US1864296A - Electromagnetic switch - Google Patents

Description

June 21, 1932.

F; a. CREED ET AL ELECTROMAGNETIC SWITCH Filed Dec. 5, 1927 4 Sheets-Sheet l F. G. CREED ET AL 4,296 ELECTROMAGNETIC SWITCH 4 Sheets-Sheet- 2 Filed Dec. 5. 1927 u 21,1932- F. G. CREED ETAL 8 4,296

ELECTROMAGNETIC SWITCH 4 sheets-squat 3 Filed Dec. 5. 1927 June 21, 1932.

F. e. CREED ET AL ELECTROMAGNETIC SWITCH Filed Dec. 5. 1927 4 Sheets-Sheet 4 Patented June 21, 1 932 UNITED-STATES PATENT orrlca FREDERICK GEORGE CR-EED, WILLIAM HENRY STOREY, AND REGINALD DENNIS SALMON, OF CROYDON, ENGLAND, ASSIGNORS T CREED & COMPANY LIMITED, A

COMPANY OF GREAT BRITAIN ELECTROMAGNETIC SWITCH Application flied December 5, 1927, Serial No. 237,951, and in Great Britain September 8, 1927.

This invention has reference to improvements in electro-magnetic apparatus of the matures is or are mounted to oscillate in relation to an electro-magnetic system comprising one or more magnetic pole pieces and one or more windings subject to the action of electric currents or impulses.

Theinvention has for its object to ensure that those portions of such a relay which are ordinarily required to be fixed in relation to each other, as for instance, the magnetic pole piece or pieces, a hearing, or one at least of the bearings, for the armature or armatures associated therewith, and a pivot whereby the associated pole piece or piecesand armature bearing or bearings can be adjusted in relation to separate supporting means, shall be maintained 'in rigid and unalterable relationship to each other.

It also has for its object, in the case of an electric relay in which the armature is provided with a contact adapted to oscillate be-- tween normally stationary but adjustable contacts carried by separate supporting means, to enable the electro-magnetic system to be readily and accurately adjusted in relation to the armature whilst the armature contact is hearing against one or other of its associated stationary contacts, in order to vary the bias of the armature.

I It also has for its object to enable the normally stationary but adjustable contacts to become automatically clamped in position after adjustment.

It also has for its object to enable the electrical connections to the movable and normally stationary contacts to be maintained in rigid and unalterable relationship to the stationary contacts and to supporting means carrying such stationary contacts.

It also has for its object to enable a permanent magnet used to polarize the pole piece or pieces formed of soft iron 'to be readily removed and replaced but in such manner that it cannot be replaced with its poles in a wrongposition in relation to the pole pieces.

It also has for its object to simplify and cheapen the construction of relays, of the kind referred to, to admit of easy adjustment of parts thereof without the aid of tools such as screw-drivers, spanners and the like, and to enable them to be maintained in working order without the aid of a skllled mechanic. 7

For attaining the first mentioned object a portion of electro-magnetic apparatus of the kind herein referred to, which is required to be in adjustable relationship to the remainder of the apparatus, is, broadly considered, formed as a unit embodying a carrier or casing of insulating material, which is provided with a pivot pin or like device that is fixed in relation thereto by being moulded in or formed integrally with the carrier or casing. More specifically considered, the portion of the electro-magnetic apparatus w ich is required to be in adjustable relationship to the remainder of the apparatus, is formed as a unit by having moulded arou'nd'it, or

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partly around it, a carrier or casing of insu lating material provided with" a pivot pin or like device that is fixed in relation thereto by being moulded therein or formed integrally therewith. The portion of the apparatus in relation to which the said unit is adjustably mounted, is provided with a bearing for the .pivot or like device. The moulding material used for the carrier or casing may be of a kind that can be softened or melted by heat and becomes hard and rigid at normal temperatures and. cannot afterwards be softened or melted by heat. Moulding materials suitable for the purpose mentioned, are well known, such for instance as phenolic condensation products. The moulding material which it is at present preferred to use, is material of the kind known under the trade name of Mouldensite. The other above mentioned objects of the invention are attained in a manner that will hereinafter be explained with the aid of the accompanying drawings.

The invention is applicable generall to various constructions of electric relay 0 the type herein referred to. Thus, it may advantageously be applied in connection with electric relays of the kind in which an armature is mounted to oscillate in the gaps formed between the pairs of poles of two oppositely arranged shaped pole pieces forme of magnetic material, in which the said oles are constantly and oppositely polariz by a permanent magnet placed in contact with them, and in which the armature winding is placed within the rectangularly shaped opening formed between the two pole pieces and surrounds the armature one end of which is provided with an extended portion or tongue that ma be provided with a contact arranged to osci late between two stationary but adjustable contacts, when the relay is to be used as a switch, for closing and opening electric cir-' cuits, or is adapted to actuate some mechanical device when the relay is to be used as a power relay or motor.

The invention may also advantageously be applied in connection with a rela of the kind well known as the British Post 0 cc standard relay, which comprises two complete electromagnets, double wound on the difierential prmciple and so connected and arran ed that when a current is passed throu h their windings their opposite poles are adjacent to one another, a vertical spindle carrying two soft iron tongues or armatures arranged to oscillate in the gaps between the two pairs of opposite poles a fixed permanent magnet for polarizing the said tongues or armatures and a third tongue fixed to the said spindle and carrying a movable contact arranged to oscillate between two stationary but adjustable contacts. v

In order that the manner of carrying the invention into practice for attaining the. obects hereinbefore set forth, the same will now e further described with the aid of the lac companying illustrative drawings.

In these drawings, Fig. 1 is a front elevation showing one construction of electro-magnetic apparatus of the general type hereinbefore referred to, embodying the invention,

and suitable for use as an electric relay or switch. Fi 2 is a sideelevation of such aparatus. Fig. 3 is a section on the line IIIv II of Fig. 1. Fig. 4 is a plan of the apparatus shown in Fi 1. Fig. 5 is a section on the line VV of ig. 2, Fig. 6 is a section on line VIVI of Fig. 3, Fig. 7 is an underside view of Fig. 2. Fi 8 is a plan of a base piece used with Sue apparatus, and Fi 9 1s a section thereof onthe line IXI of Fig. 8. Figs. 10 and 11 show respectively in elevation and plan, a casing enclosing apparatus according, to the invention and mounted in a base piece. Fig. 12 is a perspective view showing a .rela of the kind known as the British Post relay'. but modified to embody the present invention. Figs. 13 and 14 are horizontal sections thereof taken.- on the lines XIII- .XIII and XIV XIV respectively of Fig. 12.

Fig. 15 shows partly in ront elevation and ce standard menace In the example shbwn in Figs. 1 to 11 inclusive of the drawings, 1 is a plate of in; sulating material, of the kind hereinbefore described, in which the two sha d pole pieces 2 and 2 are permanently xed by moulding them therein. It is arranged vertically and pivoted at its upper end 1' to the front side of a vertical support 3 that is carried by a circular base piece 4. This support is provided at its upper end portion with a pair of forwardly extending bosses 5, 5 that are moulded in one piece withthe support and are arranged with their axes'in a common horizontal plane for carrying the stationary but adjustable contacts 6, 6'. The ivoting of the plate 1 to the support 3 is e ected by a hollow conical metal pin 7 one end portion of which is permanently fixed in the said plate 1 by moulding it therein and the other end portion of which is fitted in a companion bearing 8 in the vertical support 3. The plate 1 and support 3 are firmly and closely held together, but so as to allow of movement of the plate 1 in its own plane, by spring means, conveniently by the aid of-a coiled spring 9 extending through the conical pin 7 and attached at one end to a transverse pin 10 carried by the pin 7, or by the adjacent portionof the plate 1, and at the other end to another transverse in 11 carried by the rear end of the hearing, or adjacent portion of the support ,3. By this means any wear of the pin 7 or bearing 8, will automatically be taken. up. The plate 1 with its pivot pin 7 are detachable from the support, when this may become necessary or desirable. The two pole pieces 2 and 2 are permanently magnetized by a permanent bar magnet 12 adapted to be inserted endways between the lower ends of the pole pieces 2 and- 2 and the base piece 4 of the support and to be held magnetically against the lower ends of the pole pieces. Means are provided to ensure that the permanent magnet shall be inserted in place with its north and south poles in proper position relatively to the pole pieces. Forthis purpose, a pin. 13 for example, fixed in the base piece 4, may be arranged to fit into a notch 12', formed in the lower front edge of the permanent magnet 12, only when the said edge is at the front, when putting the magnet in place, thesaid notch being formed in the correct edge, relatively y the flexible connection is fixed to a plug 25 adapted to fit into a socket 25- to the north and south poles of the said magnet.

The armature 14, arranged to extend vertically through the two gaps between the two pairs of magnetic poles formed by the inturned ends 2 of the pole pieces 2 and 2, is provided with a horizontal spindle 15 (Figs. 3 and 6) mounted in two bearings 16, 17 consisting of tubes, one of which, namely 16, is fixed in the insulated plate I by moulding it therein and the other 17 is carried by a metal cross piece 18 secured to the outer ends of two horizontal supports 19 and 19 arranged in the same horizontal plane and at the opposite sides of the spindle and midway of the height of the rectangular space between the pole pieces 2 and 2. Such supports 19 and 19 are also moulded in one piece with the insulating plate 1.

The energizing windingsv 20 and 20 for the armature 14, are arranged to extend into the said rectangular space between the pole ieces 2 and 2, and above and below the two orizontal supports 19 and 19, therein and so as to surround the armature 14. Conductors 21 from the ends of each winding extend downward through the base piece 4 of the support and are connected to terminals 22 fixed in the bottom thereof (Fig. 7).

' A tongue 23 extending upwardly from the armature 14, carries a movable contact 24 arranged between thetwo stationary but adjustable contacts 6, 6 carried by the aforesaid pair of bosses 5, 5 on the insulating support 3. The tongue 23 should be made as light as possible to reduce its/amount of inertia. For this purpose, it may advantageously be made, as shown,.of tapering shape outwardly to its free end which may almost be a oint and to which the movable contact 24, a so made very light, is attached. The movable contact 24 is connected by means of a flexible connection 25, in the form of a coiled spring, to a conductor 25. extending downwardly through the support 3 (Fi 6) to a terminal 26 in the bottom of the ase piece 4. To enable the flexible connection 25 to be readily disconnected from the conductor 25 when the plate 1 and associated parts are removed from the support 3, one end of I mounted in the support 3,-a'nd connected to the conductor 25 and the plug is provided with a collar 25""against which a projection 1 on the plate 1 will act to withdraw the plug automatically from the socket when the plate 1 is detached from the support 3. Each of the stationary is carried by a horizontal screw 27 that is versely through an endways movable metal pin 28 fitted'to slide in a hole 29 in the cor responding boss 5 or 5, the pin 28 being acted upon by a coiled spring 30 within the boss, in a direction to press the, screw 27 firmly screwed transliable to do if a separate clamping device were used, and such evice was left in its unclamped position, due to forgetfulness on the part of the operator. Further, the risk of .the adjustment becoming unset during the clamping operation is avoided. The arrangement described also avoids the use of a tommy bar, or a screw driver, for adjusting purposes. The heads 27 of the adjusting screws 27 are preferably, and as shown, of large diameter, and milled and may advantageously be provided with index lines to facilitate accurate adjustment.of the contacts. Each of the springs 30 referred to, is connected to conductor 31 that extends downward through the support 3 (Fig. 6) to a terminal 32 in' the base 4 of the support. The conductors 25 and 31 are fixed in the support 3 by moulding them therein. The support 3 may, as shown, be stiffened by a vertical rib 3 at the back thereof and integral therewith.

To adjust the position of the pole pieces 2 and 2 relatively tothe armature 14,- the lower end of the insulating plate 1 carrying the-pole ieces, is provided with an extension 1 ig. 5) a ainst one side of which bears the inner en of a horizontal bias adjusting screw 33 that is screwed through the port with a lateral projection 33, and arranged near to and parallel with the screw extension and fixed. to thesupport, is a pin 35 formed with an annularrrecess 35. The arrangement is such that the groove 35 in the pin'35 will allow the screw 33 to be rotated in-each direction, to an extent limited by the projection 33 abutting against one or other side of the groove 35 in the pin 35. Thisprevents an operator turning the bias adjustmg screw 33 too far in eitherdirection and thereby possiblystraining the armature, or in any other way damaging the relay. Also, by turning the said screw 33 to the middle positionv of itstravel and then adjusting the contact screws 6, 6 to correspond, the relay can be brought to its correctjadjustment in curate adjustment, the head 33 of the bias adjusting screw 33 may be provided with index lines and arrows. The middle portion of the travel ofthe bias adjusting screw may be visibly depicted by means of an arrow on the screw head and a zero mark on the supthe shortest possible timer To facilitate ac- 3 base 4 of 'the support 3. Suitable line wires .The combined support, with attached part:i

including the casing,.is adapted to be insert in a recessed base piece 38 (Figs. 8 to 11) provided, in known manner, with a number of sprin contacts 39 arranged to bear against t e a oresaid terminals in the bottom of the and other conductors corresponding to the parts of the relay .to whichconnections have i to be made, are permanently connected, as

by soldering, to the spring contacts in the base piece 38, as heretofore. The said recessed base piece 38 is provided with means, as for instance, a fixed pin 40 and a spring pin 41,

adapted to co-act with holes in the said casing 36 so as to lock the two parts together.

-A projection 42 on the recessed base 38, co-

acts witha slot in the casing 36 in such man-' nor that the casing and base piece can only be connected together when the various terminals on the base piece 4 are in proper register with the spring contacts 39 withvwhich the are to co-operate.

0 enable sparking between the associated movable-and stationary contacts 6, 6 and 24 of a paratus of the kind referred to, to be readily observed, the top of the casing 36 is provided with a glass window or lens 44 that is located over the contacts and made of small dimensions so as to keep the interior of the casing dark and'renderany sparking that may take place between the contacts more readily discernible.

The upper portion 36 of the casing 36 is made separate from the lower portion and either hinged thereto, as indicated at 36", or be made entirely detachable therefrom, so that in either case, ready access can be gained to the contacts, without having, for that purpose, to remove the whole casing from the apparatus. 5

By the construction described, the whole of the apparatus, except the armature and associated contacts, is insulated and safe to bandle, whatever voltage may be used.

In the modified construction of Post Ofiice standard relay shown in Figs. 12, 13 and 14, the soft iron cores 45 of two verticalelectromagnets 45 are each .detachably connected at bei0re .d$cribed. The vertical polar faces of each'pair of pole pieces 45 and 45 are spaced apart to form between them a gap into which extends one of the two soft iron tongues or armatures 47, 47'; .The two tongues or armatures extend through holes 46 in the carrier 46 and are fixed to a vertical spindle 48 the lower end of which is pivoted in a metal bearing 49 moulded in the base 46 of the carterminate in close roximity to the armatures 47, 47 respective y, so as to polarize them. When the permanent magnet is detached from the carrier 46, the electro-magnets 45, 45can each be connected toits upper and lower fixed pole pieces 45 and45, or be detached therefrom if desired. To the armature spindle 48 is fixed a tongue 52 carrying a movable contact 53 arranged to oscillate between normally stationary contacts 54 and 55. These contacts are endways adjustable in bosses 56 and 57 respectively of insulating material made integral witha flat horizontal plate like support 58 formed of insulating material of t e charatcter hereinbefore mentioned. Each contac 54 and 55 may be acted upon by a self-actin clamping device, as inthe relay shown in Fi 1 to 6 inclusiveand be in electrical connection with conductors excarrier 46 to contacts fixed to the bottom of the base 46". be connected through a flexible connection to a similarly arranged conductor. a

To enable the bias of the armatures 47, 47 f in relation to the polar faces of the" pole pieces 45, 45 to be capable of accurate ad-. justment, the upward extension 46 of the head 460f the carrier 46 ismade of circular shape and the plate-like support 58 is arranged to fit it closely and i's' provided with an extension 58 adapted to be acted upon on one side by a bias adjusting screw 59 and on the other side by a spring 60. Means such as those used in the rela hown in Figs. 1 to 7 inclusive, are or may provided to regulate the extent of turning of the bias adjusting screw 59 in each direction.

jThis modifiedrelay. can be enclosed in a casing of opaque material having a spark in-- The movable contact 53 may.

tending downward through holes 46' in the.

sp'ection window, like that shownin Figs. 1,.

3, 10 and 11.

To enable the adjustable contactsfi, 6".and movable contact 24 of the rela shown in Figs.1 to;11 inclusive, to be e y and efiectiyely cleaned, when this may become jny, the opposite sides of the upper portionofthe support ifl are 4 faces of the stationary but screwing, or,

shown in Figs. 15, 16 and 17 and comprises a frame consisting of side members 61 and 61 connected by a longitudinal member 61 and two overhanging members 62 and 62, and a rotary disc 63 mounted to slide along but to rotate with a spindle 64 adapted to be rotated in the members 62 and 62 by a crank handle 65. The side member 61 is provided with a fixed pin 66 adapted to pivot in one of the aligned holes and the member 61 is provided with an endways movable spring pin 67 adapted to pivot in the other aligned hole 60. The arrangement is such that the frame 61, 61 61 can readily be pivoted to the support 3 and the disc 63 be inserted between the faces of the movable contact 24 and each of the adjustable contacts 6, 6 and rotated in contact with each, contact face to clean it. A similar contact cleaning device may be applied to the head 46 of the carrier 46 of the relay shown in Figs. 12, 13 and 14 for a like purpose.

When the electro-magnetic apparatus is to be used as a power relay or motor, the insulating plate 1, Figs. 1 to 7, carrying the pole pieces 2 and 2, armature 14, coils 20 and 20 and associated parts, may, as shown in Fig. 18, be mounted on any suitable base or support 3, the electric contacts hereinbefore described as associated with the armature, be dispensed with, and the armature extension 23, be adapted, as shown, to mechanically actuate any desired device, as for instance a bar 69, for actuating or controlling an escapement device 70, ratchet wheel or other mechanism.

Instead of permanently fixing the laminated pole pieces 2, 2 to the plate 1 of insulating material b moulding them therein, as hereinbefore escribed with reference to Figs. 1 to 7 inclusive, they may be, as shown in Fig. 19, permanently fixed to the face of the plate by placing themover pins 71 that are permanently fixed in the plate and have their front ends provided with nuts 72 and washers 73 bearing against the outer sides of the pole pieces, so as to clamp the pole pieces permanently to the plate. The pins 71 may be metal pins permanently fixed in the plate. The inner bearing for the armature spindle 15 may be permanently fixed in the plate, as by it may be moulded in the plate when the plate is of insulating material of the kind heretofore referred to. The supports 19 and 19" to carry the cross piece 18 for holding the outer bearing for the armature spindle, may be made integral with the late, or be made separate and be permanently fixed to the plate. The arrangement is such that the pole pieces and the inner bearing for the armature spindle are fixed in.

.herein referred permanent and unalterable relation to each other and to the plate.

What we claim is 1 An electron-ma etic apparatus comprising magnetic po e pieces arranged opposite each other and at a distance apart, an armaturearranged to operate between said pole pieces, a'spmdle to which said armature is fixed, bearin s for said spindle and a carrier of mouldeifinsulati material carryin said pole pieces and one 0 (He bearings.

2'. Electro-magnetic apparatus of the kind herein referred to, comprising two relatively adjustable portions fc'arrying com onents of the apparatus, each ormed of insu atin material and one of which is provided with a pivotal projection moulded thereon and the other has a companion bearin moulded therein, and means carried partlyiy each of said lportions, adapted to admit of one portion eing the other.

3. In electro-ma netic apparatus of the kind herein referred to, a umt comprising oppositely arranged magneticpole pieces, an

oscillate between said {:gle pieces, a spindle fixed to said armature,

arings for said spindle a carrier of moulded insulating material or said pole ieces armature mounted to and one of said bearings and a pivota projection for the unit.

g 13, the armature spinpositivelyadjusted in relation to v 4. Electro-gnagnetic apparatus of the kind herein referred to, comprising two relatively adjustable units, co-acting lvotal members between said units, one of said units comprising oppositely arranged magnetic pole pieces, an armature mounted to oscillate between said pole pieces, a spindle fixed to said armature, bearings for said spindle and a a carrier of moulded insulating material for said pole pieces, one of said bearings and one of said pivotal members.

5.. Electro-magnetic apparatus of the kind herein referred to,- comprising two relatively adjustable units, one of said units comprising a carrier of insulating material, op' ositely arranged magnetic'pole pieces mou ded in said carrier, an armature mounted to oscillate between said pole pieces, an electric contact movable with said armature, a spindle fixed to said armature, bearings for said spindle,one of which is permanently fixed in said carrier, and a pivotal member in permanent fixed relationship to said carrier, the second unit comprising a carrier of insulating material provided with a pivotal member companion to that carriedby the first mentioned unit, and stationary but adjustable contacts between which the .contact movable with said armature can oscillate, and means torpositively adjusting said units relativelyto one aliliother about the pivotal connection between t em. Y

6. Electro-magnetic apparatus of the kind to, comprising movable and stationary units, a pivotal connectionbetween said units, and adjusting means whereby the movable unit can be positivel moved in relation to said stationary unit, t e movable unit comprising a carrier of insulating material, op ositely arranged magnetic pole.

pieces moul ed in said carrier, an armature mounted to oscillate between said (pole pieces, an electric, contact carried bysai armature, a spindle fixed to said armature, bearings for said spindle, one of which. is permanently fixed in said carrier, and a pivot pin forming one member of said pivotalconnection, per manently fixed to and projecting from said carrier, and the stationaryunit comprising a carrier of insulating material formed with a bearing for said pivot pin, and fixed but adjustable contacts carried by said stationary unit and between which the contact carried by said armature can oscillate.

7. Electro-magnetic apparatus of the kind herein referred to, comprising two oppositely arranged [shaped pole pieces, a plate of insulating material in which said pole pieces are moulded and thereby permanently and unalterably fixed in relation to each other and ,to said plate, a permanent magnet for polarizing said pole pieces, a support to which said plate is pivotally connected so that it can move in its own plane, supports carried by said plate and extending through the space between said pole pieces, about midway of the length thereof, aligned bearings carried by said plate, one of which is moulded .in said plate, a spindle mounted in said bearings, a laminated armature fixed to said spindle and extending through the gaps between the faces of the polar projections of said pole pieces, said armature having a laterally proecting arm, windings fixed within the space between the pole pieces and at o 'posite sides of the bearing supports therein and through which said armature extends and means whereby said plate with pole pieces and windin can be adjusted around its pivotal connection with said support relativelg to said armature. 1 v

8. lectro-magnetic apparatus of the liind herein referred to, comprising a plate of insulating material, two op ositelyarranged shaped pole pieces moul ed in said plate, a permanent magnet for polarizing said pole pieces, an armature mounted to oscillate between the polar faces of said pole pieces a spindle fixed to said'armature, bearings or said spindle one of which is moulded in said plate, armature windings carried by said plate, a trunnion moulded in said plate and extendingfrom one side thereof and at right angles thereto, a support wherein'said trunnion is mounted to turn, spring means acting constantly to press said trunnion endways in its bearing in said support,and means whereby said plate can be adjust'edabout the, axis of said trunnion. I

other and to sai nae-1,290

9.1Electr6-magnetic apparatus of the kind herein referred to, comprising a plate of insulating material, two oppositely arranged I: shaped pole pieces mou ded in said plate, a permanent magnet for dpolarizing said pole pieces, an armature an armature windings carried by said late, a support to which said plate is pivota ly connected, so that it can turn in its own plane, and means for adjusting said plate about its pivotal connection with said support, said ad usting means comprising a springdevice adapted to act against said p ate 1n one screw adapted to act against the plate in the opposite direction.

10. Electro-magnetic apparatus of the kind herein referred to, comprising a plate of insulating material, two op ltely arranged shaped pole pieces mou ded in said plate, a permanent magnet formagnetizing said pole pieces, an armature and armature direction and an adjustable I windings carried by said plate, a support to which said plate is pivotally connected sothat it can turn in its own plane, and means and means for limiting rotation of said screw in each direction.

11. Electro-magnetic apparatus of the kind herein referred to, comprising two oppositely arranged I; shaped pole pieces, a plate of insulating material wherein said pole pieces are moulded and thereby permanently fixed in position relatively to one an-* other and. to said plate, a support to which said plate is pivotall connected, a removable permanent magnet or magnetizing said pole pieces, and means for correctly positioning the poles of said magnet in relation to the respective pole pieces. 7

' 12. Electro-magnetic apparatus ofthekind herein referred to, comprising two oppositely arranged shaped lpole pieces, aplate of insulating materialw erein said pole pieces are moulded and thereby permanently and unalterably fixed in osition in relation to each d plate, a permanent magnet for ma etizing said pole pieces, a support to whic said plate is'pivotally conn so that it can move in its own plane, an armsture arranged to extend through the gaps between the polar projections of said pole pieces and provided with an outwardly extending. tongue, a spindle to which said armature is fixed, bearings for said spindle one of which is moulded in said plate, a movable contact carried by said tongue, armature windings fixed within the space between said pole 7 pieces and surrounding saidarmature andadieo justable contacts carried bysaid support and between which said movable contact can 0s cillate.

13. Electro-magnetic apparatus according to claim 12, wherein saidsupport is formed of insulating material with two hollow extensions integral therewith for carrying the adjustable contacts, each such contact being carried by a screw extending transversely through holes in one of said hollow extensions and through a screw threaded hole in a spring pressed pin movable endways in the corresponding extensions, and each adjustable and movable contact being connected to a separate conductor extending through said sup port to a terminal at one end thereof.

14. Electro-magnetic apparatus according to claim 12, wherein the movable contact is connected by a flexible conductor to-a metal plug fitting a metal socket fixed in the support and connected to a conductor extending through said support, said plug having a collar thereon and the pivoted plate having a part thereof adaptedjto co-act with said collar for the purpose set forth.

15. Electro-magnetic apparatus of the kind herein referred to comprising a'vertical carrier having abase, head and upper circular trunnion all formed in one piece of insulating material that is capable of being sof-' tened or melted by-heat and of becoming hard and rigid at normal temperatures, upper and lower pairs of oppositely arranged pole pieces moulded in the central portion of said carrier, two vertical electro-magnets each having its core detachably connected at its ends to one of the upper and lower ole pieces, armatures mounted to oscillate etween the adjacent faces of the pairs of pole pieces, a spindle fixed to said armatures, a lower bearing for said spindle moulded in the base of said carrier and an upper bearing for the spindle carried by the said circular trunnion, a permatangular space between said pole pieces and surrounding said armature, a fixed support to which said plate is pivotally connected so that it can move in its own plane, and bias adj usting means whereby the position of said plate and pole pieces can be varied in relation to said armature.

17. The combination with electro-magnetic apparatus of the kind herein referred to, comprising stationary but endways adjustable contacts and a movable contact arranged to oscillate between said stationary contacts, of a contact cleaning device, comprising a frame adapted to be attached to the electro-magnetic apparatus, a. disc mounted to rotate in said frame and to be inserted between the movable contact and each of the stationary contacts, means whereby said disc can be moved axially and caused to bear against any of said contacts, at will, and means for rotating said disc against the contact with which it has been caused to bear.

Signed at London, England, this 25th day of November, 1927.

FREDERICK GEORGE CREED. YVILLIAM HENRY STOREY. REGINALD DENNIS SALMON.

nent magnet detachably fixed to said carrier and having its poles arranged in proximity to said armatures, a plate of insulating material journalled to said trunnion,stationary but adjustable contacts carried by said plate, a tongue fixed to said spindle, a contact carried by said tongue and arranged to oscillate between said stationary contacts and bias adjusting means adapted to turn said plate about said trunnion.

16. Electro-magnetic apparatus of the kind herein referred to, comprising a plate of two oppositely arranged shaped pole pieces permanently and unalterably fixed in position to said plate, a permanent magnet for polarizing said pole pieces, aligned bearings carried by said plate, a spindle mounted in said bearings, an-armature fixed to said spindle and arranged to escillate between the polar faces of said pole pieces and provided with anoutwa-rdly ex tending tongue, windings fixed within the re-

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