Improvements in or relating to Pneumatic Wheel Tyres.
Year: 1892

page_text: Date of Application, 7th June, 1892-Accepted, 9th July, 1892
COMPLETE SPECIFICATION.
Improvements in or relating to Pneumatic Wheel Tyres.
I, JOHN FULLERTON PALMER, of Riverside, County of Cook, State of Illinois,
United States of America, Gentleman, 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 :-
My invention relates to pneumatic tires for bicycles, etc., and is more particularly
related to the manufacture of such tires having a continuous ring-shaped tube for
air and a tread portion made of thickened and compressed rubber, for the double
purpose of giving an increase of material at the point of greatest wear and to give
to the tire the property of automatically closing any punctures that might otherwise
permit the exhaust of the contained air.
It has heretofore been suggested by myself and others that this property may be
given to a pneumatic tire by a manipulation of the tube before the same is formed
into the necessary ring-shape and before it has been inflated, and it has also been
suggested that this character may be given to the tire by forming the same into the
ring with a concavo-convex initial shape to the tread and thereupon by the
expansion of introduced air force outward the concavo-convex tread to a convex
form. In order to bring about the compression in the rubber, however, it is quite
clear that a substantially non-extensible backing must be provided to the thickened
portion of the tread and in endeavouring to carry out this method of operation it is
found that the change of the non-extensible backing from a concave to a convex
form is impossible because it would involve the extension of the canvas 3.1416 inches
for every radial inch involved in the change from concave to convex. In other
words it being borne in mind that in order to produce compression by inflation the
tube must be made complete in the form of a ring and the non-extensible backing
will, therefore, have an unvarying diameter, any method of operation which
necessitates the increase in the diameter of the non-extensible backing to produce
compression must be discarded; and the use of an extensible backing fails to produce
compression of the thickened portion of the tube.
It is a principal object of my invention to produce a tire having these character-
istics and incidentally to supply a method of applying a flexible fibrous material
like canvas, in such a manner as to afford a compensation in tautness between the
circumference and the inner point of the tube.
My invention consists in forming a pneumatic tire of flexible material with a
radial inner portion thickened and given throughout a concavo-convex, or wholly
or partially collapsed form, applying to the thickened concave inner surface a strip
or ring of substantially non-extensible fabric, such as canvas, said canvas ring
having the diameter of the intended outside diameter of the tire, and thereupon by
a twisting operation turning the ring throughout its circumference to an inverted
position, whereby the canvas strip shall be outside and the soft rubber or other
tube shall be within the canvas, that is to say between it and the centre of the
wheel. In this manner, the canvas not being materially extended, it presents on
reversal the same diameter as before, while the thickened rubber portion being
held thereto and prevented from expanding is compressed by reason of being
changed from a concave to a convex curvature. It is true also that the remainder

page_text: of the tube, or that nearest the felly, when applied is crimped to a greater or less
extent, but this is not deemed objectionable as the subsequent external covering
of canvas, which is always applied to this species of tire, disguises the appearance
and the inherent strength and resiliency of the tire is not reduced.
It will be observed that no effort is made to utilize the introduced pneumatic
pressure for bringing about this compression and the reason may be asserted
broadly to be that it is deemed undesirable to utilize the air to effect the com-
pression and thus close any apertures, inasmuch as when an aperture shall be
formed the tendency of the air to escape will counteract its tendency to produce
a compression of the rubber, and in exact proportion as pressure is lost the
ability of the compressed tubing to prevent further loss is reduced. Hence in the
mode of manufacture which I prefer the change in the curvature of the rubber
carrying canvas is alone relied upon, regardless of the condition of air pressure
within the tube.
It is quite apparent that means must be provided for giving to the canvas a sub-
stantially non-stretching character until some material shall be found which, while
flexible and strong in cross section, is also non-stretching longitudinally. At the
same time it is quite apparent that unless each strip of canvas shall be separately
woven on a convex and ring-shaped form some means must be devised for giving to
the inner radial points of the canvas a shorter length than is given to the middle or
outer radial points, because when applied to the tire if the length were the same
at the side as at the circumference, the side being nearer the center would pucker,
or at least would not be stretched to its full limit. It is part of my invention to
provide for this requirement by cutting the canvas strips on the bias, so to speak,
that is with the fibres running diagonally of the strip. It is deemed desirable,
however, that one of the fibres shall present an acute angle while the cross fibre
presents an obtuse angle, the latter fibre being at right angles to the long fibre.
In order to give the necessary strength to the canvas so cut, and more particularly
to reduce the stretching to a minimum, I provide two strips of canvas, one super-
imposed upon the other, each cut diagonally but having the fibres inclined in
opposite directions, that is, while the long fibre of the under one will incline from
right to left the long fibre of the upper one will incline from left to right. In this
way it is found that when either strip is stretched to its limit a greater amount of
stretching is effected at the middle point than at the edges, the difference being
such as exactly to compensate for the difference in diameter between the circum-
ferential and inner side of the ring-shaped tube. Any tendency, after such
stretching, to further stretching in either strip is antagonized by the resistance of
the other strip, and hence a practically non-stretching cover is obtained.
In the drawing-
Figure 1 is a sectional edge view of a rubber tube in the form of a ring as the
same appears before it has been converted into a tire having an external thickened
compressed tread portion ;
Figure 2 is a similar view of a tire after the same has been converted into the
proper form for use;
3.
Figure 3 is a side elevation of a section of a tire partly broken away representing
the appearance of the tube after it has been compressed at the tread portion in
accordance with my invention ;
Figure 4 is a transverse section taken through the tube showing its appearance
after it has been completed and the external canvas covering applied; and
Figure 5 is a plan view of two strips of canvas showing the mode of cutting the.
same to produce a non-extensible backing.
A represents the flexible part of the tube, and B the tread portion. The air.
space of the tube is confined between the walls afforded by the flexible part A and
thickened part B, the latter, as shown at C, being composed of compressible rubber,
vulcanized, of a width sufficient substantially to cover the tread portion of the
finished tire. D represents the non-extensible canvas and E the final envelope of
canvas, which is usually applied to the tire after it has been formed. Outside of

page_text: this is usually provided a further protective coating of rubber or rubber and canvas.
The operation of forming the tire as illustrated in Figures 1 and 2 is as follows:
The rubber tube A, B, is given a diameter over all slightly in excess of the
intended diameter of the wheel for instance if the intended diameter of the wheel
including the tire is 28 inches the tube is made of an external diameter of
28 inches, or thereabout. The inner surface of the tube A B is collapsed to the
concavo-convex form shown in Figure 1, and to this concave face is applied a strip
of substantially non-extensible canvas or other fabric D. The canvas strip D has
the diameter of the intended external diameter of the wheel, say 28 inches, and
being practically non-extensible it will retain this diameter in the subsequent
manipulations. Thereupon the tube is turned upon itself so that the part A shall
be between the circumference and the center and the part B shall be at the circum-
ference. This is done by commencing the inverting at a point upon the ring, con-
tinuing it around the ring by a sort of twisting operation until completed, the
result being that the edge a, found in Figure 1, becomes the edge al of Figure 2,
and the edge 6 of Figure 1 becomes the edge 61 of Figure 2, while the central
point e of the canvas becomes the central point c in the other figure. In the finished
tire it is thus found that the thickened portion C which was formerly convex
(Figure 1) becomes reversed in its curvature and hence concave, as illustrated in
Figure 2. This change of the curvature produces the requisite compression to
cause the rubber automatically to close any apertures that may be formed in it by
perforation. The part A, which is substantially smooth before reversal, as shown
in Figure 1, becomes slightly crimped by reason of reducing it from a diameter of
28 inches, or thereabout, to a diameter of 26 inches, or thereabout, but this
crimping is not deemed objectionable as it in no manner interferes with the strength
or resiliency of the tubing and it is subsequently hidden by the envelope E, of
canvas when applied, as before stated.
To give to the curved canvas ring a non-stretching character, when not provided for
in the manufacture of the fabric, I cut two strips F F¹, one, F, of which is composed
of fibres ts, the former having an acute angle to a longitudinal middle line, and
the latter at right angles to the fibre t and hence presenting an obtuse angle to
this line. The strip F¹ is the exact opposite of the strip F, the fibres t¹ and s¹
being provided in the same manner as before but when brought together the strips
are placed back to back so that the fibres t' in the strip F1 present the opposite
angles to the fibrest in the strip F, the measurement of the angles being, however,
substantially the same. It is found that when a strip F F is stretched upon a
curved mandrel the edges are drawn inward to compensate for the lineal extension
at the center, and that the actual length of the edges of the strip is less than the
length at the center, the proportion being such as to bring about a substantial com-
pensation in the tautness of the strip in the form of a tube or partial tube made
into a ring. It is quite apparent that the number of strips FF may be increased,
as desired, to afford increased strength with the same result. In order to bring
about a uniformity in action in the strips it is preferred to secure them together
by vulcanization, or some similar process in the usual manner before applying them
to the tire.
Having thus explained in a general way the essential features of my improved
method of forming the tires, I may state that in practice I have found it con-
venient to observe the following order in building up the tire before vulcanization:
First to apply to a mandrel in the form of a ring, round in cross section, a strip or
strips of canvas cut in the manner before described and saturated with rubber with
which is combined the necessary ingredients to produce vulcanization; thereupon
to attach to the canvas, curved and made continuous in the manner before stated, a
strip of thickened soft rubber in one or more layers, as desired, and also supplied
with the necessary ingredients to effect vulcanization, thereupon to apply a
collapsed tube of soft rubber so attached to the thickened rubber by its inherent
adhesiveness, soap-stone, flour or similar substance in the form of a powder being
introduced into the tube to prevent adhesion of the two walls during the process

page_text: :
of vulcanization. In place of introducing a foreign substance like soap-stone, air
may be introduced to separate the walls of the tube while vulcanization is taking
place, the purpose being, merely to make certain the formation of the hollow tube
when the tire is completed. After the parts have been thus applied the tire may
or may not be placed in a mold, wrapped with canvas in the usual manner, or
simply placed in a vulcanizing oven and subjected to the necessary heat to effect
vulcanization. The completed tire thus formed with the usual external covering
of canvas and rubber and before inflation may then be applied to the wheel and
inflated in the usual manner, or as has been suggested, by the introduction of a
puncturing tube attached to an air-pump through the thickened portion or tread.
It is found that a tire made in accordance with my invention, as hereinbefore
described, presents at the tread portion an inherent tendency to close any apertures
that may result from perforation, whether the perforation occurs in charging with
air or subsequently, and that when the tire is once charged a substantial preventive
against loss of air is supplied.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that I am aware
that it has previously been proposed to make pneumatic tyres of india rubber in a
state of compression for the purpose of closing punctures and I make no general
claim for such tyres, but what I claim is,-
1. As a new article of manufacture a pneumatic tire formed with a continuous
air-passage and having its tread portion thickened and retained under compression
by a confining strip of substantially non-stretching fabric extending over the tread
portion, substantially as described.
2. A tube for forming a pneumatic tire having, before completion, an endless
tubular concavo-convex form with its body thickened on the concave side and pro-
vided with a continuous strip of substantially non-stretching material on the
exterior at the concave side, substantially as described.
3. In a pneumatic tire the combination with a pliable substantially non-
extensible outer layer of an internal body of rubber seated against the outer
layer and maintained under compression by the curvature given to the outer layer,
whereby the automatic closure of punctures therein is secured, substantially as
described.
4. The method of producing in a pneumatic tire a compressed and thickened
tread portion, which consists in forming a tubular ring of rubber thickened on the
hub side and having applied thereto a substantially non-stretching ring of fabric,
thereupon inverting the relation of parts so that the non-stretching fabric shall be
on the tread portion, thereby compressing the thickened body of rubber, substan-
tially as described.
5. The method of forming a pneumatic tire with a thickened and compressed
tread portion on the internal tube, which consists in building the tube in the form
of a ring out of soft rubber with a hub-side layer of substantially non-stretching
fabric, thereupon vulcanizing the product and inverting the curvature of the fabric
and attached parts, substantially as described.
6. The method of forming a pneumatic tire with a thickened and compressed
tread portion on the interior tube, which consists in forming a ring of canvas
having the intended curvature of the tread, applying to its convex face a
thickened body of rubber and then applying an endless tube of rubber having in
one-half a collapsed concavo-convex outline to conform to the convexity of the
thickened rubber, producing vulcanization in the parts, and thereupon reversing
the curvature of the fabric and attached parts with intermediate or subsequent
inflation, substantially as described.
7. The method of making strips of fabric substantially non-stretching for use
in forming a pneumatic tire, which consists in applying together oppositely cut
strips of fabric, each strip having its fibres diagonally arranged with a long fibre
on an acute angle an1 a short fibre on an obtuse angle, whereby stretching of the

page_text: strip produces a curvilinear form, and when thus produced further stretching in
either strip is substantially prevented by the resistance of the other, substan-
tially as described.
8. A pneumatic tire having an outer thickened tread portion of rubber inverted
and held in position by a substantially non-stretching backing composed of two or
more superimposed attached layers of diagonally cut fabric, the fibre in alternate
layers being arranged in opposite directions, substantially as set forth.
Dated this 7th day of June 1892.
W. P. THOMPSON & BOULT,
Agents for the Applicant.