Rensselaer Union, Volume 7, Number 7, Rensselaer, Jasper County, 5 November 1874 — HOW THE CARS STOPPED. [ARTICLE]

HOW THE CARS STOPPED.

BY CHARLES BARNARD.

I was waiting for the train to take me to the city. Very soon the engine appeared, far away up the line; and looking like a black speck in the distance. It grew bigger and bigger and came faster and faster toward us, so that I began to think it was an express train and didn’t mean to stop. Just then the engineer began to blow off steam, and with a loud roar the engine swept past and the train came to a sudden stop. “ What lively brakemen they must have on this road!” “ Oh, nd! TVe don’t use brakemen. We have the vacuum-brake,” said the man to whom I spoke. “ There it is under the car.” —“ I looked under one of the cars, and there I saw a round box, made of iron and rubber, and having creases on the sides, just like a bellows when it is shut up. As I looked at it, it seemed to swell out longer and longer, and the creases flattened out smooth, just like the leaves of an accordeon when it is stretched out to its full length. There was an iron rod fastened to the end of the rubber box, and as the box spread open the rod moved backward. This rod, I could see, was fastened to the chain that moved the brakes on the car wheels. Just then the conductor cried, “ All aboard!” and I was obliged to get in and take a seat. 1 thought no more of the vacuum-brake till we came to the next station, when I heard the roaring sound of the steam blowing off on the engine , and felt the brakes holding the train back. We slid softly into the station, and the cars came to a step without any jar and with none of that awkward start andjerk that we feel when the brakemen do not stop all the cars at once. At the next station the same thing happened again. Certainly, the vacuum-brake was a very fine thing.

Let us see just how this contrivance works. Under each car is a bellows. These are joined together by pipes and rubber hose that stretch from car to car, and finally come up through the floor of the engine-cab. When the air is sucked out of the bellows they shut up tight and so pull the brake-chains. Most of you boys and girls understand this. You have heard about a vacuum in the' philosophy class and have seen the experiments with the air-pump in school. A rubber ball cut in halves is a capital thing to show what a vacuum is. Press qne of the pieces on a board or the table, so as to squeeze all the air out and see how it will stick to the table. All around us is the air in which we live and move. When it is pushed or sucked out of any place, it presses on the surface of whatever shuts it out, and thus becomes an actual weight upon it. Under our ball we have a vacuum. In the vacuumbrake they use this pressure of the air to pull the brake-chains and so save the trouble of having a man on each car to turn the brake-wheels every time the train is to stop. In the philosophy class you have seen the teacher use an airpump to obtain a vacuum; but I did not see how they could have an air-pump here to be worked by the engine. It would take up room and be in the way. Besides, our engine Was coming into the station and about to stop, and when it* stopped the pump must stop too and, then the brakes would not work. ‘f Perhaps it would be a good idea to go forward and s>and on the platform of the first car where I could look into the engineer’s cab. The wind blew pretty strong and the cinders flew about in a shower; but I could look right into the engine, and, really; I couldn’t see anything that looked'like an air-pump. Just then a cloud of steam burst out of a small pipe on the top of the cab, and with a deafening roar the engine rolled into another station and came to a stop. x\s the cinders were pretty lively I went back into the car and looked out through the glass door to see the train start. Just therrthe train moved on, and the conductor came round for the tickets. As I gave him mine, I said ;

“You use the vacuum-brake?” “ Yes, sir. It’s a fine thing. It stops the cars quickly and without any bad jerks or strains.” “ How do you obtain the vacuum?” '» “ Oh! The engineer does that.” “Well, how?” “Oh! it’s some kind of exhaust. Don’t you hear the exhaust when she stops?” “Then it is not a pump?” “Oh, no; it’s an exhaust—the exhaust from the-engine.” “Not the waste steam from the engine? I thought that went up the smoke-stack.” “Well, no—you see—it’s exhaust steam. The engineer—he —the fact is, I haven’t looked into it. They get a vacuum with the exhaust—l heard the engineer say so—and that’s all f know about it.” The next station was the end of the route; so I went forward and climbed up into the engine, where ihe engineer sat on his high seat reading the morning jpaper. Now, railway engineers are generally pleasant people to meet. A trifle greasy and grimy, perhaps, but good-natured and sensible. They know everything about cars and engines, and are always ready to talk about their great machines, for they love their iron horses and are alw’ays glad to show them off end to tell hoW they work. As soon as I entered the cab the engineer laid down his paper and very politely asked me what he could do for me. “Tell me about the vacuum-brake, sir. Do you use a pump to obtain the vacuum?” “ Oh, no! We get it by a blast of steam from the boiler. Those two brass pipes on each side of the boiler lead back under the tender and under the cars to the rubber boxes you see under each car. This iron pipe that is joined to the brass pipe near the top of the boiler comes from the boiler. When I turn this crank the steam rushes through it and escapes out of the top of the cab.” “Is that the sound I heard when the train stopped?” “Yes, sir. It sounds just like an ex-haust-pipe, or the safety-valve. Well, as I was saying, it rushes out into the open air, and as it goes it sucks the air out of the brass pipes, and so makes a vacuum. Y’ou see it cannot get down the brass pipe because it is full of air ancTclosed up tight. It can get out through the top, and away it goes, and the air goes with it,, and we get a firstrate vacuum in a jiffy. I tell you, sir, it’s a neat thing, and works to a charm. I can stop any train they please to put behind my engine with just a turn of my finger.” “Then, when you have stopped the train, how do you let the air in again?” “ I shut oft the steam and open this valve, and the air rushes down the pipe where the steam went out, and the boxes under the cars swell up again, just like a pair of bellows when the wind comes in again. Why, sir, it’s just like a boy blowing over a key or a little vial. He blows across the mouth of the vial, and the water or dust or the air in it spurts up in his face. His breath rushing past the mouth sucks the air ont of the vial and makes a vacuum in it. If it is full of water he can see just how it works, for the water will fly up in his face, just as the air flies out of these pipes when the steam blows past the end. Any boy can fill a key with water and see just liow it works.” . This was so very simple that I felt almost ashamed to think that I had not guessed just how it was as soon as I heard the roar of the steam whenever the train stopped. :: .. _ The engineer then explained that the two brass pipes were simply to prevent accident. If one broke down he could use the other. I told the engineer what the conductor had said. He laughed and said: “Law, sir, some folks would go round the world and never see a thing.” — St. Nicholas.