Part 12 (1/2)

THE WESTINGHOUSE AIR-BRAKE

This systeh equally reliable and powerful Owing to the complexity of certain parts, such as the steam air-pump and the triple-valve, it is impossible to explain the systeraeneral principles ee Westinghouse, was a very si pipe running along the train; and a cylinder under every vehicle to work the brakes To stop the train, the high-pressure air collected in the reservoir was turned into the train pipe to force out the pistons in the coach cylinders, connected to it by short branch pipes One defect of this ”straight” syste train did not come into action until a considerable tier is ireat importance, this slowness of operation was a serious fault Also, it was found that the brakes on coaches near the engine went on long before those er of the forward coaches being bu that any coaches which house therefore patented his _autoely used all over the world The brake ensures practically instantaneous and sith_

[Illustration: FIG 88--Diagrahouse air-brake Brake ”off”]

The principle of the brake will be gathered froine, which coine or tender, and maintains a pressure of from 80 to 90 lbs per square inch A three-way cock, C, puts the train pipe into communication with A or the open air at the wish of the driver Under each coach is a triple-valve, T, an auxiliary reservoir, B, and a brake cylinder, D The triple-valve is the most noteworthy feature of the whole system The reader must reramine is coupled to the train, the compressed air in the main reservoir is turned into the train pipe, froh the triple-valve into the auxiliary reservoir, and fills it till it has a pressure of, say, 80 lbs per square inch Until the brakes are required, the pressure in the train pipethe cock C to the position shown in Fig 89), the train-pipe pressure is reduced, the triple-valve at once shi+fts, putting B in connection with the brake cylinder D, and cutting off the connection between D and the air, and the brakes go on To get them off, the pressure in the train pipe must be inal position, allowing the air in D to escape

The force hich the brake is applied depends upon the reduction of pressure in the train pipe A slight reduction would admit air very slowly from B to D, whereas a full escape from the train pipe would open the valve to its utmost We have not represented the es, for the reason given above

[Illustration: FIG 89--Brake ”on”]

The latest form of triple-valve includes a device which, when air is rapidly discharged froency application of the brake, opens a port through which compressed air is also admitted from the train pipe _directly_ into D It will easily be understood that a double advantage is hereby gained--first, in utilizing a considerable portion of the air in the train pipe to increase the available brake force in cases of e a quick reduction of pressure in the whole length of the pipe, which accelerates the action of the brakes with extraordinary rapidity

It may be added that this secondary communication is kept open only until the pressure in D is equal to that in the train pipe Then it is cut off, to prevent a return of air fro detail of the systeulation of air-pressure in the overnor is attached to the stea from the loco at F, flows through valve 14 and passes by D into the puht into operation, and continues to work until the pressure in the7 is set Any excess of pressure forces the diaphrag compressed air from the main reservoir to flow into the chamber C The air-pressure forces piston 12 doards and closes stea off the supply of steam to the pump As soon as the pressure in the reservoir is reduced (by leakage or use) below the nor 90, and pin-valve 11 closes The compressed air previously adh the s on the lower surface of valve 14, lifts it and its piston to the position shown, and again flows to the puain obtained in the reservoir

[Illustration: FIG 90--Air-puhouse brake]

[21] This resembles the upper part of the rudi 15 The reader need only iine pipe B to be connected with the train pipe A rush of steah pipe A creates a partial vacuu air from the train pipe to rush into it and be expelled by the steam blast

Chapter XI

RAILWAY SIGNALLING

The block systeear--Points--Points and signals in co operations--Single line signals--The train staff--Train staff and ticket--Electric train staff syste--Pneu

Under certain conditions--namely, at sharp curves or in darkness--the ht not avail to prevent a train running into the rear of another, if trains were allowed to follow each other closely over the line It is therefore necessary to introduce an effective syste in the same direction a sufficient distance apart, and this is done by giving visible and easily understood orders to the driver while a train is in motion

In the early days of the railway it was custos of trains, a train not being permitted to leave a station until at least fivetrain This method did not, of course, prevent collisions, as the first train so the station; and in the absence of effective brakes, its successor ran into it The advent of the electric telegraph, which put stations in rapid communication with one another, proved of the ut of railways

THE BLOCK SYSTEM

Time limits were abolished and distance liths, and two trains going in the same direction were never allowed on any one block at the sa the naline-driver, are well known to us They are usually placed on the left-hand side of the line of rails to which they apply, with their ar away from the rails

The side of the arms which faces the direction from which a train approaches has a white stripe painted on a red background, the other side has a black stripe on a white background

The distant and other signal arnal has a forked end and a V-shaped stripe; the hoht stripes When the arer”; when dropped, it is ”off,” and indicates ”All right; proceed” At the end nearest the post it carries a spectacle fralass When the arer, the red pane is opposite a lareen pane rises to that position--so that a driver is kept as fully inforht

[Illustration: FIG 91--Distant and honals]

POSITION OF SIGNALS