Improvements in Puncture-closing Tubes for Pneumatic Tyres and Process of Manufacturing the same.
Year: 1899

page_text: Date of Application, 25th July, 1899-Accepted, 14th Oct., 1899
COMPLEUITIVATION.
Improvements in Puncture-closing Tubes for Pneumatic Tyres and
Process of Manufacturing the same.
We, UZZIEL PUTNAM SMITH, of 3126, Rhodes Avenue, Counsellor at Law, and
THOMAS KANE, of 64, Wabash Avenue, Manufacturer, both in Chicago, in the
State of Illinois, United States of America, 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: -
Our invention relates to puncture closing air tubes for pneumatic tyres and
to the process of making same, and has for its object to provide an air-tube in
which the rubber of the outer or tread portion thereof shall be held normally
under a state of compression or pressure whereby it will operate to automatically
close any puncture or incision made therein.
Referring to the accompanying drawings:
Figure 1 is a section through a mandrel having an expanded tube thereon,
said tube having a strip of rubber cemented along one of its sides.
Figure 2 is a section through a mandrel with a concave side, showing the tube
thereon reversed, or turned inside out, the rubber strip thickened and lying in
the concave of the mandrel, and a canvas strip secured at its edges to the tube
and extending across said concave.
Figure 3 is a section through a completed tube as it appears when inflated.
Figures 4, 5 and 6 illustrate a different method of procedure.
Figure 4 being a section through a mandrel having a tube thereon of the
normal size, said tube having an expanded strip of rubber cemented along one of
its sides, or the tread portion.
Figure 5 being a section through a mandrel having a concave side, showing
the tube thereon compressed and lying in said concave and a canvas strip secured
at its edges to the tube and extending across said, concave; and
Figure 6 a section through a completed tube made by this second method, as
the tube appears when inflated;
Figure is a section through a completed tube when deflated.
Figure 8 is a section through a tyre illustrating an additional compressing
strip applied thereto.
The result aimed at by our invention can be secured by either one of two
methods of procedure, each of which we will describe in turn.
According to one method, we take a piece of rubber tubing, I, such as is ordi-
narily employed in making the inner tube of a tyre, and of a length sufficient
for that purpose, and we immerse the same in any suitable liquid that will cause
the rubber to expand or swell. For this purpose we find that a hydro-carbon
liquid is preferable, owing to the fact that it evaporates quickly and does not
in any manner injure or change the character of the rubber. We therefore
usually employ benzine for this swelling bath, but may use gasoline, naptha,
benzine, carbon bisulphuret, or the like. We do not, however, wish to confine
ourselves to the particular liquid employed. If the tube is made of what is
known as No. 1 rubber, we leave it in the bath from twenty to thirty minutes,

page_text: more or less, at the end of which time it will be found to have expanded or
swollen to nearly double its normal size in all directions. Thus such a tube
as described, if originally six feet in length and an inch and a quarter in diameter,
after being subjected to this swelling bath will be about from nine to ten feet
in length, about two, inches in diameter and about twice its normal thickness.
The length of time that the tube should remain in the bath depends largely, how-
ever, on the quality and thickness of the rubber, and the amount of compression
required. After the tube has been removed from the bath it is next slipped over
a mandrel 2 which is of such diameter as to permit the tube in its expanded state
to pass freely thereon, say about two inches. We next take a strip of rubber 3
in its normal condition of the same length as the expanded tube, and of the
proper width to form the tread of the tube, and preferably of about the same
thickness as the tube before its expansion,-and cement it in the ordinary manner
along one side of the tube, rolling the same firmly thereon and wrapping rubber
or canvas strips around the tube and strip to hold them in firm relation, so as to
prevent any movement of the tube, in shrinking, independent of the strip. When
the cement has completely dried, we remove the wrapping from about the tube,
and remove the tube from the mandrel by rolling, or pulling it over itself in a
manner to turn the tube inside out, and thereby bring the strip upon the inner
side of the reversed tube. By the time the cement has dried, the benzine will
have entirely evaporated, so that the tube will be free to shrink or contract to
its normal size, with the exception that that portion along which the rubber
strip is cemented will be retarded in shrinking, or contracting, or resuming its
normal condition, owing to the fact that the strip, being firmly cemented to the
tube, must be compressed as the tube contracts. As the power or force exerted
by the tube in contracting is more than sufficient to overcome the resistance of
the rubber strip to compression, the effect will be that, as the tube was expanded
in all directions it will shrink or contract in all directions, and the rubber strip,
therefore, will be compressed, or pressed together from all sides, with the result
that when the power of the tube on the tread side to shrink or contract has been
equalized by the resistance of the strip to compression, said strip will be found
to have been doubled in thickness, and will continue to be held under great
pressure exerted from every direction by the contractive force exerted by that
portion of the tube to which it is cemented. When removed from the mandrel,
the thickened portion of the tube curves inwardly in the form of an inverted
arch, and if unrestrained will curl upon itself as indicated in Figure 7. To com-
plete the tube we next place it upon a mandrel 4, having a concaved side, the
thickened portion of the tube, that is the compressed or thickened rubber strip 3,
lying snugly within the concave, as shown in Figure 2. We then take a strip
of canvas or other inextensible material, 5, of the length of the tube and stretch
it across said concave, securing its side edges by cement or otherwise to opposite
sides of the rubber strip and to the body of the tube, as shown in said Figure 2.
When the cement has dried the tube is removed from the mandrel 4 and its ends
united in any preferred manner, as usual. When removed from the mandrel,
the tube will curl upon itself in the manner shown in Figure 7. When partially
inflated, the tube will assume the shape in cross-section corresponding to that it
had in Figure 2 when on the mandrel 4, that is with its thickened or compressed
tread portion forming a reversed arch. As the tube is further inflated this arched
tread portion will be forced outward, but as the tube cannot yield laterally owing
to the connection of the inextensible strip 5, it follows that the strip 3, and the
tread portion of the tube as well, will be further compressed or thickened as the
inflation continuées, until the parts finally assume the position shown in Figure 3.
The tread portion of the tube will now be held under great compression, resulting
from the original compression of the rubber strip effected in the course of manu-
facture, as previously described, and the further compression effected by the lever
power of the arch in the compressed tread portion when acted upon and pressed
outward by the pressure of the inflating fluid within, so that if this tread portion

page_text: be punctured, or an incision be made therein, the opening will immediately
and automatically close. By this method we are able to close punctures of larger
dimensions and with greater certainty than can be done by any method of which
we are aware as every portion of the tread of the tube is under a uniform pressure
or compressive force exerted from every direction alike. Thus to illustrate; a
puncture in any part of the tread may be likened to the centre of a circle, and
the lines along which pressure is exerted to close said puncture, to an infinite
number of radii projecting from said centre.
In Figure 8 we have shown a tube which has been submitted to a further or
second compression. In this instance, after the tube has been reversed, as
described, it is again placed on a mandrel. We then take a strip of rubber, 12,
preferably slightly tougher and less elastic than the strip first used and after
subjecting it to a swelling bath, cement it to the tube in the manner before
described, and immediately above or over the first named strip, so that the wall
of the tube is confined between these two strips. The result of applying this
second is that the first strip is still further compressed and the wall of the tube
itself to which both strips are cemented is also compressed by the contraction
of the second strip. A tube so constructed will operate with certainty to close
any puncture made in it, and if desired may be used in light tyres without the
canvas strip used in the former cases, or made into a complete tyre by adding
the usual casing.
According to the second mode of procedure, we take a piece of tubing 6 of
the kind indicated in the first case, and of a length to form the completed tube
in its normal condition and without treating it in any manner, place it upon a
mandrel 7, as indicated in Figure 4. We then take a strip of rubber 8 of such
a length that after being subjected to the swelling bath it shall be of the same
length as, the tube, and cement this expanded strip to the tube, rolling the same
firmly thereon and wrapping the tube in the manner previously described with
reference to the first mode of procedure. After the cement has dried we remove
the wrappings from about the tube, and then the tube from the mandrel. In
this case the contraction or shrinkage of the strip will serve to compress or
thicken the rubber of the tube, and the tube will, when removed from the mandrel,
curve inward and roll together in the same manner as previously described. We
then place this tube upon a mandrel 9 having a concaved side, the thickened
or compressed portion 10 of the tube lying within the concave, and then stretch
the canvas strip 11 across the concave and connect its side edges to opposite
sides of the tube and strip, as in the other case.
The tube as it appears when completed and inflated is shown in section in
Figure 6.
.
The action of the tube in this case in all essential respects is the same as that
of the tube made by the first method described. We may mention, however,
that in this second method when the strip was contracted and compressed the
tread portion of the tube, said tread portion will be of a less circumference of
length than the opposite side of the tube, so that when the tube is inflated this
compressed portion will form the inner periphery of the tube instead of the
outer. To overcome this tendency we either stretch a narrow strip of rubber
and cement it to the side of the tube opposite the tread portion, or else stretch
the tube longitudinally before applying the expanded strip thereto. In either
the result will be that that portion of the tube which is to lie next the
rim will contract slightly more than the tread. side and thus cause the tread
portion to assume the correct position. We would state that applying the
stretched rubber strip to the tube, or stretching the tube itself, has no effect
on the puncture-closing property of the tube and either of these steps is resorted
to solely for the purpose of causing the tread upon inflation to occupy its proper
position.
case,
In both the methods herein set forth, we have described the tube as having
only the tread portion compressed or thickened. It is obvious, however, that we

page_text: may render the entire body of the tube puncture-closing by applying other strips,
or another and wider strip thereto, in proceeding according to either method.
It is also obvious that flat pieces of rubber suitable for constructing such a
tube may be so treated and cemented together and afterwards made into a tube,
instead of using a tube already made as hereinbefore mentioned, and such a
method of procedure is contemplated herein.
We are aware that puncture closing tubes and tyres have been made by putting
the rubber in the tread in a state of pressure or compression, by stretching one
strip and cementing it to another in its normal condition, but so far as we are
aware the method of putting the rubber under pressure or compression in the
manner above described has never been before attempted, and by this process
we obtain a higher and more even and uniform compression than it is possible
to obtain by any method of stretching heretofore adopted, and besides, this pres-
sure is exerted from every direction alike to a common centre or puncture made
in the tube, which can never be the case in the so-called stretching process, which
is generally if not universally accompanied by the cementing of a strip of canvas
or other inextensible fabric to one surface or the other of the compressed body
of rubber, the tendency of which is to destroy the puncture closing quality of
the rubber by preventing it from exerting its expansive force, and any puncture
made in the rubber will be held open half or two thirds of the way through by
the action of such cloth. It will be observed that the tread portion of our tube
is constantly under a state of compression, or pressure, even in the deflated
condition, and that this is increased when the tube is inflated by the action of
the arch. Further, it will be observed that our canvas strip is not cemented
to the body of the compressed portion of the tube, hence the rubber is free to
exert pressure in all directions, independently of the canvas, having only fric-
tional contact with the cloth.
By the use of the word "expanded" herein and in the claims, as describing
the state of the rubber, we wish to be understood as referring to the condition
of rubber which has been increased in bulk, swollen, or enlarged in all directions
by being subjected to a swelling bath, or by any equivalent means, and we hereby
expressly disclaim any method involving the mechanical stretching of rubber
or any intention of including the stretching of rubber within the scope of our
invention.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :--
1. The process of making puncture-closing tubes for pneumatic tyres, which
consists in subjecting a length of rubber tubing to a swelling bath to expand
the tube, and then cementing a strip of rubber along said expanded tube, whereby
when the tube contracts said strip will be compressed or thickened, substantially
as described.
2. The process of making puncture-closing tubes for pneumatic tyres which
consists in subjecting a length of rubber tubing to a swelling bath to expand
the tube, cementing a strip of rubber along one side of said expanded tube.
whereby when the tube contracts said strip will be compressed or thickened, and
then stretching a strip of canvas across said thickened or compressed portion
and cementing the edges only of said canvas strip to opposite sides of said tube,
substantially as described.
3. The process of making puncture-closing tubes for pneumatic tyres, which
consists in subjecting a length of rubber tubing to a swelling bath to expand
the tube, cementing a strip of rubber along one side of said expanded tube whereby
when the tube contracts said strip will be compressed or thickened. turning said
tube inside out, and then cementing to the opposite side of the wall of the tube
to which this strip has been cemented a second strip of rubber which has first
been subjected to a swelling bath, whereby when this second strip contracts the

page_text: first strip will be further compressed and the wall of the tube be placed under
compression, substantially as described.
4. The process of making puncture-closing tubes for pneumatic tyres which
consists in forming said tubes, or their tread portions of two layers of rubber one
of which is expanded relative to the other and cemented thereto while in the
expanded state, substantially as described.
5. The process for making puncture-closing tubes for pneumatic tyres which
consists in forming the tread portion of said tubes of two layers of rubber one
of which is expanded relative to the other and cemented thereto while in the
expanded state, and then stretching a strip of canvas over said tread portion and
cementing the edges only of said canvas to opposite sides of said tread portion,
substantially as described.
6. The process for making puncture-closing tubes for pneumatic tyres which
consists in forming a reverse arch throughout the tread portion of said tubes by
making said tread portion of two layers of rubber one of which is expanded rela-
tive to the other and cemented thereto while in the expanded state, whereby one
or the other of said layers is compressed by the contraction of the other and
whereby on inflating the tube the reversal of the arch will operate to further
compress the rubber of said tread portion, substantially as described.
7. A puncture-closing tube for pneumatic tyres having a tread portion formed
of two layers of rubber one of which is expanded relative to the other and
cemented thereto while in the expanded state, substantially as described.
8. A puncture closing tube for pneumatic tyres having a tread portion formed
of two layers of rubber one of which is expanded relative to each other and
cemented thereto while in the expanded state and having a length of canvas
stretched over said tread portion and cemented at its edges only to opposite sides
of said tread portion, substantially as described.
9. A puncture-closing tube for pneumatic tyres having a tread portion composed
of two or more layers of rubber, one or more of which layers is in an expanded
state, whereby one or more of said layers will be held under compression by the
contraction of such expanded layer or layers, substantially as described.
TI 1 T... 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.