The news scimitar. (Memphis, Tenn.) 1907-1926, 1920-03-27
THE Why and Wherefore
| Of The Vacuum Feed

This system seeks 70 eliminate the
disadvantages Of the Ordinary gravity
system, viz, Uncertainty OF gasoline
flow due 70 up grades and the small
available capacity OF the elevated tank
necessarily employed, and al the same
time TO do away with special pumps. the
necessity for an air-tight fuel tank
and the occasional necessity for the
creation Of the flow pressure by hand,
az starting SO far as the actual de-
livery OF gasoline TO the carburetor Is
concerned, it Is a gravity system, re-
semhling most nearly the form OF this
system in which the fuel tank Is To-
Gated forward Of the cowl board, close
to the engine. where the fuel Is sure
Il run 10 the carhuretor. no matter
what may be upward inclination OF the
ear within practical limits, and where
the fuel Is exposed so directly TO en-
n;na heat as to become warm enough
to be readily vaperiZed, very soon after
the car Is In action, The principle OF
its action is as follows: \ nearly con
slant level Of gasoline Is automatically
maintained in a small auxiliary tank.
placed In the hood space. above the
carburetor bowl, which supply is drawn
from the large main fuel tank, which
IA usually placed between the frame
members at the rear Of the chassis ana
Ii fed to the carburetor bowl by SIM =
pie gravity In the accompanying Ola.
gram A represents the rear located
main tank, G the earburetor and II the
auxiliary or vacuum tank elevated
above the earburetor, mounted upon
the front OF the cuwl board or fastened
10 the engine itself. u Is the supply
pipe from The main tank 20 the vacuum
tank, through which the later Is filled
and Z is the gravity fuel supply pipe
from the vacuum tank TO the carburetor
HAT -akaf,har i the main tank is
located below the auxiliary tank, an
external force of some kind must be
applied TO move gasoline from the for
nier into the latter and the force util-
lied ID the unbalanced pressure Of the
atmosphere acting upon the fuel in the
main tank, In the filler-cap Of which
there liz Q small afr opening Is. This
unbalanced pressure or suction forces
gasoline from the main into the aux
ulAry tank lust ms a person draws
lIuuld from d tumbler INTO his mouth
through straw, and this suction is
created In tie following manner: When
an engine Is in operation with the
throttle nearly closed, the volume q
mixture which enters the intake mani
fold and cylinders Is greater than that
which enters the carhuretor--the throt-
lie valve acting to reduce the density OF
the fuel passing it--with the result that
the gas In the intake pipe, above the
throttle, lis expanded and at a lower
pressure than that Of the atmosphere
AS the throttle Is opened the reduction
81 pressure Of this gas Is progressively
less. but 1t lie never quite up TO atinos-
uheric pressure, In the diagram, Is
Il tube leading from the upper part Of
vacuum tank b into the intake mani
fnid q and when the engine Is running,
with partly closed throttle, fun atmos-
pheric pressure acting on the gasoline
III A and pipe d overcomes the reduced
pressure acting in vacuum pipe + and
in tank b and fuel Is forced into b.,
In the system under description, b Is
IN reality a double tank, consisting OF
an upper compartment III and lower
compartment ], the former emptying
into the latter through an automatic
valve between them, The upper com
partment acts as an automatic pump
Ia keen a supply OF gasoline raised from
The main tank and available for the
ESTABLISHMENT of compartment ], which
later acts merely as a simple gravity
supply for the carburetor. The con-
asructlon and action OF the tank mech.
anEsm, which accompllshes these re-
suits, VIII he explained later, Among
the advantages of the vacuum feed sys-
tom may be mentioned the following
ii furnishes fuel to the carburetor at
practically constant head under all
conditions. II requires no mechanical
pumps, but derives its feeding power
from a condition inherent in every en-
CINE while running, II keeps available
for the carhuretor a supply OF fuel am
pie for starting purposes and the en-
CINE can be kept running In an emer-
gency, by filing the auxiliary tank by
hand. II supplies the carburetor with
warmed fuel very soon after the en-
gine Ia started. In case the carburetor
float valve leaks, when the car Is not
III use. the loss Of fuel is confined TO
the small quantity in the tank. The
auxiliary tank acts as an additional
water and sediment separator, TO pre-
vent foreign matter from entering the
carburetor The somewhat comph-
Gated mechanism within the auxiliary
tank and the fact that the force avail
able to fill II is very slight during long
periods of full throttle operation and
high fuel consumption, are its chief dis
advantages.
IC,opyrighted, International Syndicate)