f
Corliss valves.

Unlike the Manhattan engines, the main steam pipes are carried to the
high-pressure cylinders under the floor and not above it. Another
modification consists in the use of an adjustable strap for the
crank-pin boxes instead of the marine style of construction at the
crank-pin end of the connecting rod.

The weight of the revolving field is about 335,000 pounds, which gives
a flywheel effect of about 350,000 pounds at a radius of gyration of
11 feet, and with this flywheel inertia the engine is designed so that
any point on the revolving element shall not, in operation, lag behind
nor forge ahead of the position that it would have if the speed were
absolutely uniform, by an amount greater than one-eighth of a natural
degree.

[Sidenote: _Turbo-Generators_]

Arrangements have been made for the erection of four turbo generators,
but only three have been ordered. They are of the multiple expansion
parallel flow type, consisting of two turbines arranged tandem
compound. When operating at full load each of the two turbines,
comprising one unit, will develop approximately equal power for direct
connection to an alternator giving 7,200 alternations per minute at
11,000 volts and at a speed of 1,200 revolutions per minute. Each unit
will have a normal output of 1,700 electrical horse power with a steam
pressure of 175 pounds at the throttle and a vacuum in the exhaust
pipe of 27 inches, measured by a mercury column and referred to a
barometric pressure of 30 inches. The turbine is guaranteed to operate
satisfactorily with steam superheated to 450 degrees Fahrenheit. The
economy guaranteed under the foregoing conditions as to initial and
terminal pressure and speed is as follows: Full load of 1,250
kilowatts, 15.7 pounds of steam per electrical horse-power hour;
three-quarter load, 937-1/2 kilowatts, 16.6 pounds per electrical
horse-power hour; one-half load, 625 kilowatts, 18.3 pounds; and
one-quarter load, 312-1/2 kilowatts, 23.2 pounds. When operating under
the conditions of speed and steam pressure mentioned, but with a
pressure in the exhaust pipe of 27 inches vacuum by mercury column
(referred to 30 inches barometer), and with steam at the throttle
superheated 75 degrees Fahrenheit above the temperature of saturated
steam at that pressure, the guaranteed steam consumption is as
follows: Full load, 1,250 kilowatts, 13.8 pounds per electrical
horse-power hour; three-quarter load, 937-1/2 kilowatts, 14