The Richmond palladium and sun-telegram. [volume] (Richmond, Ind.) 1907-1939, 1919-08-09
Will Mixture Be Affected


up in the mixing chamber, &C." and
thus greatly reduce the vacuum here.
Thus the spray from the nozzle, and
the air entering at d." will both be
reduced
If. however. the throttle is opened
to allow say twice the amount of
mixture to pass, then the "piling up
action will be so great, there will be
greater vacuum, the spray will be
greater and the amount Of air enter
ing at ID" will be greater.
The proportion of gas to air, how
ever, will not be the same as before.
because the resistance of the opening
ID" and the friction of the walls,
will tend to check the flow of the
incoming air, more than the resist
ance of the nozzle opening will check
the gasoline. (The distance between
the top of the liquid and the opening
in the nozzle is so small, that the
friction is practically nothing). Thus,
as the throttle is opened the mixture
will constantly become richer
The mixture entering the cylinders
must always be in the same proper
ton of gas and air. Therefore, the
er than under it, and it would tend to
something must be added to allow
more air to enter at the higher speeds.
In most carburators this is done by
what is termed an auxiliary air valve,
which works automatically. Letter
Fl shows such valve. This you will
note is held against it sseat by the
spring |. the pressure of which can
be adjusted by the screw J.
When there is a vacuum in c. it
must also be in the space V and I'M
der the valve II. Now a vacuum
means an air pressure less than that
Of the atmosphere, and as the at
mosphere is on top of the valve n,
the pressure on top of it will be great
will allow but a small amount of the
open.
Extra Air Will Enter
Let us suppose that the spring S
is adjusted SO that its pressure would
just hold the valve closed against
the pressure of the atmosphere when
the engine is moving slowly. What
would happen when the vacuum in
V is increased, as it will be when
the engine is speeded up. Why, the
valve H will open, as the spring is
not strong enough to hold it closed
against the additional difference in.
pressure between the atmosphere and
the vacuum. Thus extra air will
enter the mixing chamber, and so
bring the mixture back to the right
proportion. The higher the speed
the farther the valve will open, and
the more air er.ter.
The, Carburetor
The carburetOr. as far as 1t was
explained in thelast lesson, would be
all right for single speed, uniform
hut oiy Of hn
automobile must have many speeds.
and be able to overcome varying loads.
There must, therefore, be a number of
additions to the carburetor as explain
ed so far.
First, lot us see how the speed of
the engine is varied. This is done
by means of a throttle or butterfly
valve, ar" which, when nearly closed,
will allow but small amount of the
mixture to pass and enter the cyl
inders, thus giving but mild eXplo-
sion
When the throttle is fully opened,
however, full charge of mixture will
roach the cylinders and the eXplo-
sion will be powerful. When the eX-
plOsiOn is powerful. the piston will be
driven down faster than the mildel
speed will be greater
The throttle or butterfly valve is
operated by hand by a lever on top
of the steering column, or by the
foot pressing on the accelerator
Both of these. through a series of
bell-cranks and sliding connections
operate on the rod IS" pushing it
to the right or left.
You will note that when the rod
E. is moved TO the right, it will
by acting on the lever ct" (shown
dotted), revolve the butterfly valve
r." in direction opposite to that
shown by the arrow. thus checking
the flow of the mixture, while, when
ii is moved to the left. il will open
the butterfly and so let the full charge
reach the cylinders. When we give
the engine more gas" as the say
ing is, we open the throttle or but
tegfiy as explained above.
2nd ADD THE AUTOMOBILE
| previously told you that the il
uuid gasoline will change to va
por at a temperature of about 20 de
creeS. the same as water will turn t
steam at a temperature of 212 de
grees When the steam strikes it vii
condense and again become water
In the same way. when the vaporize(
gasolene strikes cold surface it will
COndenSe.
The above is the reason why it i:
hard TO start on cold day. While
the carburetOr will do its work prop
perry. the vapOr. however. on the wa,
to the cylinders. strikes the colt
manifold and so condenses. with thu
result that practically nothing bu
air reaches the cylinders. When tn
engine Is cranked it really travel
very slowly and SO the suction, AM
the movement OF the mixture is slow
thus incre asing the chance for con
densation.
Cold Affects Start
What can we do to start in coll
weather? If when starting We maxi
the mixture very rich, then ever
though most of the gas condenses OIL
the way to the cylinders. the chance
are that enough will reach them t.
cause an explosion.
The explosion will make the engin