Improvements in the Manufacture of Pneumatic Tyres.
Year: 1896

page_text: Date of Application, 11th Aug., 1896-Accepted, 10th Oct., 1896
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Pneumatic Tyres.
I, THEODORE AYRAULT DODGE, of South Street, Brookline, Massachusetts,
United States of America, President of the Boston Woven Hose and Rubber
Company, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
This invention has for its object to provide a novel pneumatic tire and a novel
process for the manufacture of the same.
Prior to this invention in the manufacture of pneumatic tires it has been common
to build up the endless unvulcanized tube usually composed of alternate layers of
rubber and fabric and to place this tube in a mold, inflate it within the mold, and
while inflated vulcanize it.
It has been found, however, that tires produced in this way are open to the
objection that the tire surface is smooth and in the line of tread bas formed upon it
a fin or crease in the line where the two parts of the mold come together, this fin
or crease being in the line where the pressure is exerted upon the tire when in use
thereby rendering the tire unduly stiff.
Such a tire is further open to the objection that it is difficult to obtain uniformity
in product, and there is a large loss incurred in the manufacture because of pinched
or otherwise injured or distorted tires.
To obviate these objections this present invention comprehends a method of
making pneumatic tires wherein the same are first formed in an endless tube of or
containing unvulcanized rubber, which is arranged upon a suitable form with its
tread surface temporarily covered by a suitable fabric which is held or confined
tightly upon the tube in suitable manner, as, for instance, by winding a strip
of binding fabric spirally about the tube, its form, and tread covering fabric,
after which the covered and confined tire tube is vulcanized in suitable manner.
When the tread covering material is removed it is found that the threads
composing the material have been impressed into the tread surface of the tire
leaving a finely impressed or indented surface, sufficiently rough to prevent slipping
of the tire in muddy weather without interfering with the free running of the tire.
In carrying out this invention the tire tube will preferably be more or less
inflated, preferably above the atmospheric pressure, practically throughout the
entire process in order that the tire may be more readily handled without danger of
twisting or distorting the same when in its pliable unvulcanized condition in order
that the same may he built up and finished in precisely the condition in which it is
to be used thereby avoiding any line or lines of weakness which are always
caused by the inflation of the tire to a condition differing from that in which it was
manufactured.
This inflation is particularly desirable after the tire tread has been covered
with the covering fabric in order that the material of the tire tube may be
more distinctly impressed into the meshes of the covering fabric for the purpose
stated.
A tire manufactured by my process has no creases or stiffening projections
formed upon its tread surface, as is the case where tires are formed in metallic
molds.
This invention therefore primarily comprehends a pneumatic tire having a tread
surface finely indented to prevent slip without interfering with the free running of

page_text: the tire, and the invention further comprehends the method for producing said tire
to be hereinafter fully described and pointed out in the claims.
In the drawings,
Fig. 1, in perspective, illustrates an endless tire tube of or containing rubber;
Fig. 2 shows the same applied to a suitable form preparatory to the vulcani-
zation;
Fig. 3 shows the tube mounted upon the form with its tread surface covered
with a suitable fabric, the latter being broken away to better show its arrangement
upon the tube;
Fig. 4, a similar view showing the tube secured to the form in an inflated
condition by spirally wrapped coverings in condition for vulcanizing, and
Figs. 5 and 6, details respectively showing in section and in face view portions of
the completed tire.
Referring to the drawings for illustration, I will now proceed to describe the
invention as embodied in the best method now known to me for practising the
same, it being expressly understood, however, that said invention is not to be
restricted to all or the particular steps described in the specification, but that the
invention, as such, will be particularly set forth in the claims at the end of this
specification.
In the drawings, Fig. 1 is an endless tire tube built up or formed in usual
or suitable manner, of alternate layers of rubber and a woven fabric, as canvas or
duck, but the particular construction of this tube or the method of making it into
endless or ring-like form is not material to this invention, so long as it contains to
a greater or less extent rubber in a substantially unvulcanized condition.
This endless unvulcanized tube which for convenience I shall hereinafter
designate as a rubber tube, notwithstanding it has incorporated in it a fabric,
is next, preferably, sprung over and upon a ring-like form, preferably hollowed at
its outer face, and shown at b, Fig. 2, the tube when first sprung upon this form
usually assuming a flattened or collapsed condition on and following the surface of
the form.
Through the usual valve stem a' and a suitable valve or plug with which the tire a
is provided before placing upon the form, the tire tube when on the form is
preferably inflated, as shown in Fig. 2, preferably not quite to the extent to which
it will be inflated when placed in the vulcanizing chamber.
While this inflation of the tire tube is not absolutely essential, yet, for the best
results, it is preferable to so inflate the tube as a great advantage arises therefrom,
in that the tube thereby acquires sufficient stability to enable it to be handled in
the subsequent process of wrapping, etc., to be described, without fear of twisting or
distorting the tube.
I next cover the outer or tread surface of the unvulcanized tube with a suitable
fabric preferably of closely woven or coarse duck, which, for convenience, may be
wrapped circumferentially about the inflated unvulcanized tube, as best shown
in Fig. 3, this fabric, for the best results, being stretched tightly about the tire
tube to impress its threads or surface to a sufficient degree into the soft
unvulcanized rubber surface of the tire tube and secured in place in suitable
manner.
This tread covering fabric, however arranged upon the tube, is confined there-
upon in suitable manner, preferably by binding the whole, viz. :-The form, the
tire tube and its fabric covering firmly together, by spirally wrapping about the
same, as indicated in Fig. 4, a strip or strips d, of cloth or other suitable fabric,
after which the tire tube is preferably again and further inflated to a pressure say
of twenty to thirty pounds to more tightly press the tube against its covering
fabric, and further and more distinctly to impress the surface of the covering
fabric into the tread of the tire.
During the process of vulcanization the air already forced within the tube greatly
expands, by reason of its being heated, thereby tending to burst the tube, this
tendency particularly prior to complete vulcanization being restricted only by the

page_text: covering material or materials, and I have found in practice that this bursting
tendency is best restricted, and in the most simple and effective manner by the
spiral wrappings of fabric, described, and by means of this or equivalent means for
confining the tread covering fabric upon the tire tube 1 am enabled to vulcanize
the tire tube while in an inflated condition, practically such as it is called upon to
assume when in use upon the road.
Thus inflated, covered and wrapped, as in Fig. 4, the tube and its form are
placed in a suitable vulcanizing chamber and the tube vulcanized by a steam bath,
or the tube may be vulcanized in any other desired or well known manner, after
which the spiral wrappings and temporary tread cover are removed, leaving the
finished and completed tire to be removed from the form in the condition shown in
Figs. 5 and 6.
The indentations of course have the full impressions of the warp and weft
threads which appear at the surface of the tread covering fabric next the tire, and
said indentations are therefore cup-shaped in cross section, that is, they have a
rounded bottom; they are substantially rectangular in outline when viewed from
the outside, and the projecting ridges between adjacent indentations have concaved
sides, thereby giving to said ridges much greater flexibility than would be possible
were they of other and fuller cross sectional outline.
From the foregoing description it will be understood wherein lie the advantages
resulting from this novel method of construction.
The tire tube is preferably vulcanized while inflated, and, therefore, naturally
tends to remain in the very condition and form which it must assume when inflated
and in use, hence there is no distortion or weakness caused by inflating the tube as
necessarily results from the inflation of a tube vulcanized in a deflated condition,
and, since my tire, throughout the entire process of manufacture, is maintained
inflated, there can be no lines of weakness due to flattening or folding as when the
tire is vulcanized in a deflated condition, and again the material or rubber of
which my tire is composed, by the very necessities of the case, is uniformly
distributed around or throughout the tire and is so maintained.
By vulcanizing it when wrapped or covered with the fabric, as described, there
can be no ridges or creases such as are formed by the use of a vulcanizing mold,
and the tread surface of the tire tube is left finely impressed, which, so far as I
am aware, is entirely new with me and produces a tire which has a surface of
sufficient roughness to prevent slip in muddy weather without, to any appreciable
extent, interfering with the free running of the tire.
This invention is not necessarily limited to the particular number or character
of steps herein enumerated, for it is evident that the details may be varied in many
ways without departing from the essence of the invention, which lies in covering
the tread surface of the inflated unvulcanized tube with the fabric and vulcanizing
the covered tube while inflated.
In practice, a tire embodying this invention as herein described, is found to
adhere to wet or slippery roadways much m re effectively than would a smooth
tread tire, yet the free running of the tire is not interfered with, as is the case
with tires provided at the tread surface with pronounced knobs or projections, as
in the usual molded tire.
The peculiar shape or character of the indentations and the ridges between the
same also impart to this novel tire a degree of elasticity or resiliency which is
entirely lacking in other forms or types of tires.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what
I claim is :-
1. The within described tire having a finely indented tread surface to prevent
slip of the tire without retarding the free running of the same, substantially as
described.
2. The within described tire, having a smooth inner or rim surface, and a finely

page_text: indented outer or tread surface to prevent slip of the tire without retarding the
free running of the same, substantially as described.
3. The within described tire having its tread surface provided throughout with
closely arranged fine indentations curved in cross section and substantially
rectangular in surface outline, substantially as described.
4. The within described tire having a tread surface finely indented throughout,
adjacent indentations being separated by ridges having sides concaved in cross
section, whereby the walls of or ridges between said indentations furnish extremely
flexible and yielding lines of contact with the roadway, substantially as described.
5. The herein described method of manufacturing pneumatic tires, which consists
in building up an endless tube of or containing unvulcanized rubber; temporarily
covering the tread surface of the unvulcanized tube with a fabric; adapted to
make fine indentations therein; securing the said tread covering fabric temporarily
in position; pressing upon the said tube; vulcanizing the tube while so covered,
and then removing the temporary covering to leave the completed vulcanized
tube ready for use, substantially as described.
6. The described method of manufacturing pneumatic tires, which consists in
building up an endless tube of or containing unvulcanized rubber; arranging the
same upon a form; temporarily covering the said tire with a fabric adapted to
make fine indentations therein; temporarily securing the latter in position,
pressing upon the tube on the form; vulcanizing the covered tube while on its said
form; removing the temporary covering fabric from the tire, and removing the
tire from the form, substantially as described.
7. The improved method of manufacturing pneumatic tires, which consists in
building up an endless tube of or containing rubber, inflating the same; temporarily
covering the tread surface of the inflated vulcanized tube with a fabric adapted to
make fine indentations therein; confining the said covering fabric in position
pressed upon the inflated tube; vulcanizing the temporarily covered and confined
tube while inflated, and removing the said temporary covering to leave the finished
tire, substantially as described.
8. The herein described method of manufacturing pneumatic tires, which
consists in building up an endless tube of or containing unvulcanized rubber,
covering the tread surface of the unvulcanized tube with a fabric adapted to make
fine indentations therein, temporarily securing the said tread covering fabric to
impress the latter into and to form indentations in the former, vulcanizing the tube
while so covered and inflated, then removing the temporary covering to leave the
complete vulcanized tube ready for use, substantially as described.
Dated this 11th day of August 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.