To put the brakes on with full force, the air in the main brake-pipe is allowed to escape, so that the greater pressure in the auxiliary reservoir forces the piston down on a graduating-stem and closes the feed opening past the piston. The descending piston moves with it the slide-valve and lets air flow directly from the auxiliary reservoir into the brake-cylinder, thus putting on the brakes.
The En znecr's Brake and sectional cuts of which are shown in Figures 2, 3, (N. ro3), is a device designed espe cially to assist the engineer in operating train-brakes in a more perfect manner than has hitherto been possible with the three-way cock or brake valves formerly used for this purpose, without much personal skill front the operator. It mechanically measures the required volume of air to be discharged from the train-pipe when applying the brakes for ordinary stoppages, and is equally efficient on short or long trains. When the han dle S 2) is in "position for releasing brake," air-pressure from the main reservoir entering the brake-valve at _V passes through "supply-ports" (a, b), thence upward into the cavity c in the under surface of the rotary valve 13, then through "direct application and supply-port " (1) to the train pipe at 3'. While yet in tins position, port j (jig. 3) in the rotary valve and port e in its seat are ill communication, and air passes into the chamber D above the piston r7, thence through port s to a small reservoir, which is usually suspended under the right running-board of the engine, pipe-con nections being made therewith at 7: This reservoir serves the purpose of giving increased volume to the chamber D. The handle S now being placed in " position while running," direct communication between the train-pipe and the main reservoir ceases, and port/ is brought opposite feed port f, through which main-reservoir-pressure now passes to the under side of the " feed-valve" 21, which is held to its seat by a " feed-valve spring" (20) having a resistance of about twenty pounds. When this addi tional pressure is accumulated in the main reservoir, the " feed-valve" 21 is forced open, the pressure passing thence through "feed-port" to port / and the train-pipe. Pressure is maintained in chamber D (fig. 2) through port /, cavity c, and "equalizing port" g, thus equalizing the pressure on top and under piston 17, the stein of which, forming a valve, is seated in the position shown in the " bottom-cap " 5, and permits the escape of air from the train-pipe to the atmosphere through ports in and n when raised from its seat.
Locomotive speed, safety, and economy are the principal features demanded of a modern locomotive, but the public seems to be more directly interested in the matter of speed than in the other features. It may be interesting in this connection to note some of the recent locomotive performances upon both sides of the Atlantic. Not long ago there was a race between the " Flying Scotchman" and the "West Coast Flyer" from London to Edinburgh, in which 40o miles were covered by the winner in seven hours and twenty-five minutes, or an average of over 537, miles an hour.
One of the fastest runs in the United States was on the West Shore Railroad from Buffalo to New York, July 9, 1885, when 426 miles were covered in seven hours and twenty-seven minutes, the greater part of the run being made at the rate of forty-five seconds per mile, or from 7o to 83 miles per hour. Several miles were made at the rate of 78 miles per hour, one at 84 miles, and the next, between Genesee Junction and Chili, at 87 miles. Engines were changed at Buffalo, Newark, Frankfort, and Coey mans. In the same year, I i miles were made over the same road in five hundred and twelve seconds, or 74 miles per hour, three of the miles being made at So miles per hour.
On the New York Central Railroad, August 8, 1886, a newspaper train with two cars weighing sixty tons was run from Syracuse to Buffalo, 148.7 miles, in one hundred and thirty-six minutes, being drawn by Rogers engines with one change.
June 1, 1876, the Jarrett-Palmer train ran from Jersey City to San Fran cisco in half time, or three and a half days, running to Pittsburgh, 438Y, miles, in ten hours and five minutes, despite the Alleghanies; Pittsburgh to Chicago, 455.3 miles, eleven hours and six minutes—an average of 42.1 miles—including twenty-five stoppages and four changes of engines; Chi cago to Council Bluffs, 491 miles, eleven and a half hours, or 42.6 miles an hour; and from Omaha to Ogden, to32.6 miles, twenty-four hours and fourteen minutes. The entire run was made with nineteen changes of engine, there being seventy-two stops, and the running-time for 3313y, miles being eighty-four hours and seventeen minutes—au average of 40 miles an hour.