ACTION OF THE MOTION.
The action transmitted to the valve is altogether different from that transmitted by the link-gear, as by this gear it results from the two distinct motions of the connecting rod imparted to the lever E; and these two motions work variously, with and against each other, thus giving to the valve a resultant motion somewhat partaking of the nature of that produced by cams, it really being an accelerated and retarded motion; these accelerations and retardations being so arranged as to come at the right time on the revolution to give the desired result.
Thus, as the crank is passing over the center, the lever E is not affecting the valve at all as a lever, but the motion imparted to the valve is due to the center of E slipping down the curve of the slot-link J; and this gives a smart opening of the lead with a continued smart opening of the port. When the valve is fully open, as the crank travels on, the lever E has commenced acting on the valve; but its center is still sliding down the slot-link JK; and the two movements are opposite and destroying, or partially destroying, each other, producing a retardation of the valve-motion almost amounting to an arrest; and thus is given a nearly straight line on a valve-path diagram where the port is kept fully open, the crank still traveling on, and approaching the time for the cut-off to be effected. The lever E is in the best position to act as a lever at the same time that its center is completing its movement in the slot JK, and is commencing to return, being practically still: thus the lever action of E, having full effect, rapidly closes the port. And so on for the revolution, the time of release also getting its benefit.