A history of the growth of the steam-engine . Fio. 99.—GreeDe Engine. or piston descends upon a small body of water confined inthe base of the dash-pot, Corlisss air dash-pot is now oftenset horizontally. In the Greene steam-engine (Fig. 99), the valves are 323 THE STEAM-ENGINE OF TO-DAY. four in number, as in the Corliss. The cut-off gear consistsof a bar, A, moved by the steam-eccentric in a directionparallel with the centre-line of the cylinder and nearly co-incident as to time with the piston. On this bar are tap-pets, C C, supported by springs and adjustable in height bythe governor, G. T
A history of the growth of the steam-engine . Fio. 99.—GreeDe Engine. or piston descends upon a small body of water confined inthe base of the dash-pot, Corlisss air dash-pot is now oftenset horizontally. In the Greene steam-engine (Fig. 99), the valves are 323 THE STEAM-ENGINE OF TO-DAY. four in number, as in the Corliss. The cut-off gear consistsof a bar, A, moved by the steam-eccentric in a directionparallel with the centre-line of the cylinder and nearly co-incident as to time with the piston. On this bar are tap-pets, C C, supported by springs and adjustable in height bythe governor, G. These tappets engage the arms £ B, onthe ends of rock-shafts, E E, which move the steam-valvesand remain in contact with them a longer or shorter timeand holding the valve open during a greater or less part ofthe piston-stroke, as the governor permits the tappets torise with diminishing engine-speed, or forces them down asspeed increases. The exhaust-valves are moved by an in-dependent eccentric rod, which is itself moved by an eccen-. FiG. 100.—The Greene Engine. trie set, as is usual with the Corliss and with other enginesgenerally, at right angles with the crank. This engine, inconsequence of the independence of the steam-eccentric,and of the contemporary movement of steam valve-motionand steam-piston, is capable of cutting off at any pointfrom beginning to nearly the end of the stroke. The usualaiTangement, by which steam and exhaust valves are movedby the same eccentric, only permits expansion with therange from the .beginning to half-stroke. In the Corlissengine the latter construction is retained, with the object,in part, of securing a means of closing the valve by a pos-itive motion, should, by any accident, the closing not beeffected by the weight or spring usually relied upon. STATIONARY ENGINES. 323 The steam-Talve of the Greene engine, as designed bythe author, is seen in Fig. 100, where the valve, G H, cov-ering the port, D, in the steam-cylinder, A B, is moved
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Keywords: ., bookcentury1800, bookdecade1870, bookidc, booksubjectsteamengines
