Q. What is fire?
A. Fire is the rapid combustion or consuming of organic
matter.
Q. What is water?
A. Water is a compound of oxygen and hydrogen. In weight
88 9-I0 parts oxygen to II I-I0 hydrogen. It has its maximum
density at 39 degrees Fahr., changes to steam at 2I2 degrees,
and to ice at 32 degrees.
Q. What is smoke?
A. It is unconsumed carbon finely divided escaping into
open air.
Q. Is excessive smoke a waste of fuel?
A. Yes.
Q. How will you prevent it
A. Keep a thin fire, and admit cold air sufficient to insure
perfect combustion.
Q. What is low water as applied to a boiler?
A. It is when the water is insufficient to cover all parts
exposed to the flames.
Q. What is the first thing to do on discovering that you have
low water?
A. Pull out the fire.
Q. Would it be safe to open the safety valve at such time?
A. No.
Q. Why not?
A. It would relieve the pressure on the water which being
allowed to flow over the excessive hot iron would flash into
steam, and might cause an explosion.
Q. Why do boilers sometimes explode just on the point of
starting the engine?
A. Because starting the engine has the same effect as
opening the safety valve.
Q. Are there any circumstances under which an engineer is
justified in allowing the water to get low?
A. No.
Q. Why do they sometimes do it?
A. From carelessness or ignorance.
Q. May not an engineer be deceived in the gauge of water?
A. Yes.
Q. Is he to be blamed under such circumstances?
A. Yes.
Q. Why?
A. Because if he is deceived by it it shows he has neglected
something.
Q. What is meant by "Priming."
A. It is the passing of water in visible quantities into the
cylinder with the steam.
Q. What would you consider the first duty of an engineer on
discovering that the water was foaming or priming
A. Open the cylinder cocks at once, and throttle the steam.
Q. Why would you do this?
A. Open the cocks to enable the water to escape, and throttle
the steam so that the water would settle.
Q. Is foaming the same as priming?
A. Yes and no.
Q. How do you make that out?
A. A boiler may foam without priming, but it can't prime
without first foaming..
Q. Where will you first discover that the water is foaming?
A. It will appear in the glass gauge, the glass will have a
milky appearance and the water will seem to be running down
from the top, There will be a snapping or cracking in the
cylinder as quick as priming begins.
Q. What causes a boiler to foam?
A. There are a number of causes. It may come from faulty
construction of boiler; it may have insufficient steam room. It
may be, and usually is, from the use of bad water, muddy or
stagnant water, or water containing any soapy substance.
Q. What would you do after being bothered in this way?
A. Clean out the-boiler and get better water if possible.
Q. How would you manage your pumps while the water was
foaming.
A. Keep them running full.
Q. Why?
A. In order to make up for the extra amount of water going
out with the steam.
Q. What is "cushion?"
A. Cushion is steam retained or admitted in front of the
piston head at the finish of stroke, or when the engine is on
"center."
Q. What is it for?
A. It helps to overcome the "inertia" and momentum of the
reciprocating parts of the engine, and enables the engine to
pass the center without a jar.
Q. How would you increase the cushion in an engine?
A. By increasing the lead.
Q. What is lead?
A. It is the amount of opening the port shows on steam end
of cylinder when the engine is on dead center.
Q. Is there any rule for giving an engine the proper lead?
A. No.
Q. Why not?
A. Owing to their variation in construction, speed, etc.
Q. What would you consider the proper amount of lead,
generally.
A. From I/32 to I/I6.
Q. What is "lap?"
A. It is the distance the valve overlaps the steam ports when
in mid position.
Q. What is lap for?
A. In order that the steam may be worked expansively.
Q. When does expansion occur in a cylinder?
A. During the time between which the port closes and the
point at which the exhaust opens.
Q. What would be the effect on an engine if the exhaust
opened too soon?
A. It would greatly lessen the power of the engine.
Q. What effect would too much lead have.
A. It would also weaken the engine, as the steam would
enter before the piston had reached the end of the stroke, and
would tend to prevent it passing the center.
Q. What is the stroke of an engine?
A. It is the distance the piston travels in the cylinder.
Q. How do you find the speed of a piston per minute?
A. Double the stroke and multiply it by the number of
revolutions a minuet. Thus an engine with a 12 inch stroke
would travel 24 inches, or 2 feet, at a revolution. If it made
200 revolutions a minute, the travel of piston would be 400 feet
a minute.
Q. What is considered a horse power as applied to an
engine?
A. It is power sufficient to lift 33,000 pounds one foot high
in one minute.
Q. What is the indicated horse power of an engine?
A. It is the actual work done by the steam in the
cylinder as shown by an indicator.
Q. What is the actual horse power?
A. It is the power actually given off by the driving belt and
pulley.
Q. How would you find the horse power of an engine?
A. Multiply the area of the piston by the average
pressure, less 5; multiply this product by the number of feet the
piston travels per minute; divide the product by 33,000; the
result will be horse power of the engine.
Q. How will you find the area of piston?
A. Square the diameter of piston and multiply it by .7854.
Q. What do you mean by squaring the diameter?
A. Multiplying it by itself. If a cylinder is 6 inches in
diameter, 36 multiplied by .7854, gives the area in square
inches.
Q. What do you mean by average pressure?
A. If the pressure on boiler is 60 pounds, and the engine is
cutting off at 1/2 stroke, the pressure for the full stroke would
be 50 pounds.
Q. Why do you say less 5 pounds?
A. To allow for friction and condensation.
Q. What is the power of a 7 x 10 engine, running 200
revolutions, cutting off at 1/2 stroke with 60 pounds steam?
A. 7 x 7 = 49 x .7854 = 38.4846. The average pressure of
60 pounds would be 50 pounds less 5 = 45 pounds; 38-4846 x
45 = 1731.8070 x .333 1/3, (the number of feet the piston
travels per minute) 577,269.0000 by 33,000=17 1/2 horse
power.
Q. What is a high pressure engine?
A. It is an engine using steam at a high pressure and
exhausting into the open air.
Q. What is a low pressure engine?
A. It is one using steam at a low pressure and exhausting
into a condenser, producing a vacuum, the piston being under
steam pressure on one side and vacuum on the other.
Q. What class of engines are farm engines?
A. They are high pressure.
Q. Why?
A. They are less complicated and less expensive.
Q. What is the most economical pressure to carry on high
pressure engine?
A. From 90 to 110 pounds.
Q. Why is high pressure more economical than low
pressure?
A. Because the loss is greater in low pressure owing to the
atmospheric pressure. With 45 pounds steam the pressure
from the atmosphere is 15 pounds, or 1/3, leaving only 30
pounds of effective power; while with 90 pounds the
atmospheric pressure is only 1-6 of the boiler pressure.
Q. Does it require any more fuel to carry I00 pounds than it
does to carry 60 pounds?
A. It don't require quite as much.
Q. If that is the case why not increase the pressure beyond
this and save more fuel?
A. Because we would soon pass the point of safety in a
boiler, and the result would be the loss of life and property.
Q. What do you consider a safe working pressure on a
boiler?
A. That depends entirely on its diameter. While a boiler of
30 inches in diameter 3/8 inch iron would carry I40 pounds, a
boiler of the same thickness 80 inches in diameter would have
a safe working pressure of only 50 pounds, which shows that
the safe working pressure decreases very rapidly as we increase
the diameter of boiler. This is the safe working pressure for
single riveted boilers of this diameter. To find the safe
working pressure of a double riveted boiler of same diameter
multiply the safe pressure of the single riveted by 70, and
divide by 56, will give a safe pressure of a double riveted
boiler.
Q. Why is a steel boiler superior to an iron boiler?
A. Because it is much lighter and stronger.
Q. Does boiler plate become stronger or weaker as it
becomes heated?
A. It becomes tougher or stronger as it is heated, till it
reaches a temperature Of 550 degrees when it rapidly
decreases its power of resistance as it is heated beyond this
temperature.
Q. How do you account for this?
A. Because after you pass the maximum temperature
of 550 degrees, the more you raise the temperature the nearer
you approach its fusing point when its tenacity or resisting
power is nothing.
Q. What is the degree of heat necessary to fuse iron?
A. 2912 degrees.
Q. Steel?
A. 2532 degrees.
Q. What class of boilers are generally used in a threshing
engine?
A. The flue boiler and the tubular boiler.
Q. About what amount of heating and grate surface is
required per horse power in a flue boiler.
A. About 15 square feet of heating surface and 3/4 square
feet of grate surface.
Q. What would you consider a fair evaporation in a flue
boiler?
A. Six pounds of water to I pound of coal.
Q. How do these dimensions compare in a tubular boiler.
A. A tubular boiler will require I/4 less grate surface, and
will evaporate about 8 pounds of water to I pound of coal.
Q. Which do you consider the most available?
A. The tubular boiler.
Q. Why?
A. It is more economical and is less liable to "collapse?"
Q. What do you mean by "collapse?"
A. It is a crushing in of a flue by external pressure.
Q. Is a tube of a large diameter more liable to collapse than
one of small diameter?
A. Yes.
Q. Why?
A. Because its power of resistance is much less than a tube
of small diameter.
Q. Is the pressure on the shell of a boiler the same as on the
tubes?
A. No.
Q. What is the difference?
A. The shell of boiler has a tearing or internal pressure
while the tubes have a crushing or external pressure.
Q. What causes an explosion?
A. An explosion occurs generally from low water, allowing
the iron to become overheated and thereby weakened and
unable to withstand the pressure.
Q. What is a "burst?"
A. It is that which occurs when through any defect the water
and steam are allowed to escape freely without further injury
to boiler.
Q. What is the best way to prevent an explosion or burst?
A. (I) Never go beyond a safe working pressure. (2) Keep
the boiler clean and in good repair. (3) Keep the safety valves
in good shape and the water at its proper height.
Q. What is the first thing to do on going to your engine in
the morning?
A. See that the water is at its proper level.
Q. What is the proper level?
A. Up to the second gauge.
Q. When should you test or try the pop valve?
A. As soon as there is a sufficient pressure.
Q. How would you start your engine after it had been
standing over night?
A. Slowly.
Q. Why?
A. In order to allow the cylinder to become hot, and that the
water or condensed steam may escape without injury to the
cylinder.
Q. What is the last thing to do at night?
A. See that there is plenty of water in boiler, and if the
weather is cold drain all pipes.
Q. What care should be taken of the fusable plug?
A. Keep it scraped clean, and not allow it to become
corroded on top.
Q. What is a fusible plug?
A. It is a hollow cast plug screwed into the crown sheet or
top of fire box, and having the hollow or center filled with lead
or babbit.
Q. Is such a plug a protection to a boiler?
A. It is if kept in proper condition.
Q. Can you explain the principle of the fusible or soft plug
as it is sometimes called?
A. It is placed directly over the fire, and should the water
fall below the crown sheet the lead fuses or melts and allows
the steam to flow down on top of the fire, destroys the heat and
prevents the burning of crown sheet.
Q. Why don't the lead fuse with water over it?
A. Because the water absorbs the heat and prevents it
reaching the fusing point.
Q. What is the fusing point of lead?
A. 618 degrees.
Q. Is there any objection to the soft plug?
A. There is, in the hands of some engineers.
Q. Why?
A. It relieves him of the fear of a dry crown sheet, and gives
him an apparent excuse for low water.
Q. Is this a real or legitimate objection?
A. It is not.
Q. What are the two distinct classes of boilers?
A. The externally and internally fired boilers.
Q. Which is the most economical?
A. The internally fired boiler.
Q. Why?
A. Because the fuel is all consumed in close contact with the
sides of furnace and the loss from radiation is less than in the
externally fired.
Q. To what class does the farm or traction engine belong?
A. To the internally fired.
Q. How would you find the H.P. of such a boiler?
A. Multiply in inches the circumference or square of
furnace, by its length, then multiply, the circumference of one
tube by its total length, and this product by the number of
tubes also taking into account the surface in tube sheet, add
these products together and divide by I44, this will give you
the number of square feet of heating surface in boiler. Divide
this by 14 or 15 which will give the H.P. of boiler.
Q. Why do you say 14 or 15?
A. Because some claim that it requires 14 feet of heating
surface to the H.P. and others 15.
To give you my personal opinion I believe that any of the
standard engines today with good coal and properly handled,
will and are producing 1 H.P. for as low as every 10 feet of
surface. But to be on the safe side it is well to divide by 15 to
get the H.P. of your boiler, when good and bad fuel is
considered.
Q. How would you find the approximate weight of a boiler
by measurement?
A. Find the number of square feet in surface of boiler and
fire box, and as a sheet of boiler iron or steel 1/16 of an inch
thick, and one foot square, weighs 2.52 pounds, would
multiply the number of square feet by 2.52 and this product by
the number of 16ths or thickness of boiler sheet, which would
give the approximate, or very near the weight of the boiler.
Q. What would you recognize as points in a good engineer.
A. A good engineer keeps his engine clean, washes the
boiler whenever he thinks it needs it. Never meddles with his
engine, and allows no one else to do so.
Goes about his work quietly, and is always in his place,
only talks when necessary, never hammers or bruises any part
of his engine, allows no packing to become baked or burnt in
the stuffing box or glands, renews them as quick as they show
that they require it.
Never neglects to oil, and then uses no more than is
necessary.
He carries a good gauge of water and a uniform pressure
of steam. He allows no unusual noise about his engine to
escape his notice he has taught his ear to be his guide.
When a job is about finished you will see him cleaning
his ash pan, getting his tools together, a good fire in fire box,
in fact all ready to go, and he looses no time after the belt is
thrown off. He hooks up to his load quietly, and is the first
man ready to go.
*Q. When the piston head is in the exact center of cylinder, is
the engine on the quarter?
*A. It is supposed to be, but is not.
*Q. Why not?
A. The angularity of the rod prevents it reaching the quarter.
*Q. Then when the engine is on the exact quarter what
position does the piston head occupy?
A. It is nearest the end next to crank.
Q. If this is the case, which end of cylinder is supposed to be
the stronger?
A. The opposite end, or end furtherest from crank.
Q. Why?
A. Because this end gets the benefit of the most travel, and
as it makes it in the same time, it must travel faster.
*Q. At what part of the cylinder does the piston head reach
the greatest speed?
A. At and near the center.
*Q. Why?
Figure this out for yourself.
*Note. The above few questions are given for the purpose of getting
you to notice the little peculiarities of the crank engine, and are not
to be taken into consideration in the operation of the same.
Q. If you were on the road and should discover that you had
low water, what would you do?
A. I would drop my load and hunt a high place for the front
end of my engine, and would do it quickly to.
Q. If by some accident the front end of your engine should drop
down allowing the water to expose the crown sheet, what
would you do?
A. If I had a heavy and hot fire, would shovel dirt into the
fire and smother it out.
Q. Why would you prefer this to drawing the fire?
A. Because it would reduce the heat at once, instead of
increasing it for a few minutes while drawing out the hot bed of
coals, which is a very unpleasant job.
Q. Would you ever throw water in the fire box?
A. No. It might crack the side sheets, and would most
certainly start the flues.
Q. You say, in finding low water while on the road, you
would run your engine with the front end on high ground. Why
would you do this?
A. In order that the water would raise over the crown sheet,
and thus make it safe to pump up the water.
Q. While your engine was in this shape would you not
expose the front end of flues'?
A. Yes, but as the engine would not be working this would
do no damage.
Q. If you were running in a hilly country how would you
manage the boiler as regards water?
A. Would carry as high as the engine would allow, without
priming.
Q. Suppose you had a heavy load or about all you could
handle, and should approach a long steep hill, what condition
should the water and fire be to give you the most advantage?
A. A moderately low gauge of water and a very hot fire.
Q. Why a moderately low gauge of water?
A. Because the engine would not be so liable to draw the
water or prime in making the hard pull.
Q. Why a very hot fire?
A. So I could start the pumps full without impairing or
cutting the pressure.
Q. When would you start your pump?
A. As soon as fairly started up the hill.
Q. Why?
A. As most hills have two sides, I would start them full in
order to have a safe gauge to go down, without stoping to pump
up.
Q. What would a careful engineer do before starting to pull
a load over a steep hill?
A. He would examine his clutch, or gear pin.
Q. How would you proceed to figure the road speed of
traction.
A. Would first determine the circumference of driver, then
ascertain how many revolutions the engine made to one of the
drivers. Multiply the number of revolutions the engine makes
per minute by 60, this will give the number of revolutions of
engine per hour. Divide this by the number of revolutions the
engine makes to the drivers once, and this will give you the
number of revolutions the drivers will make in one hour, and
multiplying this by the circumference of driver in feet, and it
will tell you how many feet your engine is traveling per hour,
and this divided by 5280, the number of feet in a mile, would
tell you just what speed your engine would make on the road.
THINGS HANDY FOR THE ENGINEER
____________
The first edition of this work brought me a great many letters asking
where certain articles could be procured, what I would recommend, etc.
These questions required attention and as the writers had bought and
paid for their book it was due them that they get the benefit of my
experience, as nothing is so discouraging to the young engineer as to be
continually annoyed by unreliable and inferior fittings used more or
less on all engines. I have gone over my letter file and every article
asked for will be taken up in the order, showing the relative importance
of each article in the minds of engineers. For instance, more letters
reached me asking for a good brand of oil than any other one article.
Then comes injectors, lubricators have third place, and so on down the
list. Now without any intention of advertising anybody's goods I will
give you the benefit of my years of experience and will be very careful
not to mention or recommend anything which is not strictly first class,
at least so in my opinion, and as good as can be had in its class, yet
in saying that these articles are good does not say that others are not
equally as good. I am simply anticipating the numerous letters I
otherwise would receive and am answering them in a lump bunch. If you
have no occasion to procure any of these articles, the naming of them
will do no harm, but should you want one or more you will make no
mistake in any one of them.