US2845508A - Code transmitter relays - Google Patents

Description

July 29, 1958 Filed Nov. 7, 1955 L. J. LOCKETT 2,845,508

CODE TRANSMITTER RELAYS 5 Sheets-Sheet l lzzsalazion f INVENTORQ Leslie Joseph Locke'zfz BY MAW July 29, 1958 L. J. LOCKETT 2,845,503

CODE TRANSMITTER RELAYS Filed NOV. 7, 1955 3 Sheets-Sheet 2 1 Fig? 5.

INVENTOR. Leslie Jbigflll iaekeib figs HTTORJVEY July 29, 1958 LQCKETT 2,845,508

v CODE TRANSMITTER RELAYS Filed Nov. 7, 1955 5 Sheets-Sheet 3 16 1/4 uni-w E1 15 1 E5 Er: i C-Z- i 1 z, I :i I i :2 1 I l/ 2 w a I I I7 F 6 I :511 l' m ha INVENTOR. Leslie Joye vb Locked HIS A TTOHNEY CODE TRAN SMTTTER RELAYS Leslie Joseph Lockett, London, England, assignor to Westinghouse Brake and Signal (Iompany Limiter], London, England Application November 7, 1955, Serial No. 545,500

Claims priority, application Great Britain November 17, 1954 13 Claims. (Cl. Mill-9b) My invention relates to electrical relays, and particularly to electrical relays which are suitable for use in railway signaling systems employing periodically interrupted or cooled current of different frequencies for controlling signal devices in accordance with prevailing trailic conditions.

In coded railway signaling systems, the source of periodically interrupted or coded current for controlling the operation of signaling devices is usually a code transmitting relay provided with a pendulum arrangement maintained in oscillation by an electromagnet. The electromagnet of such a relay is periodically energized over a pair of pulsing contacts which are opened and closed by the oscillating pendulum. Other contacts as, for example, coding contacts, are also controlled by the periodic swings of the pendulum, the opening and closing of the coding contacts providing the necessary periodically interrupted current or code of a particular frequency to control the signaling devices.

The means for suspending the pendulums of code transmitter relays of the prior art comprised for the most part knife-edged bearings, pivoted hearings or flexible spring supports. Depending upon the particular relay structure and the suspension means employed for the pendulum, the suspension means formerly provided had one or more disadvantages. One disadvantage which may be mentioned is the friction developed between the parts of the bearings used. Another disadvantage is in the limitation of the pendulum weight because of bearing or support structure. Former suspension means in some instances limited the arc of pendulum oscillation to a small angle, or failed to constrain the pendulum to its intended position at any instant.

It is therefore an object of my invention to provide a novel means of suspension for a pendulum whereby the disadvantages as set out above may be substantially avoided so that a heavy mass may be suspended and oscillated through any desired angle of movement, its motion being closely constrained to predetermined path, yet with low frictional losses and freedom from wear, the latter object being attained by the elimination of rubbing contacts between the various bearing surfaces.

According to the invention, the suspension means comprises a cylindrical member mounted on a horizontal plane surface and positioned thereon by at least one pair of ligaments wrapped around the cylindrical surface of said member and secured at each end in such a manner that rolling said member along said plane surface causes one end of said ligament to be wound on to said cylindrical surface and the other end to be wound off said cylin: drical surface, and that said ligament constrained said cylindrical member to roll in a path substantially at right angles to its longitudinal axis, the pendulum weight or weights being rigidly attached to said cylindrical member.

The ligaments may be of thin, flexible metal strip and each pair may be formed in one piece, as by stamping from a sheet of the strip material, for example, joined together at each end. The ligaments are preferably tensioned, when in position, by a spring, which may be adjustable.

The ligaments are wrapped around the cylindrical member that they extend between the latter and the horizontal plane surface and accordinglyhave to bear the weight of the cylindrical member and the pendulum weigh Alternatively, in order to avoid undue loading on the ligaments when the pendulum weight is very heavy, the ligaments may be wrapped around parts of the cylindrical surface which lie outside the plane surface upon which the cylindrical member rolls.

The pendulum is maintained in oscillation by means of an electromagnet positioned so as to apply an attractive force to the pendulum in a direction parallel to the plane surface in response to electrical impulses applied to the energizing winding of the electromagnet. The cylindrical member is provided with axially extending pins which, as the cylindrical member rolls along the plane surface, engage contact arms to open and close electrical contacts or perform other mechanical movements. Preferably, the pins are coaxial with the cylindrical member, the contact arms being of such proportions that the flexing thereof compensates approximately for the rotation of the pins about their axes, thus minimizing the rubbing action. between the pins and the contact arms.

In an alternative method of operating electrical contacts, the cylindrical member, as it rolls, may depress a lever which, in response to said depression, operates said contacts.

Although there are many applications to which the pendulum suspension means according to the invention may be put, it is particularly suitable for code transmitters as employed in coded track circuit systems for railways and a code transmitter incorporating the invention will now be described by way of example.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

I shall describe two forms of an electrical relay embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings wherein similar reference characters designate similar parts throughout the several views,

Fig. 1 is a side elevational view of a code transmitting relay embodying my invention.

Fig. 2 is a top plan view of the code transmitter mechanism, portions of which are illustrated in section.

Fig. 3 is a sectional view taken along the line IIIIII of Fig. 2.

Fig. 4 is a plan view of ligament arrangement for the code transmitter.

Fig. 5 is a fragmentary side view of the code transmitter illustrating coding contacts.

Fig. 6 is a fragmentary side view of a second embodiment of my novel code transmitter.

Fig. 7 is a fragmentary top plan view of the code transmitter illustrated in Fig. 6; while Fig. 8 is a plan View of a band ligament used in the code transmitter illustrated in Figs. 6 and 7.

Referring now in detail to the drawings, the reference numeral 1 designates one form of a relay embodying my invention. The relay 1 comprises a circular base plate 2 having secured thereto, as by screws 3, four upright standards 4 of a nsnmagnetizable material such as brass. Supported on the four standards 4 is a rectangularly shaped platform 5 of insulating material, the platform 5 being secured to the standards 4 by threaded studs 6 which are threaded into the upper ends of the standards and pass through suitable openings in the platform and are threaded into the lower ends of upright rods 7. The rods 7 are also preferably of a nonmagnetizable material. Secured to the upper ends of the rods 7 as by screws 8, is a cover plate 9 made of insulating material. The base plate 2 and cover plate 9 are provided with a suitable annular ledge 2a and an annular groove 9a, respectively, to hold a glass or transparent plastic cylinder 10; sealing gaskets 11 being interposed between the ends of the cylinder and base and cover plates to form a sealed housing for the relay structure which will now be described.

Fixed to the top of platform 5, as by screws 12, are two spaced strips 13 of nonmagnetizable material, such as brass, hereinafter referred to as axial stops 13; and two parallel magnetizable pole pieces 14. The two pole pieces 14 are formed with tapered ends having a notch 15 cut into the lower edges thereof for the purposes hereinafter appearing. Secured between the outer ends of the pole pieces 14, as by screws 16, is a magnetizable core member 17 supporting an operating winding or electromagnet 18.

Disposed between the tapered ends of the pole pieces 14 approximately in the center of the platform 5, is roller 19 of magnetizable material, the axis of the roller being parallel to the magnetizable core member 17. The roller 19 is provided with turned down ends or studs 19a which are concentrical with the roller, the studs extending outwardly through the pole piece notches 15. Wrapped around the roller 19 is a pair of thin, flexible metal strips or ligaments 20. The two ligaments are preferably made of a non-magnetizable material, such as beryllium copper or a plastic film, such as nylon tape. The ends of the ligaments are secured to rigid cross plates 21 and 22, the cross plate 22 being provided with an opening 22a. One pair of ends of the ligaments is spaced apart so that the ligaments form, before being wound about the roller, a substantially flat triangular structure (Fig. 4). The triangular form of the ligaments permits the ligaments to be wound completely around the roller without overlapping as illustrated in Fig. 2 of the drawings. The cross plate 21 is secured to the platform 5 by means of bolts 23, while the cross plate .22 is held by a substantially U-shaped spring member 24 having one end secured to the underside of the platform, as at 25, and having the other end protruding upwardly through an opening 5a formed in the platform. The protruding end of the spring member is disposed within the opening 22a of the cross plate 22 and tends to tension the ligaments 20.

It will be noted that the ligaments are so wrapped around the roller that they extend between the roller and the horizontal plane surface of the platform. The ligaments thus bear the weight of the roller and the pendulum members hereinafter described. To avoid undue loading on the ligaments when the pendulum weights are very heavy, the ligaments may be wrapped around a recessed part of the cylindrical surface of the roller which lies outside the surface upon which the roller may roll.

Passing diametrically through the roller 19 is a rod 27 which is secured to the roller and extends radially both upwardly and downwardly, the downwardly extending end of the rod passing through an elongated slot 512 provided in the platform 5. Disposed on the extending ends of the rod 27 are sleeve spacers 28 and 29 for positioning pendulum weights 3i and 31 which are secured to the extremities of the rod. in Fig. l of the drawings, the upwardly extending end of rod 27 and the sleeve spacer 28 are illustrated as being shorter than the downwardly extending end of the rod and the sleeve spacer 29. The extending rod ends and the sleeve spacers may be of other lengths, but the mass of the lower weight should be greater than the upper weight so as to form together with the roller a compound pendulum which has a normal position of rest with the rod perpendicularly disposed to the horizontal surface of the platform 5.

4 The arrangement is therefore such that, if the roller 19 is rolled away from its normal position, the lower weight will cause the roller to roll back to its normal position upon release of the force which caused the rolling in the first instance. To prevent damage to the pendulum system in storage or during shipping, two threaded studs 27a are provided in the base and cover plates, the conical ends of the studs being adapted to abut the ends of the pendulum rod 27 when the studs are screwed inwardly.

When the roller is rolled away from its normal position of rest, the ligaments are wound on to the cylindrical surface at one end and are wound oh. that surface at the other end, the roller actually rolling on the ligaments which pass between the roller and the surface of the platform. When the force causing the roller to roll is removed, the pendulum weights provide the necessary force to return it to its normal position and beyond that position. It will be evident that the period of the pendulum will depend upon the relative mass of the two weights and the lengths of the two rods to which they are secured. It will also be noted that there is no rubbing contact between the bearing surfaces and that the major stresses to which the ligament is subjected are of substantially constant value, and unaffected by the length of travel of the roller, so that no limitation is imposed upon the arc of oscillation for this reason.

it is therefore apparent, that upon energization of the electromagnet 13, the magnetic flux threading the pole pieces 14 passes through the roller 19 to apply an attractive force tending to roll the roller toward the electromagnet. Since the pole pieces 14 are mounted on the non-magnetic axial stops 13 and are formed with tapered ends, the greater part of the magnetic flux passes through the center of the roller. The non-magnetic stops tend to keep the roller in alignment, the non-magnetic material of the stops preventing the roller from sticking. it will be appreciated that the attractive force of the electromagnet 125 may be applied to some other part of the pendulum system, the inagnetizable roller herein being illustrative of one possible way to maintain the pendulum in oscillation. The travel of the roller toward the electromagnet is limited by the vertical edge 15a of the notch 15 provided in the pole pieces 14. Upon deenergization of the electromagnet, the pendulum weights 30 and 31 provide a restoring force which tends to return the compound pendulum to its normal position. The overtravel of the pendulum beyond its normal position is limited by the vertical edge 15b of the notch in the pole pieces.

In order to maintain the pendulum arrangement described in oscillation, a pair of pulsing contacts 32 is provided in the energizing circuit (not shown) of the electromagnet 13. The pulsing contacts as herein illustrated comprise two upstanding, elongated spring fingers 33 secured in spaced relation in an insulating block 34 riveted to a nonmagnetizable bracket 34.4 on a cross piece 35 fastened to two of the standards 4 below the platform 5. Riveted to the upper extremities of the spring fingers 33 are abutment pads 36 of insulating material. The spring fingers are stressed so that the abutment pads engage opposite sides of a stud extension 37 mounted concentrically in the roller stud 1% when the pendulum arrangement is in its normal position. Inverted I-formed keepers or stops 38 are secured in the insulating block 34, the dependent ends of the stops cooperating with the ends of the abutment pads to limit the travel of their respective spring fingers when the roller rolls from its normal position. The pulsing contacts 32 will be closed when the roller is in its normal position, and as will hereinafter appear, the spring fingers are so set that the pulsing contacts will close shortly before the roller returns to its normal position from its overtravel position.

With the pendulum in its normal position as illustrated in Fig. l, the closed pulsing contacts 32 complete the energizing circuit for the electromagnet 18. The roller will be attracted toward the electromagnet, the rolling of the roller to the left, moving the stud extension 37 to open the pulsing contacts. The electromagnet 18 is thus deenergized whereupon the pendulum weights 30 and 31 return the roller to its normal position and beyond. As the roller passes through its normal position, the pulsing contacts 32 close for a short period and reenergize the eelctromagnet to exert a momentary attractive force on the roller tending to check the overtravel of the roller. As the roller rolls through its normal position the stud extension 37 will again open the pulsingco-ntacts. When the pendulum reaches the end of its overtravel swing, the weights will again provide a restoring force to the pendulum to return it to its normal position. On the return swing, the pulsing contacts are closed shortly before the roller reaches its normal position, the closed pulsing contact again energizing the electromagnet to apply an attractive force to the roller to maintain the oscillations of the pendulum.

In order to insure that the pendulum receives impulses sufficient to maintain oscillations, an assyrnetric element such as a dry disc rectifier 39 secured to the platform 5, is provided in the energizing circuit of the electromagnet. The combined effects of the inductance of the electromagnet in delaying the build-up of magnetic flux and that of the rectifier in delaying the collapse of the magnetic flux after the energizing circuit is opened provide an impulse of sufficient duration to maintain the pendulum in oscillation. The magnitude of the impulses is dependent upon the length of time during which the pulsing contacts remain closed and advantage is taken of this circumstance to prevent excessive variations in the amplitude of swing due to the changes in supply voltage for the electromagnet. The time for one complete swing of the pendulum remains constant so that an increase in the amplitude serves to reduce the time of passage through that small arc in which the pulsing contacts are closed. Thus the effective magnitude of the impulse is reduced.

The addition of contact actuated upon the movement of the roller from its normal position will provide uniform coded impulses for the operation of track circuits in railway signalling. As an example of such coding contacts, I have provided by way of illustration two sets of contacts 4-1 and 42 secured in insulating blocks 43, Figs. 2 and 5. The insulating blocks 43 are secured to a nonmagnetic bracket 44 on a cross piece 45 riveted to two of the standards below the platform 5. The contacts 41 and 42 are each provided with elongated spring fingers 46 and 47 (Fig. 5, only contacts 41 being illustrated), the contact finger 46 being the longer of the two and being provided with an insulating abutment pad 48 for engagement by the stud extension 37 provided in the end of the roller stud 19a. The contacts 46 and 47 as illustrated in Figs. 2and 5 are normally closed when the pendulum is in its normal position. Upon energization of the electromagnet 18, the attraction of the roller by the electromagnet will move the stud extension to the left (Fig. 2) to open the contacts 42, contacts 41 remaining closed. Contacts 42 will remain open and contacts 4]. will remain closed during the initial swing and return of the pendulum to its normal position. As the roller moves to the right of its normal position during its overtravel swing the contacts 41 are opened and contacts 42 remain closed until the overtravel swing of the pendulum returns the roller to its initial position. The periodic opening and closing of the contacts 41 and 42 may thus be used to transmit a code signal in railway signaling systems.

It will be readily apparent that other contact combinations are possible and that the concentrically disposed contact actuators herein illustrated may be used to operate such contacts, or contact actuators otherwise disposed either on the roller or on the pendulum rods may be used to actuate such contacts.

In Figs. 6, 7 and 8 of the drawings, I have illustrated another form of ligaments which may be used with my pivotless movement for a pendulum. In this embodiment of my invention I provide a band ligament-48 of suitable material, the ligament before being wound around the roller having a substantially flat rectangular portion 49 provided with a substantially rectangular opening 49a and terminating in a T-formed end 50 provided with openings 50a through which the pendulum rod 27 may pass. The ends of the band ligament 48 are secured to cross pieces 51 and 52 of suitable rigid and non-magnetic material. In winding the ligament about the roller 19, the T-forrned end 50 of the band ligament is passed through the opening 4% in the rectangular end (Fig. 7-), the ligament extending between the roller and the platform. The particular form of the band ligament prevents overlapping of any of its parts when wound around the roller. The F-formed end is secured by its cross piece 52 to the platform 5, while the rectangular formed end is hooked by its cross piece 51 over an eccentric band tensioner 53 mounted on the top of platform 5. Suitable ension for the ligament 48 may thus be provided by turning the eccentrically disposed tensioner. The pendulum arrangement illustrated in Figs. 6 to 8 operates in the same manner as the arrangement illustrated in Figs. 1 to 5.

The invention is evidently not limited to the particular embodiment described above. For example, the ligaments employed may take other forms, such as four separate ribbons, anchored at one end to the top of the roller and spaced apart, suitably tensioned and secured to each side of the roller. Alternatively, each ligament may be composed of multiple strands of wire, or of a nonmetallic tape. Furthermore, for the suspended weights may be substituted an eccentrically loaded wheel secured to the roller and rotating therewith.

A code transmitter relay embodying my invention may advantageously be used in railway signaling systems wherein code of different frequencies must be accurately controlled for safe operation of signaling devices. The pivotless suspension of the pendulum in my novel relay is practically free of frictional losses, the rolling friction of the cylindrical support for the pendulum system being extremely small. A further advantage in the use of the pendulum arrangement herein described is the possibility of using a heavy pendulum mass which may be oscillated through any desired angle of movement and constrained to a predetermined path.

Although I have herein shown and described only two forms of an electrical relay embodying my invention, it is understood that various changes'and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. A pendulum comprising, a horizontal support, an

I eccentrically weighted mass rollable on said support;

means including a ligament wrapped around a portion of said mass and anchored at both ends to said support .to constrain the rolling of said mass to a predetermined path, and means controlled by said mass to roll said mass in limited arcs on said support and to sustain oscillations of said mass.

2. A pendulum comprising, a horizontal support, an eccentrically weighted mass rollable on said support; means including a ligament wrapped around a portion of said mass and anchored at both ends to said support to constrain the rolling of said mass to a predetermined path, and electromagnetic means on said support and mass for rolling said mass in limited arcs on said support including an electromagnet, a magnetizable element, and means controlled by said mass for periodically energizing said electromagnet.

3. A pendulum comprising, a platform, an eccentrically weighted mass including a cylindrical portion rollable on said platform, ligaments wrapped around the cylindrical portion and secured at both ends to said platform, electromagnetic means on said mass and platform for rolling said portion in limited arcs and for sustaining oscillations of said mass including an electromagnet, a magnetizable element, and means controlled by said mass for periodically energizing said electromagnet.

4. A pendulum comprising, a platform, an eccentrically weighted mass including a cylindrical portion rollable on said platform, tensioned ligaments wrapped around said cylindrical portion, the ligaments passing under the cylindrical portion between the portion and the platform, the ends of the ligaments lying on the surface of the platform and secured to said platform, electromagnetic means on said mass and platform for rolling said portion in limited arcs and for sustaining oscillations of said mass including an electromagnet, a magnetizable element and means controlled by said mass for periodically energizing said electromagnet.

5. A pendulum comprising, a platform, an eccentrically weighted mass including a cylindrical portion rollable on said platform, said portion being of magnetizable material; means constraining the rolling of said member to a predetermined path, an electromagnet secured to said platform, magnetizable means for applying an attractive force to said portion in a plane parallel to said platform upon energization of said electromagnet to roll said cylindrical portion, and means controlled by said mass for periodically energizing said electromagnet to sustain oscillations of said mass.

6. A pendulum comprising, a platform, an eccentrically weighted mass having a cylindrical portion rollable on said platform, said portion being of magnetizable material,

tensioned ligaments wrapped completely around said cylindrical portion Without overlapping, the ends of said ligament lying on the surface of said platform and secured thereto, an electromagnet secured to said platform, magnetizable means for applying an attractive force to said cylindrical portion in a plane parallel to said platform upon energization of said electromagnet to roll said cylindrical portion, and means controlled by said mass for periodically energizing said electromagnet to sustain oscillations of said mass.

7. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in a path between the two pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed magnetic path, means for limiting the rolling of said cylinder,

weights secured to said cylinder to form a compound 7 pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to roll said cylinder and thereby oscillate said pendulum contact means controlled by said pendulum to periodically energize said electromagnet to sustain oscillations of the pendulum, and coding means controlled by the oscillations of said pendulum.

8. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in a path between the two pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed magnetic path, means for limiting he rolling of said cylinder, a rod secured to said cylinder and passing radially therethrough, weights secured to said cylinder to form therewith a compound pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to roll said cylinder and thereby oscillate said pendulum; a contact actuator on said cylinder, pulsing contacts adapted to be opened by said contact actuator when said pendulum oscillates from its normal position, said contacts being preset to close when said pendulum is in its normal position and shortly before the pendulum returns to its normal position from its return swing, the closing and opening of said contacts controlling the energization and the deenergization of the electromagnet to sustain the oscillations of the pendulum, and coding contacts adapted to be opened and closed by the contact actuator upon oscillation of said pendulum.

9. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in a path between the two pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed path of low reluctance; studs concentrically disposed in the ends of said cylinder, stops on said pole pieces engageable by the cylinder studs to limit the rolling of said cylinder, a rod secured to said cylinder and passing radially therethrough, weights secured to the extremities of the rod to form with said cylinder 21 compound pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to oscillate said pendulum; a contact actuator concentrically disposed in the end of said cylinder, pulsing contacts adapted to be opened by said contact actuator when said pendulum oscillates from its normal position, said contacts being preset to close when said pendulum is in its normal position and shortly before the pendulum returns to its normal position from its return swing, the closing and opening of said contacts controlling the energization and the deenergization of the electromagnet to sustain the oscillations of the pendulum, and coding contacts adapted to be closed and opened by the contact actuator upon oscillation of the pendulum.

10. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in a path between the two pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed magnetic path; means for limiting the rolling of said cylinder, weights secured to said cylinder to form therewith a compound pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to roll said cylinder and thereby oscillate said pendulum; a ligament wound around said cylinder, a tensioning means secured to said support, one end of said ligament being secured to said tensioning means and the other end of the ligament being anchored to said support, a contact actuator on said cylinder, pulsing contacts adapted to be opened by said contact actuator when said pendulum oscillates from its normal position, said contacts being preset to close when said pendulum is in its normal position and shortly before the pendulum returns to its normal position from its return swing, the closing and opening of said contacts controlling the energization and the deenergization of the electromagnet to sustain the oscillations of the pendulum, and coding contacts adapted to be closed and opened by said contact actuator upon oscillation of said pendulum.

11. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in a path between the two pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed magnetic path; means for limiting the rolling of said cylinder on said support, a rod secured to said cylinder and passing radially therethrough, weights secured to the extremities of the rod to form with said cylinder a compound pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to roll said cylinder and thereby oscillate said pendulum; a ligament wound around said cylinder, a tensioning means secured to said support, one end of said ligament being secured to said tensioning means and the other end of the ligament being anchored to said support, a contact actuator on said cylinder, pulsing contacts adapted to be opened by said contact actuator when said pendulum oscillates from its normal position, said contacts being preset to close when said pendulum is in its normal position and shortly before the pendulum returns to its normal position from its return swing, the closing and opening of said contacts controlling the energization and the deenergization of the electromagnet to sustain the oscillations of the pendulum, and coding contacts adapted to be closed and opened by said contact actuator upon oscillation of said pendulum.

12. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in a path between the two pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed path of low reluctance; studs concentrically disposed in the ends of said cylinder, stops on said pole pieces engageable by the cylinder studs to limit the rolling of said cylinder, a rod secured to said cylinder and passing radially therethrough, weights secured to the extremities of the rod to form with said cylinder a compound pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to roll said cylinder and thereby oscillate said pendulum; a ligament wound around said cylinder without overlapping and having its ends lying on the surface of said support, a tensioning means secured to said support, one end of said ligament being secured to said tensioning means and the other end of the ligament being anchored to said support, a contact actuator concentrically disposed in the end of said cylinder, pulsing contacts adapted to be opened by said contact actuator when said pendulum oscillates from its normal position, said contacts being preset to close when said pendulum is in its normal position and shortly before the pendulum returns to its normal position from its return swing, the closing and opening of said contacts controlling the energization and the deenergization of the electromagnet to sustain the oscillations of the pendulum, and coding contacts adapted to be opened and closed by the contact actuator upon oscillation of said pendulum.

13. In a code transmitter, the combination comprising, a horizontal, nonmagnetizable support having an opening therein, two parallel nonmagnetizable strips secured to said support, two parallel magnetizable pole pieces on said support, an electromagnet secured between said pole pieces, a magnetizable cylinder disposed between the pole pieces having its axis parallel to the axis of said electromagnet and rollable in the path between the two parallel strips and pole pieces; the electromagnet, pole pieces and cylinder forming a substantially closed path of low reluctance; studs concentrically disposed in the ends of said cylinder, stops on said pole pieces engageable by the cylinder studs to limit the rolling of said cylinder, a rod secured to said cylinder and passing radially therethrough and through the support opening, weights secured to the extremities of the rod to form with said cylinder a compound pendulum having a normal position of rest on said support, the energization of said electromagnet applying an attractive force on said cylinder to oscillate said pendulum; a ligament wound around said cylinder without overlapping and having its ends lying on the surface of said support; a tensioning means secured to said support, one end of said ligament being secured to said tensioning means and the other end of the ligament being anchored to said support, a contact actuator concentrically disposed in the end of said cylinder, pulsing contacts adapted to be opened by said contact actuator when said pendulum oscillates from its normal position, said contacts being preset to close when said pendulum is in its normal position and shortly before the pendulum returns to its normal position from its return swing, the closing and opening of said contacts controlling the energization and the deenergization of the electromagnet to sustain the oscillations of the pendulum, and coding contacts adapted to be opened and closed by the contact actuator upon oscillation of said pendulum.

References Cited in the file of this patent UNITED STATES PATENTS 293,063 Orser Feb. 5, 1884 687,723 Burdon Dec. 3, 1901 1,585,319 Tupper May 18, 1926 1,775,242 Keith Sept. 9, 1930 1,858,876 Bossart May 17, 1932 1,913,826 Blosser June 13, 1933 FOREIGN PATENTS 192,871 Germany Mar. 15, 1906 751,784 France Sept. 9, 1933

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