An Elementary Treatise on Steam and the Steam-Engine; Stationary and Portable (Paperback)

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. 1892 Excerpt: ...24. The sum of 14 and 24, or 381, is the angular motion of the crank during the middle third of the stroke, and the complements of those, 76 and 65, are the angular motions for the extreme thirds. The average speeds of the piston, therefore, in describing the successive thirds of its stroke in the direction a c, are inversely as 76, 38, 65, or directly as 1, 2,116, nearly; and the two halves of the whole stroke are described with average speeds inversely as 96 to 84, or directly as 7 to 8. The shorter the connecting-rod, the greater is the irregularity so introduced into the motion of the piston. The general effect, therefore, of the connecting-rod on the motion of the piston is, that the piston arrives sooner at the positions which it would occupy if the connecting-rod were "indefinitely " long at all points throughout the front stroke, which is described towards the crank; and that throughout the back stroke the piston is in the same degree behind the positions which it would occupy for all positions of the crank if the connecting-rod were indefinitely long. Motion and Action of the Slide-valve in relation to the Motion of the Piston. As the path of the crank-pin is represented by a circle, and the stroke of the piston by a straight line equal to the diameter of that circle, so also the path of the eccentric is represented by a circle, and the travel of the slide-valve by a straight line equal to the diameter of the eccentric circle; assuming, for the sake of illustration, that the valve is actuated in direct connection with the eccentric. If, then, two circles be described on a common centre c, Fig. 110, for the crank path and the eccentric path respectively, their diameters A B, a b, are the stroke of the piston and the travel of t...