Evening star., 1895-05-28
BICYCLE TIRE S
An Interesting Account Of How
They Are Made.
4 BUSINESS OF GROWING PROPORTIONS
Transforming the Crude Rubber
Into the Finished'ArticIe.
GREAT SKILL REQUIRED

From the Chicago Record.
| Everybody who rides a wheel nowadays
considers pneumatic tire Indispensable.
Beyond this point no two riders agree.
Some must have tires weighing five and q
half to six pounds to the pair; others could
not sleep nights If their tires weighed more
than three pounds to the pair. Some want
single-tube tires; others would not consider
life worth living unless they could have a
double tube. Therefore, what constitutes a
good tire depends entirely upon whom Is
referred to for Information. Each manu-
facturer will tell you that his kind of tire
is better than all the other kinds His bus
mess is to make tires
One thing can be said with safety of all
kinds of pneumatic tires, and that is that
the business Of making them has grown to
enormous proportions. One Chicago firm
has two factories running day and night
turning out tires at the rate of several
thousand a day. This means a great
amount of work, for tire has to go through
a great many processes before it is ready
for use.
| First, the hams" as the Jumps of crude
rubber are called. have to be boiled clean.
They are then cut into pieces and broken
down" by being passed between two huge
corrugated iron rollers running at differ
ent rates of speed. The friction thus
caused warns the gum and kneadS it thor
oughly. while a stream of water constantly
running upon the mass washes out the dirt.
| After being broken down the ma cerated
sheets of gum are subjected to further roll
ing, passing from one machine to another,
under the most watchful care They are
then taken to the drying room, where they
are subjected to temperature of 90 de-
| greeS for at least twenty-four hours. This
causes shrinkage of about 10 per cent,
and gives the rubber an odor much like that
of smoked meat
Having been dried, the gum is ready for
mixing. What it is mixed with depends
| upon the purpose for which it Is to be used.
The kind and quantity of the ingredients Is
one of the carefully guarded secrets of the
firm.
The gum used for the inner tubes is left
more nearly pure than that used for any
other purpose. The gum and the other in
gradients are passed repea tedly between
pair of smooth. hollow iron rollers running
at different rates of speed. The friction
thus caused generates great deal of heat,
so that it is necessary to keep the rollers
cooled by means Of a stream of water cir
culatng through them. When the COM
pound has been thoroughly warmed up by
this friction it finally comes from the roll
erS in a smooth. Semi-tranSparent sheet of
a delicate chocolate tint The sheet is then
carried to the calendars where it is drawn
down to one-thrty-second of an inch in
| thickness. AT the same time II IS cut to
the width required for making tire. 1t is
then rolled up on n wooden core, with a
sheet of muslin between the layers of rub
Der.
The Tube Room.
From here the rubber goes to a room
where number of men can be seen NOV
ing swiftly about in dense white cloud.
This is the tube room,' and the dense
cloud comes from the quantity of soap
stcne that is freely used at every stage of
the process to keep the rubber from stick
ing together.
The men here work in teams of twelve
First two men unroll the rubber strips upon
a table and cut them into proper lengths
for a tube. The strips are then passed over
to the next table, where they are rolled
into shape after both surfaces have been
covered with soapstone. Another man
passes the work over to the next table,
where q attaches a nozzle to the end
of the tube and blows a lot of soapstone
through 1t to prevent adhesion of the in
ner surfaces. The fourth set of men in
spect the tubes. cut them to the exact
length. and close up the ends by inserting
the forefinger, upon which is wrapped
| piece of cloth dipped in benZne and then
sticking the ends into an ordinary clothes
| wringer.
the tubes go into a heater. where they are
subjected to a steam pressure of forty
pounds for three hours and forty minutes.
| Then they are inspected second time and
passed on to the tube room. The stems
through which the tires to be inflated
are set en with a rubber solution. Then
| the tires are subjected to a final rigid in
| spection by being inflated with compressed
| air and immersed in tank of water. If
any bubbles rise in the water the workman
knows there must be faulty tube in the
| lot, and 1t Is hunted out and thrown aside
| to be sold for scraps.
Then the valves are thrust into the stems
by boy, while a second boy ties them
firmly in place with strong cord. This fin
| isles the tubes.
The casing stock from which the outer
part of the tire is made, is mixed by a
tube stock. After this the process of mill
ing and calendering and cutting to the
requisite width is Identical with that just
| described for the tube stock
| The friction CLOTH which forms the
| inner part of the outer tube, is made of a
| strong duck, which is tested by being SUBJ
jected to a breaking strain of 200 pounds,
and is then passed through a calender,
| which presses rubber, mixed by still an
other secret process, upon both sides and
into the meshes of the cloth at an enor-
| nous pressure This friction cloth is then
cut into diagonal strips just half the
| length necessary for a tire, by two men.
who stand one on each side of a glass
| table.
A Delicate Process.
In the building room the only skilled
labor in the factory is employed. The
| builders work at benches the length of a
tire. Two strips of friction cloth are laid
on bench with little groove down the
center. A steel mandrel the size the tire is
to be lifted up on the bench and dex-
terously rolled down the groove, the friction
cloth being taken up and wrapped around
| the mandrel as it rolls. These mandrels are
| warm, having just come from the presses,
and have been painted with solution of
soapstone to prevent the rubber from stick
| ing.A strip of casting stock is then laid down
over the groove on the bench and the man
drel covered with the friction cloth is rolled
back the other way, the builder gathering
UP the casing and pressing it upon the
| friction cloth until it adheres smoothly
| upon the outer surface This is the most
delicate part of the entire process. If the
| outer casing is not perfectly put on there
will be bisters, and the tire will be worth
less. The workmen in this department are
| expert at their business.
| From the builders the mandrels go to the
| press room, where they are put in pom
| derous iron molds and subjected to heavy
pr ressure and heat. The men here work in
pairs and each pair has certain number