POINTS FOR THE YOUNG ENGINEER.--(CONT.)
MISCELLANEOUS.
Q. What is Foaming?
A. The word is used to describe the rising of water in large bubbles or
foam. You will detect it by noticing that the water in the glass gauge
rises and falls, or is foamy. It is due to sediment in the boiler, or
grease and other impurities in the feed supply. Shaking up the boiler
will start foaming sometimes; at other times it will start without
apparent cause. In such cases it is due to the steam trying to get
through a thick crust on the surface of the water.
Q. How may you prevent foaming?
A. It may be checked for a moment by turning off the throttle, so
giving the water a chance to settle. It is generally prevented by
frequently using the surface blow-off to clear away the scum. Of course
the water must be kept as pure as possible, and especially should
alkali water be avoided.
Q. What is priming?
A. Priming is not the same as foaming, though it is often caused by
foaming. Priming is the carrying of water into the steam cylinder with
the steam. It is caused by various things beside foaming, for it may
be found when the boiler is quite clean. A sudden and very hot fire
may start priming. Priming sometimes follows lowering of the steam
pressure. Often it is due to lack of capacity in the boiler, especially
lack of steam space, or lack of good circulation.
Q. How can you detect priming?
A. By the clicking sound it makes in the steam cylinder. The water in
the gauge will also go up and down violently. There will also be a
shower of water from the exhaust.
Q. What is the proper remedy for priming?
A. If it is due to lack of capacity in the boiler nothing can be done
but get a new boiler. In other cases it may be remedied by carrying
less water in the boiler when that can be done safely, by taking steam
from a different point in the steam dome, or if there is no dome by
using a long dry pipe with perforation at the end.
A larger steam pipe may help it; or it may be remedied by taking out
the top row of flues.
Leaky cylinder rings or a leaky valve may also have something to do
with it. In all cases these should be made steam tight. If the exhaust
nozzle is choked up with grease or sediment, clean it out.
A traction engine with small steam ports would prime quickly under
forced speed.
Q. How would you bank your fires?
A. Push the fire as far to the back of the firebox as possible and
cover it over with very fine coal or with dry ashes. As large a portion
as possible of the grate should be left open, so that the air may pass
over the fire. Close the damper tight. By banking your fires at night
you keep the boiler warm and can get up steam more quickly in the
morning.
Q. When water is left in the boiler with banked fire in cold weather,
what precautions ought to be taken?
A. The cocks in the glass water gauge should be closed and the drain
cock at the bottom opened, for fear the water in the exposed gauge
should freeze. Likewise all drain cocks in steam cylinder and pump
should be opened.
Q. How should a traction engine be prepared for laying up during the
winter?
A. First, the outside of the boiler and engine should be thoroughly
cleaned, seeing that all gummy oil or grease is removed. Then give the
outside of the boiler and smokestack a coat of asphalt paint, or a coat
of lampblack and linseed oil, or at any rate a doping of grease.
The outside of the boiler should be cleaned while it is hot, so that
grease, etc., may be easily removed while soft.
After the outside has been attended to, blow out the water at low
pressure and thoroughly clean the inside in the usual way, taking
out the handhole and manhole plates, and scraping off all scale and
sediment.
After the boiler has been cleaned on the inside, fill it nearly full of
water, and pour upon the top a bucket of black oil. Then let the water
out through the blow-off at the bottom. As the water goes down it will
have a coating of oil down the sides of the boiler.
All the brass fittings should be removed, including gauge cocks, check
valves, safety valve, etc. Disconnect all pipes that may contain water,
to be sure none remains in any of them. Open all stuffing boxes and
take out packing, for the packing will cause the parts they surround to
rust.
Finally, clean out the inside of the firebox and the fire flues, and
give the ash-pan a good coat of paint all over, inside as well as out.
The inside of the cylinder should be well greased, which can be done by
removing the cylinder head.
See that the top of the smoke stack is covered to keep out the weather.
All brass fittings should be carefully packed and put away in a dry
place.
A little attention to the engine when you put it up will save twice
as much time when you take it out next season, and besides save many
dollars of value in the life of the engine.
Q. How should belting be cared for?
A. First, keep belts free from dust and dirt.
Never overload belts.
Do not let oil or grease drip upon them.
Never put any sticky or pasty grease on a belt.
Never allow any animal oil or grease to touch a rubber belt, since it
will destroy the life of the rubber.
The grain or hair side should run next the pulley, as it holds better
and is not so likely to slip.
Rubber belts will be greatly improved if they are covered with a
mixture of black lead and litharge, equal parts, mixed with boiled oil,
and just enough japan to dry them quickly. This mixture will do to put
on places that peel.
Q. What is the proper way to lace a belt?
A. First, square the ends with a proper square, cutting them off to
a nicety. Begin to lace in the middle, and do not cross the laces on
the pulley side. On that side the lacings should run straight with the
length of the belt.
The holes in the belt should be punched if possible with an oval punch,
the long diameter coinciding with the length of the belt. Make two rows
of holes in each end of the belt, so that the holes in each row will
alternate with those in preceding row, making a zigzag. Four holes will
be required for a three-inch belt in each end, two holes in each row;
in a six-inch belt, place seven holes in each end, four in the row
nearest the end.
To find the length of a belt when the exact length cannot be measured
conveniently, measure a straight line from the center of one pulley
to the center of the other. Add together half the diameter of each
pulley, and multiply that by 3¼ (3.1416). The result added to twice the
distance between the centers will give the total length of the belt.
A belt will work best if it is allowed to sag just a trifle.
The seam side of a rubber belt should be placed outward, or away from
the pulley.
If such a belt slips, coat the inside with boiled linseed oil or soap.
Cotton belting may be preserved by painting the pulley side while
running with common paint, afterward applying soft oil or grease.
If a belt slips apply a little oil or soap to the pulley side.
Q. How does the capacity of belts vary?
A. In proportion to width and also to the speed. Double the width and
you double the capacity; also, within a certain limit, double the
speed and you double the capacity. A belt should not be run over 5,000
feet per minute. One four-inch belt will have the same capacity as two
two-inch belts.
Q. How are piston rods and valve rods packed so that the steam cannot
escape around them?
A. By packing placed in stuffing-boxes. The stuffing is of some
material that has a certain amount of elasticity, such as lamp wick,
hemp, soap stone, etc., and certain patent preparations. The packing is
held in place by a gland, as it is called, which acts to tighten the
packing as the cap of the stuffing-box is screwed up.
Q. How would you repack a stuffing-box?
A. First remove the cap and the gland, and with a proper tool take out
all the old packing. Do not use any rough instrument like a file, which
is liable to scratch the rod, for any injury to the smooth surface of
the rod will make it leak steam or work hard.
If patent packing is used, cut off a sufficient number of lengths to
make the required rings. They should be exactly the right length to go
around inside the stuffing-box. If too long, they cannot be screwed up
tight, as the ends will press together and cause irregularities. If
too short, the ends will not meet and will leak steam. Cut the ends
diagonally so that they will make a lap joint instead of a square one.
When the stuffing-box has been filled, place the gland in position and
screw up tight. Afterwards loosen the nuts a trifle, as the steam will
cause the packing to expand, usually. The stuffing-box should be just
as loose as it can be and not allow leakage of steam. If steam leaks,
screw up the box a little tighter. If it still leaks, do not screw up
as tight as you possibly can, but repack the box. If the stuffing-box
is too tight, either for the piston rod or valve steam, it will cause
the engine to work hard, and may groove the rods and spoil them.
If hemp packing is used, pull the fibres out straight and free, getting
rid of all knots and lumps. Twist together a few of the fibres, making
three cords, and braid these three cords together and soak them with
oil or grease, wind around the rod till stuffing-box is sufficiently
full, replace the gland, and screw up as before.
Stuffing-box for water piston of pump may be packed as described above,
but little oil or grease will be needed.
Never pack the stuffing-box too tight, or you may flute the rod and
spoil it.
Always keep the packing in a clean place, well covered up, never
allowing any dust to get into it, for the dust or grit is liable to cut
the rod.