This page originally appeared on Thomas Ehrenreich's Railroad Extra Website
|
|---|
This page originally appeared on Thomas Ehrenreich's Railroad Extra Website
|
|---|
CHAPTER XIV.
ACCIDENTS TO CYLINDERS AND STEAM CONNECTIONS.
IMPORTANCE OF THE PISTON IN THE TRAIN
OF MECHANISM.
THE piston is an autocratic member of the machine. For thousands
of miles it toils to push the engine ahead, every thing going
smoothly so long as it is confined to its recurring journey; but
let any attachment break, or a key fly out that will increase
the piston's travel, and away the piston goes, right through a
cylinder-head.
CAUSES THAT LEAD TO BROKEN CYLINDER-HEADS.
The causes which most commonly lead the piston to smash out cylinder-heads,
are broken cross-heads, broken piston-rods, and broken main-rods.
A main crank-pin or wrist-pin breaking, is almost certain to leave
one end of the cylinder a wreck. These may be termed the major
causes for breaking out cylinder-heads; but there are numerous
minor causes, which are scarcely less destructive. A piston-rod
key begins to work loose. It is hammered down occasionally, which
does not improve its fit; and some day it jumps out altogether,
letting the piston go on a voyage of discovery. A machinist of
the careless sort has been examining a piston's packing, and,
in screwing up the follower-bolts, one of them gets a twist too
much. Drilling out a follower-bolt is a troublesome operation,
so Mr. Careless lets it go. On the road this head drops out, and
a broken cylinder-head is the consequence. One of the worst causes
of breakage to a cylinder that I have ever seen, was caused by
the packing-ring of the piston catching in the steam-passage.
Part of the ring broke off, and wedged itself between the advancing
piston and the cylinder. The wedge split the cylinder open, and
the remainder of the piston acted like a pulverizer upon the fragment
of the cylinder.
BROKEN CYLINDER-HEADS OFTEN PREVENTABLE.
The causes which eventually lead to broken cylinder-heads often
originate from preventable strains. Thus, cross-heads are frequently
fractured by main-rod connections pounding; and weaknesses, that
ultimately bring crank-pins to disaster, originate in a similar
way. A loose piston-key is liable to crack the piston-rod, if
it does not give trouble by jumping out. Loose guides have a tendency
to spring piston-rods, and throw unnecessary strain upon them.
Pistons lined out of true, are dangerous for the same reason.
A pump-plunger working out of line, or badly secured in the lug,
throws a distressing load upon the cross-head. And so the list
of potential accidents grows. Like the steady water-drop that
wears into the adamantine rock, trifling defects, assisted by
time's action, prove stronger than the most massive machine.
When any thing happens to permit the piston to break out a cylinder-head, the engine can be put in running trim by taking off the valve-rod and main-rod, and setting the valve on the center of the valve-seat. Blocking the cross-head is unnecessary, if the break will allow the escaping steam to pass through; for then no further tension can be put upon the piston to cause further damage. If, by an extraordinary freak of good luck, a piston-rod breaks without causing other damage, the cylinder-head must be taken off, and the piston removed. Then cover the ports, and take down the main-rod on that side. Or, if the cross-head is all right, the mainrod may be left untouched. When the cross-head breaks, it generally entails taking out the piston, centering the valve, and taking down the main-rod on that side.
WHEN A MAIN-ROD BREAKS.
With a broken main-rod which does not knock out the cylinder-head,
the main-rod and valve-rod should be taken down, the valve secured
on the center of the seat, and the cross-head blocked with the
piston at the back end of the cylinder.
CRANK-PIN BROKEN.
For a broken main crank-pin, the above method of stripping the
engine will do with the addition of taking down both side-rods.
An accident which disables one side-rod, requires that the other
one shall be taken down also, or there will be trouble when the
engine is attempted to be run with one side-rod. The rod might
go all right so long as no slipping happened. But, if the engine
began to slip while passing over the center, the side-rod would
have no leverage on the back crank to slip its wheel; and a broken
rod or crank-pin would almost certainly ensue.
A broken side-rod, that is not accompanied by other damage, requires both side-rods to be taken down. All the inconvenience arising from this is, that the engine is more liable to slip. But, with dry rails, an engine can get along very well without its side-rods.
THROTTLE DISCONNECTED.
Any accident to the throttle-valve or its attachments, which deprives
the engineer of power to shut off steam, is very dangerous, and
calls for prompt action. Lose no time in reducing the head of
steam to fifty or sixty pounds, or to the pressure where the engine
can easily be managed with the reverse-lever.
With the aid of a power-brake, an engineer can get along fairly with a light train, after an accident has happened which prevents the closing of the steam from the cylinders; but constant vigilance and thoughtful labor are needed.
OILING THE VALVES WHEN THE THROTTLE IS
DISCONNECTED.
The greatest difficulty will be experienced in oiling the valves,
unless the steam-chests are provided with the automatic feeders,
which work with steam on.
If he is running on an undulatory road, an engineer can oil the valves from the cab, by letting the steam down at the top of a hill, and running down at a high speed. It can also generally be done on a level track, by letting the fire burn low, getting up the best speed the engine will attain, then putting the feed full on. As the steam drops suddenly, put the reverse-lever in full motion; and the chances are, that the valves can be oiled.
WHAT CAUSES A DISCONNECTED THROTTLE.
The most common causes of trouble with the throttle are the breaking
or working out of one of the bolts that operate the valve within
the dome, the breaking of a valve-rod, or working off of nuts
that should secure the connection. Where the throttle fails with
the valve closed, and the engineer finds it necessary to take
the dome-cover off to prevent his engine from being hauled in,
he will generally find the trouble to lie with the connections
mentioned, or with the bolts belonging to the bell-crank, that
is located near the bottom of the standpipe. Sometimes the nuts
on the top of the throttle-valve stem work off: but, in such a
case, there is no difficulty in opening the valve; it is when
the engineer wants to close it, that the discomfiture comes in.
Some steam-pipes are provided with a release-valve near the throttle,
to relieve the pipe from intense back-pressure when the engine
is reversed. The sudden reversing of an engine sometimes jerks
this valve out of its seat, leaving an open passage between the
boiler and steam- chest. This acts like a mild case of unshipped
throttle, and must be controlled in a similar way.
BURSTING A DRY PIPE.
The bursting of a dry pipe is similar in effect to the action
of a throttle becoming disconnected while open; and it may even
prove harder to control, according to the size of the opening.
Engineer Halliday had a trying time with a case of this kind.
While swinging along the E., F., & G. road, with a heavy train
of freight, a herd of horses ran in from an open crossing-gate,
and started up the track just in front of the engine. As there
was a bridge a short distance ahead, Halliday reversed the engine
in his anxiety to prevent an accident. The train stopped for an
instant, when the engine began to push it back. Halliday tried
to throw the lever to the center, but never before had he felt
such a pressure acting upon it. Again and again he tried to throw
the lever over; but every time it proved too formidable a struggle,
and the catch found its way into the full-back notch. Meanwhile,
the train was gaining speed in the wrong direction, and a passenger
train was not many miles behind. Beginning to realize the true
state of affairs, Halliday called for brakes, opened the fire-box
door, closed the dampers, and started the injector. Then he directed
the fireman to throw some bucketfuls of water upon the fire, while
he tied down the whistle-lever, letting the steam blow. The promptest
means for reducing the pressure of steam were now in operation,
and his next move was to try the reverse-lever again. Both men
grasped the lever, and, by a combined effort, forced it past the
center; and Samson's hair was cut. It was afterwards found that
a long rent had opened in the dry pipe, letting the full boiler
pressure upon the valves, which moved hard through being dry;
the hot gases pumped through them in reverse motion having licked
off every trace of lubricating unguent.
OTHER THROTTLE ACCIDENTS.
Cases of serious trouble resulting from accidents to throttle
connections would be easy to multiply. Two incidents with similar
originating conditions, but with very different results, will
suffice. Engineer Phelps was pulling a full train of coal over
rails that were neither wet nor dry, and had just enough frost
upon them to be wicked. He was having a bad time slipping, but
was working patiently along, when the throttle became disconnected
with the valve open. The engine at once started on a whirl of
slipping that threatened disaster, but it was immediately controlled
by the engineer pulling the reverse-lever to the center notch.
Engineer Cook of the F., G., & H. road, was not so fortunate
when the stern of his throttle-valve broke on a slippery day.
As the wheels began spinning round, Cook lost his head, and kept
working at the throttle-lever to try to stop. Seeing this was
of no avail, he grasped the sand-lever, and tugged vigorously
at the valves. A season of tumult succeeded; and, when the engine
stopped presently, it was found to be a deplorable wreck. It was
hard to tell, from the look of the ruin, what part of the locomotive
broke first; but the crank-pins on one side were cleaned off,
and the piston was out through the cylinder-head. The side-rod
on the other side broke close to the strap, and was twisted up
like a spiral spring.
POUNDING OF THE WORKING-PARTS.
It is good for an ambitious young engineer, who desires to thoroughly
master his calling, to walk occasionally into the room where a
well-managed automatic cut-off engine is at work, and watch its
smooth, noiseless movements. There he may find an ideal of how
an engine should run. The nature of the work performed by a locomotive
engine prevents it from being operated noiselessly, and the smoothness
of its action must always compare unfavorably with a well-constructed
stationary engine; but the connections which transmit the power
of a locomotive should be free from knock or jar, if they are
properly proportioned, and skillfully put together.
SOME CAUSES OF POUNDING.
To an engineer with a well-regulated mind, a pound about the engine
is a source of continual irritation. If a pound arises from a
cause which can be remedied by an engineer, the careful man will
soon perform the necessary work to end the noise. Sometimes the
origin of a pound is hard to discover: very often it is beyond
the power of the engineer to stop it. Some makes of locomotives
always pound when working in full gear. With such an engine, a
nervous engineer will fuss, pushing up wedges until they stick
fast, and cause no end of grief to get them down again. He will
key up the main-rod connections till they run hot, and he will
prophesy that the engine is going to pieces. But the engine hangs
together all the same, and is only suffering from want of lead,
or want of compression. Where an engine is deficient in the cushioning
to the piston, due to compression or lead, the momentum of the
piston and connecting-rod is suddenly checked at the end of each
stroke. The concussion to these working-parts is so great that
pounding will be produced. As the engine gets hooked towards the
center, this pounding will cease, because the lead opening increases
as the motion is notched back. The most common causes for pounding
with locomotives are worn main-rod connections, and driving-boxes
too loose in the jaws, or the brasses loose in the driving-boxes.
If side-rods are out of tram, or have the brasses badly worn,
they sometimes pound when passing the centers. A cross-head will
pound when the guides are worn very open. This last defect is
liable to cause a bent piston-rod. A piston makes a tremendous
pound when a badly connected rod allows it to touch a cylinder-head,
and a very ominous pound is produced when the spider gets loose
on the piston-rod, and a piston-rod loose in the cross-head will
make itself heard all over the engine.
LOCATING A MYSTERIOUS POUND.
Several years ago a very troublesome and mysterious pound caused
the writer a great deaf of annoyance. He was running an old engine,
with cylinders that had been bored out until no counter-bore was
left. The piston had worn a seat leaving a small ridge at the
end of its back travel. The main-rod was taken down one day; and,
in putting it up again, the travel of the piston was slightly
altered. The engine started out with a pound, and kept it up.
If any of my readers have been working an engine that seemed to
hang together merely by luck, away on construction work on the
wild prairies, with no machine-shops in the rear to appeal to
for aid or counsel, with all his own repairing to do without tools
or skilled assistance, they will understand the difficulty experienced
in locating that pound at the back end of the cylinder.
A cylinder loose on the frame, or a broken frame, will jar the whole machine; and both of these defects are serious, and demand increased care in taking the engine along with the train. Loose driving-box brasses produce a pound which is sometimes difficult to locate.
In searching for the cause of a pound, it is a good plan to place the engine with one of the cranks on the quarter, block the wheels, and have the fireman open the throttle a little, and reverse the engine with the steam on. By closely watching in turn each connection, as the steam through the piston gives a pull or a thrust to the cross-head, the defect which causes the pound may be located. Never run with a serious pound inside of a cylinder. It is an almost certain indication that a smash is imminent.
 |
|---|