HOW A FAST TRAIN IS RUN
The conductor stood at the end of the train, watch in hand, and at the moment when the hands indicated the appointed hour he leisurely climbed aboard and pulled the whistle cord. A sharp, penetrating hiss of escaping air answered the pull, and the train moved out of the great train-shed in its race against time. It was all so easy and comfortable that the passengers never thought of the work and study that had been spent to produce the result. The train gathered speed and rushed on at an appalling rate, but the passengers did not realise how fast they were going unless they looked out of the windows and saw the houses and trees, telegraph poles, and signal towers flash by.
It is the purpose of this chapter to tell how high speed is attained without loss of comfort to the passengers—in other words, to tell how a fast train is run.
When the conductor pulled the cord at the rear end of the long train a whistling signal was thus given in the engine-cab, and the engineer, after glancing down the tracks to see that the signals indicated a clear track, pulled out the long handle of the throttle, and the great machine obeyed his will as a docile horse answers a touch on the rein. He opened the throttle-valve just a little, so that but little steam was admitted to the cylinders, and the pistons being pushed out slowly, the driving-wheels revolved slowly and the train started gradually. When the end of the piston stroke was reached the used steam was expelled into the smokestack, creating a draught which in turn strengthened the heat of the fire. With each revolution of the driving-wheels, each cylinder—there is one on each side of every locomotive—blew its steamy breath into the stack twice. This kept the fire glowing and made the chou-chou sound that everybody knows and every baby imitates.
As the train gathered speed the engineer pulled the throttle open wider and wider, the puffs in the short, stubby stack grew more and more frequent, and the rattle and roar of the iron horse increased.
Down in the pit of the engine-cab the fireman, a great shovel in his hands, stood ready to feed the ravenous fires. Every minute or two he pulled the chain and yanked the furnace door open to throw in the coal, shutting the door again after each shovelful, to keep the fire hot.
The fireman on a fast locomotive is kept extremely busy, for he must keep the steam-pressure up to the required standard—150 or 200 pounds—no matter how fast the sucking cylinders may draw it out. He kept his eyes on the steam-gage most of the time, and the minute the quivering finger began to drop, showing reduced pressure, he opened the door to the glowing furnace and fed the fire. The steam-cylinders act on the boiler a good deal as a lung-tester acts on a human being; the cylinders draw out the steam from the boiler, requiring a roaring fire to make the vapour rapidly enough and keep up the pressure.
Though the engineer seemed to be taking it easily enough with his hand resting lightly on the reversing-lever, his body at rest, the fireman was kept on the jump. If he was not shovelling coal he was looking ahead for signals (for many roads require him to verify the engineer), or adjusting the valves that admitted steam to the train-pipes and heated the cars, or else, noticing that the water in the boiler was getting low—and this is one of his greatest responsibilities, which, however, the engineer sometimes shares—he turned on the steam in the injector, which forced the water against the pressure into the boiler. All these things he has to do repeatedly even on a short run.
The engineer—or “runner,” as he is called by his fellows—has much to do also, and has infinitely greater responsibility. On him depends the safety and the comfort of the passengers to a large degree; he must nurse his engine to produce the greatest speed at the least cost of coal, and he must round the curves, climb the grades, and make the slow-downs and stops so gradually that the passengers will not be disturbed.
To the outsider who rides in a locomotive-cab for the first time it seems as if the engineer settles down to his real work with a sigh of relief when the limits of the city have been passed; for in the towns there are many signals to be watched, many crossings to be looked out for, and a multitude of moving trains, snorting engines, and tooting whistles to distract one's attention. The “runner,” however, seemed not to mind it at all. He pulled on his cap a little more firmly, and, after glancing at his watch, reached out for the throttle handle. A very little pull satisfied him, and though the increase in speed was hardly perceptible, the more rapid exhaust told the story of faster movement. As the train sped on, the engineer moved the reversing-lever notch by notch nearer the centre of the guide. This adjusted the “link-motion” mechanism, which is operated by the driving-axle, and cut off the steam entering the cylinders in such a way that it expanded more fully and economically, thus saving fuel without loss of power.
When a station was reached, when a “caution” signal was displayed, or whenever any one of the hundred or more things occurred that might require a stop or a slow-down, the engineer closed down the throttle and very gradually opened the air-brake valve that admitted compressed air to the brake-cylinders, not only on the locomotive but on all the cars. The speed of the train slackened steadily but without jar, until the power of the compressed air clamped the brake-shoes on the wheels so tightly that they were practically locked and the train was stopped. By means of the air-brake the engineer had almost entire control of the train. The pump that compresses the air is on the engine, and keeps the pressure in the car and locomotive reservoirs automatically up to the required standard.