File:The steam-engine and other heat-motors (1909) (14772877162).jpg

Identifier: steamengineother00crei (find matches)
Title: The steam-engine and other heat-motors
Year: 1909 (1900s)
Authors: Creighton, William Henry Paul, 1859-
Subjects: Steam-engines Heat-engines
Publisher: New York, J. Wiley & sons (etc., etc.)
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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s motion in atangential direction. In 1, as long as WC is perpendicular to OW, all tangentialstress is taken by the pin C, and motion, due to tangential stressalone, is impossible, but if the centrifugal force throws the weightW so that the arm WC is no longer perpendicular to OW, as in3 and 4, the motion will be due to a combination of the centrifugaland tangential forces. The tangential force may either increase or decrease the centrif-ugal force. In 3 the weight precedes the pivot, but in 4 the pivotprecedes the weight, hence, while the disc in each case is revolvingclockwise, the effects of the tangential force are opposite. If thespeed of 3 is increased, the inertia of the weight produces a force,acting in the direction WB, which tends to increase the radius OW;whereas if the disc slows down the tangential force then tends todecrease OW. In both cases the tangential effect has aided thecentrifugal effect and hence made the governor more sensitive.The opposite effect is seen in 4.
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d a.. a oO d 6 9 pq-d o REVOLUTION CONTROL. 347 w The amount of this tangential force is equal to —Xthe tan-gential acceleration, and its moment is equal to the product of theabove force and its lever-arm CA. Theoretical calculations givean approximation to required quantities, but the final results areobtained only by setting the engine up and running it at speed andvarying the tension of the springs by trial. Angular Acceleration.—Another method of using tangentialforce is shown in 5. Suppose two weights are connected by a barpivoted in the middle to a fixed or component part of the fly-wheeLIf the latter slows down, the inertia of the revolving weights causesthem to set up a rotation around the pivot C in the direction of thearrows. On the other hand, an increase of velocity of rotation of thefly-wheel will cause rotation in the opposite direction. The rotationaround the pivot C is said to be caused by angular inertia. Springs.—If to the above forces we add the force of gravi

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