Oxford Democrat., 1913-09-09
Under the Auto Hood.
THE THEORY OF THE FoUR-CYCLE GAS
oLINE ENGINE As USED IN
AUTOMOBILES.

It IN nv Intention In this theme to
state in technical language the the
ory of the four.cycle gasoline engine.
This type of the gas engine has It's high-
cat development in the automobile, ior
which ft 10 admirably suited, as 1t works
silently and smoothly. The reader must
not confuse this type with the two-cJcle
engine, found mostly in motor.6oats, a.
though sometimes In automobiles, or the
stationary engine seen on almost any
mudsrn farm. Although all these en-
pines use gasoline as fuel, they differ
materially In the theory Of their opera
ton.
First, I-shall take mp the physical fea'
lures OF the gasoline engine; the means
BIZ which the up and down motion oil the
piston 10 changed into . rotary motion
suitable to be used to drive an automo-
bile. will use as an example the hn-
man hand turning crank. The motion
from the shoulder ls up and down while
the motion at the crank 10 rotary; thus,
the piston goes up and down In a hollow
cylinder In the gas engine. All that re-
mains 10 to furnish some power to push
the piston.
Imagine hollow cylinder with tight
fitting piston sliding in 1t so that no air
Can pass the piston into the chamber
above. Now let two pipes be connected
wi; b the chamber above the piston, each
having valve In 1t. 1t will now be seen
that II both valves be closed and the
piston moved down 1t will cause a va
cuum In tho chamber. Now suppose
the piston to be up and one valve open.
We will call this the intake valve and
the pipe the intake pipe. Let the other
end Of the pipe be connected with the
csrburetor or gasoline vaporizing ma
chine. Under these conditions 1t will be
seen that II the piston is moved down 1t
will cause suction through tho intake
pipe which will pull the gasoline vapor
into the cylinder. Now II both valves
are closed and the piston forced up
again the vapor will be compressed.
This increases It's explosiveness. II this
vapor is ignited now 1t will explode and
drive the piston down again with great
force. Now the other valve is opened
(pxhaust valve) and the piston comes up
again. This forces the exhaust gases
out of the chamber into the exhaust
pipe and thence into the air. 1t will
now be seen that four operations ale
necessary to complete cycle, hence the
name, four cycle. To summarize, the
operations are as follows: First, sue
tion; second, compression; third, explo-
sion; and fourth. exhaust. II an engine
such as have described should be con-
structed the result would be as follows:
the engine would explode and stop;
then we should have to turn 1t, by hand,
through the three idle strokes of the
piston. Then 1t would explode again.
To overcome this difficulty we have the
fiy.wheel. This Is made very heavy so
as to furnish momentum enough to carry
the engine through the idle strokes with
out stopping. Our engine will now run.
The essentials are all present. I will
now take up the refinements.
The engine that we have developed is
not, In its present stage, satisfactory for
automobile work for three reasons.
First, it runs jsrkily, as it generates
power only one.fourth Il the time. Sec
ond, in an engine Of thirty horse power
or above, the fly.wheel would become
too large and heavy to be carried con.
veuiently. Third, in an engine of large
size, the vibration caused by the moving
parts would be tremendous. I'm the
same way that man jumping on
bridge can set the whole bridge in mo-
tion.) As remedy for these troubles
we have the multi.c cylinder engine. The
four cylinder is the type the most COM
monty used In automobiles and will
explain how this eliminates the troubles
mentioned above. Taking the first
trouble, this engine will run steadily, as
one cy Under is practically always develop
ing power. Second, the fly-wheel can be
made much smaller ON account OF the
practically continuous power. In six
cylinder motor 1t can be eliminated en-.
iirely. Third, the vibration is greatly
reduced, az the moving parts are much
smaller and better balanced. When one
piston is coming up another is going
down and vice versa. This is the high
est development OF the gasoline engine
in any form and while small improve
ments may be made in the future, It will
probably never be changed radically.
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Foley's Honey and Tar Compound are
not duplicated in any other medicine for
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accept 1t for 1t cannot produce the hoal-
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and Tar Compound. Insist upon the
genuine, which contains no opiates. A.
f. Shur.leff & Co., South Paris; s. K.
Newell & Co., Paris.