The electrical circuit (grounded circuit) is as follows: From battery
to ignition switch; switch to binding post on base, through magnet
winding (16), through breaker spring, armature (10), base casting,
through fuel pipes to battery.
Arcing of the contacts is reduced to the vanishing point by means
of a "short circuited" secondary winding.
Capacity: About 7 gallons per hour through orifice rl„" dia.,
while lifting 18" to 20" and on a 6 or 12-volt battery.
Fuel pipe: For full capacity use rn" tubing; for installation
where capacity is less than 6 gallons per hour use %" tubing;
for duplex delivery use re" tubing.
INSTRUCTION No. 103
AIR CLEANERS:, Purpose; Types; Construction
Air cleaners are devices placed at the main air intake of carburetors,
their purpose being to remove the road dust and deliver clean air
to the carburetor.
It is said that automobile engines consume an average of 9,000
gallons of air for every gallon of gasoline and that if the air,
containing road dust is placed under a powerful microscope it will
be found that a portion contains minute particles of silica, an
abrasive element, and also sand.
One manufacturer of an air cleaner states that tests have proved
that 25 per cent to 75 per cent of the formation of carbon is silica
or road dust and only from 5 to 25 per cent is actual carbon. Hence
it is readily seen that by removing the road dust, carbon formation
can be reduced considerably, as well as the wear on the moving
Whether or not all road dust contains silica depends upon the locality
and the kind of road dust, but there is no doubt that a large percentage
of most road dust contains particles which are sharp, irregular
crystals, hard enough to scratch the cylinder walls.
The air cleaner is not a new device. It has been used on tractor
engines for a number of years.
Types of Air Cleaners
There are two major types of air cleaners: the wet and the dry
An example of the wet type is shown on page 989, which uses water
to wash the air. On other makes oil is used instead of water. The
wet type is con-fined to tractors and trucks.
The dry type is the type generally used on passenger cars, motor-coaches
and trucks. The principle of construction and action may be: (1)
filter; (2) centrifugal; (3) inertia.
Examples of some of the different makes of dry types of air cleaners
are given below.
Operation: Air enters a large number of small openings (1) in outer
shell at low velocity, and thus the coarse particles of dust are
separated by gravity; specially constructed filtering material
(2) consisting of a frame of galvanoid steel wire cloth covered
with a piece of specially prepared felt, chemically treated, removes
even the finest (those that cause wear) particles of dust, but
readily permits air to pass through. Clean filtered warm air passes
through this outlet to carburetor and engine, with the fine dust
Care: Under average conditions it needs no attention for 25,000
miles of use. However, when the car or truck is exposed to dust
conditions such as are encountered on country roads or on construction
work, the manufacturers recommend the cleaning of the felt every
six months or every 5,000 miles of driving.
To clean: Unscrew the cap at the top of the retaining bolt and
apply an air hose such as is used for inflating tires. With a few
turns of the bolt in order to distribute the cleaning air blast
throughout the interior of the fins, the insert is effectively
cleaned. (\I'f'd. by Staynew Filter Corpn., Rochester, N.Y.)
Fig. 2. The United air cleaner. bus*r.o„...,w --This air
cleaner uses what is termed by its manufacturer as a combination
of centrifugal and centripetal force to eject the particles of
dust and dirt from the air entering the carburetor. How this air
cleaner is applied to a carburetor main air intake and its principle
of action are described as follows:
Operation: The action of the United air cleaner depends upon centrifugal
Suction of the piston, during inlet stroke, draws air through
the main air intake of the carburetor. With this device placed
main air intake of carburetor the passage of air through the cleaner
turns the rotating member by means of a small fan. This fan is
attached to a horizontal disk with four vertical vanes which by
centrifugal force throw off and separate from the air stream particles
of dust and dirt.
The lift valve moves up and down on a pin through its center.
At extremely high speeds the suction of the engine raises this
valve, thereby allowing the greater volume of air to pass into
The valve remains closed, however, at the driving range be-cause
the suction of the engine is not great enough to raise it except
at high speeds.
Clean air freed of dust, dirt and grit is drawn through the lift
valve, as shown by arrows, into the carburetor past the spray nozzle
where it mixes with gasoline and thence passes into the combustion
chamber of engine.
Here is the principle in simplified form: you have seen the long
chute down which the little folks slide in playgrounds and amusement
parks. Now imagine that the youngsters were landed on a rapidly
revolving circular table which was perfectly smooth. The youngsters
would be deposited somewhere beyond the edge of the table very
That is the way the United air cleaner works. The particles of
dust„ dirt and grit slide down an air current or chute on
to a rapidly revolving table and are instantly shot over the edge.
Being heavier than air, they are shot out of the way at a tremendous
Care: The hearing of the cleaner is supplied with felts which
are thoroughly soaked with oil at the time the cleaner is assembled.
In addition to this, oil bronze bushings of durex metal are used
as guide bearings. The entire weight of the moving part lies upon
a hardened steel ball which is highly polished, and because the
weight of the moving part is extremely slight,
1 There are many other makes of air cleaners not shown here. See
automobile trade magazines for advertisements.
Fig. 1. The Protectomotor, a filtering type of air cleaner, which
filters the air through very fine textile fabric. It is claimed
the effective filtering area is two hundred times the area of the
carburetor air intake opening.
Previous page 1927
Supplement Home Next page