GB191506889A - Improvements in or relating to Valve Control Gears and Cylinders for Steam Locomotives and other Engines Worked by Elastic Fluids. - Google Patents

Abstract

6889. Todd, L. J. May 8. Link-motions and linkage gears; slide valves, cylindrical and piston; expansion valves.-Relates to a combined shut-off, expansion, and reversing-gear primarily intended for a dualexhaust engine. The engine, which may have central exhaust ports, is provided with a piston valve which controls the admission and an exhaust release, and with oscillating expansion valves which are connected by levers or links 2 to a point 1 which has longitudinal motion given to it by an eccentric, the cross-head, or other means, and transverse motion through a lever 7 connected to a reversing-lever or a governor. When the point 1 is down, the reciprocation does not open the valves 5, i.e. fluid is cut off. When the axis of the lever 7 is brought to position O, the cut-off edges of the valves just come to the cut-off edges of the ports, but without admission. Various degrees of cut-off are given by raising the lever 7. The end of the lever 7 moves in a curve 71 so designed as to prevent unequal admission to the two ends of the cylinder. The reversing- lever 21 and lever 7 are connected so as to be simultaneously operated. The parts are so constructed that the lever 21 is moved half the distance from its central position before steam is supplied to the cylinder. This permits the full opening of the piston-valve controlled exhaust. In the construction shown in Fig. 4, the piston valve is operated by a reversible linkmotion, and the link-motion and the cut-off gear are simultaneously operated by a common handlever. In the construction shown in Fig. 7, wherein the expansion gear is controlled by a governor, the joint 1 lies between the line C-D and the cylinder, the levers 3, 3 lie in the opposite direction outside, while the control lever 7 lies outside the pivot line C-D with respect to the cylinder. Modifications are described showing the axes of the oscillating valves outside the axes of the levers 3 and connected thereto by links. The engine may be single-acting.