Identifier: textbookonlocomo02inte (find matches)
Title: A textbook on the locomotive and the air brake
Year: 1901 (1900s)
Authors: International Correspondence Schools
Subjects: Locomotives Locomotive boilers Locomotives Railroad cars
Publisher: Scranton, Pa., International textbook co
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Northeastern University, Snell Library

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slack adjusters, also,are frequently used. The pipe p leads from the brake cylinderto the triple valve. LEVERS AND LEVERAGE. 53. The foundation brake gear on engines, tenders, andcars consists simply of a system of levers connected togetherby rods; and it is by means of these levers that the forcedeveloped in the brake cylinder is transmitted and applied tothe wheels. It is desirable, therefore, to be able to calculate the brakingpower that a system of levers is capable of exerting, and to dothis the different classes of levers must be studied. SIMPLE LEVERS. 54. The Straiglit Lever.—A lever is any bar that iscapable of being turned about a fixed axis or pivot, called thefulcrum, as in Figs. 3,4, and 5. In these figures, W, the objectto be lifted, is called the weight; the force F, emplo3ed to liftthe weight, is called the power; and the point F, round whichthe lever turns, is called the fulcrum. That part of the lever Fhbetween the fulcrum and the weight is called the weight arm of
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42 THE NEW YORK AIR BRAKE. §17 the lever, while the part Fc between the fulcrum and the poweris called the power arm. The fulcrum F, it is to be remembered, is stationary, and thelever is perfectly free to turn on it. Now, if the weight IF isgreat enough, it will cause the lever to turn or rotate about thepoint F against the action of the power P; if, on the other hand, the power is great \p c enough, it will cause the lever to rotate about Fagainst the action of theweight W. In otherwords, it will raise theweight. When the powerP is just sufficient tobalance the weight W,and the lever, therefore,does not move, it will befound that: Rule I.— The power multiplied by the power arm is equal to the weight multiplied by the weight arm; that is, the power P multiplied by the PiG.b. distance Fc will just equal the weight W multiplied b)^ the distance F b. Or, expressing this in symbolic form, PXFc = W X Fb.From this it can readily be shown that p = ^-^ (1) Fc = i^^ (3) F, ^ ^^A (4) § 1*7

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