Improvements in Pneumatic Tyres.
Year: 1896

page_text: Date of Application, 3rd Mar., 1896
Complete Specification Left, 3rd Dec., 1896-Accepted, 3rd Apr., 1897
PROVISIONAL SPECIFICATION.
Improvements in Pneumatic Tyres.
I, WILLIAM GLASS WRENCH, of 27 Oswald Street, Glasgow, in the County of
Lanark, Consulting Engineer, do hereby declare the nature of this invention to be
as follows:-
The object of this invention is to render the pneumatic wheel tyres of cycles or
other vehicles self-closing in the event of puncture and also to increase their resiliency
by constructing the inner or air tube of same in such a manner that while under
inflation the internal pressure will have the effect of compressing its entire substance
instead of distending it.
To attain this end I propose to make the outer surface of the said tube uneven by
corrugating or otherwise indenting or depressing it below its normal surface line so
that such surface may be reduced to a mere series of interconnected ridges which
shall surround and form the bases of such pockets or depressions whose corresponding
convex surfaces become formed into separate or detached bag-like forms which
project themselves into the tube, each capable of acting independently of another so
as to cause no stretch of adjoining material and giving a greater skin surface to such
a tube than is obtained with a plain one of the same over-all length and diameter.
Before or on partial inflation these ridges representing the external surface of this tube
will be the first to come in contact with the outer cover of the tyre as well as the
wheel rim at certain points and he thereby slightly compressed while the pockets
which hang internally between such points, and meanwhile bridge the spaces between,
will on further inflation of the tube be forced outward against their own elastic
resistance towards their own bases and against the wall of the cover, and their convex
surfaces within the tube as well as their concave surfaces without the tube pressed flat
into a lesser skin area than before, the whole tube being thus straightened as it
were within the confined limits of its surroundings into a plain one; hence squeezed
into a state of compression. The principle sought to be embodied in this invention
therefore is the application of an internal elastic pressure to force outwards towards
its own fixed immovable and unspreadable base the free and elastic crown of any
independent pocket or bag, which constitutes part of the formation of an air-tight
tube or chamber and protrudes itself within such space in such a manner as to be
forced by inflation of the tube into an abnormal state of compression by the
flattening of its curved surfaces without permitting of a corresponding lateral or
longitudinal spread of its material which in the case of this endless tube is limited
laterally by its own circumference and longitudinally by the circumference of the
wheel. The ridges and depressions on the surface of this tube may therefore take
any suitable shape and run in any desired direction and may either extend wholly
round the tube's circumference or only part thereof. A further point aimed at in
connection with this invention is to have a tube which (in its normal or deflated
condition and also in the first stages of inflation) will be stiffer and not so liable
o kink or get nipped as a thin plain one which under the same conditions lies limp
nd flat.
Dated this 2nd day of March 180
WALLACE FAIRWEATHER,
Chartered Patent Agent,
62 Saint Vincent Street, Glasgow, Agent for the Applicant.

page_text: Improvements in Pneumatio Tyres.
I, WILLIAM GLASS WRENCH, of 27 Oswald Street, Glasgow, in the County of
Lanark, Consulting Engineer, 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:-
The object of this invention is to render the pneumatic wheel tyres of cycles or
other vehicles self-closing in the event of puncture and also to increase their resiliency
by constructing the inner or air tube of same in such a manner that while under
inflation the internal pressure will have the effect of compressing its entire substance
instead of distending it.
The invention is illustrated by the accompanying drawings, Figure 1 of which is a
cross section, Figure 2 a longitudinal section of part of a pneumatic tyre showing the
tyre deflated, and Figare 2 a detail hereinafter referred to. Figures 3 and 4 are like
views respectively of the tyre under inflation, and Figure 5 is a cross section showing
a modification of the air tube.
To attain the object of the invention, I propose to make the outer surface of the inner
or air tahu A uneven by indenting or depressing it below its normal surface line so that
such surface may be reduced to a mere series of interconnected ridges 13 which shall
surround and form the bases of such pockets or depressions whose corresponding
convex surfaces become formed into separate or detached bag-like forms which project.
themselves into the tube A, each capable of acting independently of another without
causing any streich of its own or adjoining material by reason of its sectional curves
in overy direction from base to base being generated on a radius external to the
tube A, and its convex surface within the tube A being much larger in this normally
moulded condition than when pressed against its surroundings, and which form
also gives a greater effective skin surface to such a tube iban is obtained with a
plain or even otherwise figured one of the same over-all length and diameter,
whose curves in some direction or other have an internal radius and coincide or
are more or less concentric with the circle of such a tube. Before or on partial
inflation these ridges B representing what is left of the external surface of this
tube A will be the first to come in contact with the outer cover D of the tyre us
well as the wheel rim E at certain points while the pockets C which hang internally
between such points, and bridge the spaces between, will on further inflation of
the tube he forced ontward against their own elastic resistance towards their own
hases which rest against the wall of the cover D, and their convex surfaces within
the tube as well as their concave surfaces without the tube pressed flat into the same
base area and therefore into a lesser skin surface than before, the whole tube A
being thus straightened as it were within the confined limits of its surroundings into
a plain one, as shown at Figures 3 and 4, hence staved up or squeezed into a state of
compression. The principle sought to be embodied in this invention therefore is the
application of an internal elastic pressure to force outwards towards its own fixed
and unspreadable base formed by the surrounding ridge the free and elastic crown of
any independent pocket or bag such as C which constitutes part of the formation of
an air-tight chamber such as the tube A and protrudes itself within such space in such
a manner as to be forced by inflation of the tube A into an abnormal state of
compression by the flattening of its curved surfaces without permitting any spread
of its material, which in the case of this endless tube A is limited laterally by its
own circumference and longitudinally by the circumference of the wheel. The ridges B
and depressions C on the surface of this tubo A may therefore take any suitable shape
as shown by Figures 1, 2 and 5 and run in any desired direction, and may either
extend wholly round the tube's circumference or only round part thereof. Should a

page_text: circular pocket be adopted such as shown at Figures 1 and 2 (which protrudes itself
within the tube A as a simple dome or pocket C instead of any other form) it is
possible that under certian conditions during the earlier stages of inflation its crown
may first become deformed as shown by Figure 24 and the depression become an
annular one. The pockets may therefore be moulded in this or other approximately
formed shape with the view of further increasing if necessary the length of their
moulded curves in every direction in relation to the length of such when flattened
against the cover, by which means and in virtue of the properties due to the
particular curved formation of the pockets generally, the self closing properties
claimed from compression may be in a higher degree obtained without making such
pockets too deep. A further point aimed at in connection with this invention is to
have a tube which (in its normal or deflated condition and also in the first stages of
inflation) will be stiffer and not so liable to kink or get nipped as a thin plain one
which under the same conditions lies limp and flat.
The term ridge is used throughout this specification to designate the tube surface
and is in no case meant to apply to a raised surface or surface external to that of
the tube.
Whilst the shape of the pockets formed in the air tube may be somewhat varied the
following features should be retained, viz:-(1) A normal formation of pocket whose
sectional curves or lines will become shorter in every direction from base to base
under the influence of applied pressure within the tube. (2) A normal formation of
pocket which has no curves in any direction coincident or concentric with any circle
of the tube proper.
(3) A normal formation of pocket which in being flattened
exerts itself radially and spreads its base, thereby compressing the strip which
surrounds and separates it from its neighbour, which resists or presses on the other
side with a similar action.
I am aware that it has been proposed to corrugate, longitudinally, transversely and
in other ways, the air tube of a pneumatic tyre with the object of subjecting the
rubber of which it is composed, to compression upon inflation, but such formation
of the contour of the tube has the effect of reducing its effective circumferential
length or diameter at the lines of corrugation thereby resolving its outer surface into
a series of disconnected ridges or protuberances beyond the tube proper, and involves
a stretching of the material in the direction of these lines to bring it into close contact
with the outer sheath or covering before any compressive action can take place; thus
any advantage resulting from the part compression, part tension of the material is to
a certain extent neutralized. I therefore make no claim to the use of a tube so
formed hut confine my invention to the formation of the tube with depressed or
indented pockets entirely isolated from each other by the interconnected strip of skin
surface which intervenes between and surrounds each pocket.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is
An air tube for a pneumatic tyre having its surface depressed or indented into
pockets entirely isolated from each other and separated by an interconnected strip of
the normal surface of the tube which intervenes between each pocket and fully
surrounds it as a base to receive its thrust substantially as described.
Dated this 2nd day of December 1896.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62 Saint Vincent Street, Glasgow, Agent for the Applicant.