US2730592A

US2730592A - Code following relay with frequency decoding contacts

Info

Publication number: US2730592A
Application number: US210358A
Authority: US
Inventors: Hufnagel Andrew
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1951-02-10
Filing date: 1951-02-10
Publication date: 1956-01-10
Anticipated expiration: 1973-01-10
Also published as: BE507483A; FR1057890A

Description

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CROSS REFERENCE 7 10, 1956 A. HUFNAGEL 2,730,592

CODE FOLLOWING RELAY WITH FREQUENCY DECODING CONTACTS Filed Feb. 10 1951 4 Sheets-Sheet l Insulation INVENTOR. BY/In w Halzagol H15 ATTORNEY Jan. 10, 1956 A. HUFNAGEL 2,730,592

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INVENTOR.

Andrew Hai'nagel BY HIS ATTORNEY United States Patent CODE FOLLOWING RELAY WITH FREQUENCY DECODING CONTACTS Andrew Hufnagel, Penn Township, Allegheny County, Pa.,

assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application February 10, 1951, Serial No. 210,358

18 Claims. (Cl. 200-91) My invention relates to electrical relays, and particularly to electrical relays which are suitable for use as track or line relays in railway signaling systems in which periodically interrupted or coded current is used to control signaling devices in accordance with different traffic conditions.

In coded track circuits for controlling wayside signals, code transmitters periodically interrupt, or code, direct current supplied to the track in accordance with trafiic conditions. Such track circuits include a code following track relay periodically energized and deenergized by the on and off periods of the code, the back and front contacts of the relay alternately opening and closing. The code following track relay contacts energize a decoding transformer, the transformer supplying energy to a proceed signal control relay and to an approach and proceed signal control relay through a decoding unit comprising a resonant electrical circuit and a full wave rectifier. In some instances frequency responsive relays have been used to eliminate the need of the decoding units.

In frequency responsive relays of the type in which a mechanically resonant structure serves as the armature, the response of the armature varies with the amplitude of the voltage applied to the operating windings of the relay. Such relays are adjusted to be responsive to the resonant code frequency at the lowest voltage to be expected. The periodic attractions of the resonant armature at resonant frequency will store successive increments of energy in the armature causing the armature to oscillate at the resonant frequency in its intended manner. Difliculty however arises when the amplitude of the voltage applied to the operating windings is increased and such voltage is not at resonant frequency. The strong magnetic field developed due to the higher applied voltage may overcome the inertia of the resonant armature structure and cause the resonant armature to operate at non-resonant frequencies.

In the resonant electrical decoding units which have been in use, it is likewise necessary to adjust the output of the decoding unit to a level where the proceed signal control relay will pick up properly, at resonant frequency, and at the lowest voltage to be expected. Difiiculty again arises when the relay may be picked up falsely at nonresonant frequencies because of the applied voltage being abnormally high.

An object of my invention is to provide a code following relay with a resonant contact structure coupled to the oscillating contact structure of the relay, the non-resonant contact structure operating at all code frequencies while the resonant contact structure is operated only on a resonant frequency code.

Another object of my invention is to provide a code following track relay with a resonant contact structure in which none of the contacts will operate when energy of improper polarity is applied to the windings of the relay.

Another object of my invention is to provide a code following relay with frequency decoding contacts in 2,730,592 Patented Jan. 10, 1956 which the operation of the resonant contact structure supporting the decoding contacts is independent of variations in the amplitude of the voltage applied to the relay coils.

A further object of this invention is to provide a code following relay with frequency decoding contacts responsive to limited side bands of the resonant code frequency.

Still another object of my invention is to provide a code following relay with frequency decoding contacts which are quickly responsive to changes in code frequency, which are immune to abnormal code frequencies and which are not susceptible to external mechanical vibrations.

Still a further object of the invention is to provide a code following relay with frequency decoding contacts in which the resonant contact structure supporting the decoding contacts may readily be tuned to be responsive to another code frequency.

In carrying out my invention, I provide a resonant contact structure mounted on a hinge spring so that the contact structure is free to oscillate about a vertical axis. The resonant contact structure comprises a weighted rocker arm carrying two electrical contact fingers, the rocker arm being oscillated about its mid point in a horizontal plane by an operating spring and an operating post. The operating post is carried by the rocker arm and is engaged by the operating spring, the upper ends of the spring being fixed to the nonresonant contact structure oscillated about a horizontal axis by the operating armature of the relay.

The operating spring and the operating post provide a drive for the resonant contact structure in which the stroke of the armature is completed during a very small portion of the total movement of the rocker arm. The force moving the rocker arm is thus constant and independent of relay energization. The energization of the relay may thus be varied over wide limits with no appreciable variation in response of the resonant contact structure. The operating spring and operating post also provide the necessary friction for damping the oscillations of the rocker arm. The operating spring and the operating post are offset with respect to the center line of the rocker arm so that friction at the post will occur due to the sliding of the operating post over the face of the spring. The friction at the operating post damps the oscillation of the rocker arm so that the resonant contact structure is not too selective at the resonant code frequency. By permitting response of the resonant structure to limited side bands of the resonant frequency, allowance is made for the minor variations in the code frequency which occur at times in any given code transmitter.

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

I shall describe one form of a code following relay embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a front elevational view of my code following relay with some of the parts in section to better illustrate the remaining parts. Fig. 2 is a side elevational view of the code following relay with some of the parts in section. Fig. 3 is a sectional view taken along the line IIl'-III of Fig. 1, a portion thereof being broken away to illustrate to better advantage certain features of construction. Fig. 4 is a front elevational view of the resonant contact structure shown in Fig. 3. Fig. 5 is a detail view of the hinge spring for pivoting the resonant contact structure. Fig. 6 is a sectional view taken along the line VI-VI of Fig. 2 showing the non-resonant contact structure movable by the armature of the relay; while Fig. 7 is an enlarged view showing the spring guides used in connection with the hinge spring illustrated in Fig. 5.

Referring to Figs. 1 and 2 of the drawings, the relay comprises a suitable case consisting of a top plate 1 of insulating material secured to the upper end of a substantially U-shaped nonmagnetizable bracket 2, a metallic base plate 3 secured to the lower end of the bracket and a transparent glass cylinder 4 clamped between the top plate 1 and the base plate 3. A gasket 5 of cork or other suitable material is interposed between the top plate 1 and the upper end of the cylinder 4, and a similar gasket 6 is interposed between the bottom plate and the lower end of cylinder 4, thereby sealing the case against the entry of dust and other foreign substances.

The operating mechanism of the relay is mounted on the U-shaped bracket 2, and, as here shown, comprises a core structure consisting of two vertically disposed

magnetizable bars

7a and 7b secured respectively to the

legs

2a and 2b of the bracket 2 by screws 8. The

bars

7a and 7b are provided at their upper ends with

adjustable pole pieces

9a and 9b having confronting

pole faces

10a and 10b, and at their lower ends with adjustable pole pieces 11a and 11b provided with confronting

pole faces

12a and 12b, respectively.

Associated with the core structure is a permanent magnet 13 which comprises a rectangular bar cast into a U- shape. This magnet is disposed with its two legs engaging the

magnetizable bars

7a and 7b at points approximately midway between the two sets of pole pieces. The magnet is secured to the bracket 2 by means of a clamping strap 14 and screws 15. A resilient strip 16 of suitable material such as phosphor bronze is clamped at its lower end between two clamping plates 17 which are secured to the bracket 2 by means of screws 18, the upper end of this strip being fastened, as by riveting, to the lower end of a magnetizable armature 19. The armature 19 extends upwardly between the confronting

pole faces

12a and 12b of the pole pieces 11a and 11b and the confronting

pole faces

10a and 10b of the

pole pieces

9a and 9b, and is provided adjacent its upper end with

core pins

20a and 20b (Fig. 6) made of bronze or other nonmagnetic material, the core pins cooperating with the

pole pieces

9a and 9b to prevent the armature from coming into direct contact with the pole pieces. The resilient strip 16 is set or stressed so that the armature 19 is biased toward the right as shown in Figs. 1 and 6, with the core pin 20a engaging the pole face 10a.

When the relay is in operation, the armature 19 oscillates between the

pole pieces

9a and 9b at a rapid rate, and to prevent breakage of the resilient strip 16 due to the resultant flexing of this strip, the upper ends of the clamping plates 17 are rounded, as shown in Fig. 1, in

such a manner that any flexing of the strip which occurs adjacent the upper end of these plates will be in the form of a gradual curve. Furthermore, the lower end of the armature 19 is likewise rounded, and a clamping plate 21 having a rounded lower edge is disposed on the opposite side of strip 16 from the armature to prevent sharp bends in the flexible strip adjacent the lower end of the armature.

Surrounding the armature 19 between the two sets of pole pieces is an operating winding 22 wound on a hollow spool 23. The terminal leads of the operating winding (not shown) extend upwardly and are secured at their upper ends to two terminal posts 24 fixed in the top plate 1. The lower end of the spool 23 rests on the pole pieces 11a and 11b, the spool being held in place by the pressure exerted by leaf springs 25 interposed between the upper end of the spool 23 and the lower edges of the

pole pieces

9a and 9b.

With the above-described construction, the polarizing flux due to the permanent magnet 13 traverses several different paths. One of these paths passes downwardly from the right-hand end of the permanent magnet 13, as viewed in Fig. 1, through the lower end of the bar 7a, the pole piece 11a, the air gap between the pole piece 11a and the lower end of the armature 19, the air gap between the lower end of the armature 19 and the pole piece 11b, the pole piece 11b, and then upwardly through the lower end of the bar 7b to the other end of the permanent magnet. Another path passes upwardly from the righthand end of the permanent magnet 13, as viewed in Fig. 1, through the upper end of the bar 7a, the pole piece 9a, the air gap between the pole piece 9a and the upper end of the armature 19, the upper end of the armature 19, the air gap between the upper end of the armature 19 and the pole piece 9b, the pole piece 9b, and downwardly through the bar 7b to the left-hand end of the permanent magnet 13. Another path for the polarizing flux extends upwardly through the bar 7a, as viewed in Fig. l, pole piece 9a, the air gap between the pole piece 9a and the armature 19, downwardly through the length of the armature 19, the air gap between the lower end of the armature 19 and the pole piece 11b, the pole piece 11b, and then upwardly through the bar 7b to the left-hand end of the permanent magnet. When the armature occupies the opposite extreme position from that in which it is shown in Fig. 1, some of the fiux which leaves the righthand end of the permanent magnet will pass downwardly through bar 7a, through pole piece 11a, the air gap between the pole piece 11a and the lower end of the armature 19, then upwardly through the armature, across the air gap between the upper end of the armature and the pole piece 9b, the pole piece 9b, and then downwardly through bar 7b to the left-hand end of the permanent magnet.

It will be apparent, therefore, that both the amount and the direction of the polarizing flux which passes lengthwise through the armature 19 depends upon the position of the armature with respect to the pole pieces 9:: and 9b. When the armature is midway between these pole pieces, there is no polarizing flux through the armature in the direction of its length because both ends of the armature are then at the same magnetic potential, but as the armature moves toward one or the other of the

pole pieces

9a and 9b, flux flows through the armature in one direction or the other depending upon which one of these pole pieces is approached. The armature 19 being mechanically biased by the resilient strip 16 to an off-center position between the pole faces 10a and 10b will be magnetically biased toward the pole piece 9a by the polarizing flux threading the armature in the manner described.

The path of the flux due to the current flowing in the operating winding 22 of the relay may be traced from the upper end of the armature 19 where it divides between the air gaps to

pole pieces

9a and 9b, then through the

bars

7a and 7b, the pole pieces 11aand 11b, and the air gaps between the pole pieces 11a and 11b to the lower end of the armature. The direction of the flux in these paths depends of course upon the polarity of the current supplied to the operating winding 22, and it will be apparent that when this current is in one direction, the armature 19 will be repelled from the pole piece 9a and attracted to the pole piece 9b, but when the current is reversed, this flux is in an opposite direction and the armature will then be repelled from the pole piece 9b and attracted to the pole piece 9a.

The extreme upper end of the armature 19 engages and operates a contact operating structure comprising a contact spring support 26 of insulating material suspended from the top plate 1 by leaf springs 27 secured adjacent the ends of said contact spring support,(Figs. 1, 2 and 6). Fixed at about the mid point of the contact spring support is a dependent bifurcated member 28, the confronting faces thereof being provided with buttons 29 which engage the reduced end of the armature 19. Secured to the contact spring support 26 are two pairs of

dependent contact fingers

30a and 30b, adapted to engage fixed

contacts

31a and 31b, respectively, upon operation of said contact spring support by said armature. The fixed

contacts

31a and 31b are adjustably mounted in adjustable brackets 32a secured to the dependent ends of terminal posts 32 mountedin the top plate 1. The

contacts

31a and 31b are so adjusted that when the contact spring support occupies its biased position illustrated, the back contacts 30a31a will be closed while the front contacts 30b-31b will be open, but when the armature 19 is moved to its opposite position, the front contacts 30b-31b will be closed and the back contacts 30a-31a will be open.

The relay structure and the contact assembly thus far described are similar in construction and operation to the relay structure and contact assembly illustrated and described in Letters Patent of the United States No. 2,057,605, granted to Herman G. Blosser on October 13, 1936, for Electrical Relays.

Fixed to the underside of the top plate 1 as by screws 33 is a T-shaped mounting bracket 34 formed with a dependent arm 34a (Figs. 1 to 4). Secured to the dependent arm 34a for oscillation about a vertical axis is a resonant contact structure generally designated by the reference character 35. The resonant contact structure comprises a rocker 36 substantially E-shaped, as viewed in Fig. 4, having a horizontal member 36a, two dependent arms 36b and 360 at the ends of the horizontal member, and a dependent arm 36d intermediate the ends and off center toward the dependent arm 36b. The resonant contact structure 35 is secured to the dependent arm 34a of the mounting bracket by a flat U-shaped hinge spring 37 (Fig. the base of the U-shaped spring being fixed by two screws 38 to the arm 34a of the mounting bracket while the arms 37a and 37b of the hinge spring are fixed to the dependent arm 36d on the rocker by screws 39. To guard against accidental distortion of the hinge spring 37 when the relay is handled, the arms of the U-shaped hinge spring are interposed between spring guides, the upper arm 37a of the spring being interposed between spring guides 40a secured to the dependent arm 34 by screw 38 and cooperating with spring guides 41a secured to the dependent arm 36d by screw 39, while the lower arm 37b on the hinge spring is similarly provided with spring guides 40b and 41b fixed to the lower ends of the

dependent arms

34a and 36b by

screws

38 and 39 respectively.

For purposes of providing a simpler assembly, the spring guides 40a and 40b may be made the upper and lower arms of a U-shaped spring member (not shown) similar to the hinge spring 37. Spring guides 41a and 41b may also be of the same construction. It will be noted in the enlarged view of the hinge spring and spring guides in Fig. 7 that the overlapping ends of the spring guides are spaced apart. The spring guides do not cooperate with each other or with the hinge spring during the normal operation of the resonant contact structure. The spring guides will cooperate with each other to prevent twisting or flexing of the hinge spring in handling or making adjustments to the relay, the ends of the spring guides abutting to limit the displacement of the rocker 36, thereby preventing the hinge spring from becoming biased or set. Also, in normal operation, the spring guides prevent any severe flexing of the spring where clamped.

Secured to the dependent arms 36b and 360 as by

screws

42 and 43 are a plurality of adjusting Weights 44 of various weights, the weights being of the same size but differing in thickness, together with weighting washers 45, the weights secured to both arms being equal. The weights 44, the washers 45 and the rocker 36 are so proportioned that the parts are symmetrically balanced about the vertical center line of the relay. Any extraneous vibrational forces which may be applied to the relay casing or relay structure will be neutralized by the symmetry of the parts, and so will not cause the resonant contact structure to oscillate.

The resonant contact structure further comprises two forwardly extending contact fingers 46a and 461; secured to the dependent arm 36d on the rocker arm 36 by screws 47, the contacts being spaced from each other and the rocker arm 36 by metallic spacers 48 interposed between the contact fingers and the dependent arm. Circuit connections to the

contact fingers

46a and 46b are made through a terminal post 46 (Fig. 2) secured in the top plate 1, through screws 33 and the resonant contact structure. The

contact fingers

46a and 46b are adapted to engage fixed

contacts

49a and 49b, respectively, which are adjustably secured in dependent arms 50, the contacts 46a-49a and 46b-49b hereinafter being referred to as the decoding contacts. The dependent arms are secured to brackets 51a integral with the lower ends of terminal posts 51 by screws 52 and clamping pieces 52a; the screws passing through a slotted opening 51b provided in each of the brackets and threaded into suitable openings in the dependent arms. The dependent arms may be pivotally and longitudinally adjusted to align the

contacts

49a, 49b with the

contact fingers

46a, 46b carried by the resonant contact structure, while the

contacts

49a and 49b may be longitudinally adjusted in the dependent arms 50. The

contacts

49a and 49b are so adjusted that when the resonant contact structure 35 is in the position illustrated in Figs. 1 and 3, the back contacts 46a49a will be closed with some pressure, while the front contacts 46b49b remain open, the contact 49b being particularly adjusted so that contacts 46b-49b will be open even with the back contacts 46a-49a just engaging. To limit the amplitude of the oscillations of the resonant contact structure, two eccentrically adjustable stops 53 are secured to the under side of the T-shaped mounting bracket 34 by screws 54.

Means are provided for oscillating the resonant contact structure 35 on the hinge spring 37 in response to an energizing current of the resonant frequency and proper polarity in the operating winding 22 of the relay. To this end, there is fixed to the contact spring support 26 an upstanding plate 55 terminating at its upper end in a block 55a. Riveted to said block is a second block 56 and a depending leaf spring 57, hereinafter referred to as the operating spring 57. Secured to the dependent arm 36d of the resonant contact structure by the same screws 39 securing the upper and lower arms of the hinge spring 37, is a bracket 58 having a forwardly extended arm 58a formed with a vertical slot 58b (Fig. 2). A dependent arm 59 is secured to said extended bracket arm by a screw 60 passing through said slot and threaded into a suitable opening provided in the dependent arm 59. Threaded through the lower end of the arm 59 is an operating post 61, preferably graphite tipped, which abuts the lower end of the operating spring 57 at all times. The operating post may be pivotally and vertically adjusted with respect to the operating spring by the slotted connection of the dependent arm 59 and the bracket 58a, and may be longitudinally adjusted by the threaded shank 61a provided therefor, the operating post being secured by the usual locknut 61b.

It should be noted that the operating spring 57 and the operating post 61 are oifset to the right of the center line of the relay. Also that the operating spring 57 bears against the operating post 61 with some pressure, maintaining the back decoding contacts 46a--49a under compression when the rocker arm is not oscillating. The contact 49a is adjusted so that the back decoding contacts 46a-49a will remain closed even though all pressure of the operating spring 57 against the operating post 61 is lost. Should the relay remain energized the force exerted by the operating spring against the operating post will be decreased, but the decrease in the force with respect to the rocker is so small that the back decoding contacts remain closed, losing only a small amount of compression.

To prevent damage to the resonant contact structure 35 and to the hinge spring 37 while shipping or handling the relay described, I provide two shipping screws 62 which pass upwardly through openings 63 in the base 3 of the casing, through openings 64 provided in the horizontal member 36a of the rocker and are screwed into threaded openings 65 provided in the mounting bracket 34. With the shipping screws in place, the resonant contact structure 35 is prevented from oscillating during handling of the relay, the screws being readily removed when the relay is placed in operation.

In adjusting the code following relay and the frequency decoding contacts described, the

weights

44 and 45 secured to the rocker 36 are added to or subtracted from the rocker arms so that the contact structure will be mechanically resonant at a predetermined frequency, the weights secured to both arms being kept equal. In the accompanying drawings the

weights

44 and 45 secured to the arms, provide a contact structure which is resonant at 180 impulses per minute, or responsive to 180 code. By the addition of weights to the rocker arms, the contact structure may be made to be mechanically resonant to 120 code or to any of the usual code frequencies used in railway signaling. Operation of the frequency decoding contacts 46a-49a and 46b-49b will be dependent upon the natural frequency of the rocker 36.

With coded energy of proper polarity applied to the operating winding 22 of the relay, the armature 19 will be oscillated between the

pole pieces

9a and 9b to drive the contact spring support 26 by way of the bifurcated member 28. The contact spring support 26 will be oscillated about a horizontal axis on the leaf springs 27 to alternately open the back contacts 30a-31a and close the front contacts 30b31b, and to close the back contacts 30a-31a and open the front contacts 30b31b. The non-resonant contacts 30a--31a and 30b31b will be operated by the oscillating armature regardless of the particular code frequency applied to the operating winding 22.

The contact spring support 26 oscillating about its horizontal axis due to the drive of the oscillating armature will oscillate the operating spring 57 bearing against the operating post 61 carried by the rocker 36, tending o oscillate the resonant contact structure about its vertical pivot. If the relay is responding to coded energy of any frequency other than the resonant frequency to which the rocker 36 is tuned, the small forces applied to the operating post of the rocker will not be in a direction to open back contacts 46a49a and close front contacts 46b-49b. A slight rocking or weaving of the rocker 36 will take place under these conditions, but at no time will the rocker be moved sufiiciently to open the back decoding contacts 46a-49a. When the relay is responding to coded energy of the frequency to which the rocker is tuned, the oscillating operating spring will bear against the operating post at the resonant frequency storing successive increments of energy in the oscillatory rocker to set the resonant contact structure oscillating at the resonant frequency to alternately close the back and front decoding contacts 46a-49a and 46b-49b.

Because of its light weight, armature 19 moves very rapidly between

pole pieces

9a and 9b at the times when the relay is responding to on" or off periods of coded energy. The resonant contact structure responds much more slowly, because of the inertia of

weights

44 and 45. As a result the armature stroke is in effect a snap action, occurring during a small fraction of the stroke of the resonant contact structure. Since the armature has practically a snap action, and has a fixed total stroke, it follows that the amplitude of oscillation of the resonant contact structure will be practically independent of the voltage applied to the relay winding. As a result, at abnormally high voltage the resonant contact structure will not respond to non-resonant frequencies, and at resonant frequency it will not strike with excessive force against its stops.

When the resonant contact structure 35 is oscillating about its vertical axis the pressure of the operating spring against the operating post increases and decreases depending upon the relative positions of the spring and the rocker. As previously described, the operating post is so adjusted that the' operating spring will always bear against the operating post The operating post will slide laterally across the face of the spring during the oscillation of the rocker introducing a certain amount of friction between the parts. This friction serves as a damping means for the oscillating rocker. Without damping, the tuning of the rocker 36 at resonance would be so sharp that no allowance would be made for the minor variations in frequency which occur in any given code transmitter. The frictional damping of the rocker 36 is analogous to resistance in a tuned electrical circuit, the damping of the rocker oscillations broadening the band Width to which the rocker would be responsive. Damping of the rocker 36 also serves to limit the amplitude of the rocker oscillations; without damping the response of the rocker may at times become so great that the rocker would strike severely against the adjustable stops 53. The rocker 36 would also be slow in responding to changes in code frequency without the frictional damping provided. With friction the oscillations are quickly damped upon a change in code. The damping of the rocker further serves to eliminate the effects of external vibrations.

The resilient drive of the rocker 36 compensates to some extent for any loss in tension of the operating spring and for the loss of friction due to wear at the operating post. Since the operating post engages the operating spring at all times, any Wear of the operating post or loss of tension in the operating spring would reduce the force exerted by the operating spring on the rocker. The reduced force exerted by the operating spring will tend to reduce the friction between the operating spring and post. The damping of the rocker oscillations being reduced, less force is then required to oscillate the rocker in the manner described.

The resilient drive of the rocker 36 by the operating spring as described prevents the response of the rocker arm to certain abnormal codes which are characterized by missing on periods. The coded energy applied to the operating winding of the relay is in the form of on period energy pulses during which the relay is energized, separated by off period intervals during which the relay is deenergized, the on" and off periods being approximately equal. At times due to faulty code generation or for other reasons, electrically tuned decoding circuits resonant at one frequency may respond to a code of another frequency. As, for example, a circuit tuned to 180 code may respond to .90 code. code has an abnormally short on period, so that it becomes identical with a 180 code having alternate on periods missing.

When the relay hereinbefore described is deenergized, the operating spring 57 bears against the operating post with some pressure as previously described. When the relay is energized, the operating spring exerts less pressure on the operating post and consequently there is less frictional damping than when the relay is deenergized. During code operation of the relay there is therefore more frictional damping during code ofF periods than during code on periods. The increased frictional damping of the rocker during code off periods thus prevents the rocker from responding to abnormal codes which are characterized by missing on periods.

By providing a resonant contact structure for a code following relay in addition to the normal non-resonant contact structure, I am able to use a relay embodying my invention in a coded track circuit for controlling wayside signals, as a code following track relay, the nonresonant contacts operating the proceed signal control relay while the frequency decoding contacts of the resonant constact structure operate the approach and proceed control relay. In such circuits the use of a relay embodying my invention will eliminate the use of decoding transformers and decoding units, thereby reducing the number of pieces of equipment required, reducing the space requirements of the equipment, and lowering the costs of coded track installations.

Another advantage of a relay embodying my invention In this case the 90 9 is the ease with which the natural frequency of vibration of the resonant contact structure may be changed by adding or subtracting weights to the structure so that the structure will be responsive to another code frequency. The resilient drive of the resonant contact structure is also advantageous in that the necessary damping is provided to broaden the frequency response of the structure to allow for the minor variations in code frequency, the damping also preventing operation of the resonant contact structure by abnormal codes characterized by missing on periods. A further advantage is that even under abnormal voltage conditions, the amplitude of oscillation of the resonant contact structure will remain practically constant, and the resonant contacts will not respond to non-resonant frequencies.

Although I have herein shown and described only one form of 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 mechanically resonant structure comprising a support, a member mounted for oscillation on said support, said member being mechanically tuned to be responsive to a predetermined frequency, an operating post on said member, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and recurrently biased thereby, said spring oscillating said first member only in response to the recurrent biasing of said operating spring at the resonant frequency to which said first member is tuned.

2. A mechanically resonant structure comprising a support, a member mounted for oscillation on said support, said member being mechanically tuned to be responsive to a predetermined frequency, an operating post on said member, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and recurrently biased thereby, said spring oscillating said first member only in response to the recurrent biasing of said operating spring at the resonant frequency to which said first member is tuned, said operating spring and said operating post being so adjusted to frictionally damp the oscillations of said first member to broaden the frequency band width of response of said first member.

3. A mechanically resonant structure comprising a support, a member mounted for oscillation on said support, said member being mechanically tuned to be responsive to a predetermined frequency, an operating post on said member, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and recurrently biased thereby, said spring oscillating said first member only in response to the recurrent biasing of said operating spring at the resonant frequency to which said first member is tuned, the oscillations of said first member sliding the operating post over the face of said operating spring thereby frictionally damping the oscillations of said first member to broaden the frequency band width of response of said first member.

4. A mechanically resonant structure comprising a support, a rocker arm, a hinge spring pivotally mounting said rocker arm on said support, symmetrical masses fixed to said rocker arm for mechanically tuning said rocker arm to be responsive to a predetermined frequency, an operating post on said rocker arm, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and recurrently biased thereby, said spring oscillating said rocker arm only in response to the oscillations of said spring at the resonant frequency to which said rocker arm is tuned.

5. A mechanically resonant structure comprising a support, a rocker arm, a hinge spring pivotally mounting said rocker arm on said support, symmetrical masses fixed to said rocker arm for mechanically tuning said rocker arm to be responsive to a predetermined frequency, an operating post on said rocker arm, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and recurrently biased thereby, said spring oscillating said rocker arm only in response to the oscillations of said spring at the resonant frequency to which said rocker arm is tuned, said operating spring and said operating post being so adjusted that the face of said spring abuts said operating post at all times with varying pressure as said rocker arm is oscillated at resonant frequency, the oscillating rocker arm sliding said operating post over the face of said operating spring thereby frictionally damping the rocker arm oscillations to broaden the frequency band Width of rocker arm response.

6. A mechanically resonant structure comprising a support, a rocker arm, a hinge spring pivotally mounting said rocker arm on said support, symmetrical masses fixed to said rocker arm for mechanically tuning said rocker arm to be responsive to a predetermined frequency, an operating post on said rocker arm, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and recurrently biased thereby, spring guides fixed to said support and said rocker arm with the hinge spring therebetween, the ends of said spring guides being spaced from each other and adapted to cooperate with each other when said hinge spring is flexed about an axis other than its pivotal axis, said spring oscillating said rocker arm only in response to the oscillations of said spring at the resonant frequency to which said rocker arm is tuned, said operating spring and said operating post being so adjusted that the face of said spring abuts said operating post at all times with varying pressure as said rocker arm is oscillated at resonant frequency, the oscillating rocker arm sliding said operating post over the face of said operating spring thereby frictionally damping the rocker arm oscillations to broaden the frequency band width of rocker arm response.

7. A mechanically resonant structure comprising a support, a rocker arm, a hinge spring pivotally mounting said rocker arm on said support for oscillation about a first axis, symmetrical masses fixed to said rocker arm for mechanically tuning said rocker arm to be responsive to a predetermined frequency, an operating post on said rocker arm, a flat operating spring having one face thereof abutting said operating post, a second member mounted for oscillation on said support, and means for imparting oscillatory movements of varying periods to said second member, said operating spring being secured to said second member and oscillating said spring about a second axis normal to the axis of oscillation of the rocker arm, said spring oscillating said rocker arm only in response to the oscillations of said spring at the resonant frequency to which said rocker arm is tuned, said operating spring and said operating post being so adjusted that the face of said spring abuts said operating post at all times with varying pressure as said rocker arm is oscillated at resonant frequency, the oscillating rocker arm sliding said operating post over the face of said operating spring thereby frictionally damping the rocker arm oscillations to broaden the frequency band width of rocker arm response.

8. A relay comprising an armature, means for oscillating said armature, a contact operating structure oscillated by said armature, a second contact operating structure mechanically resonant at a predetermined frequency, and resilient means biased by the oscillating first contact operating structure and in engagement with said second contact operating structure for oscillating said second contact operating structure only in response to armature oscillations of resonant frequency.

9. A relay comprising an armature, means for oscillating said armature, a contact operating structure oscillated by said armature about a first axis, a second contact operating structure mechanically resonant at a predetermined frequency, and resilient means biased by the oscillating first contact operating structure and in engagement with said second contact operating structure for oscillating said second contact operating structure about a second axis normal to said first axis only in response to armature oscillations of resonant frequency.

10. A relay comprising an armature, an operating winding for oscillating said armature, a contact operating structure oscillated by said armature, a second contact operating structure mechanically resonant at a predetermined frequency, and resilient means oscillated by said first contact operating structure and in engagement with said second contact operating structure for oscillating said second contact structure only in response to armature oscillations of resonant frequency.

11. A relay comprising an armature, an operating winding for oscillating said armature, a contact operating structure oscillated by said armature, a second contact operating structure mechanically resonant at a predetermined frequency, a flat operating spring fixed adjacent one end to said first contact operating structure and oscillated thereby, and an operating post on said second contact operating structure abutting the face of said spring adjacent its other end whereby said second contact structure is oscillated only in response to armature oscillations of resonant frequency.

12. A relay comprising an armature, an operating winding for oscillating said armature, a contact operating structure oscillated by said armature, a second contact operating structure mechanically resonant at a predetermined frequency, a fiat operating spring fixed adjacent one end to said first contact operating structure and oscillated thereby, and an operating post on said second contact operating structure abutting the face of said spring adjacent its other end whereby said second con tact structure is oscillated only in response to armature oscillations of resonant frequency, said operating post sliding over the face of said operating spring upon oscillation of said second contact operating structure thereby providing frictional damping for said second contact operating structure to broaden the frequency band width to which said second contact operating structure is responsive.

13. A relay comprising an armature, an operating winding for oscillating said armature, a support, a contact operating structure including a rocker, a hinge spring pivotally mounting said rocker to said support for oscillation between two extreme positions, an operating post fixed to said rocker, a fiat operating spring having a face thereof abutting said operating post, and means cooperating with said armature for oscillating said operating spring tending to oscillate said contact operating structure between its two extreme positions, symmetrical masses fixed to said rocker for mechanically tuning said contact operating structure, said contact operating structure being oscillated by said operating spring only in response to armature oscillations of resonant frequency, said operating spring and said operating post being so adjusted to frictionally damp the oscillations of said contact operating structure to broaden the frequency band width to which said contact operating structure is responsive.

14. A relay comprising an armature, an operating winding for oscillating said armature, a support, a contact operating structure including a rocker, a hinge spring pivotally mounting said rocker to said support for oscillation between two extreme positions, an operating post fixed to said rocker, a fiat operating spring having face thereof abutting said operating post, and means cooperating with said armature for oscillating said operating spring tending to oscillate said contact operating structure between its two extreme positions, symmetrical masses fixed to said rocker for mechanically tuning said contact operating structure, said contact operating structure being oscillated by said operating spring only in response to armature oscillations of resonant frequency, said operating spring and said operating post being so adjusted that the face of said operating spring abuts said operating post at all times with varying pressure as said contact operating structure is oscillated in response to armature oscillations of resonant frequency, the oscillation of said contact operating member sliding said operating post across the face of said operating spring thereby frictionally damping the oscillations of said second contact structure to broaden the frequency band width to which said contact operating structure is responsive.

15. A relay comprising an armature, an operating winding for oscillating said armature in response to coded energy applied to said winding, a support, a contact operating structure including a rocker, a hinge spring pivotally mounting said rocker to said support for oscillation between two extreme positions, spring guides fixed to said support and said rocker with the hinge spring therebetween, the ends of said spring guides being spaced from each other and adapted to cooperate with each other when said hinge spring is flexed about an axis other than its pivotal axis, an operating post fixed to said rocker, a fiat operating spring oscillated by said armature and abutting said operating post tending to oscillate said contact operating structure between its two extreme positions, symmetrical masses fixed to said rocker for mechanically tuning said contact operating structure, said contact operating structure being oscillated by said operating spring only in response to coded energy of resonant frequency in said operating winding, said operating spring and said operating post being so adjusted that said operating spring abuts said operating post at all times with varying pressure as said operating spring and said contact operating structure are oscillated in response to coded energy of resonant frequency, the oscillation of said contact operating member sliding said operating post across the face of said operating spring thereby frictionally damping the oscillations of said contact operating structure to broaden the frequency band width of coded energy to which said contact operating structure is responsive, and limit stops for limiting the amplitude of oscillations of said contact operating structure.

16. A relay comprising an armature, an operating winding for oscillating said armature in response to coded energy applied to said winding, a contact operating structure movable between two extreme positions and oscillated by said armature in response to the coded energy in said operating winding, a support, a second contact operating structure including a rocker, a hinge spring pivotally mounting said rocker to said support for oscillation between two extreme positions, an operating post fixed to said rocker, and a flat operating spring fixed to said first contact operating structure, said operating post abutting the face of said spring; said first contact operating structure oscillating said operating spring tending to oscillate said second contact operating structure between its two extreme positions, symmetrical masses fixed to said rocker for mechanically tuning the second contact operating structure, said second contact operating structure being oscillated by said operating spring only in response to coded energy of resonant frequency in said operating winding, said operating spring and said operating post being so adjusted that the face of said operating spring abuts said operating post at all times with varying pressure as said first and second contact operating structures are osciliated between their respective extreme positions in response to coded energy of resonant frequency, the oscillation of said second contact operating member sliding said operating post across the face of said operating spring thereby frictionally damping the oscillations of said second contact structure to broaden the frequency band width of coded energy to which said second contact operating structure is responsive.

17. A relay comprising an armature, an operating winding for oscillating said armature in response to coded energy applied to said winding, a contact operating structure oscillated by said armature in response to the coded energy in said operating winding, a support, a second contact operating structure including a rocker, a hinge spring pivotally mounting said rocker to said support for oscillation, spring guides fixed to said support and said rocker with the hinge spring therebetween, the ends of said spring guides being spaced from each other and adapted to cooperate with each other when said hinge spring is flexed about an axis other than its pivotal axis, an operating post fixed to said rocker, and a fiat operating spring fixed to said first contact operating structure and abutting said operating post, said first contact operating structure oscillating said operating spring tending to oscillate said second contact operating structure, symmetrical masses fixed to said rocker for mechanically tuning the second contact operating structure, said second contact operating structure being oscillated by said operating spring only in response to coded energy of resonant frequency in said operating winding, said operating spring and said operating post being so adjusted that said operating spring abuts said operating post at all times with varying pressure as said first and second contact operating structures are oscillated in response to coded energy of resonant frequency, the oscillation of said second contact operating member sliding said operating post across the face of said operating spring thereby frictionally damping the oscillations of said second contact structure to broaden the frequency band width of coded energy to which said second contact operating structure is responsive.

18. A relay comprising an armature, an operating winding for oscillating said armature in response to coded energy applied to said winding, a contact operating structure movable between two extreme positions and oscillated by said armature in response to the coded energy in said operating winding, a support, a second contact operating structure including a rocker, a hinge spring pivotally mounting said rocker to said support for oscillation between two extreme positions, spring guides fixed to said support and said rocker with the hinge spring therebetween, the ends of said spring guides being spaced from each other and adapted to cooperate with each other when said hinge spring is flexed about an axis other than its pivotal axis, an operating post fixed to said rocker, a fiat operating spring fixed to said first contact operating structure and abutting said operating post, said first contact operating structure oscillating said operating spring tending to oscillate said second contact operating structure between its two extreme positions, symmetrical masses fixed to said rocker for mechanically tuning the second contact operating structure, said second contact operating structure being oscillated by said operating spring only in response to coded energy of resonant frequency in said operating winding, said operating spring and said operating postbeing so adjusted that said operating spring abuts said operating post at all times with varying pressure as said first and second contact operating structures are oscillated between their respective extreme positions in response to coded energy of resonant frequency, the oscillation of said second contact operating member sliding said operating post across the face of said operating spring thereby frictionally damping the oscillations of said second contact operating structure to broaden the frequency band width of coded energy to which said second contact operating structure is responsive, and limit stops for limiting the amplitude of oscillations of said second contact operating structure.

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