US1316811A

US1316811A - Railway signaling

Info

Publication number: US1316811A
Authority: US
Publication date: 1919-09-23
Anticipated expiration: 1936-09-23

Description

C. STEPHENS.

HAILWAYSIGNALING. APPLICATION FILED Ausl. I9I6.

CHARLES STEPHENS, 0F RICI-IMOND, VIRGINIA.

RAILWAY SIGNALIN G.

Specification of Letters Patent.

Patented Sept. 23, 1919.

Application filed` August 2, 1916. `Serial No. 112,700.

' To all whom it may concern:

Be it known that I, CHARLES STEPHENS, a citizen of the United States, residing a-t Richmond, in the county of Henrico and State of Virginia, have invented certain new and useful Improvements in Railway Signaling, of which the following is a speci ication.

My invention relates to railway signaling, and particularly to apparatus for the control of signals governing traflic in opposite directions over a stretch of track.

I shall describe one form and arrangement of apparatus and circuits embodying my invention, and will then point out the'novel features thereof in claims.

In the accompanying drawing, Figure 1 is a diagrammatic view showing one form and arrangement of apparatus and circuits embodying my invention.' Fig. 2 is a view showing in vertical section and on an enlarged scale one of the locking devices h of Fig. 1.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, reference characters 1 and 2 designate the westbound and the eastbound tracks respectively of a double track railway. A portion of track 1 between points X and Y is `provided with a so-called automatic block signaling system. For this signaling system stretch X-Y of track 1 is divided into block sections X--V andv Y-Z respectively, in which sections are crossovers Ca and Cb for switching traffic from one track to the other. It is at times desirable to send eastbound traflic through stretch X-Y over track 1 in opposite to normal direction, via the following route, from track 2 through crossover Ca, track 1 o-f stretch X-Y, crossover Cb to track 2.

Traffic over this route is governed by a signal A at the entrance to section Traffic over -track l in normal direction is governed by a signal B at the entrance to loca-ted in so-called. interlocking towers Tt*` and Tb. Each ofthe signal levers is capable of two positions, a normal position designated N, corresponding to the stop indication of the signal governed by the lever, and a reversed position designated R corresponding to the proceed indication of the corresponding signal. Contact segments a and are provided on the shafts of the signal levers for the control of the signal circuits, as I shall describe hereinafter.

Located also in towers Ta and Tb respectively are levers L? and Lb, which I shall term tralic levers to intimate that their purpose is to control the direction of trafiic on track 1. Each of these levers is capable of three positions a normal posi-tion, designated N,` in which traflic may be allowed to pass over track 1 in the normal direction, z'. e. from east to west; a reversed position designated R, in which traffic may be permitted to proceed over track l in the reversed direction (from west to east), and a central position, designated C in which no traffic` can, be sent over track 1 in either diy rection. These positions of the traffic levers are controlled by locking devices 7L. Refer ring also to Fig. 2, each locking device comprises a segment 4- fiXed to the lever shaft 3, allatch 5 adapted to coact with a doge on the segment, and a motor M?L to control the latch 5. When lever La is turned from its normal position toward its reversed position, the lever is arrested in the central position, by the engagement of dog 6 with latch 5. To permit a completion of the stroke of the lever latch 5 must be raised until the `upper bar of the latch clears dog 6. The up and down movements of the latch are controlled by the motor Ma, through the medium of a centrifugal governor 7. As shown in Fig. 2, motor M"1L has a hollow vertical shaft 90, which rotates in

bearings

91 and 92 of a frame 93, which is secured by a threaded neck to the frame of the interlocking Inachine for the lever. The arms 94 of the governor are pivoted in brackets 95 secured to the shaft 90. Immediately below these brackets the shaft is slotted to receive a bar 96 attached Ato the arms 94 by links 9S. Bar 96 is drilled to receive the pointed tip of a rod 97 which is free to move in shaft 90. The latch 5 isattached to the upper end of rod 97. When the motor Mb is rotated the governor fly balls spread and lift bar 96, raising thereby rod 97 a sufficient distance that the upper bar of latch 5 clears dog 6. It should here be noted that this mechanism is so adjusted that the centrifugal force developed by the governor is sufiicient to raise the latch only if the motor is rotating at or above a predetermined speed, as controlled by the frequency of the current supplied to the motor. Lever Lb is provided with a similar locking device controlled by a motor Mb which locking device, however, functions to look the lever against a movement from the reversed to the normal position. I shall describe hereinafter the control of motors MbL and Mb for effecting at the proper time a release of the corresponding levers.

Located also in towers Ta and Tb respectively7 are buzzers UaL and Ub, and drop annunciators Ob and Ob for signaling between the towers as I shall describe hereinafter. I-Ia and Hb are hand generators for furnishing current of the proper frequency to oper- `ate the motors Mb and Mb, buzzers Ub and Ub, and annuncia-tors ObL and Ob, as I shall describe hereinafter. a relay Q at tower 'Ia Vand relays Pb and Pb at towers 'Ib and Tb respectively, which relays enter into the control of the signaling circuits as I shall describe presently.

As described hereinbefore a complete stroke of lever La from its normal position t-o its reversed position is prevented by its locking device L until motor ML is energized by current of a predetermined frequency. The circuit for energizing motor Mat is: from hand generator I-Ib in tower Tb, through wire 52, contact 45 of relay Rb, wire 46, push button Fb, wire 47, contact segment b of lever Lb reversed,

wires

48 and 39, buzzer Ub, wire 38, Contact 37 of relay Rb, wire 36, contact 35 of relay Rb, wire 34, buzzer b, wire 33, contact of lever La in the center position, wire 54, motor Mb,

wires

55, 44 and 51 to hand generator Hb. It follows1 therefore, that a complete reverse movement of lever Lb can be effected only when lever Lb is in the reversed position. Similarly, the traflic lever Lb can be returned from its reversed position to its normal position only if motor Mb is energized when the lever arrives in the center position. The circuit for energizing motor Mb is: from hand generator Hb, through wire 16, con- There are also located i tact 30 of relay Pb, wire 31, push button Fb, wire 32, contact segment a of lever La normal, wire 33, buzzer Ub, wire 34, contact 35 of relay Rd, wire 36, contact 37 of relay Re, wire 38, buzzer Ub, wire 39, wire 48, contact segment C of lever' Lb in the center position, wire 70, motor Mb, and

wires

44 and 71 to generator II, It follows that lever Lb can be operated to its normal position only when lever La is in the normal position. Since it is also true that traffic lever La can be reversed only when traffic lever Lb is reversed, it follows that it is never possible to have simultaneously a reverse position of lever La and a normal position of lever Lb.

The circuits traced above for the control of motors Mb and Mb, show that each motor can be energized only by the hand generator located at the other tower, Hb or I'Iba respectively. However, to prevent an energization of either motor when by an accidental cross of wires the adjacent hand generator is connected into the adjacent motor circuit, the generator fields are controlled in the following manner. The field 10 of generator Ha is controlled by the circuit: from battery Kb, through wire 11, field l0 of generator IIb, wire 12, push button Fb, wire 13, contact segment c of traffic lever Lb in the normal position, and wire 15 to battery Kb. In the Kabove circuit the contact segment e of levers Lb is provided with a shunt coinprising contact segment f of the same lever, which segment is closed when the lever is in the reversedv position. The circuit for field 10 is closed therefore when push button Fb is depressed and lever La is in either its normal or reversed positions, but not when this lever is in the center position. Consequently, when lever Lb is turned to its center'position (in order to close the circuit for motor Mb), the circuit for field 10 of generator IIa is open, so that current cannot be obtained from this generator, thus making it impossible to receive a false energization of motor Mb. The control for the circuit of field 10 of generator I-Ib is similar to the circuit described above for the control of the field 10 of generator Hb.

The traffic levers control the adjacent signal levers, preferably by mechanical interlocking. This control (which I have indicated by legends on the drawings) is such that signal lever Sa can be reversed only when traffic lever La is in the reversed position, whereas signal lever Sb can he reversed only when traffic lever Lb is in the normal position. I have shown hereinbefore that because of locking devices 7L it is impossible to get, simultaneously, the reversed position of lever La and the normal position of lever Lb. It follows, therefore, that both of the signal levers cannot be in their reversed positions at one time.

A reverse movement of signal lever SbL operates signalA to the proceed indication by closure of the following circuit: from battery Bb, through

wires

17 and 62, contact ,63 or relay Q, wire 64, contact segment b segment CZ of traiiic lever Lb normal, wire 79, contact segment b of signal lever Sb reversed, wire 80, contact-81 of relay Pb, wire 82, operating mechanism of signal B and Wire 83 to battery Bb. 1n view of the fact that the tWo signal levers cannot be in the reversed positions simultaneously1 it is now apparent that the signals A and B cannot indicate proceed at one time. Thus t'wo cars or trains can never secure permission at the saine time to pass over track 1 in opposite directions.

Y The circuit traced above for signal A is controlled not only by lever Sa but also by contact 63 of relay Q, and it is apparent that signal A can be operated to and retained in the proceed posit-ion by signal lever Sb only while relay (a, is energized. The energizing circuit for relay Q is: from battery Bb, through

wires

17 and 56, contact 57 of relay Pb, wire 58, contact segment d of tratiic lever Lb reversed, wire 59, relay Q, wires 60 and 66 to battery Bb. Relay Q, therefore, is closed only when relay Pb is energized and traiiic lever Lb is reversed, so that it is apparent that aproceed indication of signal 'A can be given and maintained only while traffic lever La is reversed and relay Pa is energized.

Relay PbL has two circuits, a pick-up circuit and a holding circuit. The former circuit comprises the following connections:

'from battery Bb, through wire 17, contactV y 18 of relay Rb, Wire 20, relay Pb. Wire 21,

contact segment c of traine lever La normal, wire 22, contact segment a of signal lever Sb normal, and wire 28 to battery Bb. This circuit cank be closed to pick up relay Pa only if levers La and Sa are normal, provided however that section V-X of track 1 is unoccupied by a car or train. The holding circuit for this relay is the same as the pick-up circuit up to and including relay Pb, then through contact finger 73,

wires

74 and 66 to battery Bb. Y This circuitV is independent of the control of levers Lb and Sa so that relay PbI after it has been picked up remains closed, regardless ofthe positions of these levers, until relay Rb is denergized by the entrance of a car or train into section W-X.

From the above described circuits, it follows that signal A can be operated to its proceed position only by irst throwing levers La and Sa to their normal positions to pick up relay Pb, then reversing lever La to energize relay Q and finally reversing lever Sa to close the signal circuit. The presence of a train in sectionvW-Q, however, makes it impossible either to eii'ect or to retain the proceed indication of signal A.

Signal B is controlled by relay Pb, traffic lever Lb and signal lever Sb, as pointed out in a previous description oi the circuit for this signal. For closure of this circuit lever Lb must be at normal and relay Pb must be energized when the signal lever Sb is operated toits reversed position. The relay Pb, similar to relay Pa of tower Tb, has a pick-up and a holding circuit. The former circuit is as follows: from battery Bb, through wire 75, contact 28 of relay Rb, wire 27, contact segment g oi lever Lb, wire 26, relay Pb, wire 25, contact segment a of lever Sb and wire 24 to battery Bb. Relay Pb can, therefore, be energized by throwing levers Sb and Lb to the normal positions, provided, however, that section Y-Z of track l is unoccupied. The'holding circuit for relay Pb is the same as the pick-up circuit up to and including relay Pb, then through contact 76,

wires

77 and 24 to battery Bb. Relay Pb, therefore, once picked up remains energized independent of the position of levers Sb and Lb, as long as track section YZ is unoccupied. It is now apparent that signal B can be operated to its proceed position only by iirst throwing levers Lb and Sb to their normal positions to energize relay Pb, and then reversing signal lever Sb to close the signal circuit. The presence of a car or train in section Y-Z, however, makes it impossible to effect or to retain the proceed indication of signal B.

For purposes of signaling from one tower to the other I provide communication circuits for operating the annunciators Ob and Ob and buzzers U and Ub. The circuit for signaling from tower Tb to tower Tb is as follows: from generator Hb, through Wire 16, contact 30 of relay Pb, wire 31, push button Fb, wire 82, contact segment a of tratlic lever Lb normal, wire 33, buzzer Ua, wire 34, contact 35 ofrelay Rd, wire 36, contact 37 of relay Rb, wire 38, buzzer Ub, wire 39, contact segment c of traffic lever Lb normal, wire 40, push button 41, wire 42, annunciator 0b,

wires

43, 44 and 71 to generator Hb. This circuit is provided with a branch around contact segment a of lever Lb, which branch comprises contact segment b of lever Lb reversed, wire 47 push button Fb, and wire 471, so that this circuit is closed when the traiiic lever Lb is in either its normal or its reversed position. The circuit for signaling from tower Tb to tower Ta is as follows: from generator Hb, through wire 52, contact 45 of relay Rb, wire 46, push button Fb, wire 47, contact of tra'fc lever Lb reversed,

wires

48 and 39, buzzer Ub, wire 38, contact`37 of relay Rb, wire 36, contact 35 of relay Rd, wire 34C, buzzer U, wire 33, contact segment a of lever Ln normal, wire 32, push butto-n F, wire 49, annunciator O,

wires

50, 44 and 51 to hand generator Hb.

The operation of the system is as follows: When there is no car or train in the stretch of track between W and Z, the track relays Ra, Rd, Re and Rb are energized, and sign als D and E are in the proceed positions indicated in the drawing. It the trairic levers La and Lb and signal levers Sa and Sb are in their normal positions, relays P and Pb are energized, both their pick-up and holding circuits being closed. Relay Q is denergized, its circuit being open at contact segment Z of lever La. Motors MEL and-M'.b are also denergized.

Under these conditions the operator at tower Tl may move the signal B to its proceed position to permit a train to pass through stretch K Y in the normal direction of trafiic by simply reversing signal lever Sb, so that this lever closes at its contact segment b the circuit for signal B, as I have described hereinbel'ore. When a train accepts signal B and enters section Y-Z, it denergizes track relay Rb. This relay opens at contact 2S the holding circuit of relay Pb, which in turn opens the circuit for signal B, causing it to display the stop indication. As the train enters section V- Y, it denergizes relay Re, which opens the circuit for signal E, so that this signal is brought to the stop indication. As the rear end of the train leaves section Y-Z, relay R is renergized and closes at contact 28 the circuit for relay Pl. But this relay remains denergized because its pick-up circuit is open at signal lever Sb. As the car or train proceeds into section V-X, it deenergizes relay Rd so that signal D changes to the stop position. As the rear end of the train leaves section V-Y, relay RC again closes the circuit for signal E so that this signal is returned to the proceed position. As the train enters section 1lV-X, it deenergizes relay Ra, causing this relay to break both the pick-up and the holding cii'- cuits of relay PfL so that the circuit for signal A cannot be closed until after the train has passed out of the section. To permit the passage of a second westbound train through stretch lV--X on track l, the operator must iirst restore signal lever S" to normal in order to pick up relay Pb. Then he can operate the signal B to its proceed position by again reversing signal lever Sb. Thus it is seen that when the traffic levers La and Lb-are in the normal positions the operator at tower Tb is enabled to permit the passage of westbound trains over track 1 without coperation of the man at tower Tn.V

.Howeveig if the operator at tower Ta desires to send a train through stretch X-Y over track 1 in the reverse direction, he can do so only with the cooperation of the operator at tower Tb. To notify the lat-l ter of this intention, the operator at tower Ta depresses push button F2l and turns hand generator Ha so that current is sent through the communication circuit hereinbefore traced, sounding buzzers Ua and Ub and operating annunciator Ob. It will be noted that this communication circuit is closed only if the track relays R, Rd, and Re are energized; in other words, when track l is unoccupied between W and Y. Tf this circuit is closed, as indicated by the sounding vof buzzer Ua, the operator at tower 'lla turns lever La to the center position and waits `for a release of the lever by the man at tower Tb. This operator, in response to buzzer b, restores the latch of annunciator Ob and reverses traliie lever L". He then depresses push button Fb and turns hand generator Hb, thus sending current through the circuit for motor i a, which circuit was hereinbefore described. This current sounds buzzer Ua in tower Ta, notifying the operator that lever La is free to be turned to the reversed position. When the operator reverses lever L, relay Q, is energized permitting signal A to be operated to the proceed indication by reversal of signal lever Sa.

When a car or train accepts signal A and enters upon track l via crossover Ca, it deenergizes relay Ra so that signal A changes to the stop indication. As the car or train proceeds over its route, it opens successively,

relays Rd, RE and Rb which hold ,open ,the communication circuits between the towers and the energizing circuits for motors M and Ml until the car or train passes out of the corresponding sections. As explained hereinbefore, signal A can be restored to the proceed position only by first restoring both the trahie lever La and the signal lever Sa to their normal positions in order to pick up relay Pa. Once the traic lever Vis in the normal position, it cannot be reversed until again unlocked by the operator at tower Tb. As explained hereinbefore, the communication and locking circuits between the towers are open until the car or train on track l has passed completely out of the stretch. VIt follow-s, therefore, that the operator at tower TLL must receive an unlock from the man at tower 'Tb for each train movement opposite tothe direction of traffic.

On the other hand, if after the passage of an eastbound train over track l, the operator at tower Tb desires to restore his traiiic lever-Lb to normal in order to send a train over this track in the normal direction, he signals .to the operator at tower Tal by depressing push button Fb and cranking Y hereinbefore, sounds buzzers UD and Ua and operates annunciator Oa. The operator at to-wer Ta gives the unlock by depressing push button Fa and turning generator Ha to sound buzzer Uh. The man at tower Tb then moves his tralic lever Lb to the center position so that motor Mb is energized to permit the operator to turn the lever Lb into the normal position. After movement of this lever to normal, the current from generator I-Ia flows through contact segment a of lever Lb and push button l1 to annunciator Ob, The man at tower Tb notifies the operator at the other tower that he has. received the unlock by depressingpush button 4l to interrupt the i'low of the signaling current. The resultant break in the sounding of buzzer Ua is a signal to the operator at tower Ta that leve-r Lb is imlocked and restored to normal. The operator at tower Tb is now able to operate signal B to the proceed position by reversal of levers Sb as hereinbefore described. j

Although I have herein shown and described only oneform and arrangement of apparatus and circuits embodying my invention, it is understood that various changes and modiiications' 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:

1. In combination, two stations, a communication circuit between said stations comprising a source of current at each station, and means at each station responsive thereto, a control device at each station 'comprising a lever having anormal and a reverse position, means Jfor controlling said circuit by one of said levers so that saidvcircuit is closed when said lever is in either position, and means for controlling the circuit by the other lever so that it is closed only when the lever is in thev normal position.

2. In combination, a stretch of railway track, means for controlling railway traffic over said stretch in both directions comprising a lever adjacent each end of the stretch, each of said levers having a normal and a reverse position, a communication circuit comprising a source of current at each end of the stretch and means at each end of the stretch responsive thereto, means for controlling said circuit by the presence and absence of cars or trains in the stretch, means for controlling said circuit by one of said le'- vers sc that said circuit is closed when said lever is in either position, and means for controlling the circuit by the other lever so that it is closed only when the lever is in the normal position.

8J In combination, a stretch of railwayV track, means for controlling trailic over said stretch in both directions ,comprising a lever adjacent each end of the stretch, each of said levers having a normal and a reverse position, a communication circuit extending throughout said stretch, track circuits for said stretch comprising relays for the control of said signal circuit, a hand generator at each end of the stretch for energizing the signal circuit, a buzzer and an annunciator at each end of the stretch responsive thereto, means for controlling said circuit by one of said levers so that the circuit is closed when said lever is in either position, and means for controlling said circuit by the other leveil so that it is closed only when the lever is in the normal position.

4. In combination, a stretch of railway track, traiiic controlling Vmeans for said stretch comprising a lever adjacent each end of the stretch each lever being capable of occupying two or more positions, locking means for each lever, a current generating means at each end of the stretch for energizing the locking means for the lever at the other end of the stretch to release suoli lever, means controlled by each lever for completing the connection of the corresponding locking means with the generating means at the opposite end of the stretch only when such lever occupies one position, and means controlled by each lever when in such po# sition for rendering the adjacent generating means incapable of generating current.

5. In combination, a stretch of railway track, traffic controlling means for said stretch comprising a lever adjacent each end 100 of the stretch each lever bein capable of occupying two or more positions, locking means for each lever, a current generating means at each end of the stretch for energizing the locking means for the lever at the 105 other end of the stretch to release such lever, each generating means comprising an armature, an exciting Vwinding and a source of exciting current, means controlled by each lever for completing the Iconnection of the 110 corresponding locking means with the armature of the generating means at the other end of the stretch only when such lever occupies one'position, and means controlled by each lever when in such position for dis- 115 connecting the source of exciting current from the exciting winding of the adjacent generating means.

6. In combination, a stretch of railway track, traiic controlling means comprising a 120 lever adjacent each end of the stretch each lever having a normal, a center and a reverse position, locking means for each lever,

a circuit for the control of each locking means and comprising a source of current 125 at the Opposite end of the stretch, track circuits for said stretch comprising track re- `for the first lever.

7. In combination, a stretch of railway track, traiiic controlling means comprising a lever adjacent each end of the stretch, each lever having a normal, a center and a reverse position, locking means for each lever, a circuit for the control of each locking means and comprising a sourceof current at the opposite end of the stretch, track circuits for said stretch comprising track relays for the control of said circuit, means for each lever for closing the circuit for its locking means when the lever is in the center position, means controlled by one lever for closJ ing when in the normal position the locking circuit of the other lever, means controlled by the other lever for closing when in 'reverse positions the locking circuit of the irst lever, and means for each locking `means controlled by the position of the corresponding lever for preventing the operation thereof by current from the adjacent source.

8. In combination, a stretch of track, trafic controlling means comprising` a lever adjacent each end of the stretch each lever having a normal, a center and a reverse position, locking means for one lever for preventing movement thereof from normal to reverse position, locking means for the other lever for preventing movement thereof from reverse to normal position, a circuit for controlling both of said locking means, a hand generator at each end of the stretch for generating a distinctive current for said circuit for operating said locking means to release the levers, said locking means being responsive only to said distinctive current, means for each lever for closing the circuit of its locking means when in the center position, means controlled by one lever when in the normal position for closing the circuit for the locking means of the other lever, means controlled by the other lever when in the reverse position for closing the circuit for the first lever, and track circuits for said stretch comprising track relays for controlling said circuit.

9. In combination, a stretch of railway track comprising a section adjacent each end, track circuits therefor comprising track relays, a signal at each end of the stretch for governing traliic therethrough, a signal lever for the control of each signal, a traffic lever for the control of each signal lever, a relay adjacent each end of the stretch controlled by the track relay for the section adjacent said end and by the adjacent traffic and signal levers, means for controlling each end signal by the relay and the traf o and signal levers adjacent its end of the stretch, a locking device for each traffic lever, a circuit for said locking devices controlled by the track relays for the stretch, and comprising a source of distinctive current at each end of the stretch, and means for controlling said circuit so that each locking ldevice cannot be operated by current from the adjacent source.

v l0. A stretch of railway track, track circuits therefor comprising track relays, a railway signal for each end of the stretch, a signal lever for controlling each signal, a

traffic lever for controlling each signal lever and having a normal, a center and a reverse position, locking means for controlling each traiiic lever, a source of distinctive current and signaling means adjacent each end of the stretch, said signaling means and said locking means being responsive to said sources of current, a line wire parallel to the stretch of track and controlled by the said track relays, means adjacent one end of the stretch for connecting the adjacent source of current or the adjacent signaling means to one end of the line wire when the correspending traffic lever is normal, and for con necting the adjacent locking device to said end of the wire when the traflic lever is in the center position and means adjacent the other end of the stretch for connecting the other source of current or the other signaling device to the other end of said line wire when said other trafhc lever is in reverse position and for connecting the other locking device to said other end of the line wire when the, said other traffic lever is in the center position.

l1. In combination, a stretch of single track, two signals A and B for governing trafiic into said stretch from opposite directions, two traiiic levers Lu and Lb for said two signals A and B respectively, each lever having normal and reverse positions, means controlled by lever La and operable only when the lever is in reverse position for causing signal A to indicate proceed, means controlled by lever Lb and operable only when the lever is in normal posit-ion for causing signal B to indicate proceed, means for preventing lever LEL from being moved from normal to reverse position except when lever Lb is in reverse position, and means for preventing lever Lb from being moved from reverse to normal position except wher lever Ll is in normal position. A

'12. In combination, a stretch of railway track, a traffic lever adjacent each end of the stretch each lever having a normal and a reverse position, means for preventing one lever from being moved from normal to reverse position except when the other lever is 1n reverse position, means for. preventing the second lever from being moved from reverse to normal position exceptvvhenthei llU first lever is in normal position, a signal controlled by the rst lever and prevented from indicating proceed except when the lever is in reverse position, and a signal controlled by thel second lever and prevented from indicating proceed except when the lever is in normal position.

13. In combination, a stretch of railway track, a traffic lever adjacent each end oi' the stretch each having a normal and a reverse position, means for preventing a complete movement of one lever from normal to reverse position except when such lever is 1n an intermediate position and the vother lever is in reverse position, means for preventing a complete movement of the second lever from reverse to normal position except when such lever is in an intermediate position and the first lever is in normal position, a signal controlled by the first lever and prevented from indicating proceed except when the lever is in reverse position, and a signal controlled by the second'lever and prevented from indicating proceed except when the lever is in normal position.

11i. In combination, a stretch of railway track, a traiiic lever adjacent each end of the stretch and each lever having a normal, an intermediate and a reverse position, means for locking one lever in intermediate position while moving from normal toward reverse position, means for locking the other lever in its intermediate position while moving from reverse toward normal position, means for releasing the iirstlever only when the second lever is in reverse position, means for releasing the second lever only when first lever is in normal position, a signal controlled by the iirst lever and prevented from indicating proceed except when the lever is in reverse position, and a signal controlled by the second lever and prevented from indicating proceed except when the lever is in normal position.

15. In combination, a stretch .of railway track, a trafic lever adjacent each end of the stretch and each lever having a normal, an intermediate and a reverse position, means for locking one lever in intermediate position while moving from normal toward reverse position, means for locking the other lever in its intermediate position while moving from reverse toward normal position, means for releasing the iirst lever only when it is in its intermediate position and the second lever is in reverse position, means for releasing the second lever only when it is in its intermediate position and the iirst lever is in normal position, asignal con- Jrolled by the first lever and prevented from indicating proceed except when the lever is in reverse position, and a signal controlled by the second lever and prevented from indicating proceed except when the lever is in normal position.

16. In combination, a stretch of railway track, a traic lever adjacent each end of the stretch and each lever having a normal, an intermediate and a reverse position, means for locking one lever in intermediate position while moving Yfrom normal toward reverse position, means for looking the other lever in its intermediate position while moving from reverse toward normal position, an electrically operated releasing device for each locking means adapted when energized to release the locking mea-ns, a line wire extending between said levers, a source of current adjacent each lever, means for each lever arranged to connect the adjacent end of said line wire with the corresponding releasing device when the lever is in the intermediate position but not when the lever is in normal or reverse position, means for one lever for connecting the adjacent end of said line wire with the adjacent source of current when such lever is in normal position only, means for the other lever for connecting the adjacent end of said line wire with the adjacent source of ,current when such lever is in reverse position only, and signals for said stretch controlled by said levers.

17. In combination, a stretch of railway track comprising a track circuited section,

a traffic lever capable of a normal and a reverse position, a signal lever capable of a normal and a reverse position, a relay, means for energizing said relay only when the track circuited section is unoccupied and both of said levers are in normal position, means for maintaining said relay energized irrespective of the position of said levers provided said track circuited section is unoccupied, a second relay, means for energizing said second relay only when said iirst relay is energized and said traic lever is in reverse position, and a signal controlled by said second relay and signal lever and prevented from indicating'proc-eed except when said second relay is energized and said signal lever is in reverse position.

18. In combination, a stretch of railway track comprising a track circuited section, a trafiic lever capable of a normal and a reverse position, a signal lever capable of a normal and a reverse position, a relay, means for energizing said relay only when the track circuited section is unoccupied and both of said levers are in normal position, means for maintaining said relay energized irrespective of the position of said signal lever provided the track circuited section is unoccupied and the traffic lever is in normal position, and a signal controlled by said relay and signal lever and prevented from indicating proceed except when said relay is energized and said signal lever is in reverse position.

19. In combination, a stretch of railway track comprising a track circuited section, a traffic lever capable of a normal and a reverse position, a signal lever capable of a normal and a reverse position, a relay, means for energizing said relay only When the track circuited section is unoccupied and both of said levers are in normal position, means for maintaining said relay energized irrespective of the position of said levers provided said track circuited section is unoccupied, and a signal controlled by said relay and levers and prevented from indicating proceed eX- cept ivlien said relay is energized and botll of said levers are in reverse positions.

In testimony whereof I aliix my signature in presence of tWo Witnesses.

CHARLES STEPHENS. Witnesses:

H. E. JOHNSON, GEO. J. HoornR.

Copies of this patent may be obtained for ve cents each, -by addressing the Commissioner of Yatents, Washington, 2D. C.