300

MODERN STEAM PRACTICE.

Speed of the engine shaft:. 21 revolutions per minute.

Do. second shaft. 102 ,, ,,

Do. third shaft. 150 , „

The total length of the shafting is about 932 feet, in parallel lengths,the diameter of the pinion shaft being 8 inches, and that of the

d n

Fig. 200.—High and Low Pressure Combined Beam Engines of 80 horse-power collectively.

a, High-pressure cylinder. b, Low-pressure cylinder. c, Condenser and cistern. d, Cold-waterpump. e, Governor and feed-pump rod. f, Spring beam. g, Main beam. h, Crankshaft. r, Pinion shaft. k, Entablature . L, Columns. M, Stone pedestal. N, Foundation.

smaller line of shafting 3 inches at the end. The diameter of eachhigh-pressure cylinder is 15 y 2 inches, stroke of piston 4 feet 6 inches;and the diameter of each low-pressure cylinder is 31 inches, with apiston stroke of 6 feet. The valve mechanism for those engines hasalready been described, p. 102, Fig. 51. The diameter of each airpump is 21 inches, with a stroke of bücket of 3 feet. The crankshaft is of cast iron, the journals being 10 inches in diameter and15 inches long, and the crank pins S /4 inches in diameter and7^4 inches long. There are three large boilers, 35 feet long and7 feet in diameter, with two inside furnaces, and flues running theentire length, 2 feet 6 inches in diameter, with return wheel flues ofbrickwork. The steam pressure is 40 lbs. per square inch, and thethickness of the plates is as follows:—

Shell. % inch thick. I Flues.. Y% inch thick.

Ends. % ,, I Rivets. Y. ' m diameter.