ACCIDENTS TO THE VALVE-MOTION.
RUNNING WORN-OUT ENGINES.
Some of our most successful engineers, the men who pull our most
important trains daily on time, attribute their good fortune in
avoiding delays, to training they received in youth, while running
or firing worn-out engines that could only be kept going by constant
attention and labor. In such cases men must resort to innumerable
makeshifts to get over the road; they have frequently to dissect
the machinery to remedy defects; they learn in the impressive
school of experience how a broken-down engine can best be taken
home, and how breaking down can best be prevented. Firemen and
young engineers, generally feel aggrieved at being assigned to
run on worn-out engines, the scrap heaps as they are called:
but the man who has not passed through this ordeal has missed
a Golconda of experience; his potentialities are petrified without
CARE AND ENERGY DEFY DEFEAT.
Among a certain class of seafaring men, the captain of a ship
who fails from any cause to bring his vessel safely into port,
is regarded as disgraced; and, therefore, a true sailor will use
superhuman efforts to prevent his ship from becoming derelict,
often preferring to follow it to the bottom rather than abandon
his trust. In many instances the sentiments and traditions of
seamen teach railroad men valuable lessons. The sacrifice of life
is not desired or expected of engineers in their care of the vessel
they command; but every engineer worthy of the name will spare
no personal exertion, will shrink from no hardship, that will
be necessary to prevent his charge from becoming derelict. Once
I heard a hoary engineer, who had become gray on the footboard,
make the proud boast, "My engine never was towed in."
His calm words conveyed an eloquent sermon on care and perseverance.
He had been in many hard straits, he had been in collisions, he
had been ditched with engines, but had always managed to get them
home without assistance.
WATCHING THE EXHAUST.
What the beating pulse is as an aid to the physician in diagnosing
diseases, the sound of the exhaust is to the engineer as a means
of enabling him to distinguish between perfective and defective
working of the locomotive The ability to detect a slight derangement
by the sound of the exhaust, can only be acquired by practice
in watching those steam-notes day after day, as they play their
tune of labor through the smokestack. When the steam-ports are
even, and the valves correctly set, with tight piston-packing,
and valves free from leaks, the notes of the exhaust will sound
forth in regular succession in sharp, ringing, clear tones, every
puff seeming to cut the steam clean off at the top of the stack.
There is a long array of defects represented in the journey from
this case of apparently perfect steam performance, to that where
the exhaust steam escapes as an unbroken roar mixed with uncertain,
THE ATTENTIVE EAR DETECTS DETERIORATION
The deterioration of piston-packing, and the rounding of valve-seats,
which produce an asthmatic exhaust, may be followed in their downward
course if the engineer gets into the habit of listening to the
exhaust, and marking its changes. It is very important that he
should do so. The man whose ear from long practice has become
sensitive to a false tone of the exhaust, needs not to make experiments,
by applying steam to the engine while it stands in various positions,
in order to find out where a blow comes from, whether it
is in the pistons or in the valves.
LOCATING THE FOUR EXHAUST SOUNDS.
Leaning out of the cab-window, he watches the crank as it revolves,
and compares the noise made by the blowing steam with the crank
position. When pulling on a heavy grade is an excellent time for
noting imperfections in the working of valves and pistons; for
the movements are comparatively slow, while the pressure of steam
on the working-parts is so heavy that any leak sounds prominently
forth. The observing engineer perceives that the four sounds of
the exhaust, due to each revolution of the drivers, occur a few
inches before the crank reaches, first, the forward center, second,
the bottom quarter, third, the back center, fourth, the top quarter.
The first and third position exhausts emit the steam from the
forward and back strokes of the right-hand piston: the second
and fourth exhausts are due to discharges of the steam that has
been propelling the left-hand piston. With these facts impressed
upon his mind, he will understand, that if an intermittent blow,
occurs during the periods when the crank is traveling from the
forward center to the bottom quarter, or from the back center
to the top quarter, the chances will be that the right-hand piston
needs to be examined. For the greatest pressure of steam follows
the piston just after the beginning of each stroke, and that is
the time a blow will assert itself. Should the blow occur while
the right-hand crank is moving from the bottom quarter to the
back center, or from the top quarter to the forward center, it
will indicate that the left-hand piston is at fault. For at these
periods the left-hand cylinder is receiving its greatest pressure
IDENTIFYING DEFECTS BY SOUND OF THE STEAM.
It is generally understood that an intermittent or recurring blow
belongs to the pistons, and that a constant blow comes from the
valves. But sometimes the valves blow intermittently, being tight
at certain points of the travel, and leaky at other points. To
distinguish between the character of these blows is sometimes
a little difficult except to the thoroughly practiced ear. The
sound of the blow can be heard best when the door is open, and
the novice should not fail to listen for it under that condition.
The valve blow is a sort of wheeze, with the suggestion of a whistle
in it: the piston makes a clean, honest blow, which would break
into a distinct roar if enough steam could get through. But a
whistling sound in the exhaust is, by no means, a certain indication
of the valves blowing through; for sometimes the nozzles get clogged
up with a gummy substance from the lubricating oils, and a distinct
whistling exhaust results therefrom. With a watchful ear, the
progress of degeneration in the valves can be noted day, after
day; for it is a decay which goes on by degrees, the inevitable
slow destruction that friction inflicts upon rubbing surfaces.
Pistons are more erratic in their calls for attention. With them
it is quite common for a stalwart blow to start out without any
warning, the cause generally being broken packing rings. The various
kinds of steam packing seem more liable to have broken rings than
the old-fashioned spring packing, but they generally run longer
with less attention.
ACCIDENTS PREVENTED BY ATTENDING TO THE
NOTE OF WARNING FROM THE EXHAUST.
The habit of closely watching the exhaust is likely to prove serviceable
in more ways than in keeping the engineer posted on the condition
of the steam-distribution gear. Its sound often acts as a danger
alarm, which should never go unheeded. Many an engine has gone
home on one side, and not a few have been towed in cold, through
accidents to the valve-gear, which could have been prevented had
the engineer attended to the warning voice of a false exhaust.
The nuts work off an eccentric-strap bolt; and it drops out, letting
the strap open far enough to cause an uneven valve-travel. If
the engineer hears this, and stops immediately to examine the
machinery, he is likely to detect the defect before the strap
breaks. Again, one side of a valve yoke may have snapped, leaving
the other side to bear the load; or bolts belonging to different
parts of the links or eccentric-straps may be working out,
so that the uniformity of the valve-travel is affected; and the
same result may be produced by the eccentrics getting loose. Young
engineers, to whom these pages are addressed, should make up their
minds that an engine never exhausts an irregular note without
something being the matter which does not admit of running to
a station before being examined. It may only be an eccentric slipped
a little way, a mishap that is not calculated to result disastrously;
but, on the other hand, it is probably something of a more dangerous
NEGLECTING A WARNING.
Engineer Joy of the D. & E. road went in with a broken eccentric-strap.
Questioning him about the accident brought out the fact, that,
in starting from a station, he heard the engine make two or three
curious exhausts; but he was running on a time-order, and did
not wish to cause delay by stopping to examine the engine. But
he had not gone half a mile when he found it necessary to stop
and disconnect the engine, and by doing so held an express train
HOW AN ECCENTRIC-STRAP PUNCHED A HOLE
IN A FIRE-BOX.
A representative case of neglecting a plain warning happened on
an Illinois road some time ago. John Thomas was pulling a freight
train up a grade, when, to use his own words, "The engine
began to exhaust in the funniest way you ever heard. She would
get on to three legs for an engine length or so, then she would
work as square and true as she ever did, but only for a few turns,
when she got to limping again." This runner knew that something
was wrong, and he determined to examine the engine at the next
stopping point. But delays in such a case are full of peril. When
he got over the grade, and shut off steam, there was a tumultuous
rattling of the reverse-lever, succeeded by a fearful pounding
about the machinery; a tearing up of road-bed sent a shower of
sand and gravel over the train; then a scream from escaping steam
and water drowned all other noises, and the engine was enveloped
in a cloud of blinding vapor. The forward bolt of one of the eccentric-strap
rods had worked out, and allowed the end of the rod to drop on
the track. Then it doubled up, and tore away the whole side of
the motion; and part of a broken eccentric-strap knocked a hole
in the fire-box. Here was the progress towards destruction. A
small pin got lost, which permitted the nut of an important bolt
to unscrew itself; then this bolt, with many a warning jar and
jerk, escaped from its place in the link; and the conditions for
a first-class break-down had come round.
INTEREST IN THE VALVE--MOTION AMONG ENGINEERS.
Whenever locomotive engineers congregate in the round-house, in
the lodge or division room, a fruitful theme of conversation and
discussion is the valve-motion, Curious opinions are often heard
expressed upon this complex subject. There are comparatively few
men who understand it properly: but it has a fascination which
attracts all alike, the wise and the ignorant; and the man who
is altogether uncertain about the true meaning of lap and lead,
expansion and compression, is generally more loquacious on valve-motion
than the engineer who has made the subject an industrious study.
TROUBLE WITH THE VALVE-MOTION.
However well each may understand his business, in one respect
all engineers are in perfect harmony; that is, in hating to encounter
trouble with the valve-gear on the road. The valves being the
lungs of the machine, any injury. or defect to their connections
strikes at a vital organ. With a good valve-motion, and valves
properly set, the steam is distributed so that nearly an equal
amount is admitted through each part in regular rotation; the
release taking place in even succession. This makes the exhaust
notes uniform in pitch and period. A sudden departure from this
uniformity indicates that something is wrong with the valve-motion.
It should be the signal to stop, and institute a searching examination.
In doing so, avoid jumping at conclusions regarding the cause
of the irregularity, and coolly examine, separately, each part
whose motion influences the valve-travel.
A WRONG CONCLUSION.
Fred Bemis missed his luck by jumping too readily at conclusions.
Something happened to his engine; and he stopped by compulsion,
and found it would not move either way. He felt certain that both
eccentrics on one side had slipped; and, considering himself equal
to setting any number of eccentrics, he got down, and fixed them
in what he supposed was the proper position. But, on trying to
move the engine, he found it still refused to go. He kept working
at those eccentrics without result till his water got low, and
he was compelled to dump the fire; the consequence being, that
the engine went cold, and was towed home. When an examination
was made, it was found that a broken valve-yoke was the cause
LOCATING DEFECTS OF THE VALVE-MOTION.
When any thing goes wrong with the valve-motion, the first point
of investigation is, to find out which side is at fault. This
can be ascertained by opening the cylinder-cocks, and giving the
engine steam. With the reverse-lever in forward motion, the forward
cylinder-cocks should show steam when the crank-pins are traveling
below the axle, and the back cocks should blow when the pins make
their similar revolution above the axle. Any departure from this
method of steam distribution will make one side work against the
other. When the engineer has satisfied himself on which side the
defect lies, he will do well to thoroughly examine the eccentrics
with their straps and rods, the links with their hangers and saddles,
the rocker box and arms with all the bolts and pins connecting
these articles. What might be regarded as a trifling defect, sometimes
makes an engine lame. I have known a loose valve-stem key put
an engine badly out of square. Eccentric-rods, slipping, often
produce this effect. When the eccentrics are found in the proper
position, the rocker-box secure in the shaft, and all the bolts,
pins, and keys in good order, and in their proper positions, the
fault may be looked for in the steam-chest.
POSITION OF ECCENTRICS.
With engines where keys are not used to secure the eccentrics
to the shaft, their slipping on the road is a common occurrence.
Eccentric-strap oil-passages getting stopped up, or neglect in
not oiling these straps or the valves, puts an unnecessary tension
on the eccentrics, which often results in their slipping on the
shaft. Engineers ought to mark the proper position for eccentrics
on the shaft; so that, when slipping happens, it can be adjusted
without the delay that often occurs in calculating the right position.
When the crank-pin is on the forward center, the body of the go-ahead
eccentric is above the axle, and the body of the back-up eccentric
is below the axle, each of the eccentrics being advanced about
z of the revolution from the
right angle position towards the crank-pin; or, to state it more
accurately, the center of the eccentric is advanced a horizontal
distance to equal the lap and lead of the valve. If the valve
had neither lap nor lead, the eccentrics would stand exactly at
right angles to the crank. As it is, both of them have a tendency
to hug the crank; the eccentric which regulates the distribution
of steam following the crank. Every engineer should familiarize
himself with the correct position of eccentrics, so that, when
trouble happens with the valve-gear on the road, he will experience
no difficulty in grappling with the mishap.
METHOD OF SETTING SLIPPED ECCENTRICS.
The slipping of one eccentric is a trifling matter, which can
be quickly remedied if the set screws are in a position where
they can be reached conveniently. If it is a go-ahead eccentric,
set the engine on the center of the disabled side, no matter
which centerput the reverse-lever in the back notch of the
quadrant, and scratch a line with a knife on the valve-stem close
to the gland. Then put the lever in the forward notch, and move
the slipped eccentric till the line appears in the point where
it was made. Fasten the set screws, and the engine will be found
true enough to proceed with the train. Care must be taken in moving
the eccentric to see that the full part is not placed in the same
position as the other one, or they will both be set for back motion.
A back-up eccentric slipped, while the go-ahead one remains intact,
can be adjusted in a similar way; the scratch on the valve-stem
being made with the engine in full forward motion, and the adjustment
of the eccentric done in full back motion. The philosophy of this
method is, that the valve is in nearly the same position at the
beginning of the stroke for the forward or back motion; and the
position of the eccentric, which has not moved, is used to find
the proper place for the one which slipped. Should the unusual
circumstance of both eccentrics on one side slipping overtake
an engineer, he will have to pursue a different method of adjustment.
The most systematic plan is to place the engine on the forward
center, and set the go-ahead eccentric above the axle, and the
back-up eccentric below the axle. With the reverse-lever in the
forward notch, advance the top eccentric till the front cylinder-cock
shows steam, which can be ascertained by blocking the wheels,
and slightly opening the throttle. That will put the go-ahead
eccentric near enough to the proper position for running. For
the back-up eccentric, pull the reverse-lever into back motion,
and turn the eccentric towards the crank-pin till steam appears
at the front cylinder-cock; and that part of the motion will be
right. Or the back-up eccentric can be set by the forward eccentric
in the manner described where one eccentric has slipped.
Where slotted rods are used, they frequently slip, making the
engine lame. The cause of trouble in such a case can be identified
by moving the engine slowly, with the cylinder-cocks open. The
disturbance to the regularity of the valve's motion, caused by
a slipped rod, will admit steam prematurely on one end of the
cylinder, while it delays the admission on the other end. The
valve is made to travel more on one side of the exhaust center
than on the other. Lengthening or shortening the valve-stem has
a similar effect, but this makes the engine lame in both gears;
while the slipping of an eccentric-rod only makes the engine lame
in the motion that the rod belongs to. This is subject to a slight
modification, however; for the back-motion eccentric being badly
out of square, will affect the correctness of the forward motion,
when the engine is working close hooked up. But in full motion
it will not be perceptible.
DETECTING THE CAUSE OF A LAME EXHAUST.
If in moving the engine ahead slowly, with the cylinder-cocks
open, it is found that steam is admitted to the cylinder before
the piston has nearly reached the center or dead point, or that
the back cylinder-cock does not show steam till after the piston
has passed the back center, the eccentric-rod is too long. The
rod being too short produces precisely an opposite effect. The
steam arrives late on the back stroke, and ahead of time on the
forward stroke. This is different from the action of the steam
where an eccentric has slipped. In that case, there will be pre-admission
of steam before the beginning of both strokes, or post-admission,
that is, late arrival of steam, for both strokes. Take a go-ahead
eccentric for example. If it slips backward on the shaft, its
effect will be to delay the admission of steam till after the
beginning of each stroke; and, if it slips forward, the result
will be to accelerate the lead of the valve opening the steam-port
before the piston has reached the commencement of each stroke.
WHAT TO DO WHEN ECCENTRICS, STRAPS OR
When either of these accidents happens, the safest plan is to
take down both straps and rods on the defective side. Some engineers
leave the back-up eccentric Strap and rod on, when the forward
strap or rod has broken; but it is a little risky under certain
conditions. After getting the eccentric straps and rods down,
drop the link-hanger away from the tumbling-shaft, disconnect
the valve-stem, and tie the valve-rod to the hand-rail. Then set
the valve in the middle of the, seat, so that it will cover both
the steam-ports, and hold it in that position by pinching the
stem with the gland, which is done by screwing up the gland obliquely.
Take down the main rod, and block the cross-head securely at the
back end of the guides. Good hardwood blocking prepared beforehand
should be used for this purpose, and it ought to be fastened with
a rope or marline. A neater plan for holding the cross-head in
place is described by Frank C. Smith, in the Torch. He says; "
Have the blacksmith make a hook out of a piece of inch and a half
round iron; also a piece about fifteen inches long by one and
a half thick, and four inches wide, with a hole through the center
for the shank of the hook to pass through. This shank is threaded
for a nut. Now, when it is necessary to block a piston, get it
to the back end, pass the hook around the wrist of the cross-head,
and the other end through the straight piece which bears against
the yoke supporting the back end of the guides; run up a nut on
the shank of the hook, hard against the crosspiece, and the piston
is secured." The piston being properly fastened, it is a
wise supplement to the work to tie the cylinder-cocks open, or
to take them out altogether. The engine is now ready to proceed
on one side.
Young engineers can not be too strongly impressed with the
necessity for having the cross-head properly secured before trying
to move the engine. I have repeatedly known of serious damage
being caused by placing too much confidence in weak blocking.
Taking out the cylinder-cocks is a wise security against accidents
of this kind; for, should a little steam be passing through the
valve, it has a port of escape without putting heavy pressure
on the piston.
DIFFERENT WAYS OF SECURING THE CROSS-HEAD.
In regard to the method of securing the piston when one side of
an engine is taken down, there is considerable diversity of opinion
among engineers. Some men maintain that the proper and quick plan
is, merely to move the piston to one end of the cylinder, pushing
the valve in the same direction, so that the steam-port will be
open at the end away from the piston. This will keep the cylinder
full of steam, and hold the piston from moving. But, if by any
accident the valve should be moved to the opposite end of the
seat, steam would get to the wrong end of the cylinder, and the
piston would certainly smash out the head. Another risky plan,
practiced by men economical of work, is to place the valve on
the center of the seat, and let the piston go without fastening.
These slipshod methods do not pay.
This accident is very serious; but it need not disable the engine,
although it will lessen the engineer's power to manage it freely.
To get the engine going; calculate the position the links must
stand in to pull the train, and cut pieces of wood to fit between
the block and the top and bottom of the links, so that the latter
may be kept in the required position. For forward motion, there
will be short pieces in the top, and long pieces in the bottom.
When back motion is needed, reverse the pieces of wood. A common
plan is to use one piece of wood, working the engine in full gear.
The same treatment will keep an engine going when the tumbling-shaft
arms, the reach-rod, the link-hanger, or the saddle-pin breaks.
The failure of a link-hanger or saddle-pin will only necessitate
the blocking of one side.
BROKEN VALVE-STEM, OR VALVE-YOKE.
For a valve-stem broken, the eccentric-strap or link need not
be interfered with. If the break is outside the steam-chest, take
down the valve-stem rod, and set the valve on the middle of the
seat; take down the main rod, and secure the piston as previously
directed, With a valve-stem broken inside the chest, or a valve-yoke
broken, a little additional work is necessary. The steam-chest
cover must now come up, and the valve be secured in its proper
place by pieces of wood, or any other material that will keep
it from moving; and the stuffing-box must be closed, to prevent
escape of steam through the space vacated by the valve-stem.
WHEN A ROCKER-SHAFT OR LOWER ROCKER-ARM
A broken rocker-shaft, or the fracture of the lower arm, entails
the taking down of both eccentrics and the link, besides the main
rod, and the securing of the valves and piston. The breaking of
an upper rocker-arm is equivalent to a broken valve-stem, and
requires the same treatment.
MISCELLANEOUS ACCIDENTS TO VALVE-MOTION.
Accidents to the valve-seat, such as the breaking of a bridge,
can be fixed for running the engine home on one side, by covering
the ports, and stripping that side of the engine, just as had
to be done for a broken valve-yoke. If a serious break in a bridge
occurs, it is indicated by a tremendous blow through the exhaust
port, out by the stack. A mishap of much less consequence than
a broken bridge is a "cocked" valve, and the small mishap
is very liable to be mistaken for the greater one. Where the yoke
is tight fitted, or out of true with the line of the stem, some
engines have a trick of raising the valve away from the seat,
and holding it there. This generally happens going into a station;
and, when steam is applied in starting out, an empty roar sounds
through the stack. Moving the valve with the reverse-lever by
quick jerks will generally reseat a cocked valve, but sometimes
it gets stuck so fast that it has to be hammered out of the yoke.
When a locomotive shows the symptoms which indicate a broken
valve, a broken bridge, or a cocked valve, the engineer should
exhaust every means of testing the matter from the outside before
he begins an interior inspection by raising the steam-chest cover.
If jerking the valve with the reverse-lever, or moving the engine
a little, will not stop the blow, he should disconnect the valve-stem,
and shake the valve by that means.
When a valve breaks, disabling its side of the engine so badly
that it can not be used, the valve should be taken out, and a
piece of strong pine-plank secured over the ports.
BROKEN STEAM-CHEST COVER.
A very serious and troublesome accident, which may come under
the head of steam-distribution gear, is the breaking of a steam-chest,
or of a steam-chest cover. It takes skillful management to get
an engine along when this has happened. The most effectual way
to restrain loss of steam when a chest or cover has broken, is
to slack up the steam-pipe, and slip a piece of iron plate, lined
with sheet-rubber, leather, canvas, or any other substance that
will help to make a steam-tight joint, into the lower joint of
the steam-pipe. If this is properly done, it ends the trouble,
when the joints are tightened up. But the difficulties in the
way of loosening steam-pipe joints in a hot smoke-box are often
insurmountable, especially when the nuts and bolts are solid from
corrosion, which is generally the case where they have not been
touched for months. In such a case it is better to resort to the
more clumsy contrivance of fitting pieces of wood into the openings
to the steam-passage, and bracing them in place by means of the
steam-chest bolts. A man of any ingenuity can generally, by this
means, save himself the humiliation of being towed home, and yet
avoid spending much time over the operation. When the engineer
has succeeded in securing means for preventing the escape of steam,
the main rod must be taken down, and the valve-stem rod disconnected
from the rocker-arm. In this instance the piston needs no further
attention, after the main rod has been disconnected; or there
will be no ingress of steam to the cylinder to endanger its safety.
The breaking of a steam-pipe in the smoke-box is even a more harassing
mishap than a bursted steam-chest or cover. The only remedy for
this is the fastening of an iron plate to the top joint of the
steam-pipe, thereby closing up the opening. A heavy plug of hard
wood may be driven into the opening, and braced there for a short
run; but such a stopper is hard to keep in place, owing to the
shrinkage caused by the intense heat of the smoke-box.
TESTING THE VALVES.
An experienced engineer will most easily determine the existence
of leaks between the valves and their seats when the engine is
working, and the indications of that weakness have already been
noticed. But it sometimes happens that a man wishes to test the
condition of the valves when the engine is at rest. This can be
most readily accomplished by placing the engine so that the rocker-arm
stands in the vertical position. Open the smoke-box door so that
the exhaust nozzles can be seen. Now block the wheels, and give
the engine steam. If the valve blows, the steam will be seen issuing
from the nozzle on the side under examination. As the tendency
of a slide-valve is to wear the seat concave, it sometimes happens
that a valve is tight on the center, yet leaky in other positions.
Moving the valve with the reverse-lever as far as can be done
without opening the steam-port, will sometimes demonstrate this.
The cranks should be placed on the eighths positions when the
valves are being tested.
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