Improvements in Pneumatic Tyres.
Year: 1896

page_text: Date of Application, 22nd July, 1896
Complete Specification Left, 22nd Apr., 1897-Accepted, 19th June, 1897
PROVISIONAL SPECIFICATION.
Improvements in Pneumatic Tyres.
I FRANK REDDAWAY, Managing Director of the Firm of F. Reddaway & Co.
Limited, of Cheltenham Street, Pendleton, Manchester, in the County of
Lancaster, Manufacturers of Woven Machine Belting and Hose, do hereby
declare the nature of this invention to be as follows:-
My said invention relates to pneumatic tyres in which there is an inner inflatable
rubber air bag and an outer cover usually also of rubber and held in the wheel
rim so as to surround and confine the said inflatable bag.
In such tyres, punctures and consequent collapse of the tyre are of frequent
occurrence, the inner air bag being so thin that the smallest thorn or object capable
of penetrating the outer cover causes deflation.
To remedy this I form the said inner air bag thickened at the part confined and
surrounded by the outer cover, and especially over the tread, where objects most
usually penetrate the cover. The air bag may be of the usual thickness at the
part contained in and protected by the rim and sides. This thinner part takes up
all or almost all of the expansion of the bag and tyre under pressure, while the
thicker portion presents a cushion or tread of rubber which is not so easily
punctured or which if punctured closes up the hole by the resilience of the
material and so prevents any escape of air.
Dated this 21st day of 7.1 1000
Improvements in Pneumatic Tyres.
1 FRANK REDDAWAY, Managing Director of the Firm of F. Reddaway & Co.
Limited, of Cheltenham Street, Pendleton, Manchester, in the County of
Lancaster, Manufacturers of Woven Machine Belting and Hose, 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 and accompanying drawings :--
My said invention relates to pneumatic tyres in which there is an inner inflatable
air bag of rubber and an outer cover usually of rubber also and held to the wheel
rim so as to surround and confine the said inflatable air bag.
In such tyres punctures and consequent collapse of the tyre are of frequent
occurrence the inner air bag being so thin that the smallest thorn or object capable
of penetrating the outer cover injures the air bag and causes deflation. An
additional reason why the said inner air bag is so easily punctured or ruptured is
that being composed of rubber and in a constant state of stretch or distension the

page_text: smallest puncture is enlarged and aggravated by the radial retraction or drawing
away of the rubber from the puncture so that an almost imperceptible hole is at
once enlarged by the behaviour of the rubber itself.
To obviate these defects I make the said inner air bag thicker in section at the
part more immediately confined and surrounded by the outer cover and especially
over the tread where objects most usually penetrate the cover.
The air bag is thinner or of the usual thickness at the part contained and
protected by the rim and sides. This thinner and weaker part of the bag takes
up all of the expansion or distension of the material of the bag when inflated, the
thicker portion of the bag being practically unaffected by the distension of the
bag, and presenting a cushion or tread of rubber which by virtue of its mere
thickness is not easily punctured and which even if punctured closes up the hole
by the resilient falling in or contraction of the rubber upon the hole so that any
escape of air is prevented.
In order still more effectually to prevent any distension of the thickened portion
of the air bag, I might make the said bag of such circumferential proportions in
cross section relatively to the space constituted by the inside of the outer cover
and the rim that the said air bag shall in its undistended condition be of the same
size or slightly larger than the said space.
When this is so the inflation of the air bag presses the material of the bag
tightly against the interior of the cover and rim but does not stretch the material
of the bag at all, even at the thinner portion. Thus instead of the rubber of the
air bag being in a state of distension it is actually in a state of consolidation
throughout so that if it should happen to be punctured, the rubber instead of
creeping away from the puncture closes in upon it and stops the hole so effectually
as to prevent any escape of air.
The annexed drawing which is a cross sectional view of my improved thickened
tread air bag in position in a rim and cover will render my present description
more easily understood. The section of the air bag is of two different thicknesses
viz. the thickened portion or tread A and the thinner portion A'. The outer
cover is marked B and the rim C. In manufacturing my improved air bag I make
it of rubber, moulded or otherwise formed homogeneously to the required section
or shape no canvas or other layers being introduced into the thickness.
If the rubber of the air bag is subject to any distension at all when inflated
such distension or stretching is taken up by the thinner portion A' which is not
subject to puncture the thicker portion being too thick to yield to the distending
force of the contained air pressure and being on the contrary consolidated by the
squeezing influence of the air pressure. Nevertheless to prevent distension of
even the thinner portion of the bag, I might as hereinbefore set forth make the
bag of equal or of slightly larger circumference in cross section than the space in
which it is enclosed by the cover and rim.
In such latter case no actual distension of even the thinner portion of the
material of the bag takes place under inflation, the thickness of the bag being
simply squeezed tightly against the interior of the cover and rim and consolidated
by the pressure. The presence of the thickened and consolidated portion A of the
air bag renders puncturing exceedingly difficult, but should sucli puncture take
place, the thickened rubber closes in upon the hole as soon as the thoru, nail or
other object is withdrawn thereby preventing the escape of air.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be perforined I declare that what I
claim is.
1. The improved air bag for pneumatic tyres manufactured and applied
substantially as hereinbefore set forth.
2. An improved air bag for pneumatic tyres moulded or otherwise formed
homogeneously from rubber with a thickened base or tread for the purposes and
substantially as described and shown.

page_text: 3. An improved air bag for pneumatic tyres, moulded or otherwise formed
homogeneously from rubber with a thickened base or tread and in cross section
slightly larger than the confining space it is intended to occupy in the outer cover
and rim substantially as hereinbefore set forth.
Dated this 21st day of April 1897.
For the Applicant,
E. K. DUTTON & Co.,
5 John Dalton Street, Manchester, Chartered Patent Agents.