_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 main-rod 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 stand-pipe.
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 stem 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,
noise-less 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 deal 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.