US2027246A - Railway traffic controlling apparatus - Google Patents

Description

Jan. 7, 1936. F. H. NICHOLSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Oct. 20, 1952 I 0 T T f m & 2 w a 2 3. 3

Fmm? H/Wclzolson BY 22W H18 ATTORNEY.

Patented Jan. 7, 1936 RAILWAY TRAFFICQOONTROLLING g a APPARATUS Frank H. Nicholson, Edgewood, Pa., assignor to The Union Switch & Signal Company, Swiss vale, Pa, a corporation of Pennsylvania Application October 20, 1932, Serial No. 638,700

3 Claims.

My invention relates to railway trafiic controlling apparatus, and more specificallyto apparatus for the elimination of interference caused by propulsion current harmonics or other foreign current withthe operation of the wayside signaling equipment.

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

The accompanying drawing is a diagrammatic view showing an alternating current track circuit and the associated wayside signaling apparatus embodying my invention.

Referring to the drawing, the rails. l and 2 of track section DE are supplied with alternating current from the secondary winding of a track transformer T connected across the rails at one end of the track section, for the purpose of energizing the track relay R which is connected across the rails at the other end of the section, and for the additional purpose of supplying codedtrack circuit current for the operation of locomotivecarried train control equipment. Track relay R is 'of the two-element type which requires simultaneous energization of both windings 3 and 4 with current of the proper relative polarity for operation.

If a rail of section D-E carries alternating propulsion current having harmonics the frequency of which coincides with the track circuit frequency, it may happen that the propulsion potential existing across track winding 3 of relay R will be of sufficient magnitude and of proper phase relation to pick up relay R falsely, or to interfere with the proper operation of this relay in case the foreign current frequency approaches the track circuit frequency. In order to eliminate the possibility of false pick up and to decrease the above interference in the apparatus embodying my invention the polarity of the currents supplied to track winding 3 as well as to local winding 4 of relay R is periodically and simultaneously reversed, whereby this relay becomes incapable of attaining its energized position by the energization of either winding with steady alternating current.

As a means for periodically reversing the currents supplied to windings 3 and 4, I have provided a flashing or oscillating type of relay FR, which when energized, causes contacts 5-6 and 5-! to become closed alternately, thereby supplying periodically reversed current from a transformer T having a mid-tap 8 on its secondary winding, to winding 4, and to winding 3 through the medium of transformer T and the rails I and 2. The open circuit interval of contacts 5-6 and 5-'l is sufficiently short to prevent release of relay R during the pole-change interval, and the closed circuit interval is sufiiciently short so that relay R will not close its front contacts on but one such interval. This latter requirement is for the purpose of preventing an intermittent pick-up of relay R in the event of foreign current in the track winding and pole-changed current in the local winding of this relay.

When section DE and the next section in adjvance are both unoccupied, approach relay V is energized over front contact 9 of relay R, and periodically pole-changed steady alternating current is supplied to relay R and track section D--E over front contact H) of relay V. When section D-E becomes occupied, front contact 9 of relay R will open, deenergizing relay V, and energizing the code transmitter CT over back contact II of relay V. The code transmitter CT is so designed that contact fingers I80, I20 and operate at a speed of I80, I20 and 8D movements per minute, respectively, periodically closing their respective front and back contacts to pole-change and also to code the current supplied to rails I and 2 from transformer T The code speed effective at any particular time is dependent upon traffic conditions in section DE and the section in advance, as determined by the signal selection apparatus, which is not shown for simplicity. It will be understood that in order to provide for operation of the locomotive cab signaling equipment, the contacts of the code transmitter CT must be so designed that there is a proper time interval between reversals of the current supplied to the track circuit for producing the off intervals of the code.

The track relay R is designed in such manner that it will pick up on the coded current supplied torails I and 2, so that as soon as the train leaves section DE, relay R will pick up, energizing relay V over front contact 9, and deenergizing the code transmitter CT at back contact ll. Therefore, periodically pole-changed and uncoded current supplied from transformer T will be restored to rails l and 2 for maintaining relay R in its energized position.

It will be apparent that if the normal supply of current to winding 3 of relay R is interrupted for any reason, such as a rail broken or a train occupying section DE, it will not be possible for a foreign current, such as a harmonic current of the propulsion power, which is of constant relative polarity to pick up this relay because of the periodic reversal of current in the local winding 4 of relay R.

To make certain that winding 4 will at all times be supplied with periodically reversed current, I have provided the two-element checking relay CR having a local winding l2 supplied with alternating current of constant relative polarity from the same source BX--CX which supplies current to transformers 'I and T the control winding I3 of relay CR being connected across winding 4 of relay R. As long as the current in winding 4 continues to be periodically reversed, contact I4 of relay CR will continue to alternately close its right and left-hand contacts, supplying direct current from a source BC, first to one and then to the other half of the primary winding of transformer T thereby causing an alternating voltage to be applied across the input terminals of rectifier Q which results in the energization of slow releasing relay SR. Relay SR. is sufficiently slow acting to bridge the open circuit interval of contact M of relay CR, therefore, relay SR will remain energized and will maintain the signal control circuit, over its front contact l5, in an operative condition until such time as winding 4 of relay R becomes deenergized or its current supply ceases to be periodically reversed, whereupon relay SR will release and a restrictive indication will be displayed by suitable signals controlled over front contact 5 of this relay.

Although I have shown the apparatus embodying my invention applied to wayside signaling equipment suitable for use in connection with a code system of train control, the apparatus is equally well adapted to the control of wayside signaling equipment without train control, or with any other suitable system of train control.

'Although I have herein shown and described only one form of 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.

7 Having thus described my invention, what I claim is:

1. In combination, a section of railway track, a two-element relay having one element connected across the rails at one end of said section, a source of current, means for supplying current from said source to the track rails at the other end of said section and to the other element of said relay, a pole-changer located between said source and said track for periodically reversing the current simultaneously to both elements of said relay, and trafli'c governing means controlled by said relay effective when both elements of said relay are simultaneously supplied with said periodically reversed current.

2. In combination, a section of railway track, a two-element relay having one element connected across the rails at one end of said section, a source of current, means including a pole-changer for applying periodically reversed potential from said source simultaneously across the track rails at the other end of said section and across the other element of said relay, an auxiliary relay controlled by the potential across said other element of the relay in such manner that said auxiliary relay becomes energized when and only when the potential across said other element is periodically reversed, and traflio governing means controlled by said two-element relay as well as by said auxiliary relay.

3. In combination, a section of railway track,-

a relay having two cooperating windings one of which receives current from the rails of said section, a source of current, means including a polechanger for supplying periodically and simultaneously reversed current to the track rails and to the other winding of said relay, and trafiic governing means controlled by said relay and effective when and only when both windings of the relay are supplied with current which is periodically and simultaneously reversed.

FRANK H. NICHOLSON.

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