Half stroke forward ½F, the forward eccentric will be at ½x.
Full stroke back end B, the forward eccentric will be at a.
Half stroke back end ½B, the forward eccentric will be at ½a.
Full Stroke forward F, the backward eccentric will be at y.
Half stroke forward ½F, the backward eccentric will be at ½y.
Full stroke back end B, the backward eccentric will be at b.
Half stroke back end ½B, the backward eccentric will be at ½b.
Fig. 24.
Problem 4, [Fig. 24].—To determine the correct length of the eccentric-rods.—Let c be the center of axle. Through this point draw the horizontal line AD, also a line KL perpendicular to AD. The only purpose for which these two lines are drawn in this problem, as well as the others, is to have some lines from which we can locate other lines or points. Locate the center of rocker, and center lines of rocker-arms, as explained in Problem 2, and shown in [Fig. 22]; the lower arm standing perpendicular to the center line of motion, and the upper arm vertical. When the arms stand in this position, the rocker-pins will move through an equal distance on each side of these center lines during the time that the valve is making its full travel.