporting means to secure the la ter to said fixed support and at the same time to mechanically hold and thus electrically connect a conductor of an extraneous circuit thereto.

8. An electric switch arrangement having electro-magnetic means and an armature operated thereby, a switch contact, an adjustable support for said contact, another contact carried on said support and normally insulated from said first contact, and means mechanically connecting said second-mentioned contact to said armature to be moved by the latter toward or away from said firstmentioned contact to make and break contact therewith.

9. An electric switch arrangement having electro-magnetic means and an armature op-. erated thereby, two cooperating switch. contacts, one of which is connected to said armature to be moved thereby, and the other of which is normally fixed, a support for said fixed contact, means resiliently carrying the movable contact on said support, and means for adjusting said support whereby the contacts and armature are adjusted with respect to the electromagnetic means.

10. An electric switch arrangement having a contact, a yielding support therefor fixedly mounted at one end thereof, another contact carried by said support and held resiliently normally spaced from the first contact, means for adjusting said support relative to the fixed end thereof whereby both contacts are adjusted therewith, and electromagnetic means for operating said second contact.

11. An electric switch arrangement having an iron box like structure provided with an insulating bottom member, an electromagnet carried on the inside of said structure, an armature therefor inside said structure, a switch on the outside of and supported by said insulating bottom member, said switch being thereby insulated from said structure, and means connecting said armature to the switch to operate the switch.

12. An electric switch arrangement having an iron box like structure provided with an insulating bottom member, an electromagnct carried on the inside of structure, an armature therefor inside said structure, a main switch carried on the outside of said insulating bottom member and means connecting said armature to the main switch to operate the switch, a relay switch carried on said insulating bottom member inside the structure, said relay switch being connected to control the operation of said electromagnet, and electromagnetic means inside said structure for operating said relay switch.

13. A casing having an iron portion supporting a plurality of core members each having a winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature within said casing and pivoted adjacent the end of an intermediate member so as to be polarized by the winding about the latter and having its ends extended into operative relation to the ends of two adjacent core members to be effected by the windings about the latter, and contact means controlled by said armature.

14. In apparatus of the character described, in combination, a box-like structure having one end and two side portions of iron and having its opposite end substantially closed by a member of non-magnetic material, a core projecting from said first-mentioned end and toward said member of non magnetic material, a winding about said core, said member being also a non-conductor, switch means carried exteriorly of and insulated by said non-conducting member, an armature means carried interiorly of said boxlike structure and extending crosswise of the latter and being magnetically related to the ends of said sides and to the free end of said core, and means connecting said interiorly positioned armature means with said exte riorly positioned switch means for actuating the latter in response to movement of the former and having a universal oint connection with one of said means.

15. In apparatus of the character described, in combination, a box-like structure having one end and two side portions of iron and having its opposite end substantially closed by a member of non-magnetic material, a core projecting from said first-mentioned end and toward said member of nonmagnetic material, a winding about said core said member being also a non-conductor, a switch device carried exterior-1y of and insulated by said nonconducting member, an armature carried interiorly of said box-like structure and magnetically related to the ends of said sides and to the free end of said core, said armature extending crosswise of said core and being interposed between the latter and said non-magnetic member, means passing through said non-conducting member for connecting said armature with said switch device, and a spring interposed between said switch device and said non-conducting member for biasing said switch device in a direction to move said armature away from said core and against said non magnetic member.

16. In apparatus of the character described, in combination, a box-like structure having one end and two side portions of iron and having its opposite end substantially closed by a member of non-magnetic ma terial, a core projecting from said first-mentioned end and toward said member of nonmagnetic material, a winding about said corc, said member being also a non-conductor, a switch device carried eXteriorly of and insulated by said non-conducting member, armature carried interiorly of and extending crosswise of said box-like structure substantially parallel to said non-magnetic member and magnetically related to the ends of said sides and to the free end of said core, means passingthrough said non-conducting member for connecting said armature with said switch device, said means having a ball and socket connection with said device, and spring means interposed between said switch device and said non-conducting member for biasing said switch device and for holding said ball and socket connection intact.

17. A switch arrangement having a polarized armature, a resilient member .connected to move with the armature and carrying a contact, a cooperating contact carried by a second resilient member, means limiting the separation of said contacts, and means for adjusting the position of the second resilient member and thereby adjusting the position of the armature for magnetic balance.

18. A switch arrangement having an electromagnetically operated armature, 'a resiliently supported contact connected to move with :the armature, a second contact, means for simultaneously predetermining the posltion of the second contact, the first contact and said armature.

19. A switch arrangement having an electromagneti'cally operated armature, a contact movable therewith, a second con-tact cooperating therewith, and means for simultaneous- 1y predetermining the position of both said contacts and armature without materially varying the distance between said contacts.

20. In apparatus of the character described, in combination, supporting means carrying electromagnetic means, means of magnetic material adapted to be actuated by said electromagnetic means and also carried by said supporting means, and switching means also carried by said supporting means, said electromagnetic means having terminals mechanically constructed and related to said supporting means to permit mounting of said supporting means onto a fixed support by said terminals.

21. A casing having an iron portion supporting a. plurality of core members each having a winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature within said casing and pivoted adjacent the end of an intermediate core memberso as to be polarized by the winding about the latter and having its ends extended. into operative relation to the ends of two adjacent core members to be'afi'ected by the wind ings'about the latter, ayieldin-g supportfixed atone send to said casing and carrying a contact adjacent its free end, a contact member'connected tobe controlled by said armature and adapted to coact with said firstmentioned contact, and means for adjusting the free end of said support in a direction toward or away from said first-mentioned contact.

22. A casing having an iron portion supporting a plurality of core members each having a winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature within said casing and pivoted vadj acent the end of :an intermediate core member sons to be polarized by the winding about the latter and having its ends extended into operative relation to the ends of two adjacent core members to be efiected by the windings about the latter, a yielding support fixed at one end to said casing and carrying a contact adjacent its free end, a yielding contact carried by said yielding support for coaction with said first-mentioned contact and connected to said armature, and means for adjusting the free end of said support in a direction toward or away from said firstmentioned contact, thereby to adjust the action of said windings on said armature.

23. A casing having an iron portion supporting a plurality of core members each having .a winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature for completing the magnetic circuit, and contact means operated by said armature, said casing having a portion of non-metallic material for preventing substantial shunting of magnetic flux away from said magnetic circuit.

24. A casing having an iron portion supporting a plurality of core members each having a winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature for completing the magnetic circuit, contact means operated by said armature, and means formed of non-magnetic material and forming part of said casing for supporting said contact means and for preventing substantial shunting ofmagnetic flux away from said magnetic circuit.

25. A casing having an iron portion supporting a plurality of core members each having a winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature for completing the magnetic circuit, contact means operated by said armature, and electrical terminals for the circuits of said windings and contact means insulated from said casing and constructed to permit attachment thereby of said casing to a fixed support.

its

26. A casing having an iron portion supporting a plurality of core members each having a Winding thereabout, said iron portion forming with said core members part of the magnetic circuit of said windings, an armature coacting with at least one of said windings and adapted to form part of the magnetic circuit thereof, contact means in circuit with another of said windings for controlling said other winding, said contact means being controlled said armature, an armature for said other windin having associated therewith contact means controlled thereby, and means of nonmagnetic mate rial forming part of said casing for preventing substantial shunting of magnetic flux away from the respective magnetic circuits of said windings. g

27. A casing having an iron portion supporting a plurality of core members each having a winding thereabout, said ir n portion forming with said core members of the magnetic circuitof said windings, an armature coacting with at least one of said windings and adapted to form part of the magnetic circuit thereof, contact means in circuit with another of said windings for conrolling said other winding, said contact means being controlled by said ariaature, a member of non-magnetic material forming part of said casing and adapted to prevent substantial shunting of magnetic flux rom the respective magnetic circuits of said winding, an armature for said other winding mounted on one side of said non-magnetic member, and contact means controlled by said last-mentioned armature and mounted upon the other side of said non-magnetic member.

28. A casing having portion of magnetic material, said portion being substantially of U-shaped cross-section, a core mounted with in said casing and substantially centrally of said U-shaped crosssection and adapted to form with the latter part of a magnetic circuit, a winding about said core, a member of non-magnetic material substantially closing the open end of said U-shaped cross-sectioned portion, contact means mounted exteriorly of said casing and adjacent said non-magnetic member. an armature mounted adjacent said core and interiorly of said and adapted to complete said magnetic circuit, and means passing through said casing for operatively connecting said armature to said contact means.

29. A casing having a portion of magnetic material, said portion being substantially of U-shaped cross-section, a core mounted within said casing and substantially centrally of said U-shaped cross-section and adapted to form with the latter part of a magnetic cir suit, a winding about said core, a member of non-magnetic material substantially closing the open end of said U-shaped cross-sectioned portion, contact means mounted exteriorly of said casing and adjacent said non-magnetic member, an armature mounted adjacent said core and interiorly of said casing and adapted to complete said magnetic circuit, a member connecting said armature and said contact means and passing through said casing, and a spring interposed between said contact means and said casing.

30. An electromagnet, an armature controlled thereby, a movable contact member, and means connecting said armature to said member for movement of the latter by said armature, said means including a link and spring for holding said link, armature and member together, the tension of said spring being greater than the force exerted by said armature.

31. An electromagnet, an armature controlled thereby, a movable contact member, and means connecting said armature to said member for movement of the latter by said armature, said means including a device for limiting movement in one direction between said armature and said member, and spring means opposing movement in the other direction and having a tension greater than the force exerted by said armature.

32. An electromagnet, an armature controlled thereby, a movable contact member, and means connecting said armature to said member, said means including a link detachably connected to one and engaging the other, and spring means opposing disconnection of said link therefrom.

In testimony whereof I have signed my name to this specification.

ELI J. BLAKE.

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