unions. Of the three pipes on the left, the upper is the supply from the main reservoir; the intermediate is the application-cylinder pipe, leading to the independent and the automatic brake-valves; and the lower is the distributing-valve release pipe, leading through the independent brake-valve, when the handle is in running position, to the automatic brake-valve and through it, also, when in running position, to the atmosphere, as shown in Fig. 1 by the continuity of color. Of the two on the right, the lower is the brake-pipe branch connection, and the upper is the brake-cylinder pipe, branching to all brake cylinders on the engine and tender. In this pipe are placed cocks for cutting out, individually, the brake cylinders when necessary, one each for the tender and engine truck-brake cylinders, and one cock to cut out both driver-brake cylinders at once, as it is inadvisable to operate the driver brake on one side of the engine only; and in the engine truck and tender brake-cylinder cut-out cocks are placed choke-fittings to prevent serious loss of main-reservoir air and the release of the other locomotive brakes during a stop, in case of burst brake-cylinder hose. Each one of the pieces of the E-T equipment referred to in this description of the piping arrangement will be explained in detail, and with accompanying illustrations, further along.

The TWO DUPLEX AIR-GAUGES (see Figs. 3 A and

3 B) are connected as follows: Gauge No. 1; red hand to main-reservoir pipe under the automatic brakevalve; black hand to gauge-pipe tee of the automatic brake-valve; this gauge is piped correspondingly the same as the original duplex gauge of the automaticbrake equipment with which we have been familiar

FIG. 3 A.-Large Duplex Gauge. (Corresponding to the one duplex gauge used in former equipments.)

FIG. 3 B.-Small Duplex Gauge. (Corresponding to the brake cylinder gauge used in former equipments of the E-T brake, but with a second pointer added to show brake-pipe pressure direct.)

for years, but the inscription on the dial is more strictly accurate, for instead of the legend "black hand train line"-meaning brake-pipe pressure-it now says BLACK HAND EQUALIZING RESERVOIR, which pressure it records and always has recorded. Gauge No. 2; red hand to

the brake-cylinder pipe; black hand to the brake pipe below the double-heading cock; thus, for the first time, in connection with the equalizing-discharge automatic brake-valve a gauge is supplied that directly indicates the pressure in the brake pipe at all times, regardless of the position of the brake-valve handle, and is of special benefit on the secondary engines in double-heading whose double-heading cocks are closed.

The amount of reduction to be made during an automatic application, however, is indicated by the black hand of gauge No. 1, as the E-T equipment does not require any change in the governing of automaticbrake applications at either service or emergency reductions.

The automatic brake-valve connections, other than those already mentioned, are the brake pipe, the pipe to the equalizing reservoir (sometimes referred to as the chamber D reservoir), and the lower connection to the excess-pressure head of the pump-governor.

Before beginning on a detailed description of the operation, and the construction of the operating parts, of the No. 6 E-T equipment, it is desired that it shall be positively understood that the underlying principles governing its action are just the same as those of all previous equipments of the automatic air-brake. Instead of a triple valve and auxiliary reservoir for each of the engine and tender equipments the parts men

tioned are dispensed with, and the DISTRIBUTING VALVE is made to take the place of the triple valve, but one being used to control the supply of pressure to, and its discharge from, all brake cylinders of the engine and tender; while the presence of the main reservoir on the engine has been taken advantage of for direct brake-cylinder air supply, to supplant the auxiliary reservoir.

AN

EXPLANATION

OF THE PRINCIPLE THAT GOVERNS THE GRADUATED OR COMPLETE APPLICATION, AND THE RELEASE, OF ALL TYPES OF THE AUTOMATIC AIR BRAKE.

The first "continuous train brake" to come into general use was of the straight-air type, invented by George H. Westinghouse, and, succeeding the hand brake, was comparatively successful on a limited number of cars, and as long as everything worked all right. The straight-air brake can be, and is, absolutely reliable, but only when used on the same vehicle from which the actuating pressure is originally supplied and that carries the main operating brake-valve. The automatic brake as it exists to-day is due to the production by Mr. Westinghouse of the triple valve, which is the one essential part of each air-brake unit (car or locomotive equipment), and no automatically acting brake can be conceived to work with compressed air that does not make use of the principle of the triple valve.

THE TRIPLE VALVE.-Nominally, the Westinghouse E-T locomotive-brake equipment does not include a triple valve; really, however, that portion of the distributing valve called the equalizing valve performs the functions of a triple valve, and is necessary