The New York herald., 1920-12-05

with layers OF tough fabric thoroughly
impregnated with rubber. There are
several layers which are cemented to-
gether with rubber I'm solution. They
are stretched and shaped, Just as they
are seen on the inside OF the casing.
Upon this fabric Is placed a thin layer
of soft rubber % act as cushion. While
this Is being put on. the bead of the
tire is also formed of fabric and rubber.
Over the cushion rubber, but not ex-
tending the full cross section OF the cas-
inG. is placed stretch OF fabric known
as the breaker strip. and upon this. IN
turn. is mould.d the tread. This is
made OF as tough combination as can
be devised Usually II Is largely rub
ber and tale with .coloring matter, and
the outer surface may be smooth or
moulded into variety OF designs In
tended to minimize skidding.
The tire thus built up with mandrei
and outer mould is placed within huge
drum where a temperature OF approx
mateiy 500 degrees Fahrenheit Is main
tanned by steam pressure. They remain
In this heat chamber for about an hcur
10 cook. The steam has no part in the
cooking or curing process other than to
maintain uniform heat Too little heat
results In imperfect curing and too much
heat In burning or disintegration, and
IN either case the tire wears out rapidly.
The objects sought In manufacturine
tho casing are first strength TO support
the weight Of the car. sufficient rubber
for oushioning and a quality OF rubber
which win withstand the constant grind
CT the pavenents. The strength Is
! needed most In the side walls of the
casing, since the flattened tire produces
! a wrinkljng or bending of these side
walls. To prevent this breakdown OF the
| side walls. which means running the tire
manufacturers adopt a standard pressure
Which they require drivers TO main tain
II they are to have the benefit OF tire
mileage guarantee. This pressure Is
usually so high that II makes the tire
US hard and unyielding as solic rubber.
A great many owners, who prefer little
more comfort, even at the expense OF
tire mileage, will run their tires at ten
to twelve pounds less pressure, knowing
full we'll that the tire will not last rs
long.
The inner tube is made in n tnuch
similar manner. over an iron mandrel,
which may be stratghtpiece or curved
plpe. On these mandrels nearly pure
rubber Is placed in thin strips. building
A. up to the proper thickness. They are
lien wound with strips OF cloth and
cooked or cured. Then the two ends
are vulcanized together and the valve
stem inserted.
Tubes must be OF the right size for
the casing. If too small they will
stretch too much and IL too large they
wrinkle and wear or break. To prevent
their chatting against the casing tale or
French chalk is used as a sort OF lubrl-
cant. They are ordinarily long lived II
properly cared for. When punctured
they are easily repaired by one of the
quick vulcanizing outfits, and IL there
Is a bad blowout new section NAV be
readily vulcanized IN. They should be
kept in the castings as far as possible
and II carried in the machine should be
carefully folded and wrapped and kept
away from tools and grease
Castings coming In contact with road
ways OF varying character are subject
to much wear, and yet they are IL
properly cared for, wonderfully efficient
The wheels must run true or they grind
on the pavement somewhere. The tread
may become cut from q variety OF
causes. Even small cuts should be
closed, after proper cleaning, with one
of the cements to be procured in any
supply house and large cuts should Be
attended to by a vulcanizer. II neg
lected. water and sand will work into
the fabric and in short time produce
a blister, and this again. in an incred-
IDLY short time. will cause a blowout.
Tires should be inspected every littls
while for cuts and given proper atten-
ton. Tho careful driver will save his
tires by going around corners and
curves slowly. to prevent the wear from
even a slight skidding. and keep off car
tracks. which look smooth but have a
way OF slashing up a tire, and will
drive slowly on a wet day on a road on
which fresh rock has been newly placed
The workman in rubber vets his knife
to make 1t cut readily: water on the
sharp edges Of crushed rock gives a