US2069870A - Track shunting apparatus - Google Patents

Description

G. W. BAUGHMAN TRACK SHUNTING APPARATUS Filed June 29, 1953 INVENT OR a g mmlz I H16 ATTORNEY Patented Feb. 9, 1937 warm TRACK snnnrmc APPARATUS George W. Baughman,

Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application June 29, 1933, Serial No. 678,222

Claims.

My invention relates to track shunting apparatus of the type involving means carried on a vehicle for applying a potential to the rail surface to disrupt the resistance film formed on such 5 surface and thereby decrease the rail contact resistance.

The present invention is an improvement on the apparatus disclosed and claimed in an application for Letters Patent of the United States, Serial No. 644,188, filed by B. E. OI-Iagan on November 25, 1932, for Track shunting apparatus.

One object of my invention is the provision in apparatus of the character referred to, of means for providing low shunt impedance to the flow of track circuit current from rail to rail, and at the same time maintaining a substantial voltage across a pair of shoes which are temporarily ineffective to break down the resistance film, even though a complete break down has occurred 20 due to the associated pair of shoes.

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 one form of apparatus embodying my invention.

Referring to the drawing, the reference characters R and R designate the track rails of a stretch of railway track, which rails are divided by insulated joints to form a section D-E. This section is provided with a track circuit including a track relay F connected across the rails at one end of the section, and a transformer G, the secondary of which is connected across the rails at the other end of the section through a currentlimiting impedance 2. The primary of transformer G is constantly supplied with alternating current from a suitable source, the terminals of which are designated X and Y.

The remaining apparatus illustrated in the drawing is arranged to be carried on a rail car. The reference character H designates a transformer having a primary 3 supplied with alterhating current from a generator K, and this transformer is provided with two secondary windings 4 and 5 having substantially the same number of turns. Winding 6 is connected across the track rails B and R by means of suitable contact shoes 5E! and 53, whereas winding 5 is connected across the same rails by means of contact shoes H and i2. The polarities of the two secondary windings and their connections with the track rails are so chosen that the voltages of these windings will be series-aiding in the following circuit: from the upper terminal of secondary ii, through shoe in, rail R shoe ll, secondary 5, primary :3 of an auxiliary transformer Q shoe i2, Rail Rhshoe i3, and primary 6 of another auxiliary transformer Q, to the lower terminal of secondary Consequently, the voltages of both secondary windings t and 5 will be effective to break down any resistance film which may exist between the contact shoes and the rails.

It will be noted that the primary 6 of transformer Q is interposed between secondary 4 and one of the track rails, whereas the primary 6 of the other transformer Q is interposed between the secondary 5 and one of the track rails. The track circuit current furnished by transformer G will flow through the two secondaries 4 and 5 in such direction that the reactances of these secondaries are neutralized, but primaries t, being on separate transformers, do not neutralize each other.

The secondary l of transformer Q is provided with a circuit which includes a full-wave rectifier M and a condenser S the output terminals of the rectifier M being connected with a direct current indicating relay P The value of condenser S is so chosen as to produce the effect in transformer Q of a primary winding tuned to approximate multiple resonance at the frequency delivered by the generator K. By means of a similar circuit including a full-wave rectifier M, a condenser S and a direct current relay P winding 6 of transformer Q behaves as though tuned to approximate multiple resonance at the frequency delivered by the generator K. This frequency will usually be in the neighborhood of 350 cycles per second, although such frequency is not essential to my invention. The track circuit current will usually be 60 or 100 cycles per second. It is obvious that suitable condensers could be connected directly across the primary windings B with like effect, but for practical reasons which it is deemed unnecessary to enumerate here, these condensers are preferably connected across the secondary windings 1.

It will be apparent from the foregoing that by properly tuning the transformers Q and Q by means of the condensers S and S the impedance of windings E at 350 cycles can be made relatively high, while at the same time being relatively low for frequencies of substantially lower value. For example, with track circuit current of either 60 or lllii cycles, the transformers Q and Q will be so far out of resonance at such frequencies that the impedance of each transformer primary will be decreased to something between one-tenth and one-fifteenth of its 350 cycle value,

so that the impedance to the track circuit curfilm, a substantial voltage will be maintained across these shoes due to the relatively high 350 cycle'impedance of windings 5 even though shoes I l and l2 may-be accomplishing a complete break down of this resistance. This latter result is not ordinarily obtainable in circuits which employ a single reactor inserted, for example, in series with winding 3 of transformer H, but isaccomplished in this case by removing the current-limiting impedance from the primary circuit of transformer H and splitting this impedance into, two parts, placing the respective parts inrseries with each pair of contact shoes. These split impedances. take the form and Q V The present application is closely related to the copending application for Apparatus for decreasing railcontact resistance, Serial No; 629,030, filed by H. A. Thompson on August '16, 1932, which latter application contains claims which cover broadly certain features of theinvention disclosed in my present application.

Although Ihave herein shown and described only one form of apparatus embodying my invention,'i t 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:' V T a 1. In combination, a stretch of railway. track provided with track circuits, a car on said track,

a transformer on said car having two secondaries each of which is connected across the rails of the track, the instantaneous relative polarities of sai-d connections being opposite sothat thevoltages of the .two secondaries aid each other in breaking downthe rail contact resistance, a circuit for the primary of said transformer including a source of alternating current, and means for tuning the connection of each secondarywith the track rails to approximately multiple resonance at the frequency of said source.

2. In combination, a stretch of railway track provided with track circuits, a car on saidrtrack,

a transformer on said car having twosecondaries each of which is'connected across the rails of the track, the instantaneous relative polarities of said 7 connections being opposite so that the voltages of the: two secondaries aid each other in breaking down the rail contact resistance, a circuit for the primary of said transformer including a source of alternating current differing in frequency from of the transformers Q the current supplied to said track circuits, and means for tuning the connection of each sec: ondary with the track rails to approximately multiple resonance at the frequency of said source.

3. In combination, a stretch of railway track provided with track circuits, a car on said track, a transformer on said car having two secondaries each of which is connected across the rails of the track, the instantaneous relative polarities of said connections being opposite so that the voltages of the two secondaries aid each other in breaking down the. rail contact resistance, a circuit for the primary of said transformer including a source of alternating current, an auxiliary transformer for each of said secondaries and each having its primary included in the connection between the associated secondary and one of the track rails, and a condenser connected with the secondary of each auxiliary transformer and adjusted to tune the associated auxiliary transformer to approximate multipleiresonance at the 7 frequency of said source.

4. Incombination, a stretch of railway track provided with track circuits, a car on said track,

a transformer on said car having two secondaries each of which is connected across the rails of the track, the instantaneous relative polarities of said connections being opposite so that the volt ages of the two secondaries aid each other in breaking down the rail contact resistance, a circuit for the primary of said transformer including a source of alternating current, an auxiliary transformer for each of said seeondaries'and each having its primary included in the connection between the associated secondary'and one of the track rails, a condenser and a relay connected with the secondary of each auxiliary transformer and adjusted to tune the auxiliary transformer quency of said source, and indicating means controlled by said relays.

5. In combination, a stretchof railway track provided with trackcircuits, a car on said track,

rails of the track, the instantaneous relative po-- larities of saidconnections being opposite so that to approximate multiple resonance at the fre- V the voltages of the twosecondaries aid each other in breaking down' the rail contact resistance, a current-limiting winding for each of said ouput windings and connected in series therewith, a circuit for the input winding of said transformer including a source of alternating current, and means for tuning each ofsaid current-limiting windings to approximate resonance at the frequency of said source. 7

GEORGE W. BAUGHMAN.

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