. The railroad and engineering journal . exactly like thatwhich represents the movement of any other part. This isshown in (ig. 21S, in which the two sets of curves, below M andM, are exactly alike. Therefore, all that is needed to show themovement of any part of the valve in relation to the ports is todraw lines to represent the ports in their relative positions tothe valve. In this way one curve can be made to show themovement of all the parts of the valve in relation to the portsbelow it. To illustrate this, it will be assumed that a motion-curve, AI iV O P Q A 6 /, fig. 223, which represen
. The railroad and engineering journal . exactly like thatwhich represents the movement of any other part. This isshown in (ig. 21S, in which the two sets of curves, below M andM, are exactly alike. Therefore, all that is needed to show themovement of any part of the valve in relation to the ports is todraw lines to represent the ports in their relative positions tothe valve. In this way one curve can be made to show themovement of all the parts of the valve in relation to the portsbelow it. To illustrate this, it will be assumed that a motion-curve, AI iV O P Q A 6 /, fig. 223, which represents the max-imum travel of a valve, has been drawn with the instrumentdescribed in answer to the previous question. When this curvehas been drawn it will be supposed further that the crank-pinhas been placed on the forward dead-center, and the shaft /^,fig. 222, has been fastened by a nut provided for that purposein the position it then occupies, and that the connecting-rod //is detached from the arm G, and by a stroke of the piston the. S t Answer. One motion-curve is sufficient to represent themovement of any part of the valve in relation to the ports dur its entire travel. This will be apparent if it is remem- s r pencil P has drawn a straight line, M s, fig. 223. This line willrepresent the position of any part of the valve when the crank ison the front center, and the curve will represent the movement 366 THE RAILROAD AND [August, 1888. and position of the same part during one revoluiion of thecrank-pin. It will be supposed that the line M s representsthe position of the steam-edge M, fig. 21S, of the valve at thebeginning of the stroke. Usually, when a valve worked by alink motion has its greatest travel, it has no lead at the begin-ning of its stroke, but its edge conforms to that of the steam-port, or, as it is , it is set line-and-liiie with the that is the case the line Ms, fig. 223, will represent the edgeof the steam-port. If the valve has lead, the
Size: 1143px × 2187px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookidrailroadengi, bookyear1887
