Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 Excerpt: ...Starting Resistance. As previously stated, the resistance per ton when starting a train is considerably in excess of the ordinary resistance. When cars have been left standing for several hours, or even days, especially in winter weather, it may take a force of 40 pounds per ton to produce motion. The bearings become "frozen". But such resistance is only momentary and may be partly overcome by the impact of moving cars or engine striking against the stalled cars. When an engineer reverses his engine, backs it against the cars, and then immediately reverses again so as to go forward, he accomplishes three things: (1) the journals become loosened from the comparatively rigid condition they will assume even during a short stop; (2) the springs of the couplers will become compressed during the small backward motion and their expansion during forward motion will materially assist the forward motion; (3) if the train is very long, the total slack in the couplers is very considerable and the locomotive will have moved several feet before the last car begins to move and the cars are started one by one. Such devices in operation reduce to a variable extent the resistance which would be encountered if all cars were started at the same instant. A series of tests on the Rock Island system gave results with an ordinary range from 10 to 18 pounds per ton and averaging 14.1 pounds. An extreme value of 30 pounds was noted for "frozen bearings" and a low extreme of only 6 pounds extra when the stop was only momentary. Since a juggling of the train can produce virtually the same result as a mere momentary stop, the necessary extra starting resistance for a limiting case will be considered as only 6 pounds per ton in solving some numerical problems in a la...
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