US1399259A - Interlocking system - Google Patents

Description

W. K. HOWE.

INTERLOCKING SYSTEM.

APPLICATION FILED 1AN.21. 1920.

1,399,259, Patented Dec. 6, 1921.

2 SHEETS-SHEET I.

w. K. HOWE;

INTERLOCKING SYSTEM.

APPLICATION HLED JAN-Z1, I920- 1,399,259, 7 Patented Dec. 6, 1921.

2 SHEETS-SHEET 2- BY RNEY.

UNITED STATES PATENT OFFICE.

WINTHBOP K. HOWE, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILW'AY SIGNAL COMPANY, OF ROCHESTER, NEJRF YORK, A CORPORATION OF NEW YORK.

IIQ'T'ERLOCKING SYSTEDI.

Application filed January 21, 1920.

T 0 all whom him/1y concern Be it known that I, lVncrnnor K. Hown, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, have invented a new and useful Improvement in Interlocking Systems, of which the following is a specification. 1

This invention relates to interlocking systerns for railroads, and more particularly to the construction and operation of the detector locking devices which are usually provided in such ystems for preventing the throwing of switches under trains.

In order to prevent a switch being thrown by power under a train or directly in front of it, arrangements may be made to interrupt the control or operating circuits for the switch machine operating said switch, if and while the usual detector track circuit associated therewith is occupied by a train, some suitable arrangement being also provided so as to prev nt the switch being left in mid.- stroke or unlocked in case the train should enter the detector track circuit while the switch machine is operating. With such an arrangement, the contacts for interrupting the operating circuits have to carry the comparatively large current employedfor operating the switch machine, so that I preferably use an auxiliary relay with contacts specially constructed for this purpose, rather than control the operating circuit directly by the contacts of the track relay, said 21UX iliary relay being controlled by the track relay. The present invention relates more particularly to the manner of control of this auxiliary relay, with the view of operating it by current derived from the main battery at the tower, rather than by a local source of current at the switch which may not be availab e and which may have to be installed solely for this purpose.

One object of this invention is to provide simple and efiicient means for operating a relay at the switch, subject to the control of the track relay of the detector track circuit, by current from the main source at the tower, and without requiring additional wires running from the tower to the switch machine.

Other obiects and features of the invention will be pointed out hereinafter as the description progresses.

Specification of Letters Patent.

Patented Dec. 6, 1921.

Serial No. 352,944.

In describing the specific embodiments of my invention in detail, reference will be made to the accompanying drawing, in which like reference characters refer to corresponding parts in the several views and in which Figure 1 illustrates in a simplified and diagrammatic manner the parts and circuits of a well known type of all-electric interlocking system, with my invention applied thereto, and

Fig. 2 shows a modified construction. For the purposes of explaining the functions and operation of my invention I have shown it applied to a well known system of all-electric interlocking, such as disclosed, for example, in my prior Patent No. 1,288,595, dated December 24, 1918. The construction of the switch machine, and the manner in which it is operated and controlled by a lever at a tower, together with the various circuit controllers and circuits, are explained in my prior patent; and it is deemed sutlicient for the purpose of explaining my present invention to refer only briefly to the construction and operation of this type of interlocking system. It should be understood that this particular type of interlocking system is merely illustrative of the utility and nature of my invention, and that the invention may be applied to other types of interlocking systems by making appropriate changes in mechanical details.

Referring to the drawings, a stretch of track T, with a switch A, is shown conventionally. The track rails are divided by insulating joints and bonded in the usual way to provide a detector track circuit, comprising a track battery 4- and a track relay 5 having acontact linger or armature 6. The operating parts of the switch machine have not been shown, but the circuit contro ler for governing the operating and indication circuits, and t-he operating motor M have 7 been illustrated diagrammatically in the same way in my prior patent and are designated as whole SM. This circuit controller includes a contact block 7, which is moved mechanically from its existing extreme position to a middle or intermediate position during the unlocking movement of the switch machine, and is held in this intermediate position until the switch machine hascompleted its cycle of operation and is again fully locked, whereupon'said contact block is automatically shifted to its opposite extreme position, in the manner fully explained in my prlor patent. In connection with my present invention, this contact block 7 is provided with an additional.

contact piece 8, which is arranged to bridge or electrically connect two contact fingers 9 when said block is in its intermediate posi-' winding 10 is preferably made of comparatively high resistance, and the winding 11 of a few turns of'large size wire so as tobe of low resistance. The contact finger 12 and its cooperating contact are constructed in a manner well known in the art so as to be able to carry without injury the comparatively large operating current of the switch machine. The relay X isalso provided with copper tubes or similar means for making it slow releasing, for the purpose hereinafter ex lained.

11 order to enable the maintainer to readily cut off power from the switch machine when he desires to'crank it by hand,

9 I provide a cutout plunger 13, guided and supported in a suitable part of the main frame of the switch machine which I have indicated conventionally and designated 1a.

This cutout plunger 13 is formed with a suitable knob for facilitating its manual movement, and is provided with a key-like projection 15 fitting in a corresponding slot or key-way in its supporting member 14, so that when said plunger is pulled out and partly turned it will be held out. This plunger 13 carries an insulated contact disk 16 arranged to electrically connect contact springs 17 suitably supported on an insulated panel (not shown). A compression spring 18 tends to return said cutout plunger 13 to the normal position shown.

The parts of the interlocking system. at thetower (inclosed in a dotted rectangle) comprise the usuallever L, connected to a rod 19 which operates contact blocks, as 20, to bridge pairs of contact springs, as 21. The indication latch for the lever L is designated 22, the indication magnet I, the safety magnet S, the polarized relay PR, the indication selector IS, and the main battery B, these arts being of well known construction and t ose commonly employed in the dynamic indication type of electric interlocking system illustrated. The various wires and electrical connections will notice described in detail, since the circuits more directly involved in the operation of my invention will be explainedhereinafter.

The winding 10 is designed Operation: Referring to Fig. 1, the parts are shown in the normal position. hen it is desired to reverse the switch A, the lever is pulledouty (to the left asvshown) to its reverse indication position, thereby applying energy to the reverse control wire R and energizing the high resistance winding 10 of the auxiliary relay X, providing the detector track circuit is unoccupied, this circuit being traced as follows: commencing at the battery B, wire 23, safety magnet S, wires 24: and 25, magnet 26 of indication selector IS, wire 27, contacts 21- and block 20, wire 28, reverse control wire It, contact springs 30 and contact piece 31, through armature of motorM, contact springs 32 and contact. piece 33, wire 34, through field of motor M,' wires 35 and 36, winding 10, wire 37, contact finger 6 of the track relay 5, wire 38, contact springs 17 and contact disk 16', common wire C and wire 39 through contacts of polarized relay PR and wire 40 back to the battery B.

Winding 10 being energized, armature 12 is picked up, so that current may flow from the reverse operating wire B through the contacts of pole changer and armature and field of the motor M, along the same pathabove traced,-then along wire 11, low resistance winding 11, wire 12, armature 12,'wires 43 and i, contact springs 17 and contact disk 16 to the commonwire O and thence back to the battery -B. The winding 11, being of low resistance, does not interfere with the regular operation and indication of the switch machine. WVhen the switch machine completes its operation, the pole changer contact pieces 31 and 33 are shifted and current is cut off from the windings 10 and 11 of the relay X, but the relay being constructed so as to be slow releasing, the armature 12 1s held closed long enough to permlt the indication current, generated dynamically by the motor M in the usual,

may, to build up.

f a train should be present uponthe detector track circuit when the lever L is operated, the winding 10 of relay X will not be energized, since its energizing circuit above traced will be interrupted at the contact finger 6 of the track relay 5, Consequently, armature 12 is not picked up and the current supplied to the motor M of the switch machine is so small on account of the high resistance of the winding 10 that the switch machine does not operate. Thus, with a train on the detector track circuit, power cannot be applied to the switch machine.

If a train should enter the detector track circuit just after the lever L. is moved and while the switch machine .is operating, the operating current flowing through the low resistance winding 11 keeps the armature 12 raised and power applied, so that the switch machine may complete its movement. This some reason should put his is preferable to leaving the switch in micstroke or unlocked.

It a train should enter the detector track ci cuit while the switch machine is operating, and it the operator at the tower for 'er in the middle position, both the windings 11) and 11 would be deenergized, the winding 10 because its circuit is broken at the contact tinger 6, and the winding 11 because the operatin current is now cut oil from the switch machine. In this instance, the operator would lose his control over the switch machine; and to obviate this objection, the contacts 8-9 are provided, so that while the switch machine is unlocked, a shunt comprising wires 4C3, 15, contacts S9, and wire 16, is established for the armature 12. In order for the operator to lose control of the switch machine in the manner just described, several things must happen just at the right time, and this being a very unlikely contingency, the contacts 8-9 may be omitted if desired, without detracting from the safety of the system.

When it is desired to crank the switch machine over by hand for the purpose of inspect-ion or repair, or because the machine is out of order, the maintainer pulls out the cutoutplunger 13 which breaks the main common C at the contact disk 16 so that current cannot be applied to the machine,

This is necessary for the protection oi the maintainer, since he might be injured by the automatic reversing action characteristic of this type of machine if he should crank the machine fully over with power on. The cut out plunger 13, being positively held in its operated position, cannot be jarred back by a passing train and throw the switch under this train, as sometimes happens ith the present practice of lifting the bru es of the motor, since the brushes are sometimes not properly secured.

If the switch machine is cranked over and lo ked up by hand while a train is present on the detector track circuit, power cannot be applied to the switch machine and cause it to throw the switch points back again, even though the plunger 13 is restored to normal, for the reason that the main common C for the switch machine will be broken at the contacts of the relay X. In this way, when the switch machine is cranked fully over to one position or the other for the purpose of permitting a train to pass, the position of the switch will not be changed by power while a train is passing over it, even though its position is out of correspondence with the lever. This arrangement affords extra sateguards for the hand operation of switches and the flagging of trains over them.

In the modification shown in 2, the auxiliary relay X is provided with two oppositely wound coils or windings 50 and 51, of the same number of turns, thereby constituting in effect a differential relay. These vindings are connected in series across the normal and reverse control wires N and B, with high resistances 52 in series therewith. The common terminals of the windings 5t) and 51 are connected by a wire 53, armature 6 of the track relay 5, wires 5% and 55, contacts 1617 to the main common C. Contacts S and 9 are provided the same as in Fig. 1, but for a different purpose.

Assuming the switch machine and lever to be normal as shown, the normal control wire N is connected to the battery B at the tower, and current flows from this energized normal control relay N through resistance 52, winding 50, wire 53, armature 6, wires 54, 55, contacts 16-17, and main common C back to the battery B. The other winding 51, however, has practically no current flowing in it, since it is shunted or short-circuited by a low resistance path comprising wire 53, armature 6, wires 5 and 55, contacts 1617,common C, polarized relay PR, indication magnet 1, contacts of indication selector IS, lever contacts, and reverse control wire R. Thus, while the armature 6 of the track relay is up, the relay X is unbalanced and its armature 12 attracted. l/Vith armature 12 up, operating current may pass throu h the pole-changer contacts, as

31-33, in the usual way, through motor M, wires 56 and 57, armature 12, wires 58 and 55, and contacts 1617 to common C.

When a train comes on the detector track circuit, armature 6 of the track relay 5 drops, and the same current then flows through both windings 50 and 51 of the relay X and since these windings are wound equal and opposite, the armature 12 drops, thereby cutting off the supply or current to the switch machine in the same way as previously explained.

It a train should enter the detector track circuit while the switch machin is operating, the armature 12 drops, but the operating current may still flow through the shunt path around said armature and its Contact, 7

said shunt path comprising wires 57 and 59, contacts 89, and wire 60. The switch machine, therefore, can complete its operation and will not be left in mid-stroke or unlocked. The operation of the cutout plunger 13 and the other parts of the system are the same in this modification as previously explained.

It will be noted that the auxiliary relay X in the modification of Fig. 2 is normally energized, as distinctive from the arrangement in Fig. 1, in which the relay X is normally deenergized. The modification of 2, therefore, has one disadvantage in that it is normally consuming current. In

proper operation of the system.

this connection it should be understood that the windings and 51 are made of high resistance, and with external resistances 52 in series therewith, so as to limit the current flow and also prevent interference with the For example, I find it preferable to make the resistancesot the windings 50 and 51 so as to give with the external resistances a total resistance between the control wires of some 8000 ohms, 4000 on each side. 7

My invention provides a simple and eflicient way of operating an auxiliary relay from the main battery at the tower, subject to the control of the track relay, without running extra wires. The control oithis auxiliary relay is such that current cannot be supplied to the switch machine when the detector track circuit is occupied, while the switch machine is always allowed to ccmplete its movement, especially if it should happen to be operating when a train enters the detector track circuit.

Obviously, various illustrations, modifications and adaptations may be made with respect to the particular. parts and circuits 7 which I have selected to illustrate the nature of my invention, without changing its tunctions or operation. For instance, by making the obvious appropriate changes in mechanical details, my improved detector locking means may be applied to other types of interlocking systems, which are either operated or controlled by alternating current or direct current. I desire to have it understood, therefore, that the arrangements and constructions of parts and circuits which I have shown and described are merely illustrative and do not exhaust the various embodiments and 'forms which my invention may take in practice.

WVhat I claim as new anddesire to secure by LettersPatent of the United States, is:

1. In a power operated interlocking system including a. central source of energy, a switch machine, a detector track circuit, and means at the switch machine controlled by said track circuit and energized from said central source for preventing application of power to said switch machine while the detector track circuit is occupied, said means when initially energized being maintained energized independently of the track circuit control so long as the switch machine i operating. r

2. In a power operated interlocking system including a central source of energy, a switch machine, means including control wires between said source and the switch machine for governing the operation of said machine, a detector track circuit, and means at the switch machine controlled by said track circuit and energized from said central source over said control wires for cutting off the supply of power to said switch machine while the detector track circnitis occupied, said means being ineffective while the switch machine is operating. v

3. In a power operated interlocking system for railroads including a central source. of energy, a power operated switch machine,

a track circuit adjacent to the switch machine, control circuits between the central source and the switch machine for governing the application of power thereto, electrically operable circuit controlling means adapted when deenergized to prevent application of power to the switch machine, saidmeans permitting the switch machine to complete an operation once started prior to the occupancy of the track circuit, an initial energizing circuit for said means having its continuity governed by the track circuit and supplied with current only. when current flows in said control circuits.

4:. In an all-electric interlocking system including a main source of energy at the tower, a switch machine, control circuits for said machine including a common return connection, manually operable means for breaking said common return connection, a detector track circuit, and automatic means controlled by said track circuit for also con- 7' trolling'the continuity of said common return connection.

5. In an all-electric interlocking system including a switch machine and an operating circuit therefor, a detector track circuit, and normally inactive means controlled by said track circuit and adapted to be governed from a distant point for making and breaking said operating circuit, said means being energized by the flow of operating current to the switch machine.

6. In a power operated interlocking systerm, a switch machine, a slow releasin electromagnetic device governing the supply of power to said switch machine, a detector track circuit, a circuit controlled by said track circuit for energizing said device,and means for maintaining it energized while said switch machine is operating.

7 In an all-electric interlocking system, a

switch machine, a circuit for supplying operating current to said machine, a biased normally open circuit controller in said circuit, a detector track circuit, and means controlled by said track circuit for closing sald' sponsive to the flow of current from said source, for rendering said meensinefi'ective provided the track circuit is not occupied.

9. A power interlocking system comprising a switch operating mechanism, a track circuit, means controlled by said track circuit and normally acting to prevent the application of power to said mechanism while at rest, said means when rendered ineffective acting to continue the supply of power to the mechanism and permit it to complete a cycle of opera ion once started, a source of current and control means governing the operation of said mechanism from a distant point and also acting to render the-first mentioned means ineffective when the track circuit is not occupied.

10. In a railway traffic controlling system, a track including a track circuit, a switch, an electrically controlled mechanism for said switch havin an operating circuit, a device located at the switch and having two windings each included in the operating circuit of said mechanism, said device being controlled by said track circuit for preventing the operation of said mechanism when said track is occupied, and for maintaining the circuit of said mechanism throughout its operation.

11. In a railway trafilc controlling system, in combination, a track including a track circuit, a switch, an electrically controlled mechanism for operating said switch, a circuit controlling said mechanism, a normally deenergized relay having an operating coil controlled by said track circuit and a holding coil connected in series with the circuit controlling said mechanism, and

means operated by said relay for governing the continuity of said circuit.

12. In a railway tratfic controlling system, in combination, a track including a track circuit, a switch, an electrically controlled mechanism for operating said sw'tch, a circuit controlling said mechanism, a lever controlling said circuit, a relay having an operating coil controlled by said track circuit and responsive to the flow of current in said circuit and a holding coil connected in series with the circuit controlling said mechanism. and means operated by said relay for governing the continuity or? said circuit.

13. In a railway tratlic ontrolling system. a track including a track circuit, a switch, an electrically controlled mechanism for operating said switch, a normally deenergized relay having an operating coil contro led by said track circuit and a holding coil included in the circuit of said mechanism, said relay when energized closing said mechanism circuit, and means for supplying currentto said operating coil.

14:. In a system for controlling railway switches, a switch operating mechanism, a

circuit for governing said mechanism, a track circuit, a relay controlling the application of power to said mechanism, said relay being initially energized by current in said circuit dependent upon the track circuit being unoccupied and also being maintained energized after initially energized until said mechanism has completed a cycle of operation once started.

15. In a system for operating railway switches, a switch operating mechanism having an operating circuit, a track circuit, and a normally deenergized relay at the switch adapted when initially energized to maintain said operating circuit closed while the mechanism is operating, said relay being initially energized by current in the operating circuit provided the track circuit is not then occupied.

16. In a system for operating railway switches, switch operating mechanism having an operating circuit, a track circuit, an electro-magnetic device controlling the application of power to said mechanism, a pick-up circuit for said device energized by current in the operating circuit provided the track circuit is not occupied, and a holding circuit for said device, dependent upon the initial energization thereof, and maintained energized while the mechanism is operating.

17. In a railway trailic controlling system, an electrically operable switch machine, a source of current and control means for governing the switch machine from a distant point, a. track circuit, a relay adapted when deenergized to prevent application of current to the switch machine, means controlled by said track circuit and acting when current is supplied to the switch to cause energization 01"- said relay, and means for preventing denergization of saidrelay while the switch machine is operating.

18. In a power operated interlocking system, a switch operating mechanism," an electro-magnetic device located at mechanism -for preventing operation thereof, a track circuit, a source of current and control means for governing the operation of said mechanism from distant point and for also determining the initial energization of said device dependent upon the condition or" said track circuit, and means for maintaining said device energized while the switch machine is operating.

19. A- power interlocking system compri ing a switch operating mechanism, a track circuit, a normally .deenergized slow releasing relay adapted to prevent application of power to said mechanism, an energizing circuit for the relay controlled by said track circuit, and a source of current and control means at a distant point for causing ener gization of the relay when the track circuit is not occupied.

20. A power interlocking system comprisoffthe mechanism while the track circuit is occupied.

21. A power interlocking system comprising a switch operating mechanism, a track circuit, an electrically operable device lo cated at said mechanism for preventing operation thereof when the track circuit is occupied, said device after initial energization thereof being ineffective while the mechanism is operating, and means for governing the initial energization of said "device from a distant point subject to the control of the track circuit. 7 r

22 A power interlocking system comprising an electrically operable switch operating mechanism, a. normally de'c'nergized electromagnetic device at said mechanismior preventing application of current thereto, a

track circuit, and a source of current andcontrol means at a distant point for sup: plying current for the operation of said mechanism from said distant point, such supply of current acting to-energize said device provided the track circuit is not occupied and thereby permit" application of power to the switch operating mechanism.

23. A power interlocking system comprising a switch operating mechanism, a normally de'elnergized electrically means at said mechanism adapted to prevent application of power thereto, a track circuit controlling said means, and manually controlled means for supplying current to said electrically .operable means from a distant point subject to the control of said track circuit.

24. V A power interlocking system comprising an electrically controlled switch machine, control means for said machine, a track circult, and electrically operable means located at the switch machine and jointly governed by said track circuit and said control means for preventing application of power to the machine while the track circuit is occupied, and means for independently maintaining the supply of power to the switch machine while it is operating.

25. A power interlocking system comprising an electrically controlled switch operating mechanism, a circuit for governing said mechanism, a track circuit, and an elec-' trically operable device at said mechanisn initially controlled jointly by the track circuit and the flow of current in said governing circuit for preventing application of power to saidIn.echantsul while the track operable ing an electrically controlled switch operatcircuit is occupied, said device after its initial control permitting the mechanisni to complete a cycle of operation started prior to the entrance of a train into the track circuit.

26. A power'interlocking system comprising a switch operating mechanism, a normally deenergized electro-m'agnctic device at said mechanism normally preventing the application of power to'the mechanism, a track circuit, and means ope able at a distant point for causing energization of: said device when the track circuit is not occupied, saiddevice when once energized being auto matically maintained energized while the switch mechanism is operated.

27; A powerinterlocking system comprising a switch operating mechanism, a track circuit, means controlled by said track circuit and normally acting to prevent opera-- tion of said mechanism, and means governed from a distant point for rendering"said meansineffective when said track circuit is not occupied, said first mentioned means when once rendered ineffective being maintained in that condition so longas operating current is supplied to said mechanism.

28. A power interlocking system comprising an electrically controlled switch machine, a track circuit, means normally acting to revent operation 01: the switch machine, a source of current andcontrol means at a distant point for governing said switch machine, and means whereby said normally acting means is automatically made ineffective at times by current from' said source under the control of said control means, and subject to thecontrol of said traclrcircuit.

29. A power interlocking system comprising mechanism, control means for governii'lg' said mechanism from a distant point, a track circuit, and means normally acting to prevent operation of said mechanism and automatically rendered inactive under the control of said control. means when the track circuit is not occupied, said means permitting the mechanism to complete a cycle of operation started prior to the entrance of a train into said tra'ck circuit.

i 30. A power interlockingsystem comprising a switch operating mechanism, a track circuit, means controlled by said track circuit and normally acting to prevent applica tion of power to said mechanism, means for rendering said means ineffective and there by permit operation of the i'nechanism when thetrack circuit is not occupied, and means for maintaining the supply of power to the mechanism so long as it is operating regardless of the condition of said track circuit. 31. A power interlocking system comprising an electrically controlled switch ma chine, a track circuit, anormally open Cl cuit controller acting to cut off the sup of power to said macl1ine, nea11s controlled from distant point for closing said circuit controller to permit operation of said machine when the track circuitis not occupied, and a shunt for said circuit controller closed except when the switca machine is in one or the other'of its extreme operated positions.

32. Apower interlocking s -Jstem comprisingv an electrically operable switch machine, a control lever, two control wires and common return connection between the lever and the switch machine, a detector track circuit, and means at the switch machine ener gized by current over said wires supplied by the operation of said lever for preventing application of power to the switch ma chine while said track circuit is occupied.

A power interlocking system comprising a switch operating mechanism, a lever and control wires for governing the operation of said mechanism from a distant point, a track circuit, and means normally acting to prevent application of power to said mechanism, said meansbeing automatically rendered ineffective by current supplied over said control wires whenever the track circuit is not voccupied.

3a. A power interlocking system comprising a switch operating mechanism, a power supply therefor, a lever and control wires for governingthe operation of said mechanism from a distant point, and means normally acting to interrupt the supply of power to said. mechanism while it is at rest,

said means being automatically rendered in active by current supplied over the control wires, and being automatically maintained inactive while said mechanism is operating.

35. A power interlocking system comprising a switch operating mechanism, a power supply therefor, a lever and control wires for governing the operation of said mechanism from a distant point, a track circuit, and means normally acting to prevent application of power to said mechanism while it is at rest, said means being rendered in effective when current is supplied over the control wires and the track circuit is not occupied, said means permitting the mechanism to complete an operation once started regardless of the entrance of a train into the track circuit in the meantime.

36. A power interlocking system comprising a switch operating mechanism, a lever and control wires for governing the operation of said mechanism from a distant point, a normally deenergized relay controlling the supply of power to said mechanism, a track circuit, and means for causing said relay to he energized by current supplied over the control wires upon operation or" the lever provided said track circuit is not then occupied.

37. A power interlocking system comprising a switch operating mechanism, a lever and control wires for governing the operation of said mechanism from a distant point, a track circuit, and a device normally acting to prevent operation of the mechanism, said device being automatically rendered inactive when current is supplied over the control wires and the track circuit is not then occuied, said device also permitting the mechanism to complete an operation once started re ardless of the entrance of a train into the track circuit in the meantime. A powerinterlocking system comprising a switch machine, a, lever and control wires for governing said switch machine from a distant point, a normally deenergized electromagnetic device controllin the supply of power to said machine, a track circuit, means for causing energization of said device by current flowing in said control wires when the track circuit is not occupied, and means for maintaining a supply of power to the machine throughout an operation started, prior to the entrance of a train into the track circuit.

39. A power interlocking system comprisinga switch operating mechanism, a source of current and control means for governing the operation or said mechanism from a distant point, track circuit controlled means operated by currentfrom said source for preventing application of power to the mechanism,- and means actuated in accordance w th the movement of the mechanism and effective after the mechanism has started a cycle of operation for independently maintaining the supply of power to the mechanism.

40. A power interlocking system comprising a switch operating mechanism, a source of current and control means for governing the operation of said mechanism, a relay having two windings and acting to control the supply of power to said mechanism, a trackcircuit, and a circuit controller closed when either winding of the relay is energized, one of said windings being energized from said source when the control means is actuated provided the track circuit is not occupied, the other winding being automatically maintained energized'aiter closure of said circuit controller regardless of the condition of the trackcircuit so long as said mechanism is operating.

ll. A power interlocking system comprising a switch operatingmechanism, a distant source of current, a common return connection between said mechanism and said source in which current flows so long as the mecl:-anism is operating, a track circuit having a track relay, and a relay having two windings and contacts .closed when either winding is energized, one of said windings being included in the common return connection in series with a front contact of the track relay, the other winding being included in said common return connection in series with the contacts of the relay itself and being thereby maintained energized after closure of the relay contacts so long as the mechanism is operating regardless of the condition of the track circuit.

42. A power interlocking system comprising a switch operating mechanism, a source of current and control circuits governing the operation of said mechanism, a double wound relay for opening and closing said control circuits and having contacts closed when either of its windings is energized, and a track circuit, one winding of the relay being energized when current flows in said control circuits andthe track circuit isnot occupied, the other wfinding being energized while currentflows in said control circuits provided the contacts ofthe relay are closed.

43. A powerinterlocking system comprising an electrically operable switchmachine, a power circuit for said machine, a track circuit, and a relay for governing said power circuit having high and low resistance windings and contacts closed when either winding is energized, the high resistance winding being included in said power circuit when the track circuit is not occupied, the

other winding being included in the power circuit when the contacts of the relay are closed. and being thereby maintained energized independent of the condition of the track circuit.

44. A power interlocking system comprising a switch operating mechanism, a track circuit, and electro-magnetic means having two windings of high and low resistance re 'spectively, said means being governed by said track circuit and acting to prevent op eration of the mechanism while said track circuit is occupied but permitting the mechanism to complete an operation started prior to the occupancy of the track circuit.

45. A power interlocking system comprising an electrically operable switch machine, an operating circuit in which currentfiows while the switch machine is operating, a normally open circuit controller in said circuit, a relay having a high resistance winding and a low resistance winding each adapted when energized to close the circuit controller, the low resistance winding being included in the operating circuit inseries with said circuit controller, and a trackcircuit for governing the high resistance winding.

46. A power interlocking system comprising an electrically operable switch machine, a track circuit, and a relay having apick-up winding and-holding winding and acting when denergized to cut off the supply of current to the switch machine, the pick-up winding being energized when current is supplied to the switch machine provided the track circuit is not occupied, the holding winding including contacts of the relay it self and being maintained energized so long as current is'supplied to the-switch machine. I

irrespective ofthe condition ofcthe track circuit.

47. A power interlocking system comprispied and acting to maintain the supply of. power throughout a cycle of operation start ed prior to the entrance of a train into the track circuit.

48. A power interlocking system comprising an electrically operable switch machine adapted to give a dynamic indication, and rack circuit controlled means responsive to the flow of operating current to the switch machine for governing the operating circuits thereof, said means being slow releasing to permit transmission of the indication impulse. V I

49. A power interlocking system comprising a switch operatingmechanism, operating and indication circuit for said mechanism including'a common wire, a slow ,releasing relay for governing the continuity of the common wire, and track circuit controlled means for governing said relay.

50. A power interlocking system-compris ing a switch operating mechanism, a slow reing controlled by the track circuit, and the other winding in accordance with the operation of the mechanism.

51. A power interlockingsystem comprising a switch operating mechanism, ELCIICllll? controller"actuated1n accordance with the movements ofsaid mechanism and closing except when the mechanism is in one or the other of its extreme operating positions, a double wound relay and contacts closed when either winding is energized, a track circuit adjacent to the switch operated by said mechanism, an energizing circuit for one winding of the relay controlled by the track circuit, an energizing circuitfor the other winding of the relay including the contacts of the relay itself, and a shunt for the contacts of said relay closed when said circuit controller is closed.

52. A power interlocking system comprising a switch operating-mechanism, a manually operable device adapted to be actuated and cut ofi' the, supply of power to said mech anism to permit operation thereof by hand, track circuit controlled means for independently governing the supply of power to the able device is restored to normal regardless of the condition of the track circuit provided the mechanism is only partly operated.

53. A power interlocking system comprising an electrically controlled switch machine, a source of current and a lever at a distant point for governing the operation of said machine, a track circuit, and means jointly controlled by the track circuit and by the lever for preventing an operation of the machine from rest while the track circuit is occupied, but permitting the machine to complete a cycle of operation started prior to the entrance of a train into the track circuit, said means being adapted to permit the machine to be operated to either position in correspondence with the lever While the track circuit is occupied if the machine is operating at the time the track circuit becomes occupied.

54. An interlocking system comprising a switch operating mechanism, a track circuit, said mechanism having its operation from rest dependent upon the condition of the track circuit, normal and reverse control circuits of said mechanism, and means effective upon energization of either control circuit to permit operation of the mechanism if it is operating at the time the track circuit becomes occupied, whereby control of the mechanism is not lost upon the entrance of a train into the track circuit while the mechanism is operating although the operator may shift his lever.

WINTHROP K. HOWE.

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