GETTING UP THE HILL.
SPECIAL SKILL AND ATTENTION REQUIRED
TO GET A TRAIN UP A STEEP GRADE.
IN the last chapter, some details were given of the
methods pursued in starting out with a heavy fast freight train.
Where a train of that kind has to climb heavy grades, special
skill and attention are needed in making the ascent successfully.
GETTING READY FOR THE GRADE.
The track for the first two miles from the starting
point is nearly level, permitting the engineer and fireman to
get ready for a long pull not far distant. At the second mile-post
a light descending grade is reached, which lasts one mile, and
is succeeded by an ascending grade two and a half miles long,
rising fifty-five feet to the mile.
WORKING UP THE HILL.
At the top of the descending grade, the engineer shuts
off the steam while the fireman oils the valves: then he puts
on a little steam, using a light throttle while the train is increasing
in speed, until the base of the ascent is nearly reached, when
he gets the throttle full open, letting the engine do its best
work in the first notch off the center. By this time the train
is swinging along thirty miles an hour, and is well on to the
hill before the engine begins to feel its load. Decrease of speed
is just becoming perceptible when the valve-travel gets the benefit
of another notch, and the engine pulls at its load with renewed
vigor. But soon the steepness of the ascent asserts itself in
the laboring exhausts; and the reverse-lever is advanced another
notch, to prevent the speed from getting below the velocity at
which the engine is capable of holding the train on this grade.
While the engineer is careful to maintain the speed within the
power of his locomotive, he is also watchful not to increase the
valve-travel faster than his fire can stand it; for, were he to
jerk the lever two or three notches ahead at the beginning of
the pull, the chances would be that he would "turn"
its fire, or tear it up so badly that the steam would go back
on him before he got half a mile farther on. Before the train
is safe over the summit, it will probably be necessary to have
the engine working down to 18 inches: but the advance to this
long valve-travel is made by degrees; each increase being dependent
upon, and regulated by, the speed. The quadrant is notched to
give the cutoff at 6, 9, 12, 15, 18, and 21 inches. Repeated experiments,
carefully watched, have convinced the engineer of this locomotive,
that its maximum power is exerted in the 18-inch notch; so he
never puts the lever down in the "corner" on a hill.
A great many engines act differently, however, showing increased
power for every notch advanced. If the cars in the train should
prove easy running, and there are great differences in
cars in this respect, it may not be necessary to hook the
engine below 15 inches, or even 12 will suffice for some trains;
but this can only be determined by seeing how it holds the speed
in the various notches.
As the engine gets well on to the grade, and is exerting
heavy tractive power, the wheels are liable to commence slipping;
and it is very important that they should be prevented from doing
so. An ounce of prevention is known to be worth a pound of cure;
and it pays an engineer to assure himself that no drips from pump-glands,
or feed-pipes, or cylinder-cocks, or from any other fountain,
are dropping upon the rails ahead of the driving-wheels. There
is no use telling an engineer of the decreased adhesion which
the drivers exert on half-wet rails, from what they do on those
that are clean and dry. Knowing the difference in this respect,
every engineer should endeavor to prevent the wetting, of the
rails by leaks from his engine; for hundreds of engines get "laid
down" on hills from slipping induced by this very cause.
HOW TO USE SAND.
The first consideration in this regard is to have clean, dry sand,
and easy-working box-valves. Then the engineer should know how
far the valves open by the distance be draws the lever. In starting
from a station, or working at a point where slipping is likely
to commence, the valves should be opened a little, and a slight
sprinkling of sand dropped on the rails. This often serves the
purpose of preventing slipping just as well as a heavy coating
of sand. And it has none of the objectionable features of thick
sanding. Trains often get stalled on grades by the sand-valves
being allowed to run too freely. It is not an uncommon occurrence
for engineers to open the valves wide, and let all the sand run
upon the rails that the pipe will carry, so that a solid crust
covers each rail, and every wheel on the train gets clogged with
the powdered silica, and, after the train has passed over, a coating
is left for the next one that comes along.
The wheels scatter their burden of powdered sand into the axle-boxes,
and it grinds its way inside the rod-brasses, and part of it gets
wafted upon the guides; and in all these positions it is matter
decidedly in the wrong place. And this body of sand under the
wheels increases the resistance in the same way, as a wagon is
harder to pull among gravel than it is on a clean, hard road:
the indiscreet engineer complains about the train being stiff
to haul; and the chances are, that he goes twice up the hill before
the whole train is got over. Uncle Toby's plan is, when pulling
on a heavy grade, to open the valve enough to let the drivers
leave a slight white impression on the rails. If they slip, he
gives a few particle's more sand, but decreases the supply again
so soon as the drivers will hold with the diminished quantity.
Uncle Toby seldom needs to double a hill.
These, remarks apply to ordinary engines with ordinary
rail-conditions. Occasionally we find an engine inveterately given
to slipping, and no conditions seem able to keep it down. Such
an engine is as ready to whirl its wheels as an ugly mule is to
kick up its heels, and upon as little provocation. With a dirty,
half-wet rail, an engine of this kind loses half its power. The
causes that make an engine bad for slipping are various. Very
hard steel tires, or excess of cylinder power, are the most frequent
causes of slipping; but badly worn tires sometimes produce a similar
effect; or the blame may rest in a short-wheel base, deficient
in weight, or in too flexible driving-springs. To get a slippery
engine over the road when the rails are moist and dirty, requires
the exercise of unmeasured patience by the engineer. Job was a
cantankerous old Arab beside the engineer who passes cheerfully
through this ordeal. The tendency of an engine to slip may be
checked to some extent by working with the lever well ahead towards
full stroke, and throttling the steam. This gives a more uniform
piston-pressure than is possible while working expansively. Of
two evils, it is best to choose the least. The smallest in this
case is losing the benefits of expansion, and getting over the
FEEDING THE BOILER.
Some engineers claim that the most economical results
can be obtained from an engine by running with the water as low
as possible, consistent with safety. They hold, that, so long
as the water is sufficiently high to cover the heating-surfaces,
there is enough to make steam from; and the ample steam-room remaining
above the water, assures a more perfect supply of dry steam for
the cylinders than can be had from the more contracted space left
above a high-water line.
Old engineers, running locomotives furnished with entirely reliable
feeding-apparatus, may be able to carry a low-water level advantageously,
especially with light trains and level roads; but with ordinary
men, average pumps or injectors, and the common run of roads,
a high-water level is safest. With a high-water level the temperature
of the boiler can be kept nearly uniform; for the increased volume
of water holds an accumulated store of heat, which is not readily
affected by the feed. And the surplus store is convenient to draw
upon in making the best of a time-order, or in getting over a
heavy grade. Then, if the pumps or injectors fail, a full boiler
of water often enables a man to examine the delinquent feeding-apparatus,
and set it going; whereas, with low water, the only resource would
be to dump the fire.
CHOICE OF PUMP AND INJECTOR.
The engine on this train has one pump and one injector.
The pump is preferred for ordinary feeding purposes, and is kept
graduated to supply the needs of the boiler while the engine is
working, without the foot-cock being moved. On a heavy pull, the
pump in this condition would not keep up the water-level; so the
injector is called upon to make up the deficiency. When the engine
gets upon the heavy part of the grade, it makes steam very freely;
and, when the indications of getting hot appear, the injector
is started. During the remainder of the ascent; the water is supplied
as liberally as it can be carried; and the top of the grade finds
the engine with a full boiler. This enables the engineer to preserve
a tolerably even boiler temperature; for in running down the long
descent which follows, where the engine runs two miles without
working steam, the pump can be shut off, and sudden cooling of
the boiler avoided. The preservation of flues and fire-box sheets
depends very much upon the manner of feeding the water. Some men
are intensely careless in this matter. In climbing a grade, they
let the water run down till there is scarcely enough left to cover
the crown sheet when they reach the summit. Then they dash on
the feed, and plunge cold water into the hot boiler, which is
then, peculiarly liable to be easily cooled down, owing to the
limited quantity of hot water it contains. The fact of having
the steam shut off, greatly aggravates the evil; for there is
then no intensity of heat passing through the flues to counteract
the chilling effect of the feed-water. If it is necessary to pump
while running with the steam shut off, the blower should be kept
going; which will, in some measure, prevent the change of temperature
from being dangerously sudden. There will probably be some loss
from steam blowing off, but that is the smaller of two evils.
Engineers are not likely to feed the boiler too lavishly when
working hard, for the injection of cold water instantly shows
its effect by reducing the steam-pressure. But this is not the
case when running with the throttle closed. The circulation in
the boiler is then so sluggish, that the temperature of the water
may be reduced many degrees, while the steam continues to show
its highest pressure.
Writers on physical science tell us that the temperature of water
and steam in a boiler is always the same, and varies according
to pressure; that, at the atmosphere's pressure, water boils at
212 degrees, and produces steam of the same temperature. At 10
pounds above the atmospheric pressure, the water will not evaporate
into steam until it has reached a temperature of 240 degrees,
and so on: as the pressure increases, the temperature of water
and steam rises. But under all circumstances, while the water
and steam remain in the same vessel, their temperature is the
same. This is an acknowledged law of physical science; yet every
locomotive engineer of reflection, who has run on a hilly road,
knows that circumstances daily happen where the law does not hold
FALL OF BOILER-TEMPERATURE NOT INDICATED
BY THE STEAM GAUGE.
If an engine, of the class represented as pulling our
train, passes over the top of the grade with half an inch of water
in the glass, there will be about 700 gallons in the boiler. Now,
suppose it runs down the hill without using steam, and keeps pumping
till the water rises six inches in the glass, there will be about
200 gallons more water in the boiler. It is no unusual thing to
do this with a mild fire, and yet have no diminished tension of
steam shown by the gauge, although 200 gallons of water of about
60 degrees have been injected amongst 700 gallons at 361 degrees,
the temperature due to a steam-pressure of 140 pounds. This ought
to reduce the mean temperature below 300 degrees, yet the pointer
of the steam-gauge keeps indicating 140. That the pressure of
steam and the temperature of the water do not accord, is shown
directly the throttle is opened perform work. The brisk circulation
due to the rush of steam through the dry pipe now brings the temperature
of water and steam to equilibrium, and backward the index of the
steam-gauge travels. The steam-pressure goes back faster than
is due to the supply drawn for the cylinders; because the latent
heat of the steam passes into the water, helping to bring the
whole contents of the boiler to an even temperature.
SOME EFFECTS OF INJUDICIOUS BOILER-FEEDING.
Meanwhile, with an engine operated in this fashion,
the train will probably stand for fifteen minutes, till sufficient
steam is raised to proceed with.
The fact that newly injected water does not immediately rise in
temperature to the heat indicated by the pressure-gauge, can also
be tested by filling up a boiler with an injector while the engine
is at rest on a sidetrack. Working an injector causes greater
circulation than feeding with a pump, and the water goes into
the boiler at a higher temperature. For this reason the injector
is superior to the pump as a feeding-medium. But, if the engineer
pulls out directly after filling up the boiler with an injector,
the steam will go down a few pounds, no matter how good a fire
may be on the grates.
On level roads, the pump or injector should be set to supply the
needs of the boiler; and a skillful engineer can regulate this
so well, that the foot-cock has seldom to be moved. The best results
in getting trains over the road, and in preserving boilers, are
obtained in this way. The runner who adopts the intermittent system
of feeding is always in trouble, or, as the boys say, "he
is always nowhere."
CAREFUL FEEDING AND FIRING PRESERVE BOILERS.
A case where the conservative effect of careful firing
,and feeding was strikingly illustrated, came under the author's
notice a year or two ago. During the busiest part of, the season,
the fire-box of a freight engine belonging to a Western road became
so leaky that the engine was really unfit for service. Engines,
like individuals, soon lose their reputation if they fail to perform
their required duties for any length of time. This engine, "29,"
soon became the aversion of train-men. The loquacious brakeman,
who can instruct every railroad-man how to conduct his business,
but is lame respecting his own work, got presently to making big
stories out of the amazing quantity of water and coal that "29"
could get away with, and how many trains she would hold in the
course of a trip. 'The road was suffering from a plethora of freight,
and extreme scarcity of engines; and on this account the management
was reluctant to take this weakling into the shop. So the master
mechanic turned "29" over to Engineer Macleay, who was
running on a branch where delays were not likely to hold many
trains. Mac deliberated about taking his "time" in preference
to the engine, which others had rejected, but finally concluded
to give the bad one a fair trial. The first trip convinced the
somewhat observant engineer that the tender fire-box was peculiarly
susceptible to the free use of the pump, and to sudden changes
of the fire's intensity of heat. So he directed the fireman to
fire as evenly as possible, never to let the grates get bare enough
to let cold air pass through, to keep the door closed except when
firing, to avoid violent shaking of the grates, and never to throw
more than three or four shovelfuls of coal into the fire-box at
one time. His own method was, to feed with persistent regularity,
to go twice over heavy parts of the division in preference to
distressing the engine by letting the water get low, and then
filling up rapidly. This system soon began to tell on the improved
condition of the fire-box. The result was, that, within a month
after taking the engine, Mac was pulling full trains on time;
and this he continued to do for five months, till it was found
convenient to take the engine in for rebuilding.
OPERATING THE DAMPERS.
According to the mechanical dictionary, a damper is
a device for regulating the admission of air to a furnace, with
which the fire can be stimulated, or the draught cut off, when
necessary. Some runners regard locomotive dampers in a very different
light. They seem to think the openings to the ash-pan are merely
holes made to let air in, and ashes out; that doors are placed
upon them, which troublesome rules require to be closed at certain
points of the road to prevent causing fires. Those who have made
their business a study, however, understand that locomotive dampers
are as useful, when properly managed, as are the dampers of the
base-burner which cheers their homes in winter weather. To effect
perfect combustion in the fire-box, a certain quantity of oxygen,
one of the constituents of common air, is required to mix with
the carbon and carbureted hydrogen of the coal. The combination
takes place in certain fixed quantities. If the quantity of air
admitted be deficient, a gas of inferior calorific power will
be generated. On the other hand, when the air-supply is in excess
of that needed for, combustion, the surplus affects the steam-producing
capabilities of the fire injuriously; since it increases the speed
of the gases, lessening the time they are in contact with the
water-surface, and a violent rush of air reduces the temperature
of portions of the fire-box below the heat at which carbureted
LOSS OF HEAT THROUGH EXCESS OF AIR.
In the fire-boxes of American engines, where double
dampers are the rule, far more loss of heat is occasioned by excess
of air than there is waste of fuel through the gases not receiving
their natural supply of oxygen. The blast from the nozzles creates
an impetuous draught through the grates; and when to this is added
the rapid currents of air impelled into the open ash-pan by the
violent motion of the train, the fire-box is found to be the center
of a furious wind-storm. The excess of this storm can be regulated
by keeping the front damper closed, and letting the engine draw
its supply of air through the back damper. When the fire begins
to get dirty, and the air-passages between the grates become partly
choked, the forward damper can be opened with advantage. So long
as an engine steams freely with the front damper closed, it is
an indication that there is no necessity for keeping it open.
With vicious, heavy firing, all the air that can be injected into
the fire-box is needed to effect indifferently complete combustion;
and the man who follows this wasteful practice can not get too
much air through the fire. Consequently, it is only with moderately
light firing that regulation of draught can be practiced. Running
with the front damper open all the time is hard on the bottom
part of the fire-box, and the ever-varying attrition of cold wind
is responsible for many a leaky mud-ring.
LOSS OF HEAT FROM BAD DAMPERS.
In Britain, where far more attention has been devoted
to economy of fuel than has been bestowed upon the matter this
side of the Atlantic, locomotives are provided with ash-pans that
are practically air-tight, and the damper-doors are made to close
the openings. In many instances, the levers that operate the dampers
have notched sectors, so that the quantity of air admitted may
equal the necessities of the fire. British locomotives, as a rule,
show a better record in the use of their fuel than is found in
American practice; and a high percentage of the saving is due
to the superior damper arrangements.
Imagine the trouble and expense there would be with a kitchen-stove
that had no appliance for closing the draught! Yet some of our
locomotive builders turn out their engines with practically no
means of regulating the flow of air beneath the fire.
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