. American engineer and railroad journal . dle of the stroke, the velocity of thecrank, which it is assumed is revolving with a uniform mo-tion. During the first part of the stroke the piston acquiresan accelerated velocity, until it reaches the middle, when itmoves at the same speed as the crank, and then graduallydiminishes until the dead center is reached, after a movement of180°. In order to produce the acceleration, pressure must be ap-plied during the first half of the stroke, and the necessity ofbringing the reciprocating parts to a state of rest causes thesame amount of pressure to rea
. American engineer and railroad journal . dle of the stroke, the velocity of thecrank, which it is assumed is revolving with a uniform mo-tion. During the first part of the stroke the piston acquiresan accelerated velocity, until it reaches the middle, when itmoves at the same speed as the crank, and then graduallydiminishes until the dead center is reached, after a movement of180°. In order to produce the acceleration, pressure must be ap-plied during the first half of the stroke, and the necessity ofbringing the reciprocating parts to a state of rest causes thesame amount of pressure to reappear during the second halfof the stroke in corresponding ratios upon the crank-pin. *,-The pressure required to accelerate the reciprocating parts • Ar;hur Bii 1 Treatise on the Steam equals, when the crank is on the dead center, the entire cen-trifugal force, and gradually diminishes until at the middle ofthe stroke it becomes zero, being a minus quantity to be de-ducted from the force applied by the steam to the piston. Lr. M r,& l i During the remainder of the stroke, owing to the retarda-tion of piston speed, the same force is gradually given outuntil it equals again at dead center the centrifugal force, beingit plus quantity to be added to the steam pressure. If the force required for acceleration be calculated for thedifferent crank angles, assuming the connecting-rod to be ofinfinite length and the pressures marked off on vertical linescorresponding to the different positions of crank, it will befound by joining all these points that a straight line is pro-duced. c F % \ ° 7 X <r / \ \ \ / * F Fig. 12. Make the line A B, fig. 11, equal the piston stroke, andC D E the path of the crank, s t u v, etc., the crank the same scale as the indicator diagram make Fequal,at the commencement of the stroke, to the entire centrifugalforce of the reciprocating parts, divided by the area of the pis-Cent. F ton . L, the mid
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectrailroadengineering
