US2644120A - Railway switch machine controller - Google Patents

Description

INVENTOR C. L. Swqmon H I5 AiTORNEY 3 Sheets-Sheet l C. L. SWANTON RAILWAY SWITCH MACHINE CONTROLLER June 30, 1953 Flled May 5, 1949 June 30, 1953 SWANTON 2,644,120

RAILWAY SWITCH MACHINE CONTROLLER Filed May 5, 1949 3 Sheets-Sheet 2 IN VEN TOR.

C.L.Swan+on HIS ATTORNEY June so, 1953 L. SWANTON RAILWAY SWITCH MACHINE CONTROLLER 3 Sheets-Sheet 3 Filed May 5, 1949 FIG. 3.

5 w w m mum :q (llll w w a 7 Z. 8 mm 5 & h 1| w W. 8 1 7 N 8 I 4 MI W I l 0 I W L Mn N a T P 5 N N a o 1 W w l IL 6 N 1 5 1 flA a w m C H R m 0% w O 5 m T w a M. 5 3 a m I G m F m M? 2 L 9 H A Hmj G Patented June 30, 1953 RAILWAY SW'ITCH MACHINE CONTROLLER Charles L. Swanton, North Chili, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application May 5, 1949, Serial No. 91,449

5 Claims.

This invention relates to railway switch machine controllers and more particularly pertains to controllers of this type which employ tractive type polar relays having interlocked armatures.

In controlling railway switch machines remotely by means of line wires it is desirable to use polarized control of the switch machine because of the manyadvantages inherent in this type of control. As a result, switch machine controllers of the prior art have been devised which include a polar relay whose function it is to energize the switch machine in accordance with the polarity of the voltage applied to the line wires. Obviously, such an arrangement is not fully satisfactory since it not only requires the use of such an additional polar relay but also requires that a substantial amount of power be supplied to the line wires to hold such relay energized in the event that it is considered desirable to have a normally energized switch controller circuit. In view of these disadvantages of switch machine controllers of the prior art, the controller of the present invention has been devised which can be used in polarized control circuits but which does not require the use of an additional polar relay. The switch controller of the present invention includes two interlocked contactors and the circuit organization is so arranged in conjunction with two rectifiers as to consume a minimum of power when used in a normally energized circuit.

Since it is also considered desirable in devices of this type to provide some means for interlocking the two contactors in order to provide the utmost safety precautions, another feature of the present invention may be said to be an improved means for providing this interlocking.

The novel mechanical interlocking relay structure illustrated in this application more particularly in Figs. 1, 2, 3, 5 and 6 is claimed herein; whereas, the novel circuit organization and control system is claimed in my continuing application Ser. No. 324,210 filed December 5, 1952.

Other objects, purposes, and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in

which like reference characters designate corresponding parts throughout the several views and in which- Figs. 1, 2 and 3 illustrate side, to and front views respectively of the switch machine controller of the present invention;

Fig. 4 is a schematic diagram of a typical circuit employing the switch controller of the present invention;

Fig. 5 diagrammatically illustrates the magnetic cicruit of each of the tractive type relays included in this switch controller; and

Fig. 6 illustrates the arrangement of the permanent magnets with respect to the core pieces about which they fit.

For the purpose of simplifying the illustration and facilitating in the explanation, the various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings having been made more with the purpose of making it easy to understand the principles and mode of operation, than with the idea of illustrating the specific construction and arrangement of parts that would be employed in practice. Thus, in the schematic diagram of Fig. 4 the contactors and their contacts are illustrated in a conventional manner, and symbols are used to indicate connections to the terminals of batteries, or other sources of electric current, instead of showing all of the wiring connections to these terminals.

Without attempting at this point to define this invention in exact detail, it can be seen from the accompanying Figs. 1, 2 and 3 that there are two independent magnetic circuits each of which includes two coils wound around cylindrical cores, an armature, yoke, permanent magnets, a leakage strip, and a rectifier. The magnetic circuit associated with the armature It, for example, includes the leakage strip ll, permanent magnets 2| and 22, the coils l2 and I3, and yoke M. The rectifier unit Ill9ll0 actually com prises two separate rectifiers and one of these rectifiers is included in the electrical circuit for each pair of coils as will subsequently be brought out. Similarly, the magnetic circuit associated with the armature I6 includes two coils I1 and I8 (not shown), leakage strip i9, yoke 20, and two permanent magnets which are mounted adjacent the cores associated with coils I! and I8 (not shown) in the manner shown in Fig. 6. The armatures l0 and 15 are both pivoted at their bottom upon the projecting edge of the plate '33. Each of these magnetic circuits operates so as to attract its associated armature whenever the series connected coils of that magnetic circuit are energized with a voltage of proper polarity as will later be more fully explained.

Mechanical means for interlocking the armatures are provided by means of the arm 25 which is free to rotate about its center pin 26 in the bracket El. Each end of this arm 25 has an open ended slot such as at 28 in Fig, 2 so that upwardly projecting pins such as 36 on the top of the armatures can fit into these slots 28 in the arm 25. Thus, when either armature is revolved in a particular direction about its pivot, the other armature is rotated through the same angle in the opposite direction.

The centering device which acts to position the armatures it and it when they are both deener gized consists of a pressure plate 5?? which is pivoted upon the projecting edge of the plate 33 and spring biased by means of the spring 34 so as to press against both armatures it and it; when they are in their neutral positions. Since movement of either armature towards its associated core will cause the other armature to move away from the core, the pressure plate 32 will then be pushed outward such outwardly moving armature and a will cause the spring St to compress further. Ob viously therefore, when both armatures i and 18 are deenergized, they will move to the positions where the pressure plate 3'3 will exert equal forces upon each armature and in that position the spring 3 1 will be compressed the least.

Contacts and are mounted to the upper portion of contact arm associated with armature iii and cooperate with corresponding con tacts 38 and 39 respectively mounted onto the contact block 253. Similarly contacts ii and 42 mounted on a similar contact arm 3? of armature l6 cooperate with contacts and 51 respectively also located on the contact block 45.

Having thus described the mode or" operation of the present invention in a general manner, a more detailed description will now be given of its various components and how they cooperate one with another. Beginning with the bracket 53, it can be seen that four rectangularly shaped core heads 54 are mounted upon one face of this bracket by means of the rivets 55 in such a manner that countersunk holes in these core heads are aligned with corresponding holes of larger diameter in the bracket. Into these four larger holes in the bracket are fitted four cylindrically shaped core pieces 56 and these are firmly held to the bracket by means of screws which pass through the core heads 54 and into the tapped holes in the ends or the core pieces 53.

Although these core pieces are generally of circular cross-section as has been mentioned, they have been provided with flattened surfaces over the portions which are adjacent to the bracket. The reason for so shaping these core pieces is apparent from an examination of Fig. 6 which is a cross-sectional View of two of these core pieces taken along the line 8-6 in Fig. 1. In this Fig. 6, permanent magnets 2i and 22 have been shown placed about the core pieces 55 and, by flattening the sides of these core pieces as shown a greater area of contact is provided between the core pieces and the magnets. A clamp 60 formed of resilient material firmly holds the permanent magnets 2| and 22 adjacent the core pieces 56. A similar arrangement is provided for the two core pieces associated with the coils I! and 18 which have not been shown in this partial crosssectional view.

A leakage strip provided with a notch is mounted on to each pair of cores. Thus, the leakage strip H, having a notch at 62, has two circular holes cut through it so that it can fit over the core pieces 55 associated. with coils l2 and IS. A yoke such as the yoke It is associated with each pair of coils and completes the magnetic circuit for those coils. A terminal board 63 is attached to the cores by means of bolts 64 passing through the terminal boards into tapped holes in the ends of the cores. The spacers 65 provide the proper amount of separation between this terminal board 63 and the four coils, and the insulating plates 66 insure that a short circuit will not result from the connections made to the termi nal posts 6? on the top of the terminal board 63. The spring washers 68 are located between the coil ends and the insulating plates 66 and provide that the coils will be tightly held onto the assembly.

Figs. 1 and 3 illustrate that the plates 33 mounted upon the bottom of the bracket 53 by means of screws Ti) and Ti serve as a bearing for the armatures Hi and it and pressure plate 32. Thus, these armatures and the pressure plate are each provided with a slot into which fit the projecting edges of these bearing plates 33. The arm'atures are held onto these projecting edges of the plates by means of a retaining plate 72 which fits around the bottom portion of the armatures l0 and I6 and holds them in place. An additional retaining plate 73 is provided and is held onto the bracket 53 by means of screws M and this retaining plate in a similar manner, insures that the pressure plate 32 will remain in position with respect to the projecting edges of the bearing plates 33. By means of this arrangement, both the armatures l0 and It and the pressure plate 32 are hinged about their bottom portion.

The bearing bracket 2! is held by means of screws 15 onto a downward sloping surface of the bracket 53. This bearing bracket 21 has two concentric holes and into these holes fits the bearing pin 26. The bottom portion of this bearing pin 26 rests upon the lower edge of the hearing bracket 21 and has a circular portion 16 of greater diameter which provides a means of support for the arm 25 fitting over the 'top of this pin 26 and soldered thereto. The arm 25 and pin 26 are thus free to rotate in the bracket 21. Two open-ended slots 28 are located at the ends of the arm 25 and an upwardly projecting pin 30 from each of the armatures fit into these slots 28. Thus, it will be seen that as either armature ID or Iii is attracted towards its associated core head 55, the arm 25 will rotate about its pin 26 and cause the other armature to be moved in the opposite direction thereby providing an interlocking of these two armatures for, as one armature closes its front contact, the other armature will always be positioned so as to close its back conact.

The pivoted pressure plate 32 is positioned by means of the spring 34 which fits over the projecting stud TI on the bracket 53. This spring 34 is held in place by means of the two nuts 18 and 3'9 which fit over the threaded portion of this projecting stud 71. It will be noted that the outer nut 18 is slotted and that there is a hole drilled through this projecting stud I"! so that when the proper spring compression is obtained, thus nut 78 may be locked into place by means of a cotter pin 80 passing through the slots in the nut 78 and the associated hole in the threaded stud Ti. The compressive force of the spring 34 causes the pressure plate 32 to exert a force against the armatures l0 and It as has been described. It will be noted that rivets 8| have been placed through the upper portion of the pressure plate 32 and that the projecting heads of these rivets contact against the armatures l0 and It. With pressure plate 32 pressing with equal forceiagainst both armatures in they normal deenergized condition, they are both held in their neutral position as illustrated in Fig. 1. As has been described, movement of either armature towards its associated core head will cause the other armature to move away from its associated core head because of the interlocking arrangement which is provided. The pressure plate 32 will then exert av greater force against this other armature so that when both armatures are released, they will immediately be restored to the position shown in which the pressure plate is in contact with both armatures I and I6.

. The contact block 40 is mounted onto the bracket 53 by means of screws 91 which fasten into the threaded holes in the bosses 98 formed on the top of the bracket 53. of this block 40 has been cut away to show more clearly the manner in which the armatures I0 and I6 are interlocked. Permanent magnets 99 are fastened to the block 40 by means of the studs I00 which pass through a corresponding hole in these magnets. The contacts 38, 39, 50 and I are also mounted at the ends of these studs I00. These permanent magnets 99 are so placed with respect to these front andback contacts as to provide magnetic blow-out of an are produced by the opening of these contacts. Ceramic insulators IOI mounted to either side of these contacts provide insulation for the black 40 and prevent it from becoming overheated as th result of electrical arcing.

A block of insulating material 82 is attached to each armature by means of rivets 83. The armature brackets 84 are then mounted onto the opposite faces of each. of these insulating blocks 32 by means of additional rivets 85. Contact arms 86 having a narrowed bottom. portion fit into a corresponding hole in each armature bracket 84. Pins 81 fitting into holes cut into the bottom. of each contact arm 86 hold the compressed springs 88 in place. The studs 89 riveted onto the armature brackets 84 pass through holes in the contact arms 31, and springs 90 are mounted on each side of this contact arm with washers 9I as shown.

As has already been described, two contacts are riveted to the upper portion of each contact arm 31 and power is supplied to these contacts by'at-l rotate through a small angle about the point at which the contact arm 31 butts against its armature bracket 84. This arrangement insures that the proper pressure will be applied by the contacts as each armature makes either its front or back contacts. Thus, if the armature I0 is attracted toward its associated core head 54 by the energization of the windings I2'and I3, the front contacts 36 and 39 will be closed before the armature I0 is actually in its fully attracted positionb Thenas the armature I0 continues its travel toward its .fully attracted position, the contact arm 31 of this armature I0 is rotated about its pivoted point against the compressive force of one of the springs 90 thereby causing a force to be applied between these front contacts. Similarly,l as the other armature I6 simultaneouslyclosesj its.

In Fig. 2 a portion 6 back contacts III and 50, a force is applied to these contacts.

The unit I09-I I0 comprises two rectifiers and is mounted upon an extending arm of the bracket 53 by means of the stud I02 and the nuts I03. Two insulated binding posts I04 and I05 are provided and are attached to the block 40 and to the bracket 53 respectively. The reason for .providing these insulated binding posts as shown will later be more fully described.

The magnetic circuit associated with the armature I0 has been shown schematically in Fig. 5. Thus, there are shown in this drawing the cores 56, windings I2 and I3, yoke I4, leakage strip II, and core heads 54. A tractive type polar relay having a magnetic circuit of this type is shown in the Patent No. 2,414,583 to Duffy, dated January 21, 1947. The function of the slot in the leakage strip I I is shown and described in the application Ser. No. 699,678 of Duffy and Willing, filed September 27, 1946, now Patent No. 2,502,811. Since this type of magnetic relay has been fully shown and described in the above references, no detailed explanation will be given in the present application. It should be understood, however, that no claim is intended to be made herein to any material disclosed and claimed in the prior patent or application listed above.

Fig. 4 shows the circuit organization provided for controlling a switch machine by means of the controller of the present invention. It will be assumed in this discussion of the circuit of Fig. 4 that the contactor NC corresponds to the armature I0 and its associated contacts; whereas, the contactor RC then corresponds to the armature I6 and its associated contacts. In this drawing the switch machine has been shown schematically by the motor armature A, series field F, and brake B. This brake B is of the friction type and is controlled so as to exert a braking effect whenever the current to the switch motor is interrupted. The switch machine also includes point detector contactsid'l and I08 which open and close under certain conditions as will presently be described. The circuit for this switch controller includes, in addition to the interlocked contactors NC and RC, a rectifier I09 and IIO included between each pair of windings of each of the contactors and also includes the holding and pick-up windings H and P respectively, of an overload relay. The contactor NC is energized and its front contact closed during operation of the switch from the reverse to the normal position and; conversely, the contactor RC has its front contact closed during operation of the switch from its normal to the reverse position. The point detector contactor I0! included in series with the contactor NC is open only when the switch is in its full normal position; whereas, the similar contact I05 is open only when the switch is in its full reverse position. The two rectifiers' I09 and I I0 are preferably connected between the contactor windings as shown so that they will be protected from lightning by the inductive eifect of each of these windings. The two binding posts I00 and 05 previously mentioned and shown in Fig. 1 are for the purpose of connecting the windings I2 and I3 and the rectifier I09 in series shown in Fig. 4. Thus, simply by connecting a terminal of one coil and one terminal of the rectifier I09 to one insulated binding post and connecting one terminal of the other coil and the remaining terminal of rectifier I09 to the other insulated binding post, a circuit is provided between the tworemaining coil terminals which includes both the line wire H4 negative with respect to the line wire I I5. When the lever I I I is moved to its dotted line position, however, the line wire H4 becomes positive with respect to line wire H5. Although this control mechanism has been shown as consisting of a manually operable lever, it should be understood that any other suitable means, either manual, semi-manual, or automatic for changing the relative polarity of the line wires might be used.

As may be ascertained from the above description, Fig. 4 shows the condition of the controller when the switch is in its full normal position because the point detector contact I01 is shown open. Then with the polarity applied to the line wires as shown, a current flows through back contact H! of the overload relay, the windings of the contactor RC, rectifier Ii 0, and closed point detector contact I08. However, since this current is required to flow in the reverse direction through the rectifier Hfl, this rectifier acts as a large resistance and holds the current to a very small value, approximately of the order of four milli-amperes. The primary function of the rectifier is to limit current consumption and not to prevent actuation of its associated contactor although it also performs this latter function. To provide the greatest safety, the circuit associated with each contactor is so arranged that even a large value or current flowing through the windings in a direction opposite to that indicated by the arrows in the contactor symbols in Fig. 4 will not actuate that contactor even though the amount of current is many times the normal pick-up current.

If now the lever I I I is moved to its dotted line position, the polarity of the voltage applied to line wires H4 and H5 will be reversed with the result that the current flowing through the rectifier H0 will encounter the forward resistance of this rectifier. This resistance is of a relatively small value so that the current will now rise to such a magnitude and be of the proper polarity to energize the contactor RC. As a result, front contact H8 of this contactor RC will close and, because of the mechanical interlocking, back contact H9 of contactor NC will simultaneously be closed. The switch motor will then be energized through a circuit from front contact H8 of contactor RC, the pick-up winding of the overload relay, the brake B, field F, back contact H9 of contactor NC, the motor armature A, to It will be noted that under these conditions the current flowing through the motor field F is of the direction as shown by the solid line arrow adjacent the field winding. The switch motor when thus energized operates the switch points to their reverse position.

As soon as the switch points move from the normal position the point detector contact In? closes and, as has been stated, the contact I08 remains closed until the switch is in its full reverse position. When the switch has finally been moved to its reverse position, the point detector contact I08 opens thereby interrupting the circuit to the contactor RC. Since the contact I0! is now closed, the contactor NC will now be connected across the line wires H4 and H5 through the back contact I I! of the overload relay but the current will be of such a direction through this contactor NC as to keep it deenergized. Also, the contactor current will now encounter the back resistance of the rectifier I09 so that this current will be held to a very small value. Thus, both contactors will be deenergized and will be in their neutral positions so that the motor will be deenergized. Consequently, the mechanical brake B will be applied and will prevent creeping Or other undesired motion of the switch.

If the lever I I I is now returned to its solid line position, the polarity of the voltage applied to line wires I I 4 and I I5 will again be reversed and, as a result, the current flowing through the windings of the contactor NC will be increased and the polarity will be such as to allow this contactor to become energized. For this reason, front contact H9 or this contactor NC will be closed and back contact I I8 of contactor RC will simultaneously be closed. The switch motor will them be energized through a circuit from front contact H9 of contactor NC, the motor field F. brake B, pick-up winding P of the overload relay, back contact H8 of contactor RC, the motor armature A, to It will be noted that in this case the current flowing through the motor field F is in the direction indicated by the dotted line arrow adjacent the field F. This reversal of current through the field causes the direction of operation of the motor and thus of the switch ponts to be reversed so that the switch will now be operated to its normal position. In a similar manner, as the switch reaches its normal position, the point detector contact I01 will open and cause the deenergization of contactor NC with the result that the switch motor will become deenergized and the brake B will again be applied.

As has been explained, both contacts I01 and I08 are closed during actual operation of the switch from one position to another. Because of this feature, the direction of switch movement can be reversed during mid-stroke since either contactor NC or RC can then be energized simply by reversing the polarity of the voltage applied to the line wires H4 and H5.

With respect to the operation of the overload relay it will be noted that this relay includes two separate windings H and P which represent the hold winding and pick-up winding of this relay respectively. If, for instance, the operation of the switch from one position to another is obstructed so as to cause the motor current to rise to an abnormally high value, the current through the winding P will then be of sufiicient magnitude to cause the energization of this overload relay with the result that the back contact H1 will open thereby deenergizing both contactors NCand RC. In this condition, both of these contactors will be operated to their neutral position thereby deenergizing the switch motor. Moreover, the closing of front contact H! of this overload relay then connects the hold winding H directly across the line wires H4 and I I5 so that the overload relay remains energized and its back contact H1 open as long a a voltage is plied to these line wires H4 and 115. Thus, in order to restore the circuit to its operating condition it is necessary to open the circuit to the line wires I I4 and I I5 to allow the deener iz t of the winding H. g a 1m Summary By means of the present invention polar control of a switch machine is obtained while yet requiring only a very' small amount of current when used in a normally energized circuit. Since these contactor windings have a low duty cycle in that they are fully energized only a very small portion of the time, they can obviously be designed to carry a large amount of current when they are energized without overheating and, as a result, proper'operation of these contactors will be obtained'even when the line voltage drops to a fairly low value.

It may be said then that the switch machine controller of the present invention not only operates in an improved manner but also requires the expenditure of less equipment. The utmost in safety precautions has been included in that proved polar magnetic relay structures have been employed having two armatures and an improved means has been devised for mechanically interlocking these armatures. In addition, the circuit described'permits operation with a minimum of power and yetallows instant and positive operation of the switch to either position.

Having thus described a switch machine controller as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate in the disclosure of the invention rather than to limit the number of forms which it may assume; and, it is to be further understood that various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice without in any manner departing from the spirit or scope of the present invention.

What I claim is:

1. A circuit controller comprising in combination two substantially adjoiningU-shaped electromagnetic structures, armatures for the respective structures disposed to be attracted about respective pivot points in substantially the same plane by heir associated structures, an interlocking motion plate having a fixed pivot point at its center and having its ends operatively engaging the respective armatures, the pivot point of said motion plate being substantially midway between the two armatures, whereby the attraction of one armature is effective through said motion plate to move the other armature in a direction away from the cooperating electromagnetic structure, a pressure plate adjoining said armatures, said pressure plate being pivoted to permit motion of the plate in a direction to promote motion of the armatures toward their associated electromagnetic structures, and compression spring biasing means acting against said pressure plate to normally bias said pressure plate against said armatures, said biasing means being effective to exert substantially equal pressure against each of said armatures in a direction toward the associated electromagnetic structures when both electromagnetic structures are deenergized, and said biasing means being more fully compressed by the actuation of said motion plate about its pivot point whenever either of said armatures is attracted to its associated electromagnetic structure, whereby an armature when attracted to its associated electromagnetic structure is' spring biased away from its associated electromagnetic structure by said biasing means acting through said pressure plate and through said motion plate while the other of said armatures is biased by substantially equal pressure applied for movement in the opposite direction, and whereby said spring biasing means in acting through said pressure plate and through said motion plate biases the two armatures in the same direction to an extent limited by the fixed pivot of said motion plate when the electromagnets are both deenergized.

2. A circuit controller comprising in combination, two adjoining U-shaped electromagnetic structures, an armature for each of the structures disposed to be attracted thereby about a pivot point, the pivot points of the respective armatures being along a common axis, and each of said armatures having a pin projecting therefrom, an interlocking motion plate having bifurcated ends engaging said pins of the respective armatures, said motion plate having a fixed pivot point substantially midway between the two armatures, whereby the attraction of one armature is effective through said motion plate to move the other armature in a direction away from the cooperating electromagnetic structure, a pressure plate disposed beneath said armatures, said pressure plate having detents bearing against the underside of the respective armatures, and said pressure plate being pivoted for movement about its pivot point in substantially the same direction as movement of the respective armatures about their pivot points, and spring biasing means acting against said pressure plate to bias said pressure plate against said armatures so as to actuate said armatures toward said electromagnetic structure to an extent limited by the fixed pivot of said motion plate, whereby said pressure plate is depressed and the spring pressure of said biasing means against said plate is increased when the armature associated with either of the structures is attracted toward its associated structure.

3. A circuit controller comprising in combination, two adjoining U-shaped electromagnetic structures, an armature for each of the structures disposed to be attracted thereby about a pivot point, the pivot points of the respective armatures being along a common axis, and each of said armatures having a pin projecting therefrom, an interlocking motion plate having bifurcated ends engaging the pins of the respective armatures, said motion plate having a fixed pivot point substantially midway between the two armatures, whereby the attraction of one armature by its associated electromagnetic means is effective through said motion plate to move the other armature in a direction away from the cooperating electromagnetic structure, a pressure plate disposed adjoining said armatures so as to at times bear against the respective armatures to promote movement toward'the associated electromagnetic structures, said pressure plate being pivoted for movement about its pivot point in substantially the same direction as movement of the respective armatures when attracted by their associated electromagnets, and compression spring biasing means acting against said pressure plate, said biasing means being efiective to exert substantially equal pressure against each of said armatures in a direction toward the associated electromagnetic structures when the electromagnets of both structures are deenergized, and said biasing means being more fully compressed by the actuation of saidmotion plate about its pivot point whenever either of said armatures is attracted to its associated electromagnetic structure.

4. A circuit controller comprising in combination, two adjoining electromagnetic structures, armatures having fixed pivot points associated 1 1' with the respective structures, each of said armatures having a projecting an interlocking motion plate having its ends engaging the respective pins of said armatures and having a center pivot point substantially midway between the two armatures, whereby the attraction of one armature to its associated electromagnetic structure is effective through said motion plate to move the other armature in a direction away from its cooperating electromagnetic structure, a pressure 1 plate disposed adjoining said armatures and pivoted so as to permit actuation about its pivot point in a direction to actuate said armatures in the direction of their respective electromagnetic structure, and spring biasing means acting against said pressure plate to bias said pressure plate against the respective armatures, whereby an armature when attracted tov its associated electromagnetic structure is spring biased away from its associated electromagnetic structure by said biasing means acting through said pressure plate and through said motion plate.

5. A circuit controller comprising in combination, two substantially adjoining electromagnetic structures, armatures associated with the e respective structures and having pivot points in substantially the same plane, an interlocking mo tion plate having a center fixed pivot and having its ends operatively connected to the respective armatures, whereby the attraction of one armature is effective through said motion plate to move the other armature in a direction away from the cooperating electromagnetic structure, a pressure plate disposed adjoining said armatures and pivoted for movement in a direction to contact the armatures and actuate them toward their associated electromagnetic structures, and spring biasing means acting against said pressure plate to bias said pressure plate against said armatures whereby said biasing means in acting through said motion plate applies substantially equal pressure to said armatures in the direction of their associated electromagnetic structures when both electromagnetic structures are deenergized, and whereby an armature when attracted to its associated electromagnetic: structure is spring biased away from its associated electromagnetic structure by said biasing means.

CHARLES L. SWANTON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,248,344 Kulicke Nov. 27, 1917 2,068,581 Tritle Jan. 19, 1937 2,248,915 Logan July 8, 1941 2,299,275 Jerome Oct. 20, 1942 2,398,681 Weber Apr. 16, 1946 2,419,258 Field Apr. 22, 1947 2,446, 99 Nelsen Aug. 3, 1948 2,510,604 Pfaff June 6, 1950

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