US2204810A - Railway track circuit apparatus - Google Patents

Description

June 18, 1940. R. MILLS 2,204,810

RAILWAY TRACK CIRCUIT APPARATUS Filed April l2, 1939 Z 3 I 3a 4,

Compalledby werf ballzzdmffzb eaadlfz'aaf: C' lNvENToR Patented June 18, 1940 UNITED STATES PATENT FicE RAILWAY TRACK CIRCUIT APPARATUS Robert Mills, Kew Gardens, N. Y., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application April 12, 1939, Serial No. 267,482

v11 Claims.

My invention relatesl to railway track circuit apparatus, and has for an object the provision of novel and useful apparatus for improving thecuit apparatus embodlying my invention in which v polarized line circuits are employed for signal control." Fig. 2 is a diagrammatic view also embodying my invention and showing a modied form of a portion of Fig. l invwhich a neutral line circuit is employed. Fig. 3 is a diagrammatic view similar to Fig. 2, also embodying myinvention and showing a normally deenergized auxiliary relay.l Fig. 4 is a diagrammatic view showing my invention applied to a portion of single track.

In each of the several views, like reference vcharacters' designate similar parts.

In track circuits employing the usual form of primary-secondary track relay combination,the secondary relay operates directly on the primary or track relay by cutting out a certain number of turns from the relay winding when the section is unoccupied and inserting an equivalent resistor to replace the turns which have been'rendered ineffective.. This whole operation is usually performed at the relay end of the track circuit.y ,Under certain conditions, however, it is advantageous to permit the secondary relay to perform its improved shunting operation at the battery or feed end of the track circuit, especially` if approach lighted signals are employed which make available an auxiliary (approach lighting) relay at the signal location. This auxiliary relay may then be used to perform the additional function of improving the shunting sensitivity of thetrack circuit in a manner which will be clear from the description which follows. In the particular embodments which I have shown, the improved shunting sensitivity is obtained by increasing the total resistance in series with the battery at the feed end of the track circuit. This method is particularly advantageous in connection with track circuits in which it is important to conserve the track` battery output as much as possible.

Referring now to Fig. l, the reference characters I and la designate the rails of a stretch of track in which traffic moves in fthedirection indicated by the arrow. The rails are divided by insulated rail joints 5 to form a series of blocks of which only the blocks 2 3 and 3-4 are shown complete in the drawing. Block 3 4 includes the two cut sections 3--3a and 3ft-4. The track circuit for block 2 3 includes a track battery TB, current limiting resistors l and 6, the rails of the section, and the track relay 2TR. Each of the remaining track circuits includes corresponding apparatus designated by similar reference characters except for identifying numerals corresponding to the location. Trame entering each block isA controlled 'by a suitable signal S which, as here illustrated, is of the color light type capablel of displaying a green, yellow, or red indication as demanded by traiiic conditions in advance.

Each signal is governed by a line relay HDR, `here vshown as a polarized relay,^which is controlled by its associated track relay TR and the` line relay I-IDR at the signal next rin advance. Looking at line relay 2HDR, the polarized, -line circuit for this relay is controlled by the track relay ZTR. over its front contact 8 and pole changing contacts S and lil of the line relay :tI-IDR. next in advance. The line relays HDR are of the slow pick-up type and are so designed that their front contacts remain closed during a reversal of the polar contact structure. A relay which operates in this manner and is suitablevfor use herein is shown and described in Letters Patent of the United States No. 2,063,300 granted December 8, 1936 toArthur E. Dodd, for Railway track circuit apparatus. controlled by a front contact H ofthe associated track relay to prevent release of its neutral arma-4 ture during a reversal of the polar armature, but since the structure of this relay forms no part of my present invention no further description of this relay is necessaryfor an` understanding of my invention. y It should be pointed out that-if an HDR relay of the retained neutral armature rtype is not available, proper signal control and selection may be obtained by an HDR relay of the usual polarized type operating in conjunction with an additional slow acting repeater relay which pole changes the line circuit to the rear. This alternative combination of an HDR relay with a slow acting repeater represents well-known signaling practice and need not be described in detail as it also forms no part of my present invention. f

At each signal location I have shown anyauxiliary relay ER which is connected in series with the winding of the HDR relay next in the rear. Relay ER. may be the usual approach lighting re- This relay has a retaining Winding lay which causes illumination of its associated signal only upon the approach of a train. When such relays are already available in the system, no additional relays are required for carrying out the purposes and objects of my invention. In accordance with niy invention, the approach lighting relay is caused to perform, in addition to its approach lighting function, the function of a secondary relay of a primary-secondary track relay combination in that it operates to improve the shunting sensitivity and decrease the power consumption of its associated track circuit by introducing additional resistance in series with the battery when the section becomes unoccupied. This operation will be best understood by considering certain typical traic conditions.

With no train occupying the blocks shown, or the two blocks immediately in advance of signal 4S, all of the track relays, line relays, and approach lighting relays are energized to the positions shown, whereby the circuit for lamp G of each signal is prepared, but the signal is dark because of the open circuit at back Contact I2 of each relay ER. Under this condition, the short-circuit around resistor 'f in the track battery circuit is open at back contact I3 of each relay ER so that the track relay current is reduced, with a resulting increase in shunting sensitivity and saving in track power input. At the cut section location 3a, I have shown adjoining track feed apparatus for both of the track circuits 3 3a and 3a 4. This apparatus arrangement permits the auxiliary relay SAER to control not only the resistor l of its associated track circuit. but also to control over its back contact I4 the corresponding resistor of the adjoining track circuit.

When a train enters block 2 3, the track relay ZTR will release and in so doing will open the line circuit which supplies operating current to relays ZHDR and 3ER so that both of these relays will also release. The closing of back contact I5 of relay ZHDR will illuminate the the stop lamp R of signal 2S, and the closing of back contact I2 of relay 3ER will illuminate the proceed lamp G of signal 3S over obvious circuits, each of which starts at one terminal B of a suitable source of current (not shown) and ends at the other terminal C of the same source. At the same time, the closing of back Contact I3 of relay 3ER will shunt the resistor 'I in order that the track relay ZTR may pick up readily when the train vacates the section.

When. the train enters section 3 3a, the release of track relay 3TR will open the line circuit which energizes all three of the relays 3HDR, SAER and 4ER so that all of these relays Will release. As a result, the proceed lamp G of signal 4S will become lighted over back contact I2 of relay dER, and signal 3S will change its indication from proceed to stop due to the closing of back contact I5 of relay SHDR. The release of relay SHDR serves to pole-change the line circuit to the rear so that when relay ETR subsequently picks up and closes the line circuit, relay ZHDR will be energized in the reverse direction from that shown, in order that the caution lamp Y of signal 2S may become lighted upon the approach of a following train. The release of relay SAER will close a shunt for resistor 1 at back Contact I3, thus preparing the track circuit for pick-up of relay STR when the train vacates the section. At the same time, resistor I of the forward cut section is short-circuited over back contact I4 of relay AER. This last operation does not entail any undesired consequences because the line circuit is already open at iront contact 8 of relay STR, so that relay SATR will have ample opportunity to release before the train finally clears the rear cut section 3 3a. When the train passes location 4, relay dTR will release, opening the circuit for relay HDR and causing signal 4S to display its stop indication.

As soon as the train completely clears section 2 3, relay ZTR will pick up, thus completing a reverse energizing circuit [or relay ZHDR whereupon polar contact I6 of this relay will swing to the right so that signal 2S will be conditioned to display a caution indication at lamp Y for a following train. Completion oi the line circuit will pick up relay 3ER which will open back contact I3 to restore high shunting sensitivity and low power input to the track circuit of block 2 3. The opening of back contact I2 of relay 3ER also insures that once relay 3HDR picks up, signal 3S will become extinguished, provided a following train has not entered section 2 3.

When the train vacates section 3 3a, relay STR will pick up but nothing further will happen until the train completely clears section 3(1 4 so that relay SATR will pick up. When this occurs, the line circuit for block 3 4 will be energized with current of reverse polarity and all of the relays SHDR, SAER and 4ER will become energized. The current in relay BHDR will be of reverse polarity so that signal 3S will be conditioned for displaying a caution indication. The pick-up of relay SAER will restore the sensitivity of both track circuits 3 3a and SrL- 4. Also, the pick-up of relay AER will prepare the deenergization of signal 4S once the train Clears the block in advance of location 4, provided no following train is approaching.

When the train finally clears the block in advance of location 4, relay ll-IDR will become energized and all of the apparatus will then be restored to the condition in which it is illustrated in the drawing.

It will be apparent from the foregoing description of Fig. 1 that I have provided apparatus at the track feed end of the block operating in conjunction with the track relay for controlling the sensitivity of the track circuit and that this apparatus may be a part oi the approach lighting or other approach control apparatus associated with the track circuit.

Referring to Fig. 2, this gure shows a single track circuit corresponding, for example, to block 2 3 of Fig. l but employing a non-polarized or neutral line circuit suitable for two-position signaling. Relay HDR may. in this modification, be an ordinary slow pick-up neutral relay controlled over the line circuit in series with relay ER, as in Fig. l.. When the section is occupied, relays TR, HDR and ER will all be released and resistor 'I will be short-circuited over back contact I3 of relay ER. Contact 25 may control suitable signaling apparatus, as in Fig. 1. When the section. is vacated, these relays will be picked up and the opening of back contact I3 of relay ER will restore the high shunting sensitivity and low power input to the track circuit. Additional control by advance traic for the line circuit of Fig. 2 may be provided. if desired, but is not essential for the practice of my invention. One form of such additional control is shown, for example, in block 3 4 of Fig. l.

Referring to Fig. 3, this gure differs from Figs. l and 2 chiey in that I have provided a esv normally' deenergized relay lER.. This arrange'- rnent' is 'somewhat safer in that a broken 'Wire'or otherfailureofthe relay ER to pick -up results in a decrease rather than an increase of energy relay is energized locally, in the' usual manner. An adjustable resistor l'l is included in the line circuit in ordei` to adjust the current in this circuit with respect to the pick-up and release values of relay ER so as to obtain sensitive operation.' When a train occupies the section, relay ElR will be picked up over a circuit which includes one terminal of battery TB, the upper rail, wires 20' and 2|, back contact I9 of relay TR, Athe line wire 2'2, resistor l'l, and winding of relay ER,

to the `other terminal of battery TB. Since relay ER is now picked up, its front contact lI8 is closed,'thus shunting out resistor 'l under the occupied condition as in the two previous figures. Contact Zii'may' control signaling apparatus, as before. When the train leaves the section, relay TR will pick up, openingA back contact I9 to deenergize the line circuit so as to release ER and restore the unshunted condition of resistor .'l.

' Referring to Fig. 4, this figure shows my invention applied to a portion of single track in which trafiic may move in either direction. In this figure, the winding of relayv ER is included in the line circuit for the HDR relay as in Fig. l, and the voperation of the apparatus as a whole will 'be clear from the description presented in connection with Fig. l. It will be noted that the resistor 'l for each track circuit'is shunted by l back contacts i3 and Ill in series of the two ER relays, both of these relays beingv released due to the opening of front contacts 23 and 2d of the TR relay when a train enters the section from either end. 'The complete control of the eastbound and westbound line circuits is not shown as this control is well known and forms no part of my invention. It will be apparent that I have provided'in Fig. la simple and compact arrangement'of apparatus forv improving the y shunting sensitivity and decreasing the power input of trackcircuits for single track, two-direction signaling. y l

Although I `have herein shown and ldescribed only 'a' few forms of railway track circuit apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a section of railway track, a track relay receiving current from the rails at one end of said section, a source of track circuit current at the other end of said section, a current limiting device at said other end of the section for limiting the current supplied to the rails from said source, an auxiliary relay at said other end of the section, a line circuit for energizing said auxiliary relay including a contact of said track relay, means including a contact of said auxiliary relay effective when said section is unoccupied for increasing the effective value of said current limiting device to thereby increase the shunting sensitivity of said track section and decrease the power input thereto,

2. In combination with a section of railway track, a track relay receiving current from thev rails at one end of said section, a source of trackl circuit current at the other end of said section, a current limiting'devi'ce at said other end of the section for limitingy the current supplied tothe rails from said source, an auxiliary relay/at said Aother end of the section, a line circuit governed by said track relay for controlling the operation of said auxiliary relay, means controlled by said auxiliary relay for at times increasing the effec-v tiveness 'of said current limiting device to thereby increase the shunting sensitivity of said track section and decrease the power input thereto, and approach control means governed by said auxiliary relay, whereby'said auxiliary relay combines the functions of an approachv relay and a secondary relay.

A'3.'In combination with a section of railway track, a track relay receiving current from` the rails at one end of said section, a source of track circuit current at the other end of said section, a current limiting device at said other end of the section for limiting the vcurrent supplied to the rails from said source, an auxiliary relay at said other end of the section, a line circuit for energizing said auxiliary relay including affront contact of said track relay, means including av back contact of said auxiliary relay .for decreasing the effectiveness of said current limiting defvice when said section is occupied, and ap proach control means governed by a second back contact of said auxiliary relay, wherey said auxiliary relay combines theI functions of an approach relay and alsecondary relay.

.4. In combination with a section ofrailway track, av track relay receiving current from the' rails at one end of said section., a sourceof track circuit current at thefother end of said section, a. `current limiting device at said other end of the section for limiting the current supplied to the rails from said source, an auxiliary relays at said other end of the section, a line circuit for v'energizing said auxiliary relay including a back contact of said track relay, means including a front contact of said auxiliary relayfor decreasing the effectiveness of said current limiting device when said section is occupied, and approach control means governed by said auxiliary relay, whereby said auxiliary relay combines the functions of an approach relay and a secondary relay.

5. In combination with a section of railway track, a track relay receiving current from the rails at one end of said section, a source of track circuit current at the other end of said section, a current limiting device at said other end of the section for limiting the current supplied to the rails from said source, an auxiliary relay at said other end. of the section, a circuit controlled by said track relay for energizing said auxiliary relay from said source over a line wire and a rail of said section, and means controlled by said auxiliary relay for decreasing the effectiveness of said current limiting device when said section is occupied.

6. In combination, two adjoining sections of railway track having their feed ends at the junction of said two sections, a track relay for each section, a source of current for each section 1ocated at the respective feed end thereof, a current limiting device for each of said sources for limiting the current supplied thereby to the respective track section, an auxiliary relay associated with said sources at the track feed location for said two sections, a line circuit for energizing said auxiliary relay including a contact of the track relay for each of said two sections, and means governed by said auxiliary relay for controlling the effective value of each of said current limiting devices, whereby said one auxiliary relay performs the functions of a secondary relay for both said track relays.

7. In combination, two adjoining sections of railway track having their feed ends at the junction of said two sections, a track relay for each section, a source of current for each section located at the respective feed end thereof, a current limiting device for each of said sources for limiting the current supplied thereby to the respective track section, an auxiliary relay associated with said sources at the track feed location for said two sections, a line circuit for energizing said auxiliary relay including a front contact of the track relay for each of said two sections, and means including back contacts of said auxiliary relay for controlling the effective value of each of said current limiting devices, whereby said one auxiliary relay performs the functions of a secondary relay for both said track relays.

8. In combination with a stretch of single track railway in which traflic may move in either direction over the stretch, two track circuit sections for said stretch having their feed ends adjoining, a track relay for each section, a source of current for each section located at the respective feed end thereof, a current limiting device for each of said sources for limiting the current supplied thereby to the respective track section, an auxiliary relay for each of said sources located at the feed end of its respective track circuit, a line circuit for each auxiliary relay controlled by both said track relays, and means governed jointly by said auxiliary relays for controlling the efective value of each of said current limiting devices.

9. In combination with a section of railway track, a track relay receiving current from the rails at one end of said section, a source of track circuit current at the other end of said section, a current limiting device at said other end of the section for limiting the current supplied to the rails from said source, an approach control relay at said other end of the section, a

line circuit for said approach control relay governed by said track relay, signaling apparatus governed by said approach control relay, and means also governed by said approach control relay for decreasing the effectiveness of said current limiting device when said section is occupied, whereby said approach control relay combines the functions of an approach relay and a secondary relay.

10. In combination with a section of railway track, a track relay receiving current from the rails at one end of said section, a source of track circuit current at the other end of said section, a current limiting device at said other end of the section for limiting the current supplied to the rails from said source, a line relay at said one end of the section, an approach control relay at said other end of the section, a line circuit controlled by said track relay for energizing both said line relay and said approach control relay, a signal for said section controlled by said line relay, signaling apparatus for the section next in advance of said section controlled by said approach control relay, and means also controlled by said approach control relay for decreasing the effectiveness of said current limiting device when said section is occupied, whereby said approach control relay combines the functions of an approach relay and a secondary relay.

11. In combination with a section of railway track, a track relay receiving current from the rails at one end of said section, a source of track circuit current at the other end of said section. a current limiting device at said other end of the section for limiting the current supplied to the rails from said source, a signal control line relay at said one end of the section, an approach control relay at said other end of the section, a line circuit controlled by said track relay for energizing both said line relay and said approach control relay in series, signaling apparatus controlled by said approach control relay, and means also controlled by said approach control rela-y for decreasing the effectiveness of said current limiting device when said section is occupied, whereby said approach control relay combines the functions of an approach relay and a secondary relay.

ROBERT MILLS.

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