Interborough Rapid Transit Company.

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to take up expansion and contraction.

The main flue, which rests on the economizer floor, is what might be called a steel box, constructed of
',-inch plate, 6 feet 4 inches wide and ij feet high. The bottom is lined with brick laid flat and the sides
with brick walls 8 inches thick, and the top is formed of brick arches sprung between.

The sectional plan adopted for the power house has made a uniform and simple arrangement of steam
piping possible, with the piping tor each section, except that of the turbine bay, identical with that for every
other section. Starting with the six boilers for one main engine, the steam piping may be described as follows:
A cross-over pipe is erected on each boiler, by means of which and a combination ot valves and fittings
the steam may be passed through the superheater. In the delivery from each boiler there is a quick-closing
9-inch valve, which can be closed from the boiler room floor by hand or from a distant point individually or
in groups of six. Risers with 9-inch wrought-iron goose necks connect each boiler to the steam main,
where 9-mch angle valves are inserted in each boiler connection. These valves can be closed from the
platform over the boilers, and are grouped three over one set of three boilers and three over the opposite set.

The main from the six boilers is carried directly across the boiler house in a straight line to a point in
the pipe area where it rises to connect to the two 1 4-inch steam downtakes to the engine throttles. At this
point the steam can also be led downward to a manifold to which the compensating tie lines are connected.
These compensating lines are run lengthwise through the power house for the purpose of joining the systems
together, as desired. The two downtakes to the engine throttles drop to the basement, where each, through



INTERROROUGH RAPID TRANSIT PAGE 83



THE SUBWAY




a goose neck, delivers into a receiver and separating tank and from the tank through a second goose neck
into the corresponding throttle.

A quick-closing valve appears at the point where the ly-inch pipe divides into the two 1 4-inch down-
takes and a similar valve is provided at the point where the main connects to the manifold. The first valve
will close the steam to the engine and the second will control the flow of steam to and from the manifold.
These valves can be operated by hand from a platform located on the wall inside the engine room, or they
can be closed from a distant point by hydraulic apparatus. In the event of accident the piping to any engine
can be quickly cut out or that system of piping can quickly be disconnected from the compensating system.

The pipe area containing, as mentioned, the various valves described, together with the manifolds and
compensating pipes, is divided by means of cross-walls into sections corresponding to each pair of main
engines. Each section is thus separated from those adjoining, so that any escape of steam in one section
can be localized and, by means of the quick-closing valves, the piping for the corresponding pair of main
engines can be disconnected from the rest of the power house.

All cast iron used in the fittings is called air-furnace iron, which is a semi-steel and tougher than

ordinary iron. All line and
bent pipe is of wrought iron,
and the flanges are loose and

o

made of wrought steel. The
shell of the pipe is bent over
the face of the flange. All
the joints in the main steam
line, above 2 1 , inches in size,
are ground joints, metal to
metal, no gaskets being used.

Unlike the flanges or-
dinarily used in this country,
special extra strong propor-
tions have been adopted, and
it may be said that all flanges
and bolts used are 50 per cent.
heavier than the so-called extra
heavy proportions used in this
country.

The feed water will enter
the building at three points,
the largest water service being
i ; inches in diameter, which
enters the structure at its
southeast corner. The water
first passes through fish traps




r Piping



PAGE 84INTERBOROUGH RAPID TRANSIT



T H E S LI B W A Y



Engine and

Turbine

Equipment




and thence through meters, and from them to the main reservoir tanks, arranged along the center of the
boiler house basement. The water is allowed to flow into each tank by means of an automatic float valve.
The water will be partly heated in these reservoir tanks by means of hot water discharged from high-pres-
sure steam traps. In this way the heat contained in the drainage from the high-pressure steam is, for
the most part, returned to the boilers. From the reservoir tanks the water is conducted to the feed-water
pumps, by which it is discharged through feed-water heaters where it is further heated by the exhaust steam
from the condensing and feed-water pumps. From the feed-water heaters the water will be carried direct
to the boilers; or through the economizer system to be further heated by the waste gases from the boilers.

Like the steam-pipe system, the feed-water piping is laid out on the sectional plan, the piping for the
several sections being identical, except for the connections from the street service to the reservoir tanks.
The feed-water piping is constructed wholly of cast iron, except the piping above the floor line to the boilers,
which is of extra heavy semi-annealed brass with extra heavy cast-iron fittings.

The engine and turbine equipment under contract embraces nine 8,OOO to 11,000 horse power main
engines, direct-connected to 5,000 kilowatt generators, three steam turbines, direct-connected to 1,875 kilo-
watt lighting generators and two 400 horse power engines, direct-connected to 250 kilowatt exciter
generators.



INTERBO ROUGH RAPID TRANSIT PAGE 8 5



THE S U B W A Y



The main engines are similar in type to those installed in the 74th Street power house of the Main
Manhattan Division of the Interborough Rapid Transit Company, i.e., each consists of two component
compound engines, both connected to a common shaft, with the generator placed between the two component
engines. The type of engine is now well known and will not be described in detail, but as a comparison
of various dimensions and features of the Manhattan and Rapid Transit engines may be ot interest, the
accompanying tabulation is submitted :

Manhattan. Rapid Transit.

Diameter of high-pressure cylinders, inches, 44 42

Diameter of low-pressure cylinders, inches, 88 86

Stroke, inches, 60 60

Speed, revolutions per minute, 75 75

Steam pressure at throttle, pounds, 150 175

Indicated horse power at best efficiency, 7>5 7i5

Diameter of low-pressure piston rods, inches, 10

Diameter of high-pressure piston rods, inches, 8 10

Diameter of crank pin, inches, 18 20

Length of crank pin, inches, 18 18

Type of Low- Pressure Valves. Double Ported Single Ported

Type ot" High-Pressure Valves. Corliss Corliss

Corliss. Poppet Type.

Diameter of shaft in journals, inches, 34 34

Length of journals, inches, 60 60

Diameter of shaft in hub of revolving element, inches, 37Vi(i 37Vir,

The guarantees under which the main engines are being furnished, and which will govern their accept-
ance by the purchaser, are in substance as follows: First. The engine will be capable of operating con-
tinuously when indicating I 1 ,000 horse power with 175 Ibs. of steam pressure, a speed of 75 revolutions and
a 26-inch vacuum without normal wear, jar, noise, or other objectionable results. Second. It will be suitably
proportioned to withstand in a serviceable manner all sudden fluctuations of load as are usual and incidental
to the generation of electrical energy for railway purposes. Third. It will be capable of operating with an
atmospheric exhaust with two pounds back pressure at the low pressure cylinders, and when so operating,
will fulfill all the operating requirements, except as to economy and capacity. Fourth. It will be propor-
tioned so that when occasion shall require it can be operated with a steam pressure at the throttles ot 200
pounds above atmospheric pressure under the before mentioned conditions ot the speed and vacuum. Fifth.
It will be proportioned so that it can be operated with steam pressure at the throttle of 200 pounds above
atmospheric pressure under the before mentioned condition as to speed when exhausting in the atmosphere.
Sixth. The engine will operate successfully with a steam pressure at the throttle of 175 pounds above atmos-
phere, should the temperature of the steam be maintained at the throttle at from 450 to 500 degrees Fahr.
Seventh. It will not require more than i2'/ pounds of dry steam per indicated horse power per hour, when
indicating 7,500 horse power at 75 revolutions per minute, when the vacuum of 26 inches at the low pressure
cylinders, with a steam pressure at the throttle of 175 pounds and with saturated steam at the normal tem-
perature due to its pressure. The guarantee includes all of the steam used by the engine or by the jackets
or reheater.

The new features contained within the engine construction are principally : First, the novel construction
of the high-pressure cylinders, by which only a small strain is transmitted through the valve chamber



PAGE 86iNTERBOROUGH RAPID TRANSIT



THE SUBWAY



Turbo-
Generators



Exciter
Engines



Condensing
Equipment



between the cylinder and the slide-surface casting. This is accomplished by employing heavy bolts, which
bolt the shell of the cylinder casting to the slide-surface casting, said bolts being carried past and outside the
valve chamber. Second, the use of poppet valves, which are operated in a very simple manner from a wrist
plate on the side of the cylinder, the connections from the valves to the wrist plate and the connections from
the wrist plate to the eccentric being similar to the parts usually employed for the operation of 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 1 1 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.

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
1 1,000 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^ kilowatts, 16.6 pounds per electrical horse power hour; one-half load, 625 kilowatts, 18.3 pounds;
and one quarter load, 312^ 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, 9371/2 kilowatts, 14.6
pounds; one-half load, 625 kilowatts, 16.2 pounds; and one-quarter load, 312 1 4 kilowatts, 20.8 pounds.

The two exciter engines are each direct connected to a 250 kilowatt direct current generator. Each
engine is a vertical quarter-crank compound engine with a 17-inch high pressure cylinder and a 27-inch low-
pressure cylinder with a common 24-inch stroke. The engines will be non-condensing, for the reason that
extreme reliability is desired at the expense of some economy. They will operate at best efficiency when
indicating 400 horse power at a speed of 150 revolutions per minute with a steam pressure of 175 pounds
at the throttle. Each engine will have a maximum of 600 indicated horse power.

Each engine unit is supplied with its own condenser equipment, consisting of two barometic condensing
chambers, each attached as closely as possible to its respective low-pressure cylinder. For each engine also
is provided a vertical circulating pump along with a vacuum pump and, for the sake ot flexibility, the pumps
are cross connected with those of other engines and can be used interchangeably.



INTERBOROUGH RAPID TRANSIT PAGE 87



THE S U B W A Y



The circulating pumps are vertical, cross compound pumping engines with outside packed plungers.
Their foundations are upon the basement floor level and the steam cylinders extend above the engine-room
floor; the starting valves and control ot speed is therefore entirely under the supervision of the engineer.
Each pump has a normal capacity of 10,000,000 gallons of water per day, so that the total pumping capacity
of all the pumps is 120,000,000 gallons per day. While the head against which these pumps will be
required to work, when assisted by the vacuum in the condenser, is much less than the total lift from low
tide water to the entrance into the condensing chambers, they are so designed as to be ready to deliver the
full quantity the full height, it tor any reason the assistance ot the vacuum should be lost or not available at
times of starting up. A temporary overload can but reduce the vacuum only tor a short time and the
fluctuations ot the tide, or even a complete loss ot vacuum cannot interfere with the constant supply of
water, the governor simply admitting to the cylinders the proper amount of steam to do the work. The
high-pressure steam cylinder is 10 inches in diameter and the low-pressure is 20 inches; the two double-
acting water plungers are each 20 inches in diameter, and the stroke is 30 inches for all. The water ends
are composition fitted for salt water and have valve decks and plungers entirely of that material.

The dry vacuum pumps are of the vertical form, and each is located alongside of the corresponding
circulating pump. The steam cylinders also project above the engine-room floor. The vacuum cylinder is




COAL LNLU.-UHNG "luufck ON utsT 5&TH STKttl 1'ILK



PAGE SSjNTERBOROUGH RAPID TRANSIT



THE SUBWAY



Exhaust

Piping



Compressed
Air



Oil System



Cranes, Shops,
Etc.



immediately below the steam cylinder and has a valve that is mechanically operated by an eccentric on the
shaft. These pumps are of the close-clearance type, and, while controlled by a governor, can be changed in
speed while running to any determined rate.

From each atmospheric exhaust valve, which is direct-connected to the condensing chamber at each low-
pressure cylinder, is run downward a jo-inch riveted-steel exhaust pipe. At a point just under the engine-
room floor the exhaust pipe is carried horizontally around the engine foundations, the two from each pair ot
engines uniting in a 4O-inch riser to the roof. This riser is between the pair of engines and back of the high-
pressure cylinder, thus passing through the so-called pipe area, where it also receives exhaust steam from the
pump auxiliaries. At the roof the 4O-inch riser is run into a 48-inch stand pipe. This is capped with an
exhaust head, the top of which is 35 teet above the roof.

All the exhaust piping jo inches in diameter and over is longitudinally riveted steel with cast-iron
flanges riveted on to it. Expansion joints are provided where necessary to relieve the piping from the strains
due to expansion and contraction, and where the joints are located near the engine and generator they are ot
corrugated copper. The expansion joints in the 4O-inch risers above the pipe area are ordinarily packed
slip joints.

The exhaust piping from the auxiliaries is carried directly up into the pipe area, where it is connected
with a feed-water heater, with means for by-passing the latter. Beyond the heater it joins the 4<D-inch riser
to the roof. The feed-water heaters are three-pass, vertical, water-tube heaters, designed tor a working water
pressure of 225 pounds per square inch.

The design ot the atmospheric relief valve received special consideration. A lever is provided to assist
the valve to close, while a dash pot prevents a too quick action in either direction.

The power house will be provided with a system for supplying compressed air to various points about
the structure for cleaning electrical machinery and for such other purposes as may arise. It will also be used
for operating whistles employed tor signaling. The air is supplied to reservoir tanks by two vertical, two-
stage, electric-driven air compressors.

For the lubrication of the engines an extensive oil distributing and filtering system is provided. Fil-
tered oil will be supplied under pressure from elevated storage tanks, with a piping system leading to all the
various journals. The piping to the engines is constructed on a duplicate, or crib, system, by which the sup-
ply of oil cannot be interrupted by a break in any one pipe. The oil on leaving the engines is conducted
to the filtering tanks. A pumping equipment then redelivers the oil to the elevated storage tanks.

All piping carrying filtered oil is of brass and fittings are inserted at proper pipes to facilitate cleaning.
The immediate installation includes two oil filtering tanks at the easterly end ot the power house, but the
completed plant contemplates the addition of two extra filtering tanks at the westerly end ot the structure.

The power house is provided with the following traveling cranes : For the operating room : One 60-
ton electric traveling crane and one 25-1011 electric traveling crane. For the area over the oil switches : one
lO-ton hand-operated crane. For the center aisle of the boiler room : one loton hand-operated crane.
The span of both of the electric cranes is 74 feet 4 inches and both cranes operate over the entire length ot
the structure.

The 6o-ton crane has two trolleys, each with a lifting capacity, tor regular load, ot 50 tons. Each
trolley is also provided with an auxiliary hoist of 10 tons capacity. When loaded, the crane can operate at



INTERBOROUGH RAPID TRANSIT PAGE 8 9



THE S U B W A Y



the following speeds : Bridge, 200 feet per minute; trolley, TOO feet per minute; main hoist, 10 feet per
minute ; and auxiliary hoist, 30 feet per minute. The 25-1011 crane is provided with one trolley, having a
lifting capacity, for regular load, of 25 tons, together with auxiliary hoist of 5 tons. When loaded, the
crane can operate at the following speeds: bridge, 250 feet per minute ; trolley, 100 feet per minute; main
hoist, 12 feet per minute ; .and auxiliary hoist, 28 feet per minute.

The power house is provided with an extensive tool equipment for a repair and machine shop, which is
located on the main gallery at the northerly side of the operating room.




,OOO K r . W. ALTERNATOR MAIN POWER HOUSE



CHAPTER V

SYSTEM OF ELECTRICAL SUPPLY

THK system of electrical supply chosen for the subway comprises alternating current generation and Energy
distribution, and direct current operation of car motors. Four years ago, when the engineering plans E,HgitlC S/ltlff
were under consideration, the single-phase alternating current railway motor was not even in an f Third Rail
embryonic state, and notwithstanding the marked progress recently made in its development, it can scarcely
yet be considered to have reached a stage that would warrant any modifications in the plans adopted, even
were such modifications easily possible at the present time. The comparatively limited headroom available
in the subway prohibited the use of an overhead system of conductors, and this limitation, in conjunction
with the obvious desirability of providing a system permitting interchangeable operation with the lines of
the Manhattan Railway system practically excluded tri-phase traction systems and led directly to the adop-
tion of the third-rail direct current system.




SIDE AND END ELEVATIONS
OF ALTERNATOR .



PAGE 92 I N T E R B O R O U G H RAPID TRANSIT



THE S U B \V A Y



KEY

a Laminatfil ricM mag
6 Casl inin

l strrl \VI 1




SIDE ELEVATION AXO CROSS SECTION' OF ALTERNATOR
WITH PAUT CUT AWAY TO SHOW CONSTRUCTION.

It being considered impracticable to predict with entire certainty the ultimate traffic conditions to be
met, the generator plant has been designed to take care of all probable traffic demands expected to arise
within a year or two of the beginning of operation of the system, while the plans permit convenient and
symmetrical increase to meet the requirements of additional demand which may develop. Each express
tram will comprise five motor cars and three trail cars, and each local train will comprise three motor cars and
two trail cars. The weight of each motor car with maximum live load is 88,000 pounds, and the weight of
each trailer car 66,OOO pounds.

The plans adopted provide electric equipment at the outstart capable of operating express trains at an
average speed approximating twenty-five miles per hour, while the control system and motor units have been
so chosen that higher speeds up to a limit of about thirty miles per hour can be attained by increasing the
number of motor cars providing experience in operation demonstrates that such higher speeds can be
obtained with safety.

The speed of local trains between City Hall and 96th Street will average about i <; miles an hour, while
north of 96th Street on both the West side and East side branches their speed will average about I 8 miles
an hour, owing to the greater average distance between local stations.

As the result of careful consideration of various plans, the company's engineers recommended that all
the power required for the operation of the system be generated in a single power house in the form of three-
phase alternating current at i 1,000 volts, this current to be generated at a frequency of 25 cycles per second,
and to be delivered through three-conductor cables to transformers and converters in sub-stations suitably



INTERBOROUGH



RAPID



TRANSIT PAG E 93



THE SUBWAY






'




located with reference to the track system, the current there to be transformed and converted to direct cur-
rent for delivery to the third-rail conductor at a potential of 625 volts.

Calculations based upon contemplated schedules require for traction purposes and for heating and lighting
cars, a maximum delivery of about 45,000 kilowatts at the third rail. Allowing for losses in the distributing
cables, in transformers and converters, this implies a total generating capacity ot approximately 50,000 kilo-



< ;il>l< s to SulMaliOMS




GENERAL, DIAGRAM OF
ll.OOO VOLT CIRCUITS IN MAIN POWER STATION



PAGE 94 INTERBOROUGH



RAPID



TRANSIT



THE SUBWAY



Power
House




power and, setting aside one unit as
a reserve, the contemplated ultimate
maximum output of the power plant,
therefore, is 75,000 kilowatts, or
approximately 100,000 electrical
horse power.

The power house is fully de-
scribed elsewhere in this publication,
but it is not inappropriate to refer
briefly in this place to certain con-
siderations governing the selection
of the generating unit, and the use of
engines rather than steam turbines.

The 5,ooo-kilowatt generating
unit was chosen because it is pruc-



watts, and having in view the possi-

1 o r

bihty of future extensions of the
system it was decided to design and
construct the power house building
for the ultimate reception of eleven
5,OOO-kilowatt units for traction cur-
rent in addition to the lighting sets.
Kach 5,ooo-kilowatt unit is capable
of delivering during rush hours an
output of 7,500 kilowatts or ap-


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Online LibraryInterborough Rapid Transit CompanyInterborough Rapid Transit: the New York subway; its construction and equipment → online text (page 7 of 13)