Page:Motors and motor-driving (1902).djvu/298

266 eccentrics and  are circular discs; they are not, however, fixed to the shaft at their centres, but eccentrically. As the shaft revolves, they have an up-and-down motion, practically the same as if they were cranks. A ring encircles each eccentric, so that the eccentric itself is free to revolve in the ring. To the ring the eccentric rods and  are fixed. At the other end the eccentric rods are connected on working joints to a curved link. In the curved link is a block, which has a free sliding fit, and this is connected to the slide valve rod in figs. 17 and 22, and plainly shown in figs. 23, 24,

and 25. As the engine revolves the eccentric gives an up-and-down motion to the rods which are hinged to the link If we look at fig. 25 it will be seen that the forward eccentric rod is nearer to the slide valve rod than the backward eccentric, and this results in an up-and-down motion of the slide valve being produced by the forward eccentric, as the backward eccentric only forces the right-hand end of the link up and down, and does not drive the slide valve. In fig. 23 we see that by the link connected to the reverse lever by the side of the driver the curved link connecting the two eccentric rods to the slide valve has been so moved that the slide valve