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A History of the Growth of the Steam-Engine

Horizontal Stationary Steam Engine


This

is a type of engine frequently seen in the United States, but more rarely in Europe. It is an excellent form of engine. The vertical direct-acting engine is sometimes, though rarely, built of very considerable size, and these large engines are more frequently seen in rolling-mills than elsewhere.

Where much power is required, the stationary engine is usually an horizontal direct-acting engine, having a more or less effective cut-off valve-gear, according to the size of engine and the cost of fuel. A good example of the simpler form of this kind of engine is the small horizontal slide-valve engine, with independent cut-off valve riding on the back of the main valve--a combination generally known among engineers as the Meyer system of valve-gear. This form of steam-engine is a very effective machine, and does excellent work when properly proportioned to yield the required amount of power. It is well adapted to an expansion of from four to five times. Its disadvantages are the difficulty which it presents in the attachment of the regulator, to determine the point of cut-off by the heavy work which it throws upon the governor when attached, and the rather inflexible character of the device as an expansive valve-gear. The best examples of this class of engine have neat heavy bed-plates, well-designed cylinders and details, smooth-working valve-gear, the expansion-valve adjusted by a right and left hand screw, and regulation secured by the attachment

of the governor to the throttle-valve.

The engine shown in the accompanying illustration (Fig. 95) is an example of an excellent British stationary steam-engine. It is simple, strong, and efficient. The frame, front cylinder-head, cross-head guides, and crank-shaft "plumber-block," are cast in one piece, as has so generally been done in the United States for a long time by some of our manufacturers. The cylinder is secured against the end of the bed-plate, as was first done by Corliss. The crank-pin is set in a counterbalanced disk. The valve-gear is simple, and the governor effective, and provided with a safety-device to prevent injury by the breaking of the governor-belt. An engine of this kind of 10 inches diameter of cylinder, 20 inches stroke of piston, is rated by the builders at about 25 horse-power; a similar engine 30 inches in diameter of cylinder would yield from 225 to 250 horse-power. In this example, all parts are made to exact size by gauges standardized to Whitworth's sizes.

[Illustration: FIG. 95.--Horizontal Stationary Steam-Engine.]

[Illustration: FIG. 96.--Horizontal Stationary Steam-Engine.]

In American engines (as is seen in Fig. 96), usually, two supports are placed--the one under the latter bearing, and the other under the cylinder--to take the weight of the engine; and through them it is secured to the foundation. As in the vertical engine already described, a valve is sometimes used, consisting of two pistons connected by a rod, and worked by an ordinary eccentric. By a simple arrangement these pistons have always the same pressure inside as out, which prevents any leakage or blowing through; and they are said always to work equally as well and free from friction under 150 pounds pressure as under 10 pounds per square inch, and to require no adjustment. It is more usual, however, to adopt the three-ported valve used on locomotives, with (frequently) a cut-off valve on the back of this main valve, which cut-off valve is adjusted either by hand or by the governor.


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