Evening star., 1922-01-15
BY ALBERT n. ATKINSON.

Copyright, 1921, by Albert N. Atkinson)
The engine used In present-day auto
mobiles was first designed by N. A
Otto. an engineer Of wide experience, in
1876 He wished to improve on steam
engines by producing power directly
from gas In the steam engine the 1uei
(coal. wood or even Illuminating sas)
Is burned under q boiler to make steam.
This ia then led into an engine and 20
makes power. This means that the energy
is converted twice once into steam and
once into power. AS there Is an
enormous loss at each conversion, QUO 8
Idea was to use the fuel itself In the en-
zine and SO convert 1t directly into pow
er. He attained SO much more power
and SO much greater economy from his
engine that gas engines soon came into
general use for hoisting, pumping ana
other purposes. OF course. they could
only be used where gas In some form
was available. When this type OF en-
gine was designed for use on an auto
mobile 1t was necessary to use some
substance which could be easily changed
into q vapor and, of course. gasoline was
seized upon Immediately. Some means
had to be devised to change this into
gas as rapidly as the engine needed 1t.
AS the gasoline Of that period was very
volatile-that is, was readily eVaporated
IA very simple mixing device was all
that was necessary. The gasoline was
placed IN q small tank and the air led
over it or through it and SO mixture
was made. This did not give much
power. particularly where different
speeds were required. as the gasloine
vapor and air were not always mixed
in the right proportions. but the motor
lists Of that time were not very eXacting
or critical. But with the Improvement
in engines came a demand for better
mixing device. and the present efficient
carburetor WAS evolved, which leaves
little to be desired. The air is drawn
through 1t by suction from the engine.
Gasoline il fed into the stream of air in
Just the right proportions to give pow
erful explosion at any speed or the en-
CINE. The manner in which this mix
ture is drawn into the engine and the
be described.
The complete operation of the en-
gine takes place in four strokes OF
the piston. q stroke being a move
ment Of the piston from top to bot
tom or from bottom to top of the
cylinder.
On the suction or inlet stroke the
piston moves downward. making a
condition of partial vacuum or sue
ton in the upper part Of the cylinder.
The inlet valve is opened by the cam
shaft. allowing atmospheric pressure
TO force the air through the carburetor,
where 1t takes up the right amount Of
gasoline through the inlet valve and
| into the combustion space above the
piston.
On the compression stroke the pis-
ton Is forced upward by the crank
| shaft. Both valves are closed and the
gas is forced into the head of the
cylinder, from which place 1t cannot
escape. AS gas is elastic and com
pressible. it may be forced into a small
space or compressed. This operation
brings the piston to the top and pre-
pares the cylinder for the next stroke.
The Power Stroke.-The ignition
! system is set to give spark in the
cylinder just as the piston is about
| to start down. This sets fire to the
inflammable gas and SO produces the
explosion. The heat Of the explosion
expands the gas rapidly. making the
power necessary to force the piston
down. This power is then transmit
ted by means of the connecting rod.
i crank-shaft, fy-wheel and the diff
lferent parts of the transmission to the
| rear wheels, and drives the car. The