77u• l'rylne-('orlisa Engine.—ln the engine illus trated in lig. :in separate valves have been provided for the ioduel ion and exhaust the steam-chest and intuit ion-vaiVes sit nal ed above, and t he exhaust-chest and valves below, as in Ow eunN'enliunai CiirliSS en gine. Tin.re are, however, separate wrist-plates for the and exhitn-.1 valves. The wrist-plate, which motion to Ile exhaust-valves, derives its movement from a fixed eccentric upon the main shaft, and thus t he points of release and compression may be adjusted without interfer ing with the functions of the steam-valve, and, once determined, are positive and fixed. The eccentric, which determines the movement of the steam-valves, is operated by a shaft-governor in such a manner as to open the valves more or less according to the amount of steam required, varying the point of cut-off, while the amount of lead remains practically constant for all loads and pressures. The point of cut-off being varied by the greater or less movement of the wrist-plate instead of by means of a detachable motion, and the valves being closed by a positive connection with the wrist-plate instead of by dash-pots, high rates of rotation and the advantages of the high-speed engine, combined with a distribution of steam to which the economy of the 4-valve engine is due, are rendered possible, inasmuch as the engine is not limited by the inability of the detachable devices to act at high rotative speeds.
The Westinghouse Westinghouse engine is the leading engine of a new type which has recently come into extensive use, the principal characteristics of which are (1) two or more vertical single-acting cylinders, and (2) automatic lubrication by means of a closed chamber surrounding the crank-shaft, containing oil or oil and water. This type of engines was originally built with two cylinders of the same size, with cranks at 180°. Large sizes are built as a compound engine, with one cylinder larger than the other. Engines on the same general principle, but with three cylinders and triple expansion, with three cranks at 120°, have been brought out by other makers. Among the ad vantages claimed for this type of engine are, that, on account of its being single-acting, the press ure of the piston and of the con necting-rods on the wrist and crank pins is always in one direc tion, viz., downward, and conse quently, no matter how much the bearings are worn, there is no lost motion in them. On this account, the engine, if properly designed, may be run at a very high speed, and is therefore eco nomical of room and weight, and saves the gearing for transmis sion of power to the line-shaft ing machine or dynamo, necessa ry with slow-speed engines.
Fig. 57 shows a front view, and Figs. 58 and 59 sectional views, of the Westinghouse " standard " or non-compound engine as built in sizes from 15 to 250 horse-power. The fol lowing is a description of the de tails cylinders A A are cast in one piece with the valve-cham ber B. and are bolted to the top
of the bed or crank-case C. The cylinder-heads e a cover the upper ends of the cylinders only, the lower ends being uncovered and opening directly into the chamber of the crank case. The pistons D D are of the " trunk" form, double-walled at the top to prevent con densation, open at the button', and carrying the hardened steel wrist-pins b b. They are each packed with three rings. The connecting-rods arc made of forged steel. The cranks G 0, the crank-pins, and crank-shaft lin are all of steel, and may be removed by taking off the crank-case head e. Tire crank-shaft bearings are in the form of removable shells d d, lined with Babbitt-metal. From GO horse-power up these bearings are split for the sake of venient removal without taking out the shaft. They are slipped into the crank-ease ilea( from the inside, and adjusted by a distance-ring I, which is of an arbitrary thickness ent on the shrinkage of the casting of the erank-ease. A chamber is formed in the outer eni of the crank-ease head, in which, and revolving with the shaft, is the ring-wiper re, which takes up the oil as it work: past the bearings, and return: it through the hollow rib e int( the crank-ease a Oil is f6 to the engine from the sight feed cups 11 on the main bean• ings ; this renders all other hi brication unnecessary, an keeps the engine clean. A si phou overflow, with a funnel head 0, prevents any acemnu lation of water from risirq above the level of the button of the shaft, and thus prevent: the escape of oil. This over flow may be piped off at the hole in the funnel-head to In oil-separator, shown in Fig. 59 from which it can be skimmer and restored to the crank-ease An adjustable eenter-bearint K bridges the erauk-ease, VIM receives the thrust of the pis. tons. The bonnet h is re moved, to give access to tin cranks. The valve I' is a pis ton - valve. packed with tw( rings in each head, The valve seat is a roniovable bushing in which the ports are cut ti an exact register, mind which is then forced into its shoulders Each valve is provided with I - pressure piston, whirl prevents the balance of the governor from being disturbed when the engine exhausts against back-pressure. The valve-guide J serves also in lieu of a stuffing-box against the exhaust steam contained in the passage above it. The valve-guide as well as the valve and both pis tons are packed with simple sprung rings of cast iron. The valve-stem at is keyed fast to the guide, and grips the valve without binding between the not at the upper end and the collar at the lower end, as shown. The band-wheel is a combination-pulley I and fly-wheel cast to gether, so that the pulley overhangs the main bearing, throwing the line of belt-strain well toward the center of the bearing, and taking the spring off from the shaft.