_SHORTNESS OF WATER.--PUMP DISORDERS._
TROUBLE DEVELOPS NATURAL ENERGY.
Trouble and affliction are known to have a purifying and elevating
effect upon human character; difficulties encountered in the
execution of work, develop the skill of the true artisan; and trouble
on the road, or accidents to locomotives, furnish the engineer
with opportunities for developing natural energy, ingenuity, and
perseverance, if these attributes are in him, or they publish to his
employers his lack of these important qualities.
One of the most serious sources of trouble that an engineer can meet
with on the road, is shortness of water.
SHORTNESS OF WATER A SERIOUS PREDICAMENT.
Deficiency of steam with a locomotive that is expected to get a train
along on time, is a very trying condition for an engineer to endure.
But a more trying and more dangerous ordeal, is want of water. Where
steam is employed as a means of applying power, water must be kept
constantly over the heating-surfaces while the fire is incandescent, or
their destruction is inevitable. With a boiler which evaporates water
rapidly, and in such large quantities as that of the locomotive, the
most perfect feeding apparatus is necessary. Nearly all locomotives
are well supplied in this respect. Good pumps or efficient injectors
provide the engineer with excellent appliances for feeding the boiler
under ordinary circumstances. But conditions sometimes occur where the
best of pumps, or the most reliable of injectors, fail to force water
into the boiler.
HOW TO DEAL WITH SHORTNESS OF WATER.
When from any cause he finds the boiler getting short of water, the
engineer should resort to all known methods within his power to
overcome the difficulty, by removing the obstacle that is preventing
the feeding apparatus from operating. But, while doing so, the safety
of his fire-box and flues should not be overlooked for a moment. The
utmost care must be taken to quench the fire before the water gets
below the crown-sheet. This can be performed most effectually by
knocking the fire out; but sometimes the temporary increase of heat,
occasioned by the act of drawing the fire, is undesirable; and, in such
a case, the safest plan is to dampen the fire by throwing wet earth, or
fine coal saturated with water, upon it. Or a more urgent case still
may intervene, when drenching the fire with water is the only means
of saving the sheets from destruction. This should be a last resort,
however; for it is a very clumsy way of saving the fire-box, and is
liable to do no small amount of mischief. Cold water thrown upon hot
steel sheets, causes such sudden contraction, that cracks, or even
rupture, may ensue.
WATCHING THE WATER-GAUGES.
As “burning his engine” is the greatest disgrace that can
professionally befall an engineer, every man worthy of the name
guards against a possibility of being caught short of water unawares,
by frequent testing of the gauge-cocks. It is not enough to have
a good-working water-glass. If an engineer is ambitious to avoid
trouble, he runs by the gauge-cocks, using the glass as an auxiliary.
Careful experiments have demonstrated the fact, that the water-glass,
working properly, is a more certain indication of the water-level than
gauge-cocks; for, when the boiler is dirty, the water rises above its
natural level, and rushes at the open gauge-cock. This can be proved
when water is just below a gauge-cock level. If the cock is opened
slightly, steam alone passes out; but, when the full opening is made,
water comes. But water will not come through a gauge-cock, unless the
water-level is in its proximity; and an engineer can tell, when his
gauge shows a mixture of steam, that the water shown is not to be
relied upon. It is not “solid.” On the other hand, a water-glass out
of order sometimes shows a full head of water when the crown-sheet is
red-hot.
WHAT TO DO WHEN THE TENDER IS FOUND EMPTY BETWEEN STATIONS.
The most natural cause for pumps or injectors ceasing to work,
is absence of water from the tender. This condition comes round
on the road occasionally, where engineers neglect to fill up at
water-stations, or where there are long runs between points of
water-supply. When an engineer finds himself short of water, and the
means of replenishing his tank too distant to reach, even with the
empty engine, he should bank or smother the fire, and retain sufficient
water in the boiler to raise steam on when he has been assisted to the
nearest water-tank. This will save tedious delay, especially where an
engine has no pumps. Occasionally, from miscalculations or through
accidents, the fire has to be quenched, and insufficient water is left
in the boiler to start a fire on safely. In this event, buckets can be
resorted to, and the boiler filled at the safety-valves, should there
be no assistance, or means of pumping up. Every possible means should
be exhausted to get the engine in steam, before a runner requests to
have his engine towed in cold.
A TRYING POSITION.
I once knew a case where an engineer inadvertently passed a water-tank
without filling his tender. He had a heavy train, and was pushing along
with a heavy fire, on a severe, frosty night, when every creek and
slough by the wayside was lost in heavy ice. Presently his pump stopped
working, and he spent some time trying to start it before he discovered
that the tender was empty. By the time this fact became known, his
boiler-water was low, and a heavy fire kept the steam screaming at the
safety-valves. He had no dump-grate, and the fire was too heavy to
draw. It seemed a clear case of destroying the fire-box and flues. But
he was a man of many resources. First, he tried to get water through
the gauge-cock--he had only one gauge--to quench the fire, but found
the plan would not work. Then he filled up the fire-box nearly to the
crown-sheet with the smallest coal on the tender, and partly smothered
the fire. He then partly opened the smoke-box door, and started for
the water-station. After getting the engine going, he hooked the
reverse-lever in the center, and kept the throttle wide open, to make
the most of the steam-supply. He saved his engine.
WATCHING THE STRAINERS.
When the top of a tank is in bad order, and permits cinders and small
pieces of coal to fall through rivet-holes, or through seams, the
engineer may look out for grief with his pumps or injectors. On the
first signs of the water failing, he should examine the strainers;
and he will probably find that these copper perforations, which stand
like wardens guarding the safety of the pumps and injectors, have
accumulated a mass of cinders that obstructs the flow of the water.
CARE OF PUMPS.
Mechanical prognostications seem to indicate that pumps, as locomotive
attachments, have outgrown their usefulness, and that their days are
numbered. They have done good service while no better method of feeding
locomotive boilers was known; but, since the advent of injectors, pumps
have begun to disappear. They still hold their own, however, on a great
many roads; and a description of their management will be of general
interest.
HOW THE CONDITION OF PUMPS CAN BE TESTED.
If an engineer is in the habit of pumping regularly, and of watching
his engine closely, he can tell immediately from the steam when the
pump stops working. Then he will open the pet-cock; and its action
will indicate, to some extent, where the trouble lies. If the pet-cock
throws a feeble stream of water, the trouble probably is in the lower
valve. If that sticks up, or part of the bottom cage breaks, the
plunger will push the water back into the feed-pipe on the return
stroke, consequently there will be no pressure to throw a strong stream
through the pet-cock. When the upper or pressure-valve is damaged, or
is stuck up, the pet-cock will throw a full stream during the inward
stroke of the plunger; but, on the outward stroke, the plunger will
draw the water out of the branch-pipe, and air will be sucked in at
the open pet-cock. When the check-valve is damaged, or stuck up, steam
and water will blow back through the branch-pipe when the pet-cock
is left open. If the steam thus escaping from the check-valves heats
the pump and valves to a high temperature, it will be prevented from
working, from several causes. The heat generates a low form of steam,
which fills up the space behind the plunger; therefore, no vacuum is
formed to draw the water. Not infrequently the pump-valves expand so
much from the heat, that they stick fast away from their seats. If the
pump has stopped through the presence of impurities on either of the
valves or cages, the engineer knows that he may remove the obstruction
by steam-pressure; so, after letting the feed-pipe fill with water, he
opens the heater-cock, and closes the foot-cock, letting the steam and
water blow through the pump. If he considers the obstruction to be in
the strainer, and has not time to stop and take it down, he blows steam
from the heater through to the tender, which gives temporary relief.
If any of the pump-valves are stuck up, and can not be got back to
their seats by blowing water and steam through them, the engineer will
take a soft hammer, and tap the seats lightly, with good prospects of
remedying the defect. In case no improvement can be effected in that
way, and there is no other feeding-medium to rely upon, the engineer
can take down the top or bottom chamber in a few minutes to remove any
impurities that may be keeping the pump from working. He will then be
likely to find a piece of packing that has passed through the pump,
bushing, or some other foreign substance, jammed between the cage and
the valve, keeping the latter immovable. Or the trouble may be a broken
valve or cage, which will render the pump useless till repaired.
LIFT OF PUMP-VALVES.
When a pump-valve has much lift, it is very liable to pound itself or
the cage so heavily that breakage occurs. The proper lift required for
pump-valves depends to some extent upon the diameter of the valves
themselves, those of liberal thickness requiring less lift than a
valve of narrow compass. The engine pulling our train has pump-valves
two and one-half inches in diameter: the pump-plunger, being worked
from the cross-head, has a diameter of two inches. The bottom valve
has three-thirty-seconds of an inch of lift, the middle valve has
one-eighth of an inch of lift, and the check-valve rises one-fourth of
an inch. These dimensions produce very satisfactory results for all
speeds. The pump performs its work with remarkable smoothness, is free
from pounding or fluctuating, and gives no trouble about repairs.
Engines employed on fast passenger service have their valve-lifts
one-thirty-second of an inch less than this one, and slow freight
engines are regulated to rise one-sixteenth of an inch more than the
dimensions given.
KEEP PIPES TIGHT, AND PACKING IN ORDER.
In order to insure the regular and satisfactory working of a pump, care
should be taken to prevent leaks about the feed-pipes or heater-pipes:
the packing should be kept in good order, and the chamber-joints should
be perfectly air-tight. During the outward stroke of the plunger, a
vacuum should be produced inside the pump, into which the water rushes.
If this vacuum gets partly filled with air or vapor, the working of
the pump will be unsatisfactory. Nothing is so liable to produce this
undesirable condition as badly packed glands or leaky joints. A poor
pump can often be made to produce fair work, by attention and care
bestowed upon its attachment; and lack of care will soon render the
best-constructed pump unreliable.
SAND IN THE PUMP-CHAMBERS.
The pump has one arch-enemy, which comes off victor in every conflict.
That is sand. The railway idiom which uses the word “sand” to express
courage, originated in the knowledge of how certainly and quickly a
handful of sand would vanquish the best pump that mechanical skill
might produce. The grit works its way among the packing, and tears and
cuts the plunger out of shape: it insinuates itself up between the
cages and valves, and holds the latter so fast that hard hammering is
often needed to dissolve the compact. Proper washing out of the tank,
cleansing of feed-pipes, and the use of water free from sand, is the
only sure remedy for this evil. Where an engineer is situated so that
he must take water containing sand in suspension, partial relief will
be obtained by giving the valves free side-room in the cages; but an
injector will be found much superior to a pump as a means of putting
sand-contaminated water into a boiler.
DELIVERY ORIFICE CHOKED WITH LIME SEDIMENT.
When a pump begins to show distress from over-pressure,--which will
be indicated by the breaking out of joints, the rejection of stuffing
and box-packing, and the bursting of branch-pipe,--the orifice between
the check and the boiler should be examined; for that aperture often
becomes almost closed by the accumulation of lime-salts.
MINOR PUMP TROUBLES.
Where the feed-pipes and other connections are perfectly air-tight,
some pumps will pound badly when the water is shut off. This can
be prevented by making a minute hole in the feed-pipe; or a more
convenient place is the upper part of the heater-pipe, away above the
water-level.
Should the valves of a pump be leaky on their seats, the pump will
not work satisfactorily. Where the lower valve is not properly ground
on the seat, the plunger sucks air from the feed-pipe, or through the
joints or packing, and, at the return stroke, compresses part of the
air in the pump, and forces the remainder back into the feed-pipe
through the leaky valve. This process goes on after the feed is put
on; the accumulated air stands like a cushion between the plunger
and the water; and the pump will not go to work until the pet-cock
is opened, when the air rushes out, permitting the water to flow in.
Engineers having pumps that will not work till the pet-cock is opened,
should have the suction-valve ground in; and they will find a decided
improvement from the operation.
For slow train service, pumps perform the service of boiler-feeding
fairly well; but, for fast passenger trains, a pump should not be
tolerated. A pump can not be constructed for high-speed engines that
will throw water regularly at high velocity of stroke.