THE SIMPLE ENGINE.
The engine is the part of a power plant which converts steam pressure
into power in such form that it can do work. Properly speaking,
the engine has nothing to do with generating steam. That is done
exclusively in the boiler, which has already been described.
[Illustration: VIEW OF SIMPLE CYLINDER.
(J. I. Case Threshing Machine Co.)]
The steam engine was invented by James Watt, in England, between 1765
and 1790, and he understood all the essential parts of the engine as
now built. It was improved, however, by Seguin, Ericsson, Stephenson,
Fulton, and many others.
Let us first consider:
THE STEAM CYLINDER, ITS PARTS AND CONNECTIONS.
The cylinder proper is constructed of a single piece of cast iron bored
out smooth.
The _cylinder heads_ are the flat discs or caps bolted to the ends of
the cylinder itself. Sometimes one cylinder head is cast in the same
piece with the engine frame.
The _piston_ is a circular disc working back and forth in the cylinder.
It is usually a hollow casting, and to make it fit the cylinder steam
tight, it is supplied on its circumference with _piston rings_. These
are made of slightly larger diameter than the piston, and serve as
springs against the sides of the cylinder. The _follower plate_ and
bolts cover the piston rings on the piston head and hold them in place.
[Illustration: CONNECTING ROD AND CROSS-HEAD.
(J. I. Case Threshing Machine Co.)]
The _piston rod_ is of wrought iron or steel, and is fitted firmly and
rigidly into the piston at one end. It runs from the piston through one
head of the cylinder, passing through a steam-tight “stuffing box.” One
end of the piston rod is attached to the cross-head.
The _cross-head_ works between _guides_, and has _shoes_ above and
below. It is practically a joint, necessary in converting straight back
and forth motion into rotary. The cross-head itself works straight back
and forth, just as the piston does, which is fastened firmly to one
end. At the other end is attached the _connecting rod_, which works on
a bearing in the cross-head, called the _wrist pin_, or cross-head pin.
The _connecting rod_ is wrought iron or steel, working at one end on
the bearing known as the wrist pin, and on the other on a bearing
called the _crank pin_.
The _crank_ is a short lever which transmits the power from the
connecting rod to the _crank shaft_. It may also be a disc, called the
_crank disc_.
[Illustration: CROSS-HEAD.
(J. I. Case Threshing Machine Co.)]
Let us now return to the steam cylinder itself.
The steam leaves the boiler through a pipe leading from the top of the
steam dome, and is let on or cut off by the _throttle_ valve, which is
usually opened and closed by some sort of lever handle. It passes on to
the _Steam-chest_, usually a part of the same casting as the cylinder.
It has a cover called the _steam-chest cover_, which is securely bolted
in place.
The _steam valve_, usually spoken of simply as the _valve_, serves
to admit the steam alternately to each end of the cylinder in such a
manner that it works the piston back and forth.
There are many kinds of valves, the simplest (shown in the diagram)
being the D-valve. It slides back and forth on the bottom of the
steam-chest, which is called the _valve seat_, and alternately opens
and closes the two _steam ports_, which are long, narrow passages
through which the steam enters the cylinder, first through one port
to one end, then through the other port to the other end. The exhaust
steam also passes out at these same ports.
The _exhaust chamber_ in the type of engine now under consideration is
an opening on the lower side of the valve, and is always open into the
_exhaust port_, which connects with the exhaust pipe, which finally
discharges itself through the _exhaust nozzle_ into the smoke stack of
a locomotive or traction engine, or in other types of engines, into the
_condenser_.
The valve is worked by the _valve stem_, which works through the valve
stem _stuffing-box_.
Of course the piston does not work quite the full length of the
cylinder, else it would pound against the cylinder heads.
The _clearance_ is the distance between the cylinder head at either end
and the piston when the piston has reached the limit of its stroke in
that direction.
In most engines the valve is so set that it opens a trifle just before
the piston reaches the limit of its movement in either direction, thus
letting some steam in before the piston is ready to move back. This
opening, which usually amounts to 1-32 to 3-16 of an inch, is called
the _lead_. The steam thus let in before the piston reaches the limit
of its stroke forms _cushion_, and helps the piston to reverse its
motion without any jar, in an easy and silent manner. Of course the
cushion must be as slight as possible and serve its purpose, else
it will tend to stop the engine, and result in loss of energy. Some
engines have no lead.
_Setting a valve_ is adjusting it on its seat so that the lead will
be equal at both ends and sufficient for the needs of the engine. By
shortening the movement of the valve back and forth, the lead can be
increased or diminished. This is usually effected by changing the
eccentric or valve gear.
The _lap_ of a slide valve is the distance it extends over the edges of
the ports when it is at the middle of its travel.
Lap on the steam side is called outside lap; lap on the exhaust side
is called inside lap. The object of lap is to secure the benefit of
working steam expansively. Having lap, the valve closes one steam port
before the other is opened, and before the piston has reached the end
of its stroke; also of course before the exhaust is opened. Thus for
a short time the steam that has been let into the cylinder to drive
the piston is shut up with neither inlet nor outlet, and it drives the
piston by its own expansive force. When it passes out at the exhaust it
has a considerably reduced pressure, and less of its force is wasted.
Let us now consider the
VALVE GEAR.
The mechanism by which the valve is opened and closed is somewhat
complicated, as various things are accomplished by it besides simply
opening and closing the valve. If an engine has a _reverse lever_, it
works through the valve gear; and the _governor_ which regulates the
speed of the engine may also operate through the valve gear. It is
therefore very important.
The simplest valve gear depends for its action on a fixed eccentric.
An _eccentric_ consists of a central disc called the _sheave_, keyed to
the main shaft at a point to one side of its true center, and a grooved
ring or _strap_ surrounding it and sliding loosely around it. The strap
is usually made of brass or some anti-friction metal. It is in two
parts, which are bolted together so that they can be tightened up as
the strap wears.
The _eccentric rod_ is either bolted to the strap or forms a single
piece with it, and this rod transmits its motion to the valve.
It will be seen, therefore, that the eccentric is nothing more than a
sort of disc crank, which, however, does not need to be attached to the
end of a shaft in the manner of an ordinary crank.
The distance between the center of the eccentric sheave and the
center of the shaft is called the _throw_ of the eccentric or the
_eccentricity_.
The eccentric usually conveys its force through a connecting rod to the
valve stem, which moves the valve.
The first modification of the simple eccentric valve gear is
THE REVERSING GEAR.
It is very desirable to control the movement of the steam valve, so
that if desired the engine may be run in the opposite direction; or the
steam force may be brought to bear to stop the engine quickly; or the
travel of the valve regulated so that it will let into the cylinder
only as much steam as is needed to run the engine when the load is
light and the steam pressure in the boiler high.
There is a great variety of reversing gears; but we will consider one
of the commonest and simplest first.
[Illustration: HUBER SINGLE ECCENTRIC REVERSE.]
If the eccentric sheave could be slipped around on the shaft to a
position opposite to that in which it was keyed to shaft in its
ordinary motion, the motion of the valve would be reversed, and it
would let steam in front of the advancing end of the piston, which
would check its movement, and start it in the opposite direction.
The _link gear_, invented by Stephenson, accomplishes this in a natural
and easy manner. There are two eccentrics placed just opposite to each
other on the crank shaft, their connecting rods terminating in what
is called a _link_, through which motion is communicated to the valve
stem. The link is a curved slide, one eccentric being connected to
one end, the other eccentric to the other end, and the _link-block_,
through which motion is conveyed to the valve, slides freely from one
end to the other. Lower the link so that the block is opposite the end
of the first rod, and the valve will be moved by the corresponding
eccentric; raise the link, so that the block is opposite the end of the
other rod, and the valve will be moved by the other eccentric. In the
middle there would be a dead center, and if the block stopped here, the
valve would not move at all. At any intermediate point, the travel of
the valve would be correspondingly shortened.
[Illustration: VALVE AND LINK REVERSE.]
Such is the theoretical effect of a perfect link; but the dead center
is not absolute, and the motion of the link is varied by the point
at which the rod is attached which lifts and lowers it, and also by
the length of this rod. In full gear the block is not allowed to come
quite to the end of the link, and this surplus distance is called the
_clearance_. The _radius_ of a link is the distance from the center of
the driving shaft to the center of the link, and the curve of the link
is that of a circle with that radius. The length of the radius may vary
considerably, but the point of suspension is important. If a link is
suspended by its center, it will certainly cut off steam sooner in the
front stroke than in the back. Usually it is suspended from that point
which is most used in running the engine.
[Illustration: THE WOOLF REVERSE VALVE GEAR.]
The _Woolf reversing gear_ employs but one eccentric, to the strap of
which is cast an arm having a block pivoted at its end. This block
slides in a pivoted guide, the angle of which is controlled by the
reverse lever. To the eccentric arm is attached the eccentric rod,
which transmits the motion to the valve rod through a rocker arm on
simple engines and through a slide, as shown in cut, on compound
engines.
_The Meyer valve gear_ does not actually reverse an engine, but
controls the admission of steam by means of an additional valve
riding on the back of the main valve and controlling the cut-off.
The main valve is like an ordinary D-valve, except that the steam is
not admitted around the ends, but through ports running through the
valve, these ports being partially opened or closed by the motion of
the riding valve, which is controlled by a separate eccentric. If
this riding valve is connected with a governor, it will regulate the
speed of an engine; and by the addition of a link the gear may be made
reversible. The chief objection to it is the excessive friction of the
valves on their seats.
GOVERNORS.
A governor is a mechanism by which the supply of steam to the cylinder
is regulated by revolving balls, or the like, which runs faster or
slower as the speed of the engine increases or diminishes. Thus the
speed of an engine is regulated to varying loads and conditions.
[Illustration: SECTIONAL VIEW SHOWING VALVE OF WATERS GOVERNOR.]
The simplest type of governor, and the one commonly used on traction
engines, is that which is only a modification of the one invented by
Watt. Two balls revolve around a spindle in such a way as to rise
when the speed of the engine is high, and fall when it is low, and in
rising and falling they open and close a valve similar to the throttle
valve. The amount that the governor valve is opened or closed by the
rise and fall of the governor balls is usually regulated by a thumb
screw at the top or side, or by what is called a handle nut, which is
usually held firm by a check nut directly over it, which should be
screwed firm against the handle nut. Motion is conveyed to the governor
balls by a belt and a band wheel working on a mechanism of metred cogs.
There is considerable friction about a governor of this type and much
energy is wasted in keeping it going. The valve stem or spindle passes
through a steam-tight stuffing box, where it is liable to stick if the
packing is too tight; and if this stuffing box leaks steam, there will
be immediate loss of power.
[Illustration: PICKERING HORIZONTAL GOVERNOR.]
Such a governor as has just been described is called a throttle valve
governor. On high grade engines the difficulties inherent in this type
of governor are overcome by making the governor control, not a valve in
the steam supply pipe, but the admission of steam to the steam cylinder
through the steam valve and its gear. Such engines are described as
having an “automatic cut-off.” Sometimes the governor is attached to
the link, sometimes to a separate valve, as in the Meyer gear already
described. Usually the governor is attached to the fly-wheel, and
consequently governors of this type are called fly-wheel governors.
An automatic cut-off governor is from 15 per cent to 20 per cent more
effective than a throttle valve governor.
CRANK, SHAFT AND JOURNALS.
We have already seen how the piston conveys its power through the
piston rod, the cross-head, and the connecting rod, to the crank pin
and crank, and hence to the shaft.
_The key, gib, and strap_ are the effective means by which the
connecting rod is attached, first to the wrist pin in the cross-head,
and secondly to the crank pin on the crank.
The _strap_ is usually made of two or three pieces of wrought iron or
steel bolted together so as to hold the _brasses_, which are in two
parts and loosely surround the pin. The brasses do not quite meet, and
as they wear may be tightened up. This is effected by the _gib_, back
of which is the _key_, which is commonly a wedge which may be driven
in, or a screw, which presses on the back of the gib, which in turn
forces together the brasses; and thus the length of the piston gear is
kept uniform in spite of the wear, becoming neither shorter nor longer.
When the brasses are so worn that they have been forced together, they
must be taken out and filed equally on all four of the meeting ends,
and shims, or thin pieces of sheet iron or the like placed back of them
to equalize the wear, and prevent the piston gear from being shortened
or otherwise altered.
[Illustration: CONNECTING ROD AND BOXES.
(A. W. Stevens Co.)]
The _crank_ is a simple lever attached to the shaft by which the shaft
is rotated. There are two types of crank in common use, the side crank,
which works by what is virtually a bend in the shaft. There is also
what is called the disc crank, a variation of the side crank, in which
the power is applied to the circumference of a disc instead of to the
end of a lever arm.
The _boss_ of a crank is that part which surrounds the shaft and butts
against the main bearing, and is usually about twice the diameter of
the crank shaft journal. The _web_ of the crank is the portion between
the shaft and the pin.
To secure noiseless running, the crank pin should be turned with great
exactness, and should be set exactly parallel with the direction of the
shaft. When the pressure on the pin or any bearing is over 800 pounds
per square inch, oil is no longer able to lubricate it properly. Hence
the bearing surface should always be large enough to prevent a greater
pressure than 800 pounds to the square inch. To secure the proper
proportions the crank pin should have a diameter of one-fourth the
bore of the cylinder, and its length should be one-third that of the
cylinder.
The _shaft_ is made of wrought iron or steel, and must not only be able
to withstand the twisting motion of the crank, but the bending force of
the engine stroke. To prevent bending, the shaft should have a bearing
as near the crank as possible.
The _journals_ are those portions of the shaft which work in bearings.
The main bearings are also called _pedestals_, _pillow blocks_, and
_journal boxes_. They usually consist of boxes made of brass or some
other anti-friction material carried in iron pedestals. The pillow
blocks are usually adjustable.
THE FLY-WHEEL.
This is a heavy wheel attached to the shaft. Its object is to regulate
the variable action of the piston, and to make the motion uniform even
when the load is variable. By its inertia it stores energy, which would
keep the engine running for some time after the piston ceased to apply
any force or power.
LUBRICATORS.
All bearings must be steadily and effectively lubricated, in order
to remove friction as far as possible, or the working power of the
engine will be greatly reduced. Besides, without complete and effective
lubrication, the bearings will “cut,” or wear in irregular grooves,
etc., quickly ruining the engine.
Bearings are lubricated through automatic lubricator cups, which hold
oil or grease and discharge it uniformly upon the bearing through a
suitable hole.
[Illustration: THE “DETROIT” ZERO DOUBLE CONNECTION LUBRICATOR.
DESCRIPTION.
C 1--Body or Oil Reservoir.
C 3--Filler Plug.
C 4--Water Valve.
C 5--Plug for inserting Sight-Feed Glass.
C 6--Sight-Feed Drain Stem.
C 7--Regulating Valve.
C 8--Drain Valve.
C 9--Steam Valve.
C10--Union Nut.
C11--Tail Piece.
H--Sight-Feed Glass.]
A sight feed ordinary cup permits the drops of oil to be seen as they
pass downward through a glass tube, and also the engineer may see how
much oil there is in the cup. Such a cup is suitable for all parts
of an engine except the crank pin, cross-head, and, of course, the
cylinder.
The crank pin oiler is an oil cup so arranged as to force oil into
the bearing only when the engine is working, and more rapidly as the
engine works more rapidly. In one form, which uses liquid oil, the oil
stands below a disc, from which is the opening through the shank to the
bearing. As the engine speeds up, the centrifugal force tends to force
the oil to the top of the cup and so on to the bearing, and the higher
the speed the greater the amount of oil thrown into the crank pin.
Hard oil or grease has of late been coming into extensive use. It is
placed in a compression cup, at the top of which a disc is pressed down
by a spring, and also by some kind of a screw. From time to time the
screw is tightened up by hand, and the spring automatically forces down
the grease.
[Illustration: GLASS OIL CUP.]
[Illustration: SECTIONAL VIEW IDEAL GREASE CUP.]
_The Cylinder Lubricator_ is constructed on a different principle,
and uses an entirely different kind of oil, called “cylinder oil.” A
sight-feed automatic oiler is so arranged that the oil passes through
water drop by drop, so that each drop can be seen behind glass before
it passes into the steam pipe leading from the boiler to the cylinder.
The oil mingles with the steam and passes into the steam chest, and
thence into the cylinder, lubricating the valve and piston.
The discharge of the oil may not only be watched, but regulated, and
some judgment is necessary to make sure that enough oil is passing into
the cylinder to prevent it from cutting.
The oil is forced into the steam by the weight of the column of
water, since the steam pressure is the same at both ends. There is a
small cock by which this water of condensation may be drained off when
the engine is shut down in cold weather. Oilers are also injured by
straining from heating caused by the steam acting on cold oil when all
the cocks are closed. There is a relief cock to prevent this strain,
and it should be slightly opened, except when oiler is being filled.
[Illustration: ACORN OIL PUMP.]
There are a number of different types of oilers, with their cocks
arranged in different ways; but the manufacturer always gives diagrams
and instructions fully explaining the working of the oiler. Oil pumps
serving the same purpose are now often used.
DIFFERENTIAL GEAR.
The gearing by which the traction wheels of a traction engine are made
to drive the engine is an important item. Of course, it is desirable to
apply the power of the engine to both traction wheels; yet if both hind
wheels were geared stiff, the engine could not turn from a straight
line, since in turning one wheel must move faster than the other. The
differential or compensating gear is a device to leave both wheels free
to move one ahead of the other if occasion requires. The principle is
much the same as in case of a rachet on a geared wheel, if power were
applied to the ratchet to make the wheel turn; if for any reason the
wheel had a tendency of its own to turn faster than the ratchet forced
it, it would be free to do so. When corners are turned the power is
applied to one wheel only, and the other wheel is permitted to move
faster or slower than the wheel to which the gearing applies the power.
There are several forms of differential gears, differing largely as
to combination of spur or bevel cogs. One of the best known uses four
little beveled pinions, which are placed in the main driving wheel as
shown in the cut. Beveled cogs work into these on either side of the
main wheel. If one traction wheel moves faster than the other these
pinions move around and adjust the gears on either side.
[Illustration: THE HUBER SPUR COMPENSATING GEAR.]
[Illustration: AULTMAN & TAYLOR BEVEL COMPENSATING GEAR.]
[Illustration: DIFFERENTIAL GEAR, SHOWING CUSHION SPRINGS AND BEVEL
PINION.]
FRICTION CLUTCH.
The power of an engine is usually applied to the traction wheel by a
friction clutch working on the inside of the fly-wheel. (See plan of
Frick Engine.) The traction wheels are the two large, broad-rimmed hind
wheels, and are provided with projections to give them a firm footing
on the road. Traction engines are also provided with mud shoes and
wheel cleaning devices for mud and snow.
[Illustration: THE FRICK COMPANY TRACTION ENGINE.
Plan view of “Eclipse” Traction Engine, showing arrangement of Patent
Reverse Gear and Friction Clutch for Driving Pinion.]
THE FUSIBLE PLUG.
The fusible plug is a simple screw plug, the center of which is bored
out and subsequently filled with some other metal that will melt at a
lower temperature than steel or iron. This plug is placed in the crown
sheet of a locomotive boiler as a precaution for safety. Should the
crown sheet become free of water when the fire is very hot, the soft
metal in the fusible plug would melt and run out, and the overheated
steam would escape into the firebox, putting out the fire and giving
the boiler relief so that an explosion would be avoided. In some states
a fusible plug is required by law, and one is found in nearly every
boiler which has a crown sheet. Return flue boilers and others which do
not have crown sheets (as for example the vertical) do not have fusible
plugs. To be of value a fusible plug should be renewed or changed once
a month.
STUFFING BOXES.
Any arrangement to make a steam-tight joint about a moving rod, such
as a piston rod or steam valve rod, would be called a stuffing box.
Usually the stuffing box gives free play to a piston rod or valve rod,
without allowing any steam to escape. A stuffing box is also used on
a pump piston sometimes, or a compressed air piston. In all these
cases it consists of an annular space around the moving rod which
can be partly filled by some pliable elastic material such as hemp,
cotton, rubber, or the like; and this filling is held in place and made
tighter or looser by what is called a gland, which is forced into the
partly filled box by screwing up a cap on the outside of the cylinder.
Stuffing boxes must be repacked occasionally, since the packing
material will get hard and dead, and will either leak steam or cut the
rod.
CYLINDER COCKS.
These cocks are for the purpose of drawing the water formed by
condensation of steam out of the cylinder. They should be opened
whenever the engine is stopped or started, and should be left open when
the engine is shut down, especially in cold weather to prevent freezing
of water and consequent damage. Attention to these cocks is very
important.
These are small cocks arranged about the pump and at other places for
the purpose of testing the inside action. By them it is possible to see
if the pump is working properly, etc.
STEAM INDICATOR.
The steam indicator is an instrument that can be attached to either
end of a steam cylinder, and will indicate the character of the steam
pressure during the entire stroke of the piston. It shows clearly
whether the lead is right, how much cushion there is, etc. It is very
important in studying the economical use and distribution of steam,
expansive force of steam, etc.
LIST OF ATTACHMENTS FOR TRACTION ENGINE AND BOILER.
The following list of brasses, etc., which are packed with the Case
traction engine will be useful for reference in connection with any
similar traction engine and boiler. The young engineer should rapidly
run over every new engine and locate each of these parts, which will be
differently placed on different engines:
1 Steam Gauge with siphon.
1 Safety Valve.
1 Large Lubricator.
1 Small Lubricator for Pump.
1 Glass Water Gauge complete with glass and rods.
2 Gauge Cocks.
1 Whistle.
1 Injector Complete.
1 Globe Valve for Blow-off.
1 Compression Grease Cup for Cross Head.
1 Grease Cup for Crank Pin.
1 Oiler for Reverse Block.
1 Glass Oiler for Guides.
1 Small Oiler for Eccentric Rod.
1 Cylinder Cock (1 is left in place.)
2 Stop Cocks to drain Heater.
1 Stop Cock for Hose Coupling on Pump.
1 Bibb Nose Cock for Pump.
1 Pet Cock for Throttle.
2 Pet Cocks for Steam Cylinder of Pump.
1 Pet Cock for Water Cylinder of Pump.
1 Pet Cock for Feed Pipe from Pump.
1 Pet Cock for Feed Pipe from Injector.
1 Governor Belt.
1 Flue Cleaner.
15 ft. 1 in. Suction Hose.
5 ft. Sprinkling Hose.
1 Strainer for Suction Hose.
1 Strainer for Funnel.
4 ft. 6 in. of in. Hose for Injector.
5 ft. 6 in. of in. Hose for Pump.
2 Nipples ¾×2½ in. for Hose.
2 ¾ in. Hose Clamps.
2 ½ in. Hose Strainers.
TEST QUESTIONS ON BOILER AND ENGINE
Q. How is the modern stationary fire-flue boiler arranged?
Q. How does the locomotive type of boiler differ?
Q. What is a return flue boiler?
Q. What is a water-tube boiler and how does it differ from a fire-flue
tubular boiler?
Q. What is a vertical boiler and what are its advantages?
Q. What is the shell?
Q. What are the boiler heads?
Q. What are the tube sheets?
Q. What is the firebox?
Q. What is the water leg?
Q. What is the crown-sheet?
Q. Where is the smoke-box located?
Q. What is the steam dome intended for?
Q. What is the mud-drum for?
Q. What are man-holes and hand-holes for?
Q. What is a boiler jacket?
Q. What is a steam jacket?
Q. Where is the ash-pit?
Q. What are dead-plates?
Q. How is grate surface measured?
Q. What is forced draft?
Q. How is heating surface measured?
Q. What is steam space?
Q. What is water space?
Q. What is a diaphragm plate?
Q. What is the first duty of an engineer in taking charge of a new
boiler?
Q. What are the water gauge and try cocks for, and how are they placed?
Q. What is the steam gauge and how may it be tested?
Q. What is a safety valve? Should it be touched by the engineer? How
may he test it with the steam gauge?
Q. How is a boiler first filled with water?
Q. How is it filled when under pressure?
Q. What is an independent pump? What is a crosshead pump?
Q. What is a check valve, and what is its use, and where located?
Q. What is a heater and how does it work?
Q. What is an injector, and what is the principle of its operation?
Q. Where are the blow-off cocks located? How should they be used?
Q. In what cases should spark arrester be used?
Q. Who invented the steam engine, and when?
Q. What are the essential parts of a steam engine?
Q. What is the cylinder, and how is it used?
Q. What is the piston, and how does it work? The piston-rings?
Q. What is the piston rod and how must it be fastened?
Q. What is the crosshead, and how does it move? What are guides or
ways? Shoes?
Q. What is the connecting rod? Wrist pin? Crank pin?
Q. What is the crank? Crank shaft?
Q. Where is the throttle valve located, and what does opening and
closing it do?
Q. What is the steam chest for, and where is it placed?
Q. What is a steam valve? Valve seats? Ports?
Q. What is the exhaust? Exhaust chamber? Exhaust port? Exhaust nozzle?
What is a condenser?
Q. How is the valve worked, and what duties does it perform, and how?
Q. What is clearance?
Q. What is lead?
Q. What is cushion?
Q. How would you set a valve? What is lap?
Q. How is a steam valve moved back and forth in its seat?
Q. How may an engine be reversed?
Q. What is a governor, and how does it work?
Q. What is an eccentric? Eccentric sheave? Strap? Rod?
Q. What is the throw of an eccentric?
Q. How does the link reversing gear work?
Q. How does the Woolf reverse gear work?
Q. How does the Meyer valve gear work? Will it reverse an engine?
Q. What are the chief difficulties in the working of a governor?
Q. What are key, gib, and strap? Brasses?
Q. What is the boss of a crank? Web?
Q. How may noiseless running of a crank be secured?
Q. What are journals? Pedestals? Pillow blocks? Journal boxes?
Q. What is the object in having a fly wheel?
Q. What different kinds of lubricators are there? Where may hard oil or
grease be used? Is the oil used for lubricating the cylinder the same
as that used for rest of the engine?
Q. How does a cylinder lubricator work?
Q. What is differential gear, and what is it for?
Q. What is the use of a fusible plug, and how is it arranged?
Q. What are stuffing-boxes, and how are they constructed?
Q. What are cylinder cocks, and what are they used for?
Q. What are pet cocks?
Q. What is a steam indicator?