The Washington herald., 1921-04-17
L0W-GRADE FUEL
MEANS CONSTANT
CHANGE IN DEVICE
Mechanism Seems Com.
plex to Some, But Is
Really Simple.

While the modern caroureter Is
one Of the most efficient devices
auxiliary to the operation OF the
automobile engine, nevertheless
force of circumstances, has caused
a widespread movement toward Sc
curing even better carburetion re-
suits than those that we already
have. It is not too much to say that
the carbureter is today under more
careful scrutiny than any other part
Of the motor car.
The simple fact is that our pres
ent gasoline supply, which there
seems no way of increasing. Is not
enough to meet the demands upon
IL. OF course our military needs
must be met first and private car
owners must take what Is left over;
they are doing II gladly, but at the
same time the best brains of the
industry are striking about for
methods of making our motor fuel
60 further than it ever has before.
One of the obvious methods of in
creasinE our fuel supply is to en-
ploy greater quantities of other
fuel. principally heavier hydrOcar-
bons, such as kerosene and distil-
lates. 1t is the purpose in a fu-
ture article to discuss some of the
devices now available for using
these heavier fuels and in order to
lay a foundation of understanding
for readers this week the article
will take up some of the present
carbureter designs and explain their
construction and operation.
Is Really simple.
To most car owners the carbure-
ter probably seems a rather COM
plicated arrangement of passages.
bowls and valves. but in reality.
when we come to examine the in
strument in detail we find it is
really simple in operation and de-
sign There are, of course, many
different makes of carburetcrs now
on the market, but in the last
analysis all of those will he found
to embOdy certain basic principles
that proclaim them desce ndants Of
the same original ancestor. and this
was the MaybaCh carbureter.
This device consisted simply Of
bowl and float mechanism. with a
passage to a nozzle located direct
ly in the path of the ingoing air.
Obviously, that is the bare outline
of a present-day Carbureter, and
yet the MaybaCh gave fairly salts
factory results. though, of course.
IL had an extremely high grade of
gasoline to work with.
In due course engine designers
realized that something more was
needed in the carbUreter. If really
efficient results were to be obtained.
About 1902, 1 think, a French car
bUreter. known as the krebs (sus-
pitiOusly un-GalIic. that name). in
trOduced the auxiliary air valve as
q part of the device. This helped.
as it tended to even up the supply
Of air with the flow of fuel, which
in the earlier type had been out Of
proportion.
This early Improvement on the
original type had a spring backed
air valve in a separate air line.
making twin air openings. In this
way. as the engine speed increases
the suction on the nozzle increases.
but when a certain point is reached
the extra air valve opens, admits
more sir and thus thins the mixture
tending to keep the mixture con-
slant. This Krehs type, with nu-
rneroUs variations. is still a popu-
lar design.
Are in Four Groups.
When we come to examine modern
Carbureters we find that they fall
FEf-Iy readily into four groups or
classes. some what as follows: The
auxiliary air valve type, the meter
iar rin type. the multiple jet type.
and tho multiple throttle or progress
sivc type Beyond this there are
s.re Instruments that cannot read
H. De placed in any of these classes.
and yet they do not form a distinct
class themselves: they are simply
ord fellows.
NJ course, as might be expected,
many Of the Instruments have char
artCristiCs Of more than one class.
THUS the older type of StrOmberC
and the Browne are auxiliary air
v;ilve instruments; the Rayfield, the
row SChebler and the Fl. & y. are
r7rterinE pin carbureters: the Zenith
HrIlcy and new StromberG are com
70 nsatinC jet types. while the Mas
to- and JuhaSz are progressive types.
The air valve types in use today
are not very different from the
original devices. although there
have been a few interesting varia-
tions- The action Of this type, as
We have already explained, is simpl
the spring backed valve, to admit
NOR" air as need arises.
The new Schebler carbureter is
perhaps as =Ood an example OF the
TNtcrinE pin type as we could ask.
"Ais employs a spring backed aux
Hilary valve. interConnected with the
needle valve. so that as tie air
valve opens. admitting more air. the
needle valve opens, admitting more
fuel. The openings are propor.icned
with great nicely. so that the tend
crcy is to feed an even mixture
throughout the entire speed range.
Adjustment in the Schebler is very
simple, consisting Of a cap above
the air valve. turning which clock
wise makes the mixture richer by
lifting up the air valve. while .Urn-
inC in the opposite direction thins
the fuel.
Tho Juhasz is a good example of
the progressive type Of instrument.
which has three upright jets. with a
rotary throttle above them. COM
I.risinE three openings At different
roirts At low engine speeds one
rf these openings is above one Of the
j"fs. thn other two being out Of op-
rr7.Inn. As the speed Increases. an
other jet Is uncovered. AMI finally
tHo third also is brought INTO play.
v-Niir an air valve automatically
feeds air into the middle chamber.
Zenith Is Example.
The Zenith is an excellent ex-
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