The crank; its motion and true value for transmission of power in practical engineering

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. 1888 Excerpt: ...here is 5 inch, while the crank has one inch. The connecting-rod is divided into ten equal parts, from half to half inch, numbered 1, 2, 3, etc., beginning nearest the cross-head, and the corresponding ellipses bear the same numbers. The numbers 1, 2, 3, etc., on the central line, show where the ellipse commences, piston starting at c. (See pistonmovement on the figure.) And each ellipse shows the motion of its corresponding point from commencement of forward stroke to end of return stroke. Thus, the connecting-rod, starting with only a straight line in the centre of the cross-head, (crank on dead point,) covers in that line no space, or has no power at all; the more it elevates the greater become the ellipses or the power represented in their respective areas, until at 10, the crank-pin point, the area covered, or the power acquired, is the utmost that can be gained in a circular way. As the power has to move the crank through its right hand half also, it is obvious that its application must continue on to the perpendicular line, u, v. Now, suppose the rectangle.s, t, v, u, representing the full load or resistance, forward and return stroke, as it reacts upon the aocle of the cross-head. This is an assumption we may fairly take, because the power, no matter how little or how much it may be, to move the crank round has to travel all along from cross-head, m, n, to dead point, n, and to return from n to m, n again. Take the area covered by the ellipses and crank circle representing in their magnitude and shape the power transmitted, that is energy and speed combined, as they come from the cross-head. Comparing them with the shaded space of the whole figure, you will find that the ellipses and crank circle represent about against; that is, the power really tr...