US2833884A - Damping device for mechanically resonant relays - Google Patents

Description

May 6, 1958 Filed 001;. 19, 1956 R. w. CRAIG 2,833,884

DAMPING DEVICE FOR MECHANICALLY RESONANT-RELAYS 2 Sheets-Sheet 1 INVENTOR.

R.W.CRAIG HIS ATTORNEY May 6, 1958 R. w. CRAIG 2,833,884

DAMPING DEVICE FOR MECHANICALLY RESONANT RELAYS Filed Oct. 19, 1956 k 2 Sheets-Sheet 2 INCOMING CODES OF A PARTICULAR POLARITY STANDARD CONTACT I GROUP I 4 l 4 I INVENTOR. M -H 63 1.. RW CRAIG '1** REPEATED BY F MW HIS ATTORNEY United States Patent DAMPING DEVICE FOR MECHANICALLY RESONANT RELAYS Robert W. Craig, Rochester, N. Y., assignor to General This invention relates in general to decoding apparatus such such as mechanically resonant relays and more particularly to a mechanical damping mechanism used in conjunction with such decoding apparatus.

The mechanically resonant structure of the present invention is to be considered as an improvement over that structure disclosed by Gareld E. Marsh in his application Ser. No. 446,026, filed July 27, 1954. It should be understood, however, that adaptation of the present invention to such a mechanically resonant relay structure has been made merely for illustrative purposes.

When used as a decoding apparatus, such a mecha nically resonant relay is capable of detecting codes of a particular frequency by means of an inverted pendulum, the resonant frequency of oscillation of which is the particular code frequency to be detected. Because the resistive frictional forces inherent in an inverted pendulu'm structure are low, a relatively large amplitude of pendulum oscillation is obtained when the frequency of a periodic driving force applied to the pendulum closely approaches the resonant frequency of its oscillation; but the amplitude of pendulum decreases sharply as the frequency of the periodic driving force differs from the resonant frequency. It has been found, however, that such a mechanically resonant relay structure has extremely sharp tuning characteristics which are detrimental "ice 2 of the decoding contacts controlled by the pendulum member to be properly spaced so as to prevent actuation of the contacts by the pendulum when the pendulum is acted upon by a driving force having a rate other than the rate of the applied driving force. Therefore, any ex ternal control which is dependent upon the synchronous operation of the armature and pendulum controlled cone tacts would be free from erratic behavior of such com tact operation.

It has also been experienced that due to the time in-' terval discussed above, that is, when the pendulum memher is operating at some frequency other than resonant frequency, the response of such decoding contacts is not coextensive with the needs of a particular system. More particularly, in railroad signaling, the ordinary mechanically resonant relay will not respond to a change in actual track conditions quick enough to be considered safe for signal circuit control. Further since a pendulum may sometimes be caused to oscillate by an initiating force other than the particular periodic driving force for which it was designed, the externally controlled system would be subject to false starts. Thus, it is another object of this invention to provide a mechanical damping device whereby the relay will be rendered much quicker to respond and also resistant to foreign initiating forces, thus enabling any externally controlled system to reflect actual conditions.

to the commercial value of such structure in ordinary use. Hence, it is necessary to broaden the band frequency to which such relay structure is responsive. Therefore, it is an object of this invention to provide a mechanical damping mechanism which will broaden such band frequency without sacrificing any of the desirable qualities inherent in a mechanically resonant relay structure.

Generally in commercial use of mechanical resonant relays and more particularly those relays which employ the use of a pendulum member, decoding contacts are actuated by an armature which operates at the frequency of an external periodic driving force and other decoding contacts are actuated by the oscillatory motion of the pendulum member whose resonant frequency is essentially the same as the periodic driving force. It has been found in actual practice, however, that during the interval of time after such energizing force has been applied, the oscillatory motion of the pendulum is non-synchronous with the operation of the armature. The same condition occurs for a like interval after the energizing force has been removed and during which the pendulum memher is dissipating. During these intervals, such non-synchronous condition is reflected in the operation of the various contacts controlled by the armature and pendulum. Since these contacts are generally used to provide external controls, erratic operation of such contacts is a distinct disadvantage. Hence, it is a further object of the present invention to provide a damping mechanism which will, by applying constant frictional damping during the entire energization period, permit the adjustment Other objects, purposes and characteristic features of this invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In the accompanying drawings:

Fig. 1 is a front elevation of the relay mechanism;

Fig. 2 is an isometric view of the relay structure shown in Fig. 1 with certain parts removed to illustrate more clearly the structural formation of the supporting elements along with the particular manner in which the damping mechanism is adapted to the relay;

Fig. 3 is a detailed view showing only the damping mechanism along with its supporting structure; and

Fig. 4 show in a wholly diagrammatic manner circuit means for controlling the relay and a use for the relay in controlling, other apparatus.

The symbols and are used to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current.

It is evident from the drawings that many details of the mechanically resonant structure have been purposely omitted for the sake of simplicity since as explained before, a comprehensive detailed disclosure was made in the Marsh application referred to above. It is of course necessary to be repetitious of those supporting parts-of the structure as are necessary for a complete understanding of the invention disclosed herein. Also, some structural change was required to be made in the relay disclosed in the above cited application because of the addition of the damping mechanism, which changes will be pointed out as the description progresses.

Referring now to Figs. 1 and 2 of the drawings, the ref-, erence character B designates the base plate, made of non-magnetic material for supporting the relay structure. It is assumed that base B is engaged by a plug board having suitable contact fingers for coupling with the various electrical contact springs of the relay.

A U-shaped frame F, made of magnetic material, is attached to the base B by two screws 2 which thread into threaded inserts in the base B, and the screws 2 are restrained from vibrational loosening by lock washers.'

A permanent magnet M is centrally located along the undersurface of the top arm of the frame F and is secured to the frame by a threaded bolt 3 and a nut 4..

assess;

An intermediate bracket 5, made of non-magnetic material, is attached to the lower arm of the frame F by bolts 6, nuts 7, and lock washers 8. Two cores 9 and 10 having peripheral slots near their upper extremities are engaged by the intermediate bracket 5 along the slots. The cores 9 and 10 extend downward through axial openings in windings C1 and C2, respectively. The lower extremities of the cores 9 and 10 have fiat longitudinal surfaces against which a backstrap 11, a block 12 and a bracket plate 30 are retained. A bolt 13 passing through openings in the bracket plate 30, backstrap 11, block 12 and the core 9 is retained by a nut 14 and a lock washer 17. A similar bolt 15 passing through the plate, backstrap, block and core 10 is retained by a nut 16 and a lock washer 17. The block 12 is fastened to the frame F by two bolts (not shown) which thread into threaded inserts in brackets 19. The brackets 19 are attached to the intermediate bracket 5 thereby providing additional support for the intermediate bracket 5.

Plate 30 has a laterally extending protrusion 30A which supports an inverted pendulum structure consisting of a fiat spring 22, weights W, and a supporting base 23; the base 23 being in two sections abutting the spring 22 and being held together by screws 24 which'thread through the base assembly.

The weights W are mounted in a predetermined position near the top of the spring 22 and are attached to the spring 22 by two bolts 25 and nuts 26. The weights W have an L-shaped configuration which provides that only the upper portions of the weights abut the spring 22. In this manner a maximum free length of spring is attained.

One end of a molded contact block 32, of appropriate insulating material, is attached to plate 30 by means of bolt 40 and nut 41, while bolt 42 passes through an elongated opening in the other end of thecontact block 32 and is fastened to the outer end of plate 30 by a nut 43 and a resilient washer 44. When loosened, the bolt 42 permits vertical adjustment of the contact block 32 since vertical movement of the block 32 has been provided for by the elongated vertical opening 48.

An L-shaped strap 31, composed of non-magnetic material, is. connected to the backside of plate 30 and securely held in position by bolts 40 and 42 and nuts 41 and 43. The upper portion of strap 31 provides a means for connecting the levers 80 of the damping mechanism thereto and serves as a support for the entire damping structure as best shown in Fig. 3 of the drawings. The two lever arms 80 are constructed of an appropriate bearing material such as nylon. The levers 80 are connected on opposite sides of the strap 31 and adjustably held in position by a bolt 85. and a nut 89, such nut 89 being so machined as to house the usual cotter key assembly to prevent the nut from working loose due to vibration. A small coil spring 86 has been inserted on the bolt 85 between the nut 89 and the adjacent lever 80 so as to provide the desired friction adjustment.

Each lever 80 has been drilled near its upper end and againat a point slightly above its lower connection to the strap 31 so as toprovide a means for pin connecting insulated pusher arms 81 and 82 to the levers 80 thus forming a recessed housing for the ends ofsaid pusher arms. The pusher arm 81 is thus connected to the two lever arms 80 bythe pin 83 around which axis the pusher arm 81 may rotate during operation of the relay.

Riveted to the upper portion of the pendulum spring 22 is a plate 87 which is provided with a bearing for receiving pin 88 which attaches the extremity of the pusher arm 81 to the spring 22. A smallslotted opening has been made in the upper portion of spring 22 to permit the endof the pusher arm 81 to extend through the spring. Clearance has been provided between the extended portion of the pusher arm 81 and the slotted opening in spring 22 so that no strain is placed on the pin 88 during oscillation of the pendulum member. The pusher arm 82 is connected to the two levers in a similar manner as that described for pusher arm 81, the pusher arm 82 being free to rotate around the axis of the pin 84 during relay operation.

The contact block 32 retains a movable contact spring 33 along with two fixed contact springs 34 and 35 and stop springs 36 are provided to limit movements of the springs 34 and 35. Riveted to the upper end of the movable contact spring 33 is an insulated plate 37 which has a bearing for receiving pin 38 which attaches the extremity of the pusher arm 82 to the movable contact spring 33.

Various elements of the damping mechanism arranged in such a manner described above thus provides a pivotal means for transmitting any motion of the pendulum member to the movable contact spring 33, such spring being so positioned as to operate the fixed contacts 34 and 35 in a manner corresponding to the oscillatory motion of the pendulum member. The position of the movable contact spring 33 relative to the fixed contacts 34 and 35 is adjustable since the upper extremity of the spirng 33 is somewhat fixed by the pusher arms 81 and 82 and also since contact block 32 can be moved within the limits of its elongated opening previously described. Further the amplitude of the pendulum oscillation may be controlled by increasing or decreasing the resistive force applied at the spring pressed friction clutch by adjusting bolt 85.

Located between the permanent magnet M and the cores 9 and 10 is an armature 45. The armature rests on a non-magnetic spring 46 which is riveted to the armature and to brackets 47. One end of the spring 46 in cludes a threaded insert into which a screw 52 is threaded, thereby serving to attach the spring 46 to the intermediate bracket 5. The other end of the spring 46 is slotted and engaged by a projecting segment of the intermediate bracket 5.

The armature 45 and the spring 46 are supported by a spring 49 which is also riveted to the brackets 47. The base of the spring 49 is riveted to a bracket (not shown) which is attached to the core block 12. The spring 49 has a permanent set which produces a mechanical force on the armature 45 causing the armature to be biased to a position wherein, under conditions of relay deenergization, the left extremity of the armature is depressed toward the core 9. It should be noted that the biased armature has not been indicated on the drawings since for the purposes of illustration the armature has been shown in the horizontal position. A groove in the rear surface of the baclgstrap 11 provides clearance for the spring 49 in the region between backstrap 11 and the block 12. It is understood that if the demands of actual practice require a mechanically resonant relay structure having an armature of the magnetic-stick type, in lieu of the polar-biased type referred to and discussed herein, the spring 49 which biases the armature to a given position during the code-off period would not be required. However, the invention disclosed herein would be applicable to a mechanically resonant relay structure employing either a polar-biased or a magnetic-stick structure.

A plate 53 fits over and is riveted to the armature 45. Attached to the upper surface of the plate 53 near each end is a bearing plate 53A. Also in order to limit armature travel, stop screws 54 have been provided. These stop screws 54 thread downward through threaded inserts in the brackets 19 and are held in position by lock nuts 55. Each stop screw has a ground and polished head 56 which makes physical contact with the bearing plates 53A on the plate 53. If, under any condition, the stop screws or the bearing plates 53A should fail, the non-magnetic spring 46 will serve as a safety separator between the armature and cores 9 and 10. In such cases the spring 46 acts to reduce the effects of residual magnetism in the electromagnetic structure.

One ehd of a short metal plate 58 has been riveted to the plate 53, the other end of the plate 58 being connected to one end of a transmitting spring 27 by means of a bolt 66, lock washer 68, and nut 67. The transmitting spring 27, composed of a resilient metal, has its vertical tangent essentially parallel to and positioned in the same plane as the pendulum 22; its horizontal tangent being essentially parallel to and in the same plane as the armature 45, both tangents integrated by a circular portion formed approximately at the midpoint of the spring. Such ctu'ved portion of the spring obviously will approach a ninety degree bend. The lower end of the transmitting spring 27 has been rivetedto a bracket 28, such bracket in turn riveted to the pendulum spring 22. The spring 27, when connected in a manner as described above, serves as a transmitting spring, transmitting the motion of the armature 45 to the inverted pendulum member thereby operating as the driving force for such pendulum member.

A contact pusher 57 is slotted toengage the plate 53 so that the actuation of the armature 45 will operate the contact pusher in a vertical direction which operates the contact group. Since the contact pusher 57 operates a standard contact groupwhich is familiar to those skilled in the art, a detailed description of the contact group has been omitted from this specification. In order to provide additional contact springs, however, a second block of contacts along with a pusher could be installed on the opposite plate 53, and actuated in a like manner by movement of the armature 45.

Turning now to the operation of the mechanically resonant relay structure, and considering the relay first in the deenergized position and later in the energized position, it will be noted that in such deenergized position the armature 45 is positioned by its supporting spring 49 so that one end of the armature is depressed while the other end of the armature is positioned so that the plate 53 bears against the stop screw 54. Assuming that the lower portion of the permanent magnet M is a north pole, the flux from the permanent magnet M takes two paths through the armature 45, but with the left-hand side of the armature 45 biased so that it is close to core 9, most of the permanent magnet flux passes through this core 9 rather than core 10 where the air gap between the armature 45 and its core face is the greatest. This permanent magnet flux is of sufficient magnitude to hold the armature45and its associated contacts in a corresponding operated position without energization of the windings C1 and C2. Further, as explained before, the predetermined set in spring 49 continuously biases the left-hand side of the armature 45 in such position. Also during this period of deenergization when the armature is at rest, the pendulum operated contacts 34 and 35 are open.

Assuming therefore the armature to be in its normalat-rest position,- when energy of the proper polarity is applied to the windings which would causethe upper, portions ofcores 9 and 10 to become north and south poles respectively, the magnetic flux produced by such windings C1 and C2 opposes the flux produced by the permanent magnet M, therefore the net flux in core 9 is reduced to a relatively low value while the net flux in core 10 is increased toan operating value causing the right-hand end of the armature 45 to be depressed while the left-hand end of said armature forces plate 53 against the stop screw 54. Since the energy applied to such relay is normally a pulsating direct current energy which has alternate off-on code characteristics, it should be obvious that, even though the magnitude of the combined flux of the permanent magnet M and the windings C1 and C2 during code on will cause the right-hand end of the armature 45 to operate as described above, during code off periods the armature will return to its normal position due to the set of the armature supporting spring flux will bo -practically; zero through core 1 while being greatly increased through core '9, hence such improper energy would produce no change in the armature position. Thus, pulsating energy of the proper polarity when applied will cause the armature 45 to be alternately attracted to core and restored by spring force to core 9. The frequency of operation of the armature is that of the applied pulsating energy.

As the armature 45 oscillates about its horizontal axis, the contact pusher 57 which is connected to the plate 53, describes a vertical motion at a frequency corresponding to that of the armature. Further such armature oscillation sets up mechanical vibrations in the transmitting spring 27, such mechanical vibrations when transmitted 49. If energy of the improper polarity is applied the net through the spring 27, cause the pendulum spring 22 to vibrate. It should be noted that it is necessary to select a pendulum member which has a resonant frequency which is essentially the same as the frequency of the applied energy. For example, if the frequency of the applied energy is cycles per minute, than the mechanical resonant frequency of the pendulum member must also be 180 cycles per minute. As will be explained later, in discussing the damping mechanism, however, the band frequency to which the pendulum spring 22 will respond will be, in the case of the example given, between approximately 174 cycles per minute to 184 cycles per minute. v Hence, with a pendulum spring whose resonant frequency is similar to that of the applied energy, the

.vibratory motion of the pendulum member due to the transmission of the armature motion by the spring 27, will be synchronous with that of the armature, which is in elfect the same asthe frequency of the applied energy. The amount of time required for synchronous motion to result may be controlled so as to occur after a very few cycles of operation. Similarly, after the applied energy is removed the motion of the pendulum member may be dissipated within a very few cycles of operation. The means by which this control is brought about will be discussed later on in connection with the description of the damping mechanism.

The use of a transmitting spring 27, which is of the form described hereinbefore, has several distinct advantages over other transmitting springs found in the art. Such spring 27 provides a direct frictionless connection between the armature and the pendulum member. It has been found in actual practice, that the usual structure of this kind uses such a large plurality of working parts to transmit the driving force to the pendulum member, that a large proportion of the energy supplied was being used to overcome the friction due to these moving parts. Such a transmitting spring as disclosed in the present invention, which provides such a direct, frictionless connection between the armature and pendulum member, eliminates the moving parts along with the resistive friction, hence the amount of energy required in driving the pendulum spring is considerably reduced. Further, in such a spring having a curvilineal portion, the resultant component force transmitted through such a shaped spring will inherently be much greater, for example, than that force transmitted through the usual flat spring since the usual fiat spring in describing a vertical oscillatory motion exerts a small horizontal component of driving force to the pendulum member. It will be seen that the corresponding horizontal force in the transmitting spring used in this invention, such force derived by resolving the vertical and horizontal components of the forces involved during vibration of such transmitting spring, is much greater than that horizontal forcedescribed in connection with the usual flat spring. Hence, the transmitting spring disclosed herein would require less initial driving energy to actuate the pendulummember. If the same amount of initial energy were ap-. plied to the structure disclosed in this invention as is required by a structure utilizing a fiat spring, the greater amount of resultant applied force to the pendulum would;

cause the pendulum member to approach its resonant frequency in fewer cycles of armature operation.

Further, if the same amount of initial energy were applied to the structure having a transmitting spring as disclosed herein, in contrast to such a structure having the usual fiat spring, it will be noted that since the resultant horizontal force is greater in the former, the resultant bending moment about that point to which such spring is connected to a pendulum will be considerably reduced. By reducing the bending moment, the amplitude of the pendulum swing is thereby limited to a much smaller distance than the amplitude of the pendulum swing for a structure using a corresponding flat spring. By limiting the amplitude of the pendulum swing, the amount of force subsequently exerted on the movable spring 33 is also less and therefore the amplitude of the distance travelled by such movable spring during operation of the relay will also be reduced. Hence, the addition of the transmitting spring 27 as disclosed herein prevents injury to the contact springs 34 and 35 by severe compression of said contact springs by the movable spring 33. Further, reduction of pendulum amplitude decreases the range over which the positioning of the contact springs 34 and 35 in relation to the movable spring 33 is necessary to insure that such contacts will close only i when the pendulum is operating at resonant frequency as further described below. The feature of reducing the amount of initial applied energy required to actuate the resonant relay structure is extremely important in that it vastly broadens the commercial usage of such a structure.

Under operating conditions, therefore, the armature oscillates at the frequency of the applied periodic driving force causing the pusher am 57 to operate the various contacts comprising a standard contact group. Such oscillatory motion of the armature 45 is also transmitted by the spring 27 to the pendulum member in a manner described above. If, as previously described, the frequency of the periodic driving force approximates the resonant frequency of the pendulum, the pendulum will begin to vibrate at its resonant frequency, which vibratory motion serves as a driving force for operating the movable contact spring 33 which in turn has sufficient motional amplitude to alternately coact with the fixed contact springs 34 and 35. Under such conditions, the actuation of the contact springs 34 and 35 by the movable contact spring 33 can be adjusted to operate simultaneously with respective contacts located in the standard contact group actuated by the pusher arm 57.

The vibratory motion of the pendulum member is transmitted to the movable contact spring 33 by means of the various component parts of a damping mechanism. Such damping mechanism which has been adjustably connected to the L-shaped bracket 31 serves to regulate the behavior of the pendulum member during energization and deenergization of the mechanically resonant relay and thereby regulates the operation of the pendulum actuated contacts.

More particularly, when the relay is in its decnergized or at rest position, the pusher arm 81, being directly connected to the pendulum spring 22 by means of the pin connection assembly previously described, acts as a constant braking force minimizing the tendency of the pendulum member to vibrate under any condition. This isparticularly useful in preventing a driving force other than that applied driving force for which the operation of the relay isdependent, from causing the pendulum member to be set in motion, thereby operating its contact group. The magnitude of the braking force applied to such pendulum member may be increased or decreased in accordance with the desired operating characteristics by means of the adjustable connection of thelever arms 80 to the L-shaped bracket 31, such adjustable connection comprising a small coil spring inserted on: the shaft. of the. bolt 85. By compressing the coilspring, by tightening the bolt, the friction is increased thereby limiting the arc to which the lever arms 80 can swing. With the movement of the lever arms restricted, the magnitude of the braking force of the pusher arm 81 on the pendulum member is increased. Likewise pusher arm 82 which actuates the movable contact spring 33 and which operates harmoniously with tl e pusher am 81, is also restricted in its movement.

If the fraction force at the spring pressed slip clutch is of sufficient magnitude, the damping mechanism will be effective to prevent any appreciable response by the pendulum or pendulum operated contacts to foreign driving forces thereby limiting response to that applied driving force whose frequency approximates the resonant frequency. On the other hand, if the friction force developed at the spring pressed slip clutch were negligible, the pendulum and the pendulum operated contacts would respond in a manner similar to a mechanically resonant relay structure having no damping feature, such lack of control resulting in erratic behavior of the pendulum actuated contact.

Hence, it is apparent that the damping mechanism disclosed in the present invention provides a means for controlling the response of the pendulum to the applied driving force which is transmitted to-it by spring 27 and such invention therein provides a means controlling the operation of the pendulum actuated contacts.

As pointed out above the damping device continuously applies a braking force to the pendulum. This inherently requires a larger amount of applied energy to overcome the frictional force and drive the pendulum member. However, as previously explained in the discussion of the transmitting spring 27, the elimination of the plurality of moving parts by directly connecting the transmitting spring to the pendulum along with the additional advantage of increasing the effective horizontal component force due to the use of this particular form of spring, have combined to compensate for the added energy demand created by such damping feature.

When the relay structure is energized and the pendulum is operated at resonant frequency, the amplitude of the pendulum oscillations reach their maximum value. If the fixed contact springs are now adjusted so as to be actuated only when the amplitude of the pendulum oscillations reaches maximum, it will be noted that an applied energy having a frequency different than the resonant frequency of the pendulum member will be unable to create a pendulum oscillation whose amplitude is of sufiicient magnitude to close the contacts, since the damping mechanism will serve to hold such oscillatory pendulum motion in check. With the control circuits to which such a relay structure is adapted, arranged so as to operate only when both the pendulum operated contacts and the contacts operated by the pusher arm 57 are actuated in unison, safe operation of the control circuits is assured.

Further, when the applied driving force which energizes the relay is removed, the pendulum member will tend to oscillate until it has dissipated the kinetic energy built up in the pendulum during operation. If the damping device is constantly applied, this stored energy is dissipated much more rapidly. Hence, the flexibility of control by providing a pivotal adjustment of the damping force permits the structure to be readily adapted to the demands of the system.

It has been found in any given code transmitter that minor variations in frequency occur from time to time. Without damping, experience has indicated that the tuning of the ordinary mechanically resonant relay at resonance is so sharp that no allowance could be made for such minor variations in frequency. With the pivotal adjustment disclosed in the present invention, the relay may be tuned to the degree of sharpness that is required by the system. In the instant case, a coded driving force was used which had a frequency of approximately one hundred eighty cycles per minute. In order to enable the "particular as e s;

relay to distinguish between other frequencies, yet have a band'. widt-h broad enough to detect a minor frequency the pendulum structure can be varied to fit the needs of practice.

In Fig. 4, a circuit arrangement is shown employing the relay described in this invention. The windings C1 and C2 are shown connected in series electrically and energized by a coded circuit.

When codes of the proper polarity are applied to the relay, the armature 45 is caused to oscillate in response to the energization of the winding C1 and C2. Armature motion is transmitted to the pendulum spring 22 by the transmitting spring 27. Further, armature motion also operates the pusher arm 57 which in turn operates a standard contact group represented by the movable contact spring 64 and the fixed contacts 63 and 65.

If the code frequency very nearly approximates the resonant frequency of oscillation of the pendulum structure, the code spring 33 is actuated by the pusher arms 81 and 82 which are attached to the lever arms 80, and the motional amplitude of the movable contact spring 33 is of sufiicient magnitude to cause contact to be made alternately between the contact springs 34 and 35 respectively.

Under resonant operating conditions, the contacts 34 and 35 operated by the pendulum member through the movable contact spring 33 and the contacts 63 and 65 operated by the movable contact spring 64 when such movable contact spring 64 is actuated by the pusher arm 57 will be synchronous. For example, the movable contact spring 64 will close contact 65 at the same instant that the movable contact spring 33 closes contact 34; similarly, contact 63 will be closed simultaneously with contact 35 during an alternate operation of the respective movable contact springs. It is assumed that the code relay has slow-release characteristics which will be of sufficient length to bridge those portions of the operational cycles during which the various contact springs are separated. Thus, the code relay is actuated only when a code applied to the resonant relay is of the particular frequency to which the relay responds. Since the armature driven contacts and their corresponding pendulum driven contacts are operated in synchronism only when pulsating energy of a near-resonant frequency is applied, only actual track conditions will be reflected by this relay structure.

Having described a mechanically resonant relay and more particularly a mechanically resonant relay which has a damping feature, as one specific embodiment of the present invention, it should be understood that the form tuning of such a mechanism is dependent upon the demands of the system and the physical constants of of the invention selected to facilitate in the disclosure is not intended to limit the number of forms which it may assume, since it is further to be understood that various modifications, adaptations, and alterations may be applied to the specific forms 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. In a mechanically resonant relay structure having an armature which at times oscillates in response to a particular code frequency and a pendulum member having a resonant frequency similar to that of said particular code frequency, flexible means interconnecting said armature and said pendulum member whereby the oscillations of said armature are transmitted to said pendulum operating said pendulum member harmoniously therewith, decoding contacts having at least one movable spring capable of cooperating with said decoding contacts, a damping mechanism connected to said pendulum and to said movable spring for operating said decoding contacts when said pendulum member is oscillating, said damping device including a means for adjusting the magnitude of its damping effect on said pendulum member whereby 10 said pendulum member will dissipate its energy rapidly when said particular code frequency is not present.

2. In a mechanically resonant relay structure having armature and pendulum members and resilient means interconnecting said members causing said members to oscillate in synchronism when said armature is actuated by a particular code frequency, said structure having decoding contacts including at least one movable spring contact centrally located with respect to said decoding contacts and cooperating alternately with said decoding contacts at a rate peculiar to said particular code frequency, a damping mechanism directly connected to said pendulum member and said movable spring contact, said damping device including an adjustable friction clutch for applying constant damping to said pendulum and said movable spring when said particular code frequency is applied, said adjustable friction clutch providing a means for adjusting the magnitude of said constant damping whereby the energy stored by said pendulum can be readily dissipated when said particular code frequency ceases thereby permitting the operation of said decoding contacts to respond to the speed of the system.

3. In an electromechanical device for detecting pulsating energy of a particular frequency comprising an armature, a pendulum, and means for transmitting said pulsating energy to said armature and said pendulum whereby the oscillatory motion of each is harmonious, a movable contact spring and two fixed contact springs, said movable contact spring being located centrally between said fixed contact springs and being capable of cooperating with either of said two fixed springs, a damping mechanism having a bilateral vertical member and two horizontal members, means including a bracket for adjustably attaching the lower end of said vertical member to said bracket, the upper endof said vertical member pin-connected to an end of one of said horizontal members, the other of said horizontal members having one end pin-connected to said vertical member near the lower end of said vertical member, the other ends of said two horizontal members being rigidly connected to said pendulum and said movable spring contact respectively, both of said horizontal members having a biaxial relationship with said vertical member whereby the oscillation of said pendulum member will cause said damping mechanism to alternately actuate said two fixed spring contacts but permit said damping device to retard oscillation of the pendulum member during that period when said electromechanical device is deenergized thereby prohibiting the cooperation between said movable contact spring and said fixed contact springs.

4. In a mechanically resonant relay structure having an armature which at times oscillates in response to a particular code frequency and a pendulum member having a resonant frequency similar to that of said particular code frequency, flexible means interconnecting said armature and said pendulum member, decoding contacts retained by an adjustable contact block and including at least one centrally located movable spring contact capable of cooperating with said decoding contacts, damping means directly connected to said armature and said movable spring, said damping means pivotally connected at its lower end whereby the effectiveness of said damping means may be adjusted to limit the oscillatory an1plitudes of said pendulum member, said adjustable contact block providing a means for regulating said cooperation between said movable spring and said decoding contacts in accordance with the oscillatory amplitude of said pendulum member when said pendulum member is oscillating in accordance with said particular code frequency.

5. In a mechanically resonant relay structure having an armature which at times oscillates in response to a particular code frequency and a pendulum member having a resonant frequency similar to that of said particular code frequency, flexible means interconnecting said armature and said pendulum member, said flexible means including a resilient metal strap comprised of two straight portions tangentially interconnected to a curilinear portion, the free ends of said straight portions directly connected to said armature and to said pendulum member respectively whereby the oscillation of said armature is transmitted to said pendulum member operating said pendulum member harmoniously therewith, decoding contacts having at least one movable spring capable of cooperating with said decoding contacts, and means connecting said movable spring to said pendulum member for operating said decoding contacts when said pendulum member is oscillating in response to said particular frequency.

6. In a mechanically resonant relay structure used for detecting pulsating energy of a particular frequency comprising an armature, a pendulum, and a resilient metal strap comprising two straight portions tangentially interconnected tofa curvilinear portion, the free ends of said straight portions directly connected to said armature and to said pendulum respectively whereby the oscillation of said armature is transmitted to said pendulum operating said pendulum hormoniously therewith, decoding spring contacts including at least two fixed spring contacts and one movable spring contact, said movable spring contact centrally located between said two fixed spring contacts and capable of cooperating alternately with said two fixed spring contacts, and transmitting means connecting said movable spring contact to said pendulum for operating the two spring contacts when the pendulum is oscillating in accordance with said particular code frequency.

7. In a mechanically resonant relay structure having an armature which at times oscillates in response to a particular code frequency and a pendulum member having a resonant frequency similar to that of said particular code frequency, flexible means including a resilient metal strap for interconnecting said armature and said pendulum member respectively whereby the oscillations of said armature are transmitted to said pendulum member operating said pendulum member harmoniously therewith, said resilient metal strap having a curvilinear angle about its midpoint thereby increasing the'magnitude of the horizontal component of such transmitting force to said pendulum member, armature actuated contacts including transmitting means connected to said armature, pendulum actuated contacts including transmitting means connected to said pendulum, said armature and pendu- 12 lum actuated contacts acting in unison when said armature and said pendulum members are oscillating harmonious'ly.

8. In a mechanically resonant relay structure having an armature which at times oscillates in response to a particular code frequency and a pendulum member having a resonant frequency similar to that of said particular code frequency, a resilient metal strap having a curvilinear angle about its midpoint, the ends of said resilient metal strap directly connected to said armature and said pendulum member respectively whereby the oscillations of said armature are transmitted to said pendulum member operating said pendulum member harmoniously therewith, decoding contacts having at least one movable spring centrally located between them and capable of cooperating with said decoding contacts, an adjustable friction clutch having one vertical member interconnected to two horizontal members, the free end of one of said horizontal members connected to said pendulum membar, the free end of .the other of said horizontal members connected to said movable spring whereby the oscillations of said pendulum member will cause said movable spring to actuate said decoding contacts harmoniously with the operation of said pendulum and said armature.

9. in a mechanically resonant relay structure having an armature which at times oscillates in response to a particular code frequency and a pendulum member having a resonant frequency similar to that of said particular code frequency, a resilient metal strap having a curvilinear angle about its midpoint, the ends of said resilient metal strap directly connected to said armature and said pendulum member respectively whereby the oscillations of said armature are transmitted to said pendulum member operating said pendulum member harmoniously therewith, decoding contacts having at least one movable spring capable of cooperating with said decoding contacts, adjustable damping means directly connected to said pendulum and to said movable spring for operating said decoding contacts when said pendulum member is oscillating in accordance with said particular code frequency.

References Cited in the file of this patent UNITED STATES PATENTS

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