Part 7 out of 8
A strong and convenient running gear, so arranged as to be easily attached
and detached at pleasure, is furnished, if desired; forming, when separate,
a useful wagon.
[Illustration: Fig. 68.]
Fig. 68 is a compact vertical engine, as built by R. Hoe & Co., of this
city. It is intended to drive printing presses, but is adapted to any kind
of work, and is especially suited to such places as require economy of
space. Although the value of expansion has been called in question by some
of the engineers of the United States Navy, and under an appropriation from
Congress is now to be made the subject of experiment; yet, in almost all
the manufactories and workshops of the United States, no matter what the
form of steam engine, or the purposes to which it is applied, whether
stationary, locomotive, or marine, some form of cut-off, by which expansion
of the steam can be availed of, is considered indispensable. Many varieties
are in use, but those engines are most popular in which the cut-off is
applied directly to the valves on the cylinder, opening them quickly and
shutting off almost instantly, avoiding all wire drawing of the steam at
the ports, and regulating the speed of the engine promptly. Of this class
of engines, those manufactured by the Corliss Steam Engine Company, of
Providence, R.I., are perhaps the widest known, not only for their
extensive introduction, but also from having, by a long and successful
litigation, established the claims of the patentee, Mr. George H. Corliss.
[Illustration: Fig. 70.]
Fig. 70 is a section of the cylinder and valve chests of a horizontal
Corliss engine. _S_ is the steam connection, and _E_ the exhaust; there are
two distinct sets of valves, the steam _s, s'_, and the exhaust _e, e'_,
operated independently of each other. In their construction the valves may
be considered cylindrical plugs, of which portions near the ports are cut
away to admit the steam and reduce the bearing surface; the valves are
fitted on the lathe and the seats by boring. The motion given to the valves
is rocking, but it will be observed that the valves are not firmly
connected to the rocking shaft or cylinder; in the figure the valves are
shown shade lined, and the shaft or stem plain; in this way the valves are
not affected by the packing of the valve stem, but always rest upon the
face of the ports. In the figure the piston is just about to commence its
outstroke, the movement of the steam is supposed to be represented by the
arrows; the inner steam valve _s_, and the outer exhaust _e'_, are just
beginning to open. It will be observed that the outer steam _s'_ is fully
closed, whilst the inner exhaust valve _e_ is but barely so, showing that
there has been a cut-off on the steam valve, but no lead to the exhaust,
that it was left fully open till the completion of the stroke.
[Illustration: Fig. 71.]
Fig. 71 is a side elevation of the cylinder, with the valve connections
with the governor. _S_ is the steam pipe; _s, s'_ handles to the steam
valves, and _e, e'_ to the exhaust valves, shown in dotted line in fig. 70.
The handles to the exhaust valves are connected directly to a rocking plate
_R_, to which motion is given by a connection _x_, with an eccentric on the
engine shaft. When once set, therefore the movement of the exhaust valves
is constant, and they will always be opened and closed at the same point of
the stroke. Connected with the rocking plate _R_, and on opposite sides of
its centre, the same as the exhaust valve connections, there are two
levers, vibrating on a centre _c_, of which one only is shown, as it covers
the other; to the upper ends of these levers pawls are attached, one end of
which rests on the stems or rods connected with the handles _s, s'_, of the
steam valves; on these stems there are notches against which the pawls
strike, and as the levers vibrate inward they push back the stems and
thereby open the valves, and this continues for the whole length of the
inward motion of the levers, or till the outer extremities of the pawls
come in contact with the end of the short lever _l_, which, pushing down
the outer end of the pawls, relieves the stems at the other ends, and the
valve stem returns to its place through the force of springs attached to
the outer extremities of the valve stems _a_, are cylindrical guides to the
valve stems, at the inner extremities of which are air cushions. The lever
_l_ is connected directly with the governor. As the balls rise, they
depress the extremity, which comes in contact with the pawls sooner, and
thereby shut the valves earlier; and on the contrary when the balls are
depressed, the valves remain open longer; as the pawls come in contact with
the stems always at one point, the steam valves open constantly, but are
closed at any point by the relief of the pawls, according to the speed of
Fig. 71 represents, partly in section and partly in plan, the cylinder,
steam chests, valves, &c., of one of the Woodruff & Beach high pressure
Engines, Wright's patent.
Fig. 72 represents, in elevation, the cam shaft, to the upper end of which,
not shown in the drawing, is attached the ordinary centrifugal governor.
The cylinder, steam chests, valves, &c., being similar to those of other
engines, need no special notice; but the cam for opening and closing the
steam valves, fig. 72, requires particular attention, as it embodies a
beautiful and simple device for cutting off the steam with certainty at any
part of the stroke, the motion being produced automatically by the action
of the governor on this cam, throwing it more or less out of centre with
the spindle of the governor, as the rotation of the balls is less or more
rapid, the eccentricity of the cam determining the amount of steam admitted
to the working cylinder of the engine. To produce this effect the cam is
made as follows:
_C_ is a hollow cylinder or shell, with a part of one end formed into a cam
proper. Throughout the whole length of this piece, upon the inside, there
is a spiral groove cut to receive one end of a feather, by which its pitch
or eccentricity is regulated. _C'_ is also a hollow cylinder or shell, of
the same length and diameter as _C_, with a similar spiral groove cut on
the inside, the outside being perfectly smooth and plain, upon which the
toe (_t_) for closing the valves is fastened. The inside piece consists of
two hubs _D, D'_, eccentric with each other, and made in one piece, _D_
being turned to exactly fit the inside of the shell _C_, and _D'_ to fit
the shell _C'_, the hub _D'_ having a socket (_c_) into which the spindle
(_s_) of the governor is screwed; the end (_d_) of the hub _D_ forming a
journal or bearing, with a bevel wheel on its extremity to convey motion
from the crank-shaft gearing to the governor and cut-off. There is a hole
throughout the length of the inside hubs _D_ and _D'_, which is continued
through the spindle of the governor, and contains the rod (_r_) that
connects the cam with the governor. This hole is eccentric to the outside
surface of the hub _D_, as well as to the shell _C_, and concentric with
the hub _D'_ and shell _C'_, and with the governor rod (_r_).
The shell _C_ and hub _D_, and shell _C'_ and hub _D'_, are connected
together by feathers; one piece of each feather is of a spiral form, and
the other a straight or rectangular piece, the two being connected together
by a stub on the rectangular piece, which fits into a hole or bearing in
the other or spiral piece, so that the latter can turn on the stub and
accommodate itself to the groove in which it has to work. The spiral part
of each feather works in the spiral groove on the inside of its
corresponding shell _C_ and _C'_ respectively, and the rectangular pieces
work in a straight groove cut in the hubs _D_ and _D'_, the inner parts of
the rectangular pieces being fastened to the governor rod (_r_), so that
the feathers are permanently connected with the governor.
The shell _C'_ revolves inside of two yokes (_y_) and (_y'_), one attached
to each steam-valve toe, (_a_) and (_a'_) respectively.
On the inside of each yoke, and opposite to its valve-toe, is a raised
piece, against which the closing piece (_t_) on the shell (_C'_) acts to
close the valves.
This shell (_C'_), as before noticed, has a spiral groove on its inside,
similar in all respects to that in the cam-shell (_C_); and being acted
upon in the same manner and through the same rod by the governor, it is
evident that the closing piece (_t_) on its outside will always hold the
same relation to the opening toe on the lower or cam-shell (_C_); and
whatever alteration is made in the one, a corresponding alteration takes
place in the other, thereby insuring the closing of the valves at the
proper time at every point of the variation of the cut-off.
When the several pieces above described are put together, the apparatus for
opening and closing the valves and producing the cut-off is complete, as
shown in fig. 72, and it operates as follows:
[Illustration: Fig. 71.]
[Illustration: Fig. 72.]
Motion is communicated by gearing from the crank-shaft to the bevel wheel
on the piece (_d_) on the end of the hub _D_, and is communicated to the
spindle of the governor, which is screwed into the socket on _D'_. As the
balls rise or fall, through change of centrifugal force due to the
variation in the speed of rotation, they raise or depress the governor-rod,
which passes through the spindle and the hubs _D'_ and _D_, and is attached
to the feathers, thereby raising or depressing the feathers, which, acting
on their respective spiral grooves, instantly alters the lift of the cam on
the shell (_C_), and brings the closing toe (_t_) on the shell (_C'_) into
proper position for closing, and so regulates the amount of steam admitted
to the cylinder.
[Illustration: Fig. 71.]
Consequently, any speed may be selected at which the load of the engine is
to move, and any variation from that will be instantly felt by the
governor, and corrected by this simple and beautiful device. There is no
jar in the working of the parts; the feathers move noiselessly in their
grooves; the governor rod moves up and down through the spindle and the
hubs _D_ and _D'_, and can be regulated by hand to give any required
opening of the steam ports to suit the work to be done. Any change in the
amount of work will then alter the speed of the engine, and so affect the
governor and cam, as before said.
It is unnecessary to insist on the great economy attained by using steam
with a well-regulated cut-off, for practical men know now that the
essential points of excellence in the steam engine are a good boiler, which
generates the greatest quantity of steam for the least consumption of fuel;
and, secondly, a reliable cut-off, which uses the steam to the best
advantage, by admitting the proper quantity for the work required.
STEAM FIRE ENGINES.--Portable engines for the extinguishment of fires, are
an American invention, and to Messrs. A.B. & E. Latta, of Cincinnati,
working on the right principles, is due the credit which they claim in
their circular, as follows:
"We claim to be the _original_ and first _projectors_ of the _first
successful steam fire engine_ in the world's history. There have been many
attempts at making a machine of such construction as would answer to
extinguish fires; but none of them proved to be available in a sufficiently
short space of time to warrant their use as a fire apparatus. We hold that
a steam fire engine should be of such nature as to be brought into
requisition in as short a space of time as is necessary to get the machine
on the ground, and the hose laid and ready to work: that is, supposing the
fire to be within one square of the place where the steamer is located. The
object in locating a machine at any point is to protect that immediate
vicinity; and it is therefore absolutely necessary to have it available in
the shortest space of time, and that with unerring certainty. We think that
reliability is of the greatest importance to the protection of a city from
fire, as everything is dependent on the _working_ of such apparatus in
time; and for this reason no expense should be spared on this kind of
Fig. 73 is a representation of one of the Messrs. Latta's fire engines, of
which there are many of different classes, according to the requirements;
they say that they can furnish engines as low as $1,000, and have made some
The first peculiar feature of this engine is the boiler; it differs
entirely from all boilers now in use.
[Illustration: Fig. 73.]
The fire box or furnace is simply a square box or furnace of any required
dimensions; it is nothing more than a water space surrounding the fire,
stay-bolted as all water spaces are. It is made of boiler plate in the
usual manner. The water space extends only 2/3 of the height, the balance
being a single sheet. The bottom of this fire box is crossed by grate bars
to support the fuel; in its rear side are fire doors, inserted for firing.
The internal arrangements of the boiler are composed of a large number of
tubes, lying across in a horizontal position, put together in sections with
return bends resembling the coils for heating buildings. These coils are of
small pipe (say one inch in diameter), and as numerous as may be necessary.
They give the required amount of steam. They are secured to wrought-iron
plates at each end by rivets. These plates lie close to the box, and are
secured to it, top and bottom. These tubes are wrought iron, firmly screwed
into the bends, so as to prevent any possible breaking.
The box has a hole through both sheets, in the same manner as a hollow
stay-bolt, through which the coil pipe passes, having no connection with
the box. After passing into the box it divides into two pipes, then
subdivides into four, and so on, until its numbers equal the number of
coils in the box, and to which each limb is attached. The upper ends of
these coils are the same in number, and are carried through at the top or
nearly the top of the box. They then run down outside to the steam chamber,
or rather water space, as the box is both steam chamber and water space.
These pipes empty their contents into the box, steam and water, as it may
come, all together. It will be observed that these coils of tube are
sufficiently separated to allow the fire to pass between them freely, and
cover their whole surface.
The mode of operation of this boiler is this: The fire box is filled 2/3
full of water. The coils are dry at starting; the space for fuel being
filled with good wood, the fire is lighted, and in a few moments the
engineer moves his hand pump, which takes its water from the box to which
it is attached, and forces it through the coils. By this means steam is
generated in from 3 to 5 minutes, so as to start the engine.
It will be seen that the water performs a complete circuit; it is taken
from the box and passed through the coils; what is steam remains in the
steam chamber, and what is not (if any) drops back into the box from where
it started. Hence it will be seen that a large surface is exposed to a
small quantity of water, and in a way that it is entirely controllable. All
the engineer has to do to surcharge his steam, is to reduce the speed of
the pump (which is independent of the main engine). By raising the heat and
quantity of water, any degree of elasticity can be given to the steam, and
that, too, with the least amount of waste heat in giving a natural draft.
Hence the great economy of this boiler.
The next feature of this engine is, it has no wood work about it to perish
with the heat and roughness of the streets. All the wheels are wrought
iron; and, as yet, these are the only ones that have stood a steam fire
engine. The frame is wrought iron; truck, on which the front wheel is hung,
wrought iron. The axles are cast steel. The engine and pump is a
double-acting piston pump direct, without any rotary motion; with a
perfect balance valve, it is balanced at all times, and hence the engine
remains quiet without blocking, when at work. The engine is mounted on
three wheels, which enables it to be turned in a very short space.
Many engines have been constructed by the Messrs. Latta for the fire
companies, of different cities, and have been in successful competition
with other engines; the farthest throw ever made by one of their
first-class engines was 310 feet from a 1-5/8 inch nozzle; steaming time,
starting from cold water, 3-1/2 minutes.
[Illustration: Fig. 74 AMOSKEAG STEAM FIRE ENGINE.]
Fig. 74 is a representation of one class of steam fire engine, as built by
the Amoskeag Manufacturing Company, at Manchester, N.H. The boiler is an
upright tubular boiler, of a peculiar construction, the patent right to
which is vested in the Amoskeag Manufacturing Company. This boiler is very
simple in its combination, and for safety, strength, durability, and
capacity for generating steam is unsurpassed. No fan or artificial blower
is ever used or needed, the natural draft of the boiler being always
sufficient. Starting with cold water in the boiler, a working head of steam
can be generated in _less than five minutes_ from the time of kindling the
fire. The engine "Amoskeag," owned by the city of Manchester, has played
two streams in _three minutes and forty seconds_ after touching the match,
at the same time drawing her own water. The boilers are made and proved so
as to be safely run at a steam pressure of 140 to 150 lbs. to the square
inch; but the engines are constructed so as to give the best streams at a
pressure of about 100 lbs. to the square inch, and for service at fires a
steam pressure of about 60 lbs. to the square inch is all that is required.
The various styles of engine are all _vertical_ in their action, and in all
the pumps and steam cylinders are firmly and directly fastened to the
boiler, the steam cylinders being attached directly to the steam dome. This
arrangement obviates the necessity of carrying steam to the cylinders
through pipes of considerable length, and the machine has very little
vibratory motion when in operation--so little that it is not necessary to
block its wheels to keep it in its place, or to take the weight off the
springs before commencing work.
The pumps are placed on the engines as near the ground as they can be with
safety, and are arranged so as to attach the suction and leading hose to
either or both sides of the machine, as may be most convenient or
desirable, so that less difficulty will be found in placing an engine for
work, and when required to draw its own water, it has only to draw it the
shortest possible distance.
Each engine has two "feed pumps" for supplying the boiler, and also a
connection between the main forcing pumps and the boiler, so that it can be
supplied from that source if desirable. The tank which carries the water
for supplying the boiler is so placed that the water in it is always above
the "feed pumps," an advantage that insures the almost certain working of
these pumps. These pumps are of brass, the best locomotive pattern, and one
of them running with the engine, when at work, furnishes an ample supply of
water to the boiler.
[Illustration: Fig. 75.]
The engines are exceedingly portable; they can be turned about or placed
for service in as contracted a space as any hand engine, and two good
horses will draw a first-class engine with the greatest ease, carrying at
the same time water for the boiler, a supply of fuel sufficient to run the
engine two hours, the driver, the engineer, and the fireman.
Fig. 75 is a representation of the class of steam fire engine built by
Silsbee, Mynderse & Co., Seneca Falls, N. Y. under Holly's patent.
The boiler is vertical, with vertical water tubes passing directly through
the fire. These tubes are closed at the bottom and open at the top, where
they pass through a water-tight plate, and communicate with the water in
the boiler. The arrangement of the tubes causes a constant current, the
water rising on the outside of the tubes as they are heated, and its place
being supplied by a current flowing downward through the tube to the
boiler. The smoke and flame pass among the tubes up through flues.
Both engine and pump are rotary, and of the same type. They consist
essentially of two elliptical rotary pistons, cogged and working into one
another in an air-tight case. The pistons fit close to the inside of the
case, and gear into each on the line of their conjugate diameters. The
action is somewhat similar to the old-fashioned rotary pump, consisting of
two cog wheels in gear with, each other, the spaces at the side of the case
being filled with water, which at the centre are occupied by the teeth in
gear. In Holly's pump, instead of uniform teeth, and depending on the fit
of the teeth with the side of the case and with each other for the packing,
there are two large teeth in each piston opposite each other, which have
slide pistons, and intermediate with these large teeth are small cogs,
which continue the motion of the rotary pistons. The machine works very
smoothly, and performs the work necessary, in ordinary service, under a
pressure of 50 to 60 lbs.
There are many other makers of fire engines in this country; but sufficient
examples are given to illustrate the class; so successful have they been,
that they are fast superseding hand engines, even in the smaller cities.
Under a paid department, the following is, in the city of Boston, Mass.,
the comparative cost of running the two kinds of engines, viz.:
STEAM FIRE ENGINE.
1 engineer........................................... $720 00
1 fireman............................................ 600 00
1 driver............................................. 600 00
1 foreman of hose.................................... 150 00
8 hosemen, at $125 each.............................. 375 00
7 men................................................ $2,445 00
Keeping of 2 horses.................................. 315 00
Total......................................... $2,760 00
1 foreman............................................ $150 00
1 assistant foreman.................................. 125 00
1 clerk.............................................. 125 00
1 steward............................................ 125 00
3 leading hosemen, at $125 each...................... 375 00
33 men, at $100 each................................. 3,300 00
40 men............................................... $4,200 00
Here the engineer, fireman, and driver are constantly employed, the hosemen
have other employment in the neighborhood, but all the company sleep in the
In the city of Manchester, N.H., a steam fire engine company is composed of
fourteen men, all told, one of whom, acting as driver and steward, is
constantly employed, remaining at the engine house with a pair of horses
always ready to run out with the engine in case of an alarm of fire. The
other members of the company have other employments, and turn out only on
an alarm of fire.
STEAM FIRE ENGINES.
"Amoskcag," Expenditures..................... $864 32
"Fire King," " ..................... 855 78
"E.W. Harrington," " ..................... 496 09
The above expense includes pay of members, team expenses, cost of gas,
wood, coal, and all necessities incident to service. The "E.W. Harrington"
is a second-class engine, stationed in the outskirts of the city, and was
run cheaper from the fact that no horses were kept for it by the city.
A first-class hand-engine company is allowed to number, all told, fifty
men, and the members of the company are paid as follows:
FIRST-CLASS HAND-ENGINE COMPANY.
1 foreman.......................................... $35 00
1 assistant foreman............................... 28 00
1 clerk........................................... 28 00
1 steward........................................ 68 00
46 men, at $18 each................................ 828 00
50 men. Total.............................. $987 00
By this it will be seen, that in a city like Manchester, with from twenty
to twenty-five thousand inhabitants, a first-class steam fire engine can be
run at an expense not to exceed that of a first-class hand engine, while in
service it will do at least _four times_ the work. The cost of repairs is
found by experience to be no greater on the steam fire engines than on hand
The Excavator, fig. 76, is the invention of the late Mr. Otis, an
application of the spoon dredging machine of the docks to railway purposes,
with very important modifications. The machine consists of a strong truck,
_A_, _A_, mounted on railway wheels, on which is placed the boiler _C_, the
crane _E_, and the requisite gearing. The excavator or shovel, _D_, is a
box of wrought iron, with strong points in front to act as picks in
loosening the earth, and its bottom hung by a hinge at _d_, so that, by
detaching a catch, it may fly open and discharge the material raised. To
operate the machine, suppose the shovel _D_ to be in the position shown in
the cut; it is lowered by the chains _o_, _o_, and thrown forward or
backward, if necessary, by the drum _B_, and handle _S_, till the picks in
the front of the shovel are brought in proper contact with the face of the
cut; motion forward is now given to the shovel by the drum _B_ and handle
_S_, and at the same time it is raised by the chains _o_, _o_. These two
motions can be so adjusted to each other, as to give movement to the shovel
to enable it to loosen and scrape up a shovelful of earth. The handle _S_
is now left free, and the shovel _D_ is raised vertically by the chains
_o_, _o_. The crane is now turned round, till the shovel comes over a rail
car on a side track; the bottom of the shovel is opened, and the dirt
deposited in the car. All these motions are performed by the aid of a steam
engine, and are controlled by a man who stands on a platform at _f_.
[Illustration: Fig 76.]
692. _Q._--Having now described the most usual and approved forms of
engines applicable to numerous miscellaneous purposes for which a moderate
amount of steam power is required, will you briefly recapitulate what
amount of work of different kinds an engine of a given power will perform,
so that any one desiring to employ an engine to perform a given amount of
work, will be able to tell what the power of such engine should be?
_A._--It will of course be impossible to recapitulate all the purposes to
which engines are applicable, or to specify for every case the amount of
power necessary for the accomplishment of a given amount of work; but some
examples may be given which will be applicable to the bulk of the cases
occurring in practice.
693. _Q._--Beginning, then, with the power necessary for threshing,--a 4
horse power engine, with cylinder 6 inches diameter, pressure of steam 45
lbs., per square inch, and making 140 revolutions per minute, will thresh
out 40 quarters of wheat in 10 hours with a consumption of 3 cwt. of coals.
_A._--Although this may be done, it is probably too much to say that it can
be done on an average, and about three fourths of a quarter of wheat per
horse power would probably be a nearer average. The amount of power
consumed varies with the yield.
Messrs. Barrett, Exall, and Andrewes give the following table as
illustrative of the work done, and the fuel consumed by their portable
engines; but this must be regarded as a maximum performance:--
Number of | Weight of | Quarters of | Quantity of | Quantity of
Horse Power.| Engine. | Corn thrashed| Coals consumed| Water required
| | in 10 Hours. | in 10 Hours. | for 10 Hours
| | | | in Gallons.
|Tons. Cwts.| | Cwts. |
4 | 2 0 | 40 | 3 | 360
5 | 2 5 | 50 | 4 | 380
6 | 2 10 | 60 | 5 | 460
7 | 2 15 | 70 | 6 | 540
8 | 3 0 | 80 | 7 | 620
10 | 3 10 | 100 | 9 | 780
694. _Q._--In speaking of horses power, I suppose you mean indicator horse
_A._--Yes; or rather the dynamometer horse power, which is the same,
barring the friction of the engine. At the shows of the Royal Agricultural
Society, the power actually exerted by the different engines is ascertained
by the application of a friction wheel or dynamometer.
695. _Q._--Can you give any other examples of the power necessary for
_A._--An engine exerting 23-1/3 horses power by the indicator works two
pairs of flour stones of 4 feet 8 inches diameter, two pairs of stones
grinding oatmeal of 4 feet 8 inches diameter, one dressing machine, one
pair of fanners, one dust screen, and one sifting machine. One of the flour
stones makes 85, and the other 90 revolutions in the minute. One of the
oatmeal stones makes 120, and the other 140 revolutions in the minute. To
take another case:--An engine exerting 26-1/2 indicator horses power works
two pairs of flour stones, one dressing machine, two pairs of stones
grinding oatmeal, and one pair of shelling stones. The flour stones, one
pair of the oatmeal stones, and shelling stones, are 4 feet 8 inches
diameter. The diameter of the other pair of oatmeal stones is 3 feet 8
inches. The length of the cylinder of the dressing machine is 7 feet 6
inches. The flour stones make 87 revolutions in the minute, and the larger
oatmeal stone 111 revolutions, but the smaller oatmeal stone and the
shelling stone revolve faster than this. At the time the indicator diagram
was taken, each pair of flour stones was grinding at the rate of 5 bushels
an hour; each pair of oatmeal stones about 24 bushels an hour; and the
shelling stones were shelling at the rate of about 54 bushels an hour. The
fanners and screen were also in operation.
696. _Q._--Have you any other case to enumerate?
_A._--I may mention one in which the power of the same engine was increased
by giving it a larger supply of steam. The engine when working with 8.65
horses power, gives motion to one pair of oatmeal stones of 4 feet 6 inches
diameter, and one pair of flour stones 4 feet 8 inches diameter. The
oatmeal stone makes 100 revolutions in the minute, and the flour stone 89.
The oatmeal stones grind about 36 bushels in the hour, and the flour stones
5 bushels in the hour. The engine when working to 12 horses power drives
one pair of flour stones, 4 feet 8 inches diameter, at 89 revolutions per
minute and one pair of stones of the same diameter at 105 revolutions,
grinding beans for cattle. The flour mill stones with this proportion of
power, being more largely fed, ground 6 bushels per hour, and the other
stones also ground 6 bushels per hour. When the power was increased to 18
horses, and the engine was burdened in addition with a dressing machine
having a cylinder of 19 inches diameter, the speed of the flour stone fell
to 85, and of the beans stone to 100 revolutions per minute, and the yield
was also reduced. The dressing machine dressed 24 bushels per hour.
697. _Q._--What is the power necessary to work a sugar mill such as is used
to press the juice from canes in the West Indies?
_A._--Twenty horses power will work a sugar mill having rollers about 5
feet long and 28 inches diameter; the rollers making 2-1/3 turns in a
minute. If the rollers be 26 inches diameter and 4-1/2 feet long, 18 horses
power will suffice to work them at the same speed, and 16 horses power if
the length be reduced to 3 feet 8 inches. 12 horses power will be required
to work a sugar mill with rollers 24 inches diameter and 4 feet 2 inches
long; and 10 horses power will suffice if the rollers be 3 feet 10 inches
long and 23 inches diameter. The speed of the surface of sugar mill rollers
should not be greater than 16 feet per minute, to allow time for the canes
to part with their juice. In the old mills the speed was invariably too
great. The quantity of juice expressed will not be increased by increasing
the speed of the rollers, but more of the juice will pass away in the
begass or woody refuse of the cane.
698. _Q._--What is the amount of power necessary to drive cotton mills?
_A._--An indicator or actual horse power will drive 305 hand mule spindles,
with proportion of preparing machinery for the same; or 230 self-acting
mule spindles with preparation; or 104 throstle spindles with preparation;
or 10-1/2 power looms with common sizing. The throstles referred to are the
common throstles spinning 34's twist for power loom weaving, and the
spindles make 4000 turns per minute. The self-acting mules are Robert's,
about one half spinning 36's weft, and spindles revolving 4800 turns per
minute; and the other half spinning 36's twist, with the spindles revolving
5200 times per minute. Half the hand mules were spinning 36's weft, at 4700
revolutions, and the other half 36's twist at 5000 revolutions per minute.
The average breadth of the looms was 37 inches, weaving 37 inch cloth,
making 123 picks per minute,--all common calicoes about 60 reed, Stockport
count, and 68 picks to the inch. To take another example in the case of a
mill for twisting cotton yarn into thread:--In this mill there are 27
frames with 96 common throstle spindles in each, making in all 2592
spindles. The spindles turn 2200 times in a minute; the bobbins are 1-7/8
inches diameter, and the part which holds the thread is 2-3/16 inches long.
In addition to the twisting frames the steam engine works 4 turning lathes,
3 polishing lathes, 2 American machines for turning small bobbins, two
circular saws, one of 22 and the other of 14 inches diameter, and 24 bobbin
heads or machines for filling the bobbins with finished thread. The power
required to drive the whole of this machinery is 28-1/2 horses. When all
the machinery except the spindles is thrown off, the power required is 21
horses, so that 2592, the total number of spindles, divided by 21, the
total power, is the number of twisting spindles worked by each actual horse
power. The number is 122.84.
699. _Q._--What work will be done by a given engine in sawing timber,
pressing cotton, blowing furnaces, driving piles, and dredging earth out of
_A._--A high pressure cylinder 10 inches diameter, 4 feet stroke, making 35
revolutions with steam of 90 to 100 lbs. on the square inch, supplied by
three cylindrical boilers 30 inches diameter and 20 feet long, works two
vertical saws of 34 inches stroke, which are capable of cutting 30 feet of
yellow pine, 18 inches deep, in the minute. A high pressure cylinder 14
inches diameter and 4 feet stroke, making 60 strokes per minute with steam
of 40 lbs. on the square inch, supplied by three cylindrical boilers
without flues, 30 inches diameter and 26 feet long, with 32 square feet of
grate surface, works four cotton presses geared 6 to 1, with two screws in
each, of 7-1/2 inches diameter and 1-5/8 pitch, which presses will screw
1000 bales of cotton in the twelve hours. Also one high pressure cylinder
of 10 inches diameter and 3 feet stroke, making 45 to 60 revolutions per
minute, with steam of 45 to 50 lbs. per square inch, with two hydraulic
presses having 13 inch rams of 41 feet stroke, and force pumps 2 inches
diameter and 6 inches stroke, presses 30 bales of cotton per hour. One
condensing engine with cylinder 56 inches diameter, 10 feet stroke, and
making 15 strokes per minute with steam of 60 lbs. pressure per square
inch, cut off at 1/4th of the stroke, supplied by six boilers, each 5 feet
diameter, and 24 feet long, with a 22-inch double-return flue in each, and
198 square feet of fire grate, works a blast cylinder of 126 inches
diameter, and 10 feet stroke, at 15 strokes per minute. The pressure of the
blast is 4 to 5 lbs. per square inch; the area of pipes 2300 square inches,
and the engine blows four furnaces of 14 feet diameter, each making 100
tons of pig iron per week. Two high pressure cylinders, each of 6 inches
diameter and 18 inches stroke, making 60 to 80 strokes per minute, with
steam of 60 Lbs. per square inch, lift two rams, each weighing 1000 lbs.,
five times in a minute, the leaders for the lift being 24 feet long. One
high pressure cylinder of 12 inches diameter and 5 feet stroke, making 20
strokes per minute, with steam of 60 to 70 lbs. pressure per square inch,
lifts 6 buckets full of dredging per minute from a depth of 30 feet below
the water, or lifts 10 buckets full of mud per minute from a depth of 18
feet below the water.
MANUFACTURE AND MANAGEMENT OF STEAM ENGINES.
CONSTRUCTION OF ENGINES.
700. _Q._--What are the qualities which should be possessed by the iron of
which the cylinder of steam engines are made?
_A._--The general ambition in making cylinders is to make them sound and
hard; but it is expedient also to make them tough, so as to approach as
nearly as possible to the state of malleable iron. This may be done by
mixing in the furnace as many different kinds of iron as possible; and it
may be set down as a general rule in iron founding, that the greater the
number of the kinds of metal entering into the composition of any casting,
the denser and tougher it will be. The constituent atoms of the different
kinds of iron appear to be of different sizes, and the mixture of different
kinds maintains the toughness, while it adds to the density and cohesive
power. Hot blast iron was at one time generally believed to be weaker than
cold blast iron, but it is now questioned whether it is not the stronger of
the two. The cohesive strength of unmixed iron is not in proportion to its
specific gravity, and its elasticity and power to resist shocks appear to
become greater as the specific gravity becomes less. Nos. 3 and 4 are the
strongest irons. In most cases, iron melted in a cupola is not so strong as
when remelted in an air furnace, and when run into green sand it is not
reckoned so strong as when run into dry sand, or loam. The quality of the
fuel, and even the state of the weather, exerts an influence on the quality
of the iron: smelting furnaces, on the cold blast principle, have long been
known to yield better iron in winter than in summer, probably from the
existence of less moisture in the air; and it would probably be found to
accomplish an improvement in the quality of the iron if the blast were made
to pass through a vessel containing muriate of lime, by which the moisture
of the air would be extracted. The expense of such a preparation would not
be considerable, as, by subsequent evaporation, the salt might be used over
and over again for the same purpose.
701. _Q._--Will you explain the process of casting cylinders?
_A._--The mould into which the metal is poured is built up of bricks and
loam, the loam being clay and sand ground together in a mill, with the
addition of a little horse-dung to give it a fibrous structure and prevent
cracks. The loam board, by which the circle of the cylinder is to be swept,
is attached to an upright iron bar, at the distance of the radius of the
cylinder, and a cylindrical shell of brick is built up, which is plastered
on the inside with loam, and made quite smooth by traversing the
perpendicular loam board round it. A core is then formed in a similar
manner, but so much smaller as to leave a space between the shell and the
core equal to the thickness of the cylinder, and into this space the melted
metal is poured. Whatever nozzles or projections are required upon the
cylinder, must be formed by means of wooden patterns, which are built into
the shell, and subsequently withdrawn; but where a number of cylinders of
the same kind are required, it is advisable to make these patterns of iron,
which will not be liable to warp or twist while the loam is being dried.
Before the iron is cast into the mould, the interior of the mould must be
covered with finely powdered charcoal--or blackening, as it is technically
termed; and the secret of making finely skinned castings lies in using
plenty of blackening. In loam and dry sand castings the charcoal should be
mixed with thick clay water, and applied until it is an eighth of an inch
thick, or more; the surface should be then very carefully smoothed or
sleeked, and if the metal has been judiciously mixed, and the mould
thoroughly dried, the casting is sure to be a fine one. Dry sand and loam
castings should be, as much as possible, made in boxes; the moulds may
thereby be more rapidly and more effectually dried, and better castings
will be got with a less expense.
702. _Q._--Will you explain the next operation which a cylinder undergoes?
_A._--The next stage is the boring; and in boring cylinders of 74 inches
diameter, the boring bar must move so as to make one revolution in about
4-1/2 minutes, at which speed the cutters will move at the rate of about
5 feet per minute. In boring brass, the speed must be slower; the common
rate at which the tool moves in boring brass air pumps is about 3 feet per
minute. If this speed be materially exceeded the tool will be spoiled, and
the pump made taper. The speed proper for boring a cylinder will answer for
boring the brass air pump of the same engine. A brass air pump of 36-1/2
inches diameter requires the bar to make one turn in about three minutes,
which is also the speed proper for a cylinder 60 inches in diameter. To
bore a brass air pump 36-1/2 inches in diameter requires a week, an iron
one requires 48 hours, and a copper one 24 hours. In turning a malleable
iron shaft 12-3/4 inches in diameter, the shaft should make about five
turns per minute, which is equivalent to a speed in the tool of about 16
feet per minute; but this speed may be exceeded if soap and water be
plentifully run on the point of the tool. A boring mill, of which the speed
may be varied from one turn in six minutes to twenty-five turns in one
minute, will be suitable for all ordinary wants that can occur in practice.
703. _Q._--Are there any precautions necessary to be observed in order that
the boring may be truly effected?
_A._--In fixing a cylinder into the boring mill, great care must be taken
that it is not screwed down unequally; and indeed it will be impossible to
bore a large cylinder in a horizontal mill without being oval, unless the
cylinder be carefully gauged when standing on end, and be set up by screws
when laid in the mill until it again assumes its original form. A large
cylinder will inevitably become oval if laid upon its side; and if while
under the tension due to its own weight it be bored round, it will become
oval again when set upon end. If the bottom be cast in, the cylinder will
be probably found to be round at one end and oval at the other, unless a
vertical boring mill be employed, or the precautions here suggested be
704. _Q._--Does the boring tool make the cylinder sufficiently smooth for
the reception of the piston?
_A._--Many engine makers give no other finish to their cylinders; but
Messrs. Penn grind their cylinders after they are bored, by laying them on
their side, and rubbing a piece of lead, with a cross iron handle like that
of a rolling stone, and smeared with emery and oil, backward and forward--
the cylinder being gradually turned round so as to subject every part
successively to the operation. The lead by which this grinding is
accomplished is cast in the Cylinder, whereby it is formed of the right
curve; but the part of the cylinder in which it is cast should be
previously heated by a hot iron, else the metal may be cracked by the
705. _Q._--How are the parts of a piston fitted together so as to be
perfectly steam tight?
_A._--The old practice was to depend chiefly upon grinding as the means of
making the rings tight upon the piston or upon one another; but scraping is
now chiefly relied on. Some makers, however, finish their steam surfaces by
grinding them with powdered Turkey stone and oil. A slight grinding, or
polishing, with powdered Turkey stone and oil, appears to be expedient in
ordinary cases, and may be conveniently accomplished by setting the piston
on a revolving table, and holding the ring stationary by a cross piece of
wood while the table turns round. Pieces of wood may be interposed between
the ring and the body of the piston, to keep the ring nearly in its right
position; but these pieces of wood should be fitted so loosely as to give
some side play, else the disposition would arise to wear the flange of the
piston into a groove.
706. _Q._--What kind of tool is used for finishing surfaces by scraping?
_A._--A flat file bent, and sharpened at the end, makes an eligible scraper
for the first stages; or a flat file sharpened at the end and used like a
chisel for wood. A three-cornered file, sharpened at all the corners, is
the best instrument for finishing the operation. The scraping tool should
be of the best steel, and should be carefully sharpened at short intervals
on a Turkey stone, so as to maintain a fine edge.
707. _Q._--Will you explain the method of fitting together the valve and
_A._--Both faces must first be planed, then filed according to the
indications of a metallic straight edge, and subsequently of a thick
metallic face plate, and finally scraped very carefully until the face
plate bears equally all over the surface. In planing any surface, the
catches which retain the surface on the planing machine should be relaxed
previously to the last cut, to obviate distortion from springing. To
ascertain, whether the face plate bears equally, smear it over with a
little red ochre and oil, and move the face plate slightly, which will fix
the color upon the prominent points. This operation is to be repeated
frequently; and as the work advances, the quantity of coloring matter is to
be diminished, until finally it is spread over the face plate in a thin
film, which only dims the brightness of the plate. The surfaces at this
stage must be rubbed firmly together to make the points of contact visible,
and the higher points will become slightly clouded, while the other parts
are left more or less in shade. If too small a quantity of coloring matter
be used at first, it will be difficult to form a just conception of the
general state of the surface, as the prominent points will alone be
indicated, whereas the use of a large quantity of coloring matter in the
latter stages would destroy the delicacy of the test the face plate
affords. The number of bearing points which it is desirable to establish on
the surface of the work, depends on the use to which the surface is to be
applied; but whether it is to be finished with great elaboration, or
otherwise, the bearing points should be distributed equally over the
surface. Face plates, or planometers, as they are sometimes termed, are
supplied by most of the makers of engineering tools. Every factory should
be abundantly supplied with them, and also with steel straight edges; and
there should be a master face plate, and a master straight edge, for the
sole purpose of testing, from time to time, the accuracy of those in use.
708. _Q._--Is the operation of surfacing, which you have described,
necessary in the case of all slide valves?
_A._--Yes; and in fitting the faces of a D valve, great care must, in
addition, be taken that the valve is not made conical; for unless the back
be exactly parallel with the face, it will be impossible to keep the
packing from being rapidly cut away. When the valve is laid upon the face
plate, the back must be made quite fair along the whole length, by draw
filing, according to the indications of a straight edge; and the distance
from the face to the extreme height of the back must be made identical at
709. _Q._--When you described the operation of boring the cylinder, you
stated that the cylinder, when laid upon its side, became oval; will not
this change of figure distort the cylinder face?
_A._--It is not only in the boring of the cylinder that it is necessary to
be careful that there is no change of figure, for it will be impossible to
face the valves truly in the case of large cylinders, unless the cylinder
be placed on end, or internal props be introduced to prevent the collapse
due to the cylinder's weight. It may be added, that the change of figure is
not instantaneous, but becomes greater after some continuance of the strain
than it was at first, so that in gauging a cylinder to ascertain the
difference of diameter when it is placed on its side, it should have lain
some days upon its side to ensure the accuracy of the operation.
710. _Q._--How is any flaw in the valve or cylinder face remedied?
_A._--Should a hole occur either in the valve, in the cylinder, or any
other part where the surface requires to be smooth, it may be plugged up
with a piece of cast iron, as nearly as possible of the same texture. Bore
out the faulty part, and afterward widen the hole with an eccentric drill,
so that it will be of the least diameter at the mouth. The hole may go more
than half through the iron: fit then a plug of cast iron roughly by filing,
and hammer it into the hole, whereby the plug will become riveted in it,
and its surface may then be filed smooth. Square pieces may be let in after
the same fashion, the hole being made dovetailed, and the pieces thus
fitted will never come out.
711. _Q._--When cylinders are faced with brass, how is the face attached to
_A._--Brass faces are put upon valves or cylinders by means of small brass
screws tapped into the iron, with conical necks for the retention of the
brass: they are screwed by means of a square head, which, when the screw is
in its place, is cut off and filed smooth. In some cases the face is made
of extra thickness, and a rim not so thick runs round it, forming a step or
recess for the reception of brass rivets, the heads of which are clear of
712. _Q._--What is the best material for valve faces?
_A._--Much trouble is experienced with every modification of valve face;
but cast iron working upon cast iron is, perhaps, the best combination yet
introduced. A usual practice is to pin brass faces on the cylinder,
allowing the valve to retain its cast iron face. Some makers employ brass
valves, and others pin brass on the valves, leaving the cylinder with a
cast iron face. If brass valves are used, it is advisable to plane out two
grooves across the face, and to fill them up with hard cast iron to prevent
rutting. Speculum metal and steel have been tried for the cylinder faces,
but only with moderate success. In some cases the brass gets into ruts; but
the most prevalent affection is a degradation of the iron, owing to the
action of the steam, and the face assuming a granular appearance, something
like loaf sugar. This action shows itself only at particular spots, and
chiefly about the angles of the port or valve face. At first the action is
slow; but when once the steam has worked a passage for itself, the cutting
away becomes very rapid, and, in a short time, it will be impossible to
prevent the engine from heating when stopped, owing to the leakage of steam
through the valve into the condenser. Copper steam pipes seem to have some
galvanic action on valve faces, and malleable iron pipes have sometimes
been substituted; but they are speedily worn out by oxidation, and the
scales of rust which are carried on by the steam scratch the valves and
cylinders, so that the use of copper pipes is the least evil.
713. _Q._--Will you explain in what manner the joints of an engine are
_A._--Rust joints are not now much used in engines of any kind, yet it is
necessary that the engineer should be acquainted with the manner of their
formation. One ounce of sal-ammoniac in powder is mingled with 18 ounces or
a pound of borings of cast iron, and a sufficiency of water is added to wet
the mixture thoroughly, which should be done some hours before it is wanted
for use. Some persons add about half an ounce of flowers of brimstone to
the above proportions, and a little sludge from the grindstone trough. This
cement is caulked into the joints with a caulking iron, about three
quarters of an inch wide and one quarter of an inch thick, and after the
caulking is finished the bolts of the joints may be tried to see if they
cannot be further tightened. The skin of the iron must, in all cases, be
broken where a rust joint is to be made; and, if the place be greasy, the
surface must be well rubbed over with nitric acid, and then washed with
water, till no grease remains. The oil about engines has a tendency to
damage rust joints by recovering the oxide. Coppersmiths staunch the edges
of their plates and rivets by means of a cement formed of pounded
quicklime, with serum of blood, or white of egg; and in copper boilers such
a substance may be useful in stopping the impalpable leaks which sometimes
occur, though Roman, cement appears to be nearly as effectual.
714. _Q._--Will you explain the method of case hardening the parts of
_A._--The most common plan for case hardening consists in the insertion of
the articles to be operated upon among horn or leather cuttings, hone dust,
or animal charcoal, in an iron box provided with a tight lid, which is then
put into a furnace for a period answerable to the depth of steel required.
In some cases the plan pursued by the gunsmiths may be employed with
convenience. The article is inserted in a sheet iron case amid bone dust,
often not burned; the lid of the box is tied on with wire, and the joint
luted with clay; the box is heated to redness as quickly as possible and
kept half an hour at a uniform heat: its contents are then suddenly
immersed in cold water. The more unwieldy portions of an engine may be case
hardened by prussiate of potash--a salt made from animal substances,
composed of two atoms of carbon and one of nitrogen, and which operates on
the same principle as the charcoal. The iron is heated in the fire to a
dull red heat, and the salt is either sprinkled upon it or rubbed on in a
lump, or the iron is rubbed in the salt in powder. The iron is then
returned to the fire for a few minutes, and finally immersed in water. By
some persons the salt is supposed to act unequally, as if there were greasy
spots upon the iron which the salt refused to touch, and the effect under
any circumstances is exceedingly superficial; nevertheless, upon all parts
not exposed to wear, a sufficient coating of steel may be obtained by this
715. _Q._--What kind of iron is most suitable for the working parts of an
_A._--In the malleable iron work of engines scrap iron has long been used,
and considered preferable to other kinds; but if the parts are to be case
hardened, as is now the usual practice, the use of scrap iron is to be
reprehended, as it is almost sure to make the parts twist in the case
hardening process. In case hardening, iron absorbs carbon, which causes it
to swell; and as some kinds of iron have a greater capacity for carbon than
other kinds, in case hardening they will swell more, and any such unequal
enlargement in the constituent portions of a piece of iron will cause it to
change its figure. In some cases, case hardening has caused such a twisting
of the parts of an engine, that they could not afterward be fitted
together; it is preferable, therefore, to make such parts as are to be case
hardened to any considerable depth of Lowmoor, Bowling, or Indian iron,
which being homogeneous will absorb carbon equally, and will not twist.
716. _Q._--What is the composition of the brass used for engine bearings?
_A._--The brass bearings of an engine are composed principally of copper
and tin. A very good brass for steam engine bearings consists of old copper
112 lbs., tin 12-1/2 lbs., zinc 2 or 3 oz.; and if new tile copper be used,
there should be 13 lbs. of tin instead of 12-1/2 lbs. A tough brass for
engine work consists of 1-1/2 lb. tin, 1-1/2 lb. zinc, and 10 lbs. copper;
a brass for heavy bearings, 2-1/2 oz. tin, 1/2 oz. zinc, and 1 lb. copper.
There is a great difference in the length of time brasses wear, as made by
different manufacturers; but the difference arises as much from a different
quantity of surface, as from a varying composition of the metal. Brasses
should always be made strong and thick, as when thin they collapse upon the
bearing and increase the friction and the wear.
717. _Q._--How is Babbitt's metal for lining the bushes of machinery
_A._--Babbitt's patent lining metal for bushes has been largely employed in
the bushes of locomotive axles and other machinery: it is composed of 1 lb.
of copper, 1 lb. regulus of antimony, and 10 lbs. of tin, or other similar
proportions, the presence of tin being the only material condition. The
copper is first melted, then the antimony is added, with a small proportion
of tin-charcoal being strewed over the surface of the metal in the crucible
to prevent oxidation. The bush or article to be lined, having been cast
with a recess for the soft metal, is to be fitted to an iron mould, formed
of the shape and size of the bearing or journal, allowing a little in size
for the shrinkage. Drill a hole for the reception of the soft metal, say
1/2 to 3/4 inch diameter, wash the parts not to be tinned with a clay wash
to prevent the adhesion of the tin, wet the part to be tinned with alcohol,
and sprinkle fine sal-ammoniac upon it; heat the article until fumes arise
from the ammonia, and immerse it in a kettle of Banca tin, care being taken
to prevent oxidation. When sufficiently tinned, the bush should be soaked
in water, to take off any particles of ammonia that may remain upon it, as
the ammonia would cause the metal to blow. Wash with pipe clay, and dry;
then heat the bush to the melting point of tin, wipe it clean, and pour in
the metal, giving it sufficient head as it cools; the bush should then be
scoured with fine sand, to take off any dirt that may remain upon it, and
it is then fit for use. This metal wears for a longer time than ordinary
gun metal, and its use is attended with very little friction. If the
bearing heats, however, from the stopping of the oil hole or otherwise, the
metal will be melted out. A metallic grease, containing particles of tin in
the state of an impalpable powder, would probably be preferable to the
lining of metal just described.
718. _Q._--Can you state the composition of any other alloys that are used
in engine work?
_A._--The ordinary range of good yellow brass that files and turns well, is
about 4-1/2 to 9 ounces of zinc to the pound of copper. Flanges to stand
brazing may be made of copper 1 lb., zinc 1/2 oz., lead 3/8 oz. Brazing
solders when stated in the order of their hardness are:-three parts copper
and one part zinc (very hard), eight parts brass and one part zinc (hard),
six parts brass, one part tin, and one part zinc (soft); a very common
solder for iron, copper, and brass, consists of nearly equal parts of
copper and zinc. Muntz's metal consists of forty parts zinc and sixty of
copper; any proportions between the extremes of fifty parts of zinc and
fifty parts copper, and thirty-seven zinc and sixty-three copper, will roll
and work at a red heat, but forty zinc to sixty copper are the proportions
preferred. Bell metal, such as is used for large bells, consists of 4-1/2
ounces to 5 ounces of tin to the pound of copper; speculum metal consists
of from 7-1/2 ounces to 8-1/2 ounces of tin to the pound of copper.
ERECTION OF ENGINES.
719. _Q._--Will you explain the operation of erecting a pair of side lever
engines in the workshop?
A.--In beginning the erection of side lever marine engines in the workshop,
the first step is to level the bed plate lengthways and across, and strike
a line up the centre, as near as possible in the middle, which indent with
a chisel in various places, so that it may at any time be easily found
again. Strike another line at right angles with this, either at the
cylinder or crank centre, by drawing a perpendicular in the usual manner.
Lay the other sole plate alongside at the right distance, and strike a line
at the cylinder or crank centre of it also, shifting either sole plate a
little endways until these two transverse lines come into the same line,
which may be ascertained by applying a straight edge across the two sole
plates. Strike the rest of the centres across, and drive a pin into each
corner of each sole plate, which file down level, so as to serve for points
of reference at any future stage; next, try the cylinder, or plumb it on
the inside roughly, and see how it is for height, in order to ascertain
whether much will be required to be chipped off the bottom, or whether more
requires to be chipped off the one side than the other. Chip the cylinder
bottom fair; set it in its place, plumb the cylinder very carefully with a
straight edge and silk thread, and scribe it so as to bring the cylinder
mouth to the right height, then chip the sole plate to suit that height.
The cylinder must then be tried on again, and the parts filed wherever they
bear hard, until the whole surface is well fitted. Next, chip the place for
the framing; set up the framing, and scribe the horizontal part of the jaw
with the scriber used for the bottom of the cylinder, the upright part
being set to suit the shaft centres, and the angular flange of cylinder,
where the stay is attached, having been previously chipped plumb and level.
The stake wedges with which the framing is set up preparatorily to the
operation of scribing, must be set so as to support equally the
superincumbent weight, else the framing will spring from resting unequally,
and it will be altogether impossible to fit it well. These directions
obviously refer exclusively to the old description of side lever engine
with cast iron framing; but there is more art in erecting an engine of that
kind with accuracy, than in erecting one of the direct action engines,
where it is chiefly turned or bored surfaces that have to be dealt with.
720. _Q._--How do you lay out the positions of the centres of a side lever
_A._--In fixing the positions of the centres in side lever engines, it
appears to be the most convenient way to begin with the main centre. The
height of the centre of the cross head at half stroke above the plane of
the main centre is fixed by the drawing of the engine, which gives the
distance from the centre of cross head at half stroke to the flange of the
cylinder; and from thence it is easy to find the perpendicular distance
from the cylinder flange to the plane of the main centre, merely by putting
a straight edge along level, from the position of the main centre to the
cylinder, and measuring from the cylinder flauge down to it, raising or
lowering the straight edge until it rests at the proper measurement. The
main centre is in that plane, and the fore and aft position is to be found
by plumbing up from the centre line on the sole plate. To find the paddle
shaft centre, plumb up from the centre line marked on the edge of the sole
plate, and on this line lay off from the plane of the main centre the
length of the connecting rod, if that length be already fixed, or otherwise
the height fixed in the drawing of the paddle shaft above the main centre.
To fix the centre for the parallel motion shaft, when the parallel bars are
connected with the cross head, lay off from the plane of main centre the
length of the parallel bar from the centre of the cylinder, deduct the
length of the radius crank, and plumb up the central line of motion shaft;
lay off on this line, measuring from the plane of main centre, the length
of the side rod; this gives the centre of parallel motion shaft when the
radius bars join the cross head, as is the preferable practice where
parallel motions are used. The length of the connecting rod is the distance
from the centre of the beam when level, or the plane of the main centre, to
the centre of the paddle shaft. The length of the side rods is the distance
from the centre line of the beam when level, to the centre of the cross
head when the piston is at half stroke. The length of the radius rods of
the parallel motion is the distance from the point of attachment on the
cross head or side rod, when the piston is at half stroke, to the extremity
of the radius crank when the crank is horizontal; or in engines with the
parallel motion attached to the cross head, it is the distance from the
centre of the pin of the radius crank when horizontal to the centre of the
cylinder. Having fixed the centre of the parallel motion shaft in the
manner just described, it only remains to put the parts together when the
motion is attached to the cross head; but when the motion is attached to
the side rod, the end of the parallel bar must not move in a perpendicular
line, but in an arc, the versed sine of which bears the same ratio to that
of the side lever, that the distance from the top of the side rod to the
point of attachment bears to the total length of the side rod.
721. _Q._--How do you ascertain the accuracy of the parallel motion?
_A._--The parallel motion when put in its place should be tested by raising
and lowering the piston by means of the crane. First, set the beams level,
and shift in or out the motion shaft plummer blocks or bearings, until the
piston rod is upright. Then move the piston to the two extremes of its
motion. If at both ends the cross head is thrown too much out, the stud in
the beam to which the motion side rod is attached is too far out, and must
be shifted nearer to the main centre; if at the extremities the cross head
is thrown too far in, the stud in the beam is not out far enough. If the
cross head be thrown in at the one end, and out equally at the other, the
fault is in the motion side rod, which must be lengthened or shortened to
remedy the defect.
722. _Q._--Will you describe the method pursued in erecting oscillating
_A._--The columns here are of wrought iron, and in the case of small
engines there is a template made of wood and sheet iron, in which the holes
are set in the proper positions, by which the upper and lower frames are
adjusted; but in the case of large engines, the holes are set off by means
of trammels. The holes for the reception of the columns are cast in the
frames, and are recessed out internally: the bosses encircling the holes
are made quite level across, and made very true with a face plate, and the
pillars which have been turned to a gauge are then inserted. The top frame
is next put on, and must bear upon the collars of the columns so evenly,
that one of the columns will not be bound by it harder than another. If
this point be not attained, the surfaces must be further scraped, until a
perfect fit is established. The whole of the bearings in the best
oscillating engines are fitted by means of scraping, and on no other mode
of fitting can the same reliance be placed for exactitude.
723. _Q._--How do you set out the trunnions of oscillating engines, so that
they shall be at right angles with the interior of the cylinder?
_A._--Having bored the cylinder, faced the flange, and bored out the hole
through which the boring bar passes, put a piece of wood across the mouth
of the cylinder, and jam it in, and put a similar piece in the hole through
the bottom of the cylinder. Mark the centre of the cylinder upon each of
these pieces, and put into the bore of each trunnion an iron plate, with a
small indentation in the middle to receive the centre of a lathe, and
adjusting screws to bring the centre into any required position. The
cylinder must then be set in a lathe, and hung by the centres of the
trunnions, and a straight edge must be put across the cylinder mouth and
levelled, so as to pass through the line in which the centre of the
cylinder lies. Another similar straight edge, and similarly levelled, must
be similarly placed across the cylinder bottom, so as to pass through the
central line of the cylinder; and the cylinder is then to be turned round
in the trunnion centres-the straight edges remaining stationary, which will
at once show whether the trunnions are in the same horizontal plane as the
centre of the cylinder, and if not, the screws of the plates in the
trunnions must be adjusted until the central point of the cylinder just
comes to the straight edge, whichever end of the cylinder is presented. To
ascertain whether the trunnions stand in a transverse plane, parallel to
the cylinder flange, it is only necessary to measure down from the flange
to each trunnion centre; and if both these conditions are satisfied, the
position of the centres may be supposed to be right. The trunnion bearings
are then turned, and are fitted into blocks of wood, in which they run
while the packing space is being turned out. Where many oscillating engines
are made, a lathe with four centres is used, which makes the use of
straight edges in setting out the trunnions superfluous.
724. _Q._--Will you explain how the slide valve of a marine engine is set?
_A._--Place the crank in the position corresponding to the end of the
stroke, which can easily be done in the shop with a level, or plumb line;
but in a steam vessel another method becomes necessary. Draw the transverse
centre line, answering to the centre line of the crank shaft, on the sole
plate of the engine, or on the cylinder mouth if the engine be of the
direct action kind; describe a circle of the diameter of the crank pin upon
the large eye of the crank, and mark off on either side of the transverse
centre line a distance equal to the semi-diameter of the crank pin. From
the point thus found, stretch a line to the edge of the circle described on
the large eye of the crank, and bring round the crank shaft till the crank
pin touches the stretched line; the crank may thus be set at either end of
its stroke. When the crank is thus placed at the end of the stroke, the
valve must be adjusted so as to have the amount of lead, or opening on the
steam side, which it is intended to give at the beginning of the stroke;
the eccentric must then be turned round upon the shaft until the notch in
the eccentric rod comes opposite the pin on the valve lever, and falls into
gear: mark upon the shaft the situation of the eccentric, and put on the
catches in the usual way. The same process must be repeated for going
astern, shifting round the eccentric to the opposite side of the shaft,
until the rod again falls into gear. In setting valves, regard must of
course be had to the kind of engine, the arrangements of the levers, and
the kind of valve employed; and in any general instructions it is
impossible to specify every modification in the procedure that
circumstances may render advisable.
725. _Q._--Is a similar method of setting the valve adopted when the link
motion is employed.
_A._--Each end of the link of the link motion has the kind of motion
communicated to it that is due to the action of the particular eccentric
with which that end is in connection. In that form of the link motion in
which the link itself is moved up or down, there is a different amount of
lead for each different position of the link, since to raise or lower the
link is tantamount to turning the eccentric round on the shaft. In that
form of the link motion in which the link itself is not raised or lowered,
but is susceptible of a motion round a centre in the manner of a double
ended lever, the lead continues uniform. In both forms of the link motion,
as the stroke of the valve may be varied to any required extent while the
lap is a constant quantity, the proportion of the lap relatively to the
stroke of the valve may also be varied to any required extent, and the
amount of the lap relatively with the stroke of the valve determines the
amount of the expansion. In setting the valve when fitted with the link
motion, the mode of procedure is much the same as when it is moved by a
simple eccentric. The first thing is to determine if the eccentric rods are
of the proper length, and this is done by setting the valve at half stroke
and turning round the eccentric, marking each extremity of the travel of
the end of the rod. The valve attachment should be midway between these
extremes; and if it is not so, it must be made so by lengthening or
shortening the rod. The forward and backward eccentric rods are to be
adjusted in this way, and this being done, the engine is to be put to the
end of the stroke, and the eccentric is to be turned round until the amount
of lead has been given that is desired. The valve must be tried by turning
the engine round to see that it is right at both centres, for going ahead
and also for going astern. In some examples of the link motion, one of the
eccentric rods is made a little longer than the other, and the position of
the point of suspension or point of support powerfully influences the
action of the link in certain cases, especially if the link and this point
are not in the same vertical line. To reconcile all the conditions proper
to the satisfactory operation of the valve in the construction of the link
motion, is a problem requiring a good deal of attention and care for its
satisfactory solution; and to make sure that this result is attained, the
engine must be turned round a sufficient number of times to enable us to
ascertain if the valve occupies the desired position, both at the top and
bottom centres, whether the engine is going ahead or astern. This should
also be tried with the starting handle in the different notches, or, in
other words, with the sliding block in the slot or opening of the link in
MANAGEMENT OF MARINE BOILERS.
726. _Q._--You have already stated that the formation of salt or scale in
marine boilers is to be prevented by blowing out into the sea at frequent
intervals a portion of the concentrated water. Will you now explain how the
proper quantity of water to be blown out is determined?
_A._--By means of the salinometer, which is an instrument for determining
the density of the water, constructed on the principle of the hydrometer
for telling the strength of spirits. Some of the water is drawn off from
the boiler from time to time, and the salinometer is immersed in it after
it has been cooled. By the graduations of the salinometer the saltness of
this water is at once discovered; and if the saltness exceeds 8 ounces of
salt in the gallon, more water should be blown out of the boiler to be
replenished with fresher water from the sea, until the prescribed limit of
freshness is attained. Should the salinometer be accidentally broken, a
temporary one may be constructed of a phial weighted with a few grains of
shot or other convenient weight. The weighted phial is first to be floated
in fresh water, and its line of floatation marked; then to be floated in
salt water, and its line of floatation marked; and another mark of an equal
height above the salt water mark will be the blow off point.
727. _Q._--HOW often should boilers be blown off in order to keep them free
_A._--Flue boilers generally require to be blown off about twice every
watch, or about twice in the four hours; but tubular boilers may require to
be blown off once every twenty minutes, and such an amount of blowing off
should in every case be adopted, as will effectually prevent any injurious
amount of incrustation.
728. _Q._--In the event of scale accumulating on the flues of a boiler,
what is the best way of removing it?
_A._--If the boilers require to be scaled, the best method of performing
the operation appears to be the following:--Lay a train of shavings along
the flues, open the safety valve to prevent the existence of any pressure
within the boiler, and light the train of shavings, which, by expanding
rapidly the metal of the flues, while the scale, from its imperfect
conducting power, can only expand slowly, will crack off the scale; by
washing down the flues with a hose, the scale will be carried to the bottom
of the boiler, or issue, with the water, from the mud-hole doors. This
method of scaling must be practised only by the engineer himself, and must
not be intrusted to the firemen who, in their ignorance, might damage the
boiler by overheating the plates. It is only where the incrustation upon
the flues is considerable that this method of removing it need be
practised; in partial cases the scale may be chipped off by a hatched faced
hammer, and the flues may then be washed down with the hose in the manner
729. _Q._--Should the steam be let out of the boiler, after it has blown
out the water, when the engine is stopped?
_A._--No; it is better to retain the steam in the boiler, as the heat and
moisture it occasions soften any scale adhering to the boiler, and cause it
to peel off. Care must, however, be taken not to form a vacuum in the
boiler; and the gauge cocks, if opened, will prevent this.
730. _Q._--Are tubular boilers liable to the formation of scale in certain
places, though generally free from it?
_A._--In tubular boilers a good deal of care is required to prevent the
ends of the tubes next the furnace from becoming coated with scale. Even
when the boiler is tolerably clean in other places the scale will collect
here; and in many cases where the amount of blowing off previously found to
suffice for flue boilers has been adopted, an incrustation five eighths of
an inch in thickness has formed in twelve months round the furnace ends of
the tubes, and the stony husks enveloping them have actually grown together
in some parts so as totally to exclude the water.
731. _Q._--When a tubular boiler gets incrusted in the manner you have
described, what is the best course to be adopted for the removal of the
_A._--When a boiler gets into this state the whole of the tubes must be
pulled out, which may be done by a Spanish windlass combined with a pair of
blocks; and three men, when thus provided, will be able to draw out from 50
to 70 tubes per day,--those tubes with the thickest and firmest
incrustations being, of course, the most difficult to remove. The act of
drawing out the tubes removes the incrustation; but the tubes should
afterward be scraped by drawing them backward and forward between the old
files, fixed in a vice, in the form of the letter V. The ends of the tube
should then be heated and dressed with the hammer, and plunged while at a
blood heat into a bed of sawdust to make them cool soft, so that they may
be riveted again with facility. A few of the tubes will be so far damaged
at the ends by the act of drawing them out, as to be too short for
reinsertion: this result might be to a considerable extent obviated by
setting the tube plates at different angles, so that the several horizontal
rows of tubes would not be originally of the same length, and the damaged
tubes of the long rows would serve to replace the short ones; but the
practice would be attended with other inconveniences.
732. _Q._--Is there no other means of keeping boilers free from scale than
by blowing off?
_A._--Muriatic acid, or muriate of ammonia, commonly called sal-ammoniac,
introduced into a boiler, prevents scale to a great extent; but it is
liable to corrode the boiler internally, and also to damage the engine, by
being carried over with the steam; and the use of such intermixtures does
not appear to be necessary, if blowing off from the surface of the water is
largely practised. In old boilers, however, already incrusted with scale,
the use of muriate of ammonia may sometimes be advantageous.
733. _Q._--Are not the tubes of tubular boilers liable to be choked up by
deposits of soot?
_A._--The soot which collects in the inside of the tubes of tubular boilers
is removed by means of a brush, like a large bottle brush; and the
carbonaceous scale, which remains adhering to the interior of the tubes, is
removed by a circular scraper. Ferules in the tubes interfere with the
action of this scraper, and in the case of iron tubes ferules are now
generally discarded; but it will sometimes be necessary to use ferules for
iron tubes, where the tubes have been drawn and reinserted, as it may be
difficult to refix the tubes without such an auxiliary. Tubes one tenth of
an inch in thickness are too thin: one eighth of an inch is a better
thickness, and such tubes will better dispense with the use of ferules, and
will not so soon wear into holes.
734. _Q._--If the furnace or flue of a boiler be injured, how do you
proceed to repair it?
_A._--If from any imperfection in the roof of a furnace or flue a patch
requires to be put upon it, it will be better to let the patch be applied
upon the upper, rather than upon the lower, surface of the plate; as if
applied within the furnace a recess will be formed for the lodgment of
deposit, which will prevent the rapid transmission of the heat in that
part; and the iron will be very liable to be again burned away. A crack in
a plate may be closed by boring holes in the direction of the crack, and
inserting rivets with large heads, so as to cover up the imperfection. If
the top of the furnace be bent down, from the boiler having been
accidentally allowed to get short of water, it may be set up again by a
screw jack,--a fire of wood having been previously made beneath the injured
plate; but it will in general be nearly as expeditious a course to remove
the plate and introduce a new one, and the result will be more
735. _Q._--In the case of the chimney being carried away by shot or
otherwise, what course would you pursue?
_A._--In some cases of collision, the funnel is carried away and lost
overboard, and such cases are among the most difficult for which a remedy
can be sought. If flame come out of the chimney when the funnel is knocked
away, so as to incur the risk of setting the ship on fire, the uptake of
the boiler must be covered over with an iron plate, or be sufficiently
covered to prevent such injury. A temporary chimney must then be made of
such materials as are on board the ship. If there are bricks and clay or
lime on board, a square chimney may be built with them, or, if there be
sheet iron plates on board, a square chimney may be constructed of them. In
the absence of such materials, the awning stanchions may be set up round
the chimney, and chain rove in through among them in the manner of wicker
work, so as to make an iron wicker chimney, which may then be plastered
outside with wet ashes mixed with clay, flour, or any other material that
will give the ashes cohesion. War steamers should carry short spare
funnels, which may easily be set up should the original funnel be shot
away; and if a jet of steam be let into the chimney, a very short and small
funnel will suffice for the purpose of draught.
MANAGEMENT OF MARINE ENGINES.
736. _Q._--What are the most important of the points which suggest
themselves to you in connection with the management of marine engines?
_A._--The attendants upon engines should prepare themselves for any
casualty that may arise, by considering possible cases of derangement, and
deciding In what way they would act should certain accidents occur. The
course to be pursued must have reference to particular engines, and no
general rules can therefore be given; but every marine engineer should be
prepared with the measures to be pursued in the emergencies in which he may
be called upon to act, and where everything may depend upon his energy and
737. _Q._--What is the first point of a marine engineer's duty?
_A._--The safe custody of the boiler. He must see that the feed is
maintained, being neither too high nor too low, and that blowing out the
supersalted water is practised sufficiently. The saltness of the water at
every half hour should be entered in the log book, together with the
pressure of steam, number of revolutions of the engine, and any other
particulars which have to be recorded. The economical use of the fuel is
another matter which should receive particular attention. If the coal is
very small, it should be wetted before being put on the fire. Next to the
safety of the boiler, the bearings of the engine are the most important
consideration. These points, indeed, constitute the main parts of the duty
of an engineer, supposing no accident to the machinery to have taken place.
738. _Q._--If the eccentric catches or hoops were disabled, how would you
work the valve?
_A._--If the eccentric catches or hoops break or come off, and the damage
cannot readily be repaired, the valve may be worked by attaching the end of
the starting handle to any convenient part of the other engine, or to some
part in connection with the connecting rod of the same engine. In side
lever engines, with the starting bar hanging from the top of the diagonal
stay, as is a very common arrangement, the valve might be wrought by
leading a rope from the side lever of the other engine through blocks so as
to give a horizontal pull to the hanging starting bar, and the bar could be
brought back by a weight. Another plan would be, to lash a piece of wood to
the cross tail butt of the damaged engine, so as to obtain a sufficient
throw for working the valve, and then to lead a piece of wood or iron, from
a suitable point in the piece of wood attached to the cross tail, to the
starting handle, whereby the valve would receive its proper motion. In
oscillating engines it is easy to give the required motion to the valve, by
deriving it from the oscillation of the cylinder.
739. _Q._--What would you do if a crank pin broke?
_A._--If the crank pin breaks in a paddle vessel with two engines, the
other engine must be made to work one wheel. In a screw vessel the same
course may be pursued, provided the broken crank is not the one through
which the force of the other engine is communicated to the screw. In such a
case the vessel will be as much disabled as if she broke the screw shaft or
740. _Q._--Will the unbroken engine, in the case of disarrangement of one
of the two engines of a screw or paddle vessel, be able of itself to turn
_A._--It will sometimes happen, when there is much lead upon the slide
valve, that the single engine, on being started, cannot be got to turn the
centre if there be a strong opposing wind and sea; the piston going up to
near the end of the stroke, and then coming down again without the crank
being able to turn the centre. In such cases, it will be necessary to turn
the vessel's head sufficiently from the wind to enable some sail to be set;
and if once there is weigh got upon the vessel the engine will begin to
work properly, and will continue to do so though the vessel be put head to
wind as before.
741. _Q._--What should be done if a crack shows itself in any of the shafts
_A._--If the shafts or cranks crack, the engine may nevertheless be worked
with moderate pressure to bring the vessel into port; but if the crack be
very bad, it will be expedient to fit strong blocks of wood under the ends
of the side levers, or other suitable part, to prevent the cylinder bottom
or cover from being knocked out, should the damaged part give way. The same
remark is applicable when flaws are discovered in any of the main parts of
the engine, whether they be malleable or cast iron; but they must be
carefully watched, so that the engines may be stopped if the crack is
extending further. Should fracture occur, the first thing obviously to be
done is to throw the engines out of gear; and should there be much weigh on
the vessel, the steam should at once be thrown on the reverse side of the
piston, so as to counteract the pressure of the paddle wheel.
742. _Q._--Have you any information to offer relative to the lubrication of
_A._--A very useful species of oil cup is now employed in a number of steam
vessels, and which, it is said, accomplishes a considerable saving of oil,
at the same time that it more effectually lubricates the bearings. A
ratchet wheel is fixed upon a little shaft which passes through the side of
the oil cup, and is put into slow revolution by a pendulum attached to its
outside and in revolving it lifts up little buckets of oil and empties them
down a funnel upon the centre of the bearing. Instead of buckets a few
short pieces of wire are sometimes hung on the internal revolving wheel,
the drops of oil which adhere on rising from the liquid being deposited.
upon a high part set upon the funnel, and which, in their revolution, the
hanging wires touch. By this plan, however, the oil is not well supplied at
slow speeds, as the drops fall before the wires are in proper position for
feeding the journal. Another lubricator consists of a cock or plug inserted
in the neck of the oil cup, and set in revolution by a pendulum and ratchet
wheel, or any other means. There is a small cavity in one side of the plug,
which is filled with oil when that side is uppermost, and delivers the oil
through the bottom pipe when it comes opposite to it.
743. _Q._--What are the prevailing causes of the heating of bearings?
_A._--Bad fitting, deficient surface, and too tight screwing down.
Sometimes the oil hole will choke, or the syphon wick for conducting the
oil from the oil cup into the central pipe leading to the bearing will
become clogged with mucilage from the oil. In some cases bearings heat from
the existence of a cruciform groove on the top brass for the distribution
of the oil, the effect of which is to leave the top of the bearings dry. In
the case of revolving journals the plan for cutting a cruciform channel for
the distribution of the oil does not do much damage; but in other cases, as
in beam journals, for instance, it is most injurious, and the brasses
cannot wear well wherever the plan is pursued. The right way is to make a
horizontal groove along the brass where it meets the upper surface of the
bearing, so that the oil may be all deposited on the highest point of the
journal, leaving the force of gravity to send it downward. This channel
should, of course, stop short a small distance from each flange of the
brass, otherwise the oil would run out at the ends.
744. _Q._--If a bearing heats, what is to be done?
_A._--The first thing is to relax the screws, slow or stop the engine, and
cool the bearing with water, and if it is very hot, then hot water may be
first employed to cool it, and then cold. Oil with sulphur intermingled is
then to be administered, and as the parts cool down, the screws may be
again cautiously tightened, so as to take any jump off the engine from the
bearing being too slack. The bearings of direct acting screw engines
require constant watching, as, if there be any disposition to heat
manifested by them, they will probably heat with great rapidity from the
high velocity at which the engines work. Every bearing of a direct acting
screw engine should have a cock of water laid on to it, which may be
immediately opened wide should heating occur; and it is advisable to work
the engine constantly, partly with water, and partly with oil applied to
the bearings. The water and oil are mixed by the friction into a species of
soap which both cools and lubricates, and less oil moreover is used than if
water were not employed. It is proper to turn off the water some time
before the engine is stopped, so as to prevent the rusting of the bearings.
MANAGEMENT OF LOCOMOTIVES.
745. _Q._--What are the chief duties of the engine driver of a locomotive?
_A._--His first duties are those which concern the safety of the train; his
next those which concern the safety and right management of the engine and
boiler. The engine driver's first solicitude should be relative to the
observation and right interpretation of the signals; and it is only after
these demands upon his attention have been satisfied, that he can look to
the state of his engine.
746. _Q._--As regards the engine and boiler, what should his main duties
_A._--The engineer of a locomotive should constantly be upon the foot board
of the engine, so that the regulator, the whistle or the reversing handle
may be used instantly, if necessary; he must see that the level of the
water in the boiler is duly maintained, and that the steam is kept at a
uniform pressure. In feeding the boilers with water, and the furnaces with
fuel, a good deal of care and some tact are necessary, as irregularity in
the production of steam will often occasion priming, even though the water
be maintained at a uniform level; and an excess of water will of itself
occasion priming, while a deficiency is a source of obvious danger. The
engine is generally furnished with three gauge cocks, and water should
always come out of the second gauge cock, and steam out of the top one when
the engine is running: but when the engine is at rest, the water in the
boiler is lower than when in motion, so that when the engine is at rest,
the water will be high enough if it just reaches to the middle gauge cock.
In all boilers which generate steam rapidly, the volume of the water is
increased by the mingled steam, and in feeding with cold water the level at
first falls; but it rises on opening the safety valve, which causes the
steam in the water to swell to a larger volume. In locomotive boilers, the
rise of the water level due to the rapid generation of steam is termed
"false water." To economize fuel, the variable expansion gear, if the
engine has one, should be adjusted to the load, and the blast pipe should
be worked with the least possible contraction; and at stations the damper
should be closed to prevent the dissipation of heat.
747. _Q._--In starting from a station, what precautions should be observed
with respect to the feed?
_A._--In starting from a station, and also in ascending inclined planes,
the feed water is generally shut off; and therefore before stopping or
ascending inclined planes, the boiler should be well filled up with water.
In descending inclined planes an extra supply of water may be introduced
into the boiler, and the fire may be fed, as there, is at such times a
superfluity of steam. In descending inclined planes the regulator must be
partially closed, and it should be entirely closed if the plane be very
steep. The same precaution should be observed in the case of curves, or
rough places on the line, and in passing over points or crossings.
748. _Q._--In approaching a station, how should the supply of water and
fuel be regulated?
_A._--The boiler should be well filled with water on approaching a station,
as there is then steam to spare, and additional water cannot be
conveniently supplied when the engine is stationary. The furnace should be
fed with small quantities of fuel at a time, and the feed should be turned
off just before a fresh supply of fuel is introduced. The regulator may, at
the same time, be partially closed; and if the blast pipe be a variable
one, it will be expedient to open it widely while the fuel is being
introduced, to check the rush of air in through the furnace door, and then
to contract it very much so soon as the furnace door is closed, in order to
recover the fire quickly. The proper thickness of coke upon the grate
depends upon the intensity of the draught; but in heavily loaded engines it
is usually kept up to the bottom of the fire door. Care, however, must be
taken that the coke does not reach up to the bottom row of tubes so as to
choke them up. The fuel is usually disposed on the grate like a vault; and
if the fire box be a square one, it is heaped high in the corners, the
better to maintain the combustion.
749. _Q._--How can you tell whether the feed pumps are operating properly?
_A._--To ascertain whether the pumps are acting well, the pet cock must be
turned, and if any of the valves stick they will sometimes be induced to
act again by working with the pet cock open, or alternately open and shut.
Should the defect arise from a leakage of steam into the pump, which
prevents the pump from drawing, the pet cock remedies the evil by
permitting the steam to escape.
750. _Q._--What precautions should be taken against priming in locomotives?
_A._--Should priming occur from the water in the boiler being dirty, a
portion of it may be blown out; and should there be much boiling down
through the glass gauge tube, the stop cock may be partially closed. The
water should be wholly blown out of locomotive boilers three times a week,
and at those times two mud-hole doors at opposite corners of the boiler
should be opened, and the boiler be washed internally by means of a hose.
If the boiler be habitually fed with dirty water, the priming will be a
constant source of trouble.
751. _Q._--What measures should the locomotive engineer take, to check the
velocity of the train, on approaching a station where he has to stop?
_A._--On approaching a station the regulator should be gradually closed,
and it should be completely shut about half a mile from the station if the
train be a very heavy one: the train may then be brought to rest by means
of the breaks. Too much reliance, however, must not be put upon the breaks,
as they sometimes give way, and in frosty weather are nearly inoperative.
In cases of urgency the steam may be thrown upon the reverse side of the
piston, but it is desirable to obviate this necessity as far as possible.
At terminal stations the steam should be shut off earlier than at roadside
stations, as a collision will take place at terminal stations if the train
overshoots the place where it ought to stop. There should always be a good
supply of water when the engine stops, but the fire may be suffered
gradually to burn low toward the conclusion of the journey.
752. _Q._--What is the duty of an engine man on arriving at the end of his
_A._--So soon as the engine stops it should be wiped down, and be then
carefully examined: the brasses should be tried, to see whether they are
slack or have been heating; and, by the application of a gauge, it should
be ascertained occasionally whether the wheels are square on their axles,
and whether the axles have end play, which should be prevented. The
stuffing boxes must be tightened, and the valve gear examined, and the
eccentrics be occasionally looked at to see that they have not shifted on
their axles, though this defect will be generally intimated by the
irregular beating of the engines. The tubes should also be examined and
cleaned out, and the ashes emptied out of the smoke box through the small
ash door at the end. If the engine be a six-wheeled one, with the driving
wheels in the middle, it will be liable to pitch, and oscillate if too much
weight be thrown upon the driving wheels; and where such faults are found
to exist, the weight upon the drivings wheels should be diminished. The
practice of blowing off the boiler by the steam, as is always done in
marine boilers, should not be permitted as a general rule in locomotive
boilers, when the tubes are of brass and the fire box of copper; but when
the tubes and fire boxes are of iron, there will not be an equal risk of
injury. Before starting on a journey, the engine man should take a summary
glance beneath the engine--but before doing so he ought to assure himself
that no other engine is coming up at the time. The regulator, when the
engine is standing, should be closed and locked, and the eccentric rod be
fixed out of gear, and the tender break screwed down; the cocks of the oil
vessels should at the same time be shut, but should all be opened a short
time before the train starts.
753. _Q._--What should be done if a tube bursts in the boiler?
_A._--When a tube bursts, a wooden or iron plug must be driven into each
end of it, and if the water or steam be rushing out so fiercely that the
exact position of the imperfection cannot be discovered, it will be
advisable to diminish the pressure by increasing the supply of feed water.
Should the leak be so great that the level of the water in the boiler
cannot be maintained, it will be expedient to drop the bars and quench the
fire, so as to preserve the tubes and fire box from injury.
754. _Q._--If any of the working parts of a locomotive break or become
deranged, what should be done?
_A._--Should the piston rod or connecting rod break, or the cutters fall
out or be clipped off--as sometimes happens to the piston cutter when the
engine is suddenly reversed upon a heavy train--the parts should be
disconnected, if the connection cannot be restored, so as to enable one
engine to work; and of course the valve of the faulty engine must be kept
closed. If one engine has not power enough to enable the train to proceed
with the blast pipe full open, the engine may perhaps be able to take on a
part of the carriages, or it may run on by itself to fetch assistance. The
same course must be pursued if any of the valve gearing becomes deranged,
and the defects cannot be rectified upon the spot.
755. _Q._--What are the most usual causes of railway collisions?
_A._--Probably fogs and inexactness in the time kept by the trains.
Collisions have sometimes occurred from carriages having been blown from a
siding on to the rails by a high wind; and the slippery state of the rails,
or the fracture of a break, has sometimes occasioned collisions at terminal
stations. Collision has also repeatedly taken place from one engine having
overtaken another, from the failure of a tube in the first engine, or from
some other slight disarrangement; and collision has also taken place from
the switches having been accidentally so left as to direct the train into a
siding, instead of continuing it on the main line. Every train now carries
fog signals, which are detonating packets, which are fixed upon the rails
in advance or in the rear of a train which, whether from getting off the
rails or otherwise, is stopped upon the line, and which are exploded by the
wheels of any approaching train.
756. _Q._--What other duties of an engine-driver are there deserving
_A._--They are too various to be all enumerated here, and they also vary
somewhat with the nature of the service. One rule, however, of universal
application, is for the driver to look after matters himself, and not
delegate to the stoker the duties which the person in charge of the engine
should properly perform. Before leaving a station, the engine-driver should
assure himself that he has the requisite supply of coke and water. Besides
the firing tools and rakes for clearing the tubes, he should have with him
in the tender a set of signal lamps and, torches, for tunnels and for
night, detonating signals, screw keys, a small tank of oil, a small cask of
tallow, and a small box of waste, a coal hammer, a chipping hammer, some
wooden and iron plugs for the tubes, and an iron tube holder for inserting
them, one or two buckets, a screw jack, wooden and iron wedges, split wire
for pins, spare cutters, some chisels and files, a pinch bar, oil cans and
an oil syringe, a chain, some spare bolts, and some cord, spun yarn, and
Accidents in steam vessels, proper preparation for.
Admiralty rule for horse power.
Adhesion of wheels of locomotives to rails.
Air, velocity of, entering a vacuum,
required for combustion of coal;
law of expansion of, by heat;
Air pump, description of,
proper dimensions of.
Air pump of marine engines, details of.
Air pump of oscillating engine.
Air pump of direct acting screw engines.
Air pumps made both single and double acting,
difference of, explained.
Air pumps, double acting valves of,
bad vacuum in;
causes and remedy.
Air pump rods, brass or copper, in marine engines.
Air pump bucket, valves of.
Air pump, connecting rod and cross head of oscillating engine.
Air pump rod of oscillating engine.
Air pump arm.
Air vessels applied to suction side of pumps.
"Alma," engine of, by Messrs. John Bourne & Co.
"Amphion," engines of.
Amoskeag steam fire engine.
Angle iron in boilers, precautions respecting.
Apparatus for raising screw propeller.
Atmospheric resistance to railway trains.
Auxiliary power, screw vessels with.
Axle bearings of locomotives.
Axles and wheels of modern locomotives.
"Azof," slide valve of.
Babbitt's metal, how to compound.
Balance piston to take pressure off slide valve.
Barrel of boiler of modern locomotives.
Beam, working of land engine,
main or working strength proper for.
Bearings of engines or other machinery,
rule for determining proper surface of.
Bearings, heating of, how to prevent or remedy,
journals should always bottom, as, if they grip
on the sides, the pressure is infinite.
Belidor's valves might be used for foot and delivery valves.
Bell-metal, composition of.
Blast pipe of locomotives, description of.
Blast in locomotives, exhaustion produced by,
proper construction of the blast pipe;
the blast pipe should be set below the root of
the chimney so much that the cone of escaping steam shall just fill the
Blast pipe with variable orifice, at one time much used.
Blow-off cock of locomotives.
Blow-off cocks of marine boilers, proper construction of.
Blow-off cocks, description of.
Blowing off supersalted water from marine boilers.
Blowing off, estimate of heat lost by,
Blow through valve, description of.
Blowing furnaces, power necessary for.
Bodies, falling, laws of.
Bodmer, expansion valve by.
Boilers, general description of: the wagon boiler,
the Cornish boiler;
the marine flue boiler;
the marine tubular boiler;
locomotive boiler--_see_ Locomotives.
Boilers proportions of: heating surface of,
fire grate, surface of;
consumption of fuel on each square foot of fire bars in wagon,
Cornish, and locomotive boilers;
calorimmeter and vent of boilers;
comparison of proportions of wagon, flue, and tubular boilers;
evaporative power of boilers;
power generated by evaporation of a cubic foot of water;
proper proportions of modern marine boilers both flue and tubular;
modern locomotive boilers;
exhaustion produced by blast in locomotives;
increased evaporation from increased exhaustion;
strength of boilers;
experiments on, by Franklin Institute;
by Mr. Fairbairn;
mode of computing strength of boilers;
Boilers, marine, prevented from salting by blowing off,
early locomotive and contemporaneous marine boilers compared;
chimneys of land;
rules for proportions of chimneys;
chimneys of marine boilers.
Boilers, constructive details of: riveting and caulking of land boilers,
seams payed with mixture of whiting and linseed oil;
setting of wagon boilers;
riveting of marine boilers;
precautions respecting angle iron;
how to punch the rivet holes and shear edges of plates;
setting of marine boilers in wooden vessels;
mastic cement for setting marine boilers;
composition of mastic cement;
best length of furnace;
configuration of furnace bars;
advantages and construction of furnace bridges;
various forms of dampers;
precautions against injury to boilers from intense heat;
tubing of boilers;
proper mode of staying tube plates;
proper mode of constructing steamboat chimneys;
waste steam-pipe and funnel casing;
formation of scale in marine boilers;
injury of such incrustations;
amount of salt in sea water;
saltness permissible in boilers;
amount of heat lost by blowing off;
mode of discharging the supersalted water;
Lamb's scale preventer;
internal corrosion of marine boilers;
causes of internal corrosion;
surcharged steam produced from salt water;
stop valves between boilers;
safety or escape valve on feed pipe;
locomotive boilers consist of the fire box, barrel for
holding tubes, and smoke box;
dimensions of the barrel and thickness of plates;
mode of staying fire box and furnace crown;
fire bars, ash box, and chimney;
steam dome used only in old engines;
manhole, mudholes, and blow-oft cock;
tube plate, and mode of securing tubes;
various forms of regulator.
Boilers of modern locomotives.
Boiler, the, proper care of, the first duty of the engineer.
Bolts, proper proportions of.
Boring of cylinders.
Boulton and Watt's rules for fly wheel,
proportions of marine flue boilers;
rule for proportions of chimneys of land boilers;
of marine boilers;
experiments on the resistance of vessels in water.
Bourdon's steam and vacuum gauges.
Bourne, expansion valves by.
Bourne, Messrs. J. & Co., direct acting screw engines by.
Brass for bearings, composition of.
Bridges in furnaces, benefits of.
Burning of boilers, precautions against.
Bursting velocity of fly wheel,
and of railway wheels.
Bursting of boilers,
may be caused by accumulations of salt.
Butterfly valves of air pump.
Cabrey, expansion valve by.
Calorimeter of boilers, definition of.
Cams, proper forms of.
Cast iron, strength of,
proportions of cast iron beams;
effects of different kinds of strains on beams;
strength to resist shocks not proportional to strength to resist
to attain maximum strength should be combined with wrought iron.
Casting of cylinders.
Case-hardening, how to accomplish.
Cataract, explanation of nature and uses of.
Caulking of land boilers.
Cement, mastic, for setting marine boilers.
Centre of pressure of paddle wheels.
Centres of gravity, gyration and oscillation.
Centres for fixing arms of paddle wheel.
Centres of an engine, how to lay off.
Centrifugal force, nature of,
rule for determining;
bursting velocity of fly wheel;
and of railway wheels.
Centrifugal pump will supersede common pump.
Centripetal force, nature of.
Chimney of locomotives.
Chimney of steam vessels, what to do if carried away.
Chimneys of land boilers,
Boulton and Watt's rule for proportions of;
of marine boilers.
Chimneys, exhaustion produced by,
high and wide chimneys in locomotives injurious.
Chimneys of steamboats,
Clark's patent steam fire regulator.
Coal, constituents of,
combustion of air required for;
evaporative efficacy of;
of wood, turf, and coke.
Cocks, proper construction of.
Cog wheels for screw engines.
Coke, evaporative efficacy of.
Cold water pump, description of,
rule for size of.
Combustion, nature of.
Combustion of coal, air required for.
Combustion, slow and rapid, comparative merits of,
rapid combustion necessary in steam vessels, and enables less heating,
surface in the boiler to suffice.
Condensation of steam, water required for.
Condenser, description of,
proper dimensions of.
Condenser of oscillating engine.
Condenser of direct acting screw engine.
Condensing engine, definition of.
Condensing water, how to provide when deficient.
Conical pendulum or governor.
Connecting rod, description of,
strength proper for.
Connecting rod of direct acting screw engines,
Consumption of fuel on each square foot of fire bars in wagon, Cornish,
and locomotive boilers.
Copper, strength of.
Corliss's steam engine.
Corrosion produced by surcharged steam.
Corrosion of marine boilers,
Cost of locomotives.
Cotton spinning, power necessary for.
Counter for counting strokes of an engine.
Crank, description of,
unequal leverage of, corrected by fly wheel;
no power lost by;
strength proper for.
Crank of direct acting screw engines.
Crank pin, strength proper for.
Crank pin of direct acting screw engines.
Cranked axle of locomotives.
Cross head, description of,
strength proper for.
Cross head of direct acting screw engines.
Cross tail, description of.
Cylinder, description of,
strength proper for.
Cylinder of oscillating engine,
of direct acting screw engine.
Cylinders should have a steam jacket, and be felted and planted,
should have escape valves.
Cylinders of locomotives should be large,
proper arrangement of.
Cylinders, how to cast,
how to bore;
how to grind.
Cylinder jacket, advantages of.
Dampers, various forms of.
Deadwood, hole in, for screw.
Delivery valve, description of.
Delivery or discharge valves, proper dimensions of.
Delivery valves might be made on Belidor's plan.
Delivery valves in mouth of air pump,
of india rubber.
Direct acting screw engines should be balanced.
Direct acting screw engine by Messrs. John Bourne &, Co.,
screw shaft brasses;