. Railway mechanical engineer . ng parts and proceeds directly from one end ofthe gear to the other, starting with the combination principle involved is, of course, the same whether thegear is for inside or outside admission valves, but the appli-cation is slightly different. In Fig. 1 is shown the layout of a gear for inside admis-sion valves. As in any method, the first requirement is to casing and the cylinder center plus one-half the stroke plus4 in. Draw a vertical line HH through F, this line beingthe center line of the combination lever with the crosshead and t
. Railway mechanical engineer . ng parts and proceeds directly from one end ofthe gear to the other, starting with the combination principle involved is, of course, the same whether thegear is for inside or outside admission valves, but the appli-cation is slightly different. In Fig. 1 is shown the layout of a gear for inside admis-sion valves. As in any method, the first requirement is to casing and the cylinder center plus one-half the stroke plus4 in. Draw a vertical line HH through F, this line beingthe center line of the combination lever with the crosshead and the link block on center. Proportions of the Combination Lever.—The proportionsof the combination lever are determined Ijy the followingformula (see Fig. 2), assuming K ^ 4 in. in which R = Crank radius. C =: Lap + lead. L =: Length of combination lever. V = Distance between radius rod and valve ctem connections. If the combination lever becomes too short, increase V by4 in.; if it becomes too long, shorten F by 54 in- Lay out. Layout of Walschaer-t Valve Gear for Inside Admission Valves lay out all basic center lines, such as the center lines of thecylinders and driving wheels, and also to locate all limitingpoints by the boiler, frames, cylinder heads, casings,guides and guide yokes. For the greatest convenience a scaleof three inches to the foot should be used. Draw a line ABthrough the center of the crosshead in mid-position and thecenter of tlie main driving wheel, O. Next draw a line, CD,at right angles to AB through O; with O as a center and aradius equal to one-half the stroke draw the crank circle,cutting lines AB and C:D at the points 0\ O, O^ and O*.Points O and O^ are the correct dead centers and the othertwo points are the quarter positions of the main crank a radius equal to the main rod length and O and O ascenters, cut the crosshead path at E and F^, these points be-ing the position of the crosshead at the dead centers. Locatepoint F to the left
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
