Improvements in and relating to Pneumatic Tyres.
Year: 1892

page_text: Date of Application, 20th Dec., 1892
Complete Specification Left, 20th Sept., 1893-Accepted, 9th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to Pneumatic Tyres.
1 THOMAS DUNN of 83 Tierney Road Brixton Hill in the County of Surrey
Member of the Stock Exchange do hereby declare the nature of this invention to
be as follows:-
My invention relates particularly to an improved method of attaching a
pneumatic tyre to a wheel rim. A great variety of methods for effecting this have
already been patented, many of which are now widely used, but most of them are
complicated or troublesome, or require a special construction of tyre & rim, so that
they cannot be interchanged, the tyres requiring to be fitted on rims specially
designed for them, & the rims being unsuitable for any tyres but those they were
designed for. By my method a tyre can be made up complete in itself & capable
of being perfectly secured on any ordinary rim simply by the act of inflation; & I
claim that I accomplish this in a simpler manner than any hitherto devised.
The principle of my invention is simply to introduce a hard band, flat & stiff
transversely & flexible longitudinally but inelastic, preferably of steel, into a
channel formed underneath the canvas layer round the under side of a tyre which
is complete in itself independently of the rim. This band should be inserted close
to the valve & be of such length that, when the tyre is fully inflated, its two ends
should abut on each side of it, it being preferably one of those which are screwed
on to the rim, whereby it will secure the two ends of the band which then requires
no other fastening. It is only necessary further that the band should be slightly
narrower than the rim to which the tyre is to be affixed, & that the edges of the
rim should be of such a shape as to prevent the band being pushed off sideways.
A rim flat on the inside with slight up turned edges would be the most suitable for
tyres thus secured, but any ordinary rim of slight concavity will serve very well,
deep rims only being undesirable.
This method is applicable either to single tube tyres or to those with a separate
cover, in the case of the latter various simple methods of securing together the
edges of the cover being available. The tyres should be made to fit the rims so
that they would not be liable to come off of themselves when deflated, though easily
pulled off. Then, since on inflation an ordinary pneumatic tyre when free while
expanding in its outside diameter at the same time contracts in its length & inside
diameter, the tyre on inflation will grip the rim tightly, & the presence of the
band in its under side causes the grip of the tyre all round the rim to assist in
making it secure at every point.
I am aware that several others have designed & patented methods of securing
tyres, in which a band underneath such as herein described is employed, but, as
have already indicated, I claim that this method is simpler & in several other
respects better than any hitherto devised.
Dated this 20th day of December 1892.
HOMAS DU
UNN.
COMPLETE SPECIFICATION.
Improvements in and relating to Pneumatic Tyres.
I, THOMAS DUNN, of 83 Tierney Road, Brixton Hill, in the County of London,
Stockbroker, 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 reference to improvements in and relating to pneumatic tyres
whereby the same can be easily, quickly and firmly attached to wheel rims..

page_text: Various means have heretofore been proposed and used for this purpose but so far
as I know, they are all more or less complicated in construction, or troublesome to
apply, or require a special construction of tyre or wheel rim so that the tyres and
wheel rims are not interchangeable, the tyres requiring to be fitted on rims
specially designed for them, and the rims being unsuitable for any tyres but those
for which they were constructed.
Now my invention has reference to means whereby a pneumatic tyre when placed
upon a wheel rim and inflated, will become automatically and effectually fixed upon
the said wheel rim, which may be of various forms in cross section and such as are
commonly in use.
For this purpose I provide within the pneumatic tyre on the under side thereof,
that is to say in its inner periphery next to the wheel rim to which the tyre is to
be applied, a centrally arranged channel or sheath fitted with a flat band or
circular strip of suitably hard material, such as sheet steel that is practically rigid
transversely and flexible longitudinally but not extensible in length and the
ends of which are fiee and wholly within the tyre. This band or circular strip
(bereinafter called a circular strip) is arranged between the air tube and the canvas
or other covering within which the air tube is enclosed or held, so that it will be
subjected to the pressure of the air within the air tube. It is inserted into the
tyre through the ends of the sheath near to the air valve, and is of such a length
that when the tyre is placed on a rim and fully inflated, its two ends will come
near to opposite sides of the said air valve. This air valve should be one of those
which are screwed up to the wheel rim by a nut so that it will retain or hold the
two free ends of the circular strip in place relatively to the wheel rim, no other
fastening being then required. A pneumatic tyre thus constructed should be made
of such length as to fit a wheel of such diameter as it is designed to be applied to,
tightly so that it will not be liable to come off the wheel when deflated, but so that
it can then be easily pulled off when desired. Then as on inflation an ordinary
pneumatic tyre when free, will, while expanding in its outside diameter, simul-
taneously contract in length and inside diameter, a tyre constructed according to
this invention will, on being placed on n wheel and inflated, grip the wheel rim
tightly, and the circular strip being also contracted in diameter and pressed upon
the rim at every point will become immoveable and being inextensible, it cannot be
raised at one point without being drawn towards this point along its whole lengthi
to either or both ends, it thus will cause the grip of the tyre, exerted all round
the wheel rim to assist in making the tyre secure at every point. In the case of
ordinary cycle wheels the circular strip should be slightly narrower than the rim
of the wheel to which the tyre is to be fixed, and it is only necessary that the rim
should be of such a cross section as to receive the tyre and prevent it being pushed
off laterally.
To secure pneumatic tyres such as described in a detachable manner on any
ordinary carriage or other vehicle wheel without making any alteration to the
wheel such as is necessary by all other methods of securing pneumatic tyres to such
wheels I know of; except only to drill the valve hole, I secure on the inner side or
periphery of the tyre a band of any suitable material such as hard rubber that is
flat next the tyre but slightly concave towards the wheel and preferably with small
inwardly projecting rims round its edges to grip the sides of the wheel. This band
should therefore preferably be somewhat broader than the felloe of the wheel to
which the tyre is to be attached and the circular strip 1 should preferably be of the
same breadth as the base of such band.
In making up tyres to be secured in the manner described, I find it desirable to
make them of such a length that they require to be slightly stretched to get them
on the wheel the first time. Then on inflation, and still more by use, they are still
further stretched so that they can be taken off and replaced on the wheel without
the use of any inconvenient amount of force, but they should always grip the wheel
tightly even when deflated. When desirable I find the tyre may be given an
extremely powerful grip by. making it of bands of canvas cut on the cross and

page_text: stretched it may be by passing through sets of rollers designed for this purpose-
to about half the maximum amount of stretching the material will withstand
without breaking. A tyre made of material thus prepared will naturally afterwards
stretch less longitudinally than when made of unstretched material, but on inflation
it will stretch laterally more readily and this lateral stretching will be accompanied
by longitudinal contraction so that the tyre will thus possess a very powerful
gripping action and will attach itself securely to wheels differing in circumference
within limits of say about four inches in the case of a wheel of about 30 inches in
diameter, and proportionally more in wheels of larger size.
And in order that the nature of my invention may be fully understood I
will now proceed to explain the same by aid of the accompanying drawings,
wherein
Fig. 1 is a longitudinal section, partly in elevation, showing a portion of a
pneumatic tyre adjacent to the air valve, with my invention applied to it.
Fig. 2 is a cross section of the tyre, drawn to a larger scale.
Fig. 3 is a side elevation, partly in section, of the portion of the tyre diametri-
cally opposite to that portion shown in Fig. 1 and showing a device for securing
the circular strip at that point to keep it in its place and prevent one end shifting
closer to the air valve than the other which would impair its automatic action.
Fig. 4 is a detail view.
Fig. 5 is a cross section of the tyre near the air valve showing how a slit or
opening in the inner side of the outer cover through which the air tube, circular
strip and other parts are inserted in place, is normally closed.
The remaining figures are hereinafter referred to.
1 is a circular strip of flat sheet metal such as steel, arranged between the
air tube 2 and the inner side or periphery 3 of the outer cover 3 of the
pneumatic tyre, so that when the tyre is inflated, it will be subjected to the air
pressure within the said air tube and will clamp the inner circumferential portion 3°
of the said outer cover between its edges or sides and the wheel rim 4 at the
points 5. 5. In the example shown, the circular metal strip is of such a length
as to extend nearly entirely around the tyre, the air valve 6 being placed between
its ends as shown more clearly in Fig. 1. This valve is of the kil now commonly
in use and is firmly held to the wheel rim 4 by a nut 6" so that the adjacent ends
of the circular metal strip will be thereby held or retained in place between the
air tube and the wheel rim but nevertheless in such a manner as to permit of
these ends, which are entirely within the tyre and unconnected with external
tightening devices, moving freely toward and from each other when the tyre is
inflated and deflated respectively.
7 is a tube or sheath of suitable material such as the canvas ordinarily used
in making pneumatic tyres. secured to the inner surface of the outer cover and
within which the metal strip 1 is arranged. This sheath permits the said circular
strip to move in the direction of its length relatively to the sheath, without
undue resistance, when the tyre is contracting and expanding upon inflating and
deflating it. 8 is a short length or bridge piece of strip metal such as steel. It
is arranged between the an tube and the end portion of the said strip 1, and
is held in place by the air valve 6 which passes through it, and the end portions
of the sheath which it enters. This bridge piece serves as a guide to still further
lessen resistance to endways movement of the strip 1 and to prevent the ends of
this strip catching in the end portions of the sheath. To ensure that the two ends
of the circular strip shall move simultaneously and to an equal extent, it is advan-
tageous to secure the strip at its centre, that is at a point of the tyre opposite the
air valve 6, to the inner side or portion 3" of the outer cover 3. This may con-
veniently be done by a device such as a paper fastener 9 which may be secured to
the circular strip 1, as shown in Fig. 4, before inserting the said strip in the
sheath 7, then pushing the strip through the sheath until the fastener is diametri-
cally opposite the air valve, or approximately so, then drawing the flattened down
ends of the fastener through a hole cut in the sheath and outer cover at this point,

page_text: and finally opening the ends of the fastener and turning them over and flattening
them against the inner or under side 3 of the cover 3 as shown in Fig. 3.
By the construction described, the tyre when applied to an ordinary crescent
shaped wheel rim and inflated will become tightly held all around the wheel rim
along two circumferential lines by a force that is in proportion to the area of the
circular strip and the air pressure within the air tube, and a force tending to
displace the tyre from the wheel rim at any point thereof, will, owing to the
presence of the said strip, be resisted by the whole of the pressure upon the
strip all round the wheel, whereas in the absence of the said strip, the pressure
acting to prevent displacement would be simply that due to the internal air pressure
upon the portion of the tyre subjected to the displacing force.
To obtain the best results it is important that the circular strip 1 should as
herein before stated, be stiff or rigid in a transverse direction so that the air
pressure will not cause it to bend and adapt itself to the concave cross section of the
wheel rim, but will permit of the pressure being transmitted to its sides so as to
hold the tyre upon the wheel rim along two circumferential lines.
To obtain sufficient rigidity in a transverse direction with the minimum of weight,
the metal strip may be transversely fluted or finely corrugated, but not to such an
extent as to make the strip elastic or extensible in the direction of its length.
For this reason two strips might be used, one of which may be transversely
corrugated whilst the other is plain. I bave obtained satisfactory results with a
plain strip of sheet steel one inch in width and about 4th of an inch thick, the
pneumatic tyre being suitable for an ordinary 28 inch wheel and 1 inches in
diameter, and the wheel rim being 14 inches in width.
In Figs. 1, 2 and 3 I have shown my invention applied to a tyre composed of
an inner removable air tube 2 and a separate tubular outer cover 3, which, in order
to permit of the ready insertion and removal of the air tube and circular strip,
has a central longitudinal cut in its inner side or circumference 3* on each side
of the air valve as shown at 10 in Fig. 1 and in Fig. 5 so as to provide an
opening in it say about four or five inches in length. This opening is normally
closed by a flap 3b formed by one edge portion of a piece of suitable flexible
material such as canvas, that is secured by solution in the usual way round the
inside of the tyre to form the joint between its two ends. This flap passes out
through the slit or cut in the tyre and has a bead in its edge which, when the tyre
is in place on the wheel rim, is held between one edge of the circular strip 1 and
the wheel rim so as to effectually close the said opening..
My invention may be applied to single tube pneumatic tyres which in this case
would be provided at their inner side or circumference, during formation, with a
sheath similar to 7 into which the circular strip could afterwards be forced endways
through a slit in the inner side of the tyre. This construction of tyre is similar to
that hereinbefore described, except that the air tube and outer cover are not
detachable the one from the other.
My invention may also be applied to tyres of the kind in which the air tube is
held within an outer separate covering that is not continuous in cross section, but
in this case the edges of the cover should be connected together in some known or
suitable manner, as for example by lacing, or by making such edges tubular and
notching them as shown in cross section in Fig. 6 and in underside view in Fig. 7,
and connecting the interlocking notched edges by a number of short detachable
pieces of wire 11, so that the tyre with circular strip 1 is practically complete in
itself without the wheel rim upon which it is fastened.
The wheel rim 4 in each of the examples shown is of ordinary concave pattern.
As will be obvious however, pneumatic tyres constructed as described can be
applied to wheel rims of various constructions, a flat rim with lateral flanges that
is to say of or channel shape in cross section being very suitable, deeply
channelled rims being undesirable.
In the example shown, the circular strip is shown applied to a pneumatic tyre
constructed with a corrugated metal protecting band 12 embedded in a strip 13 of

page_text: elastic material of plano-convex form in cross section arranged between the outer
circumference of the air tube 2 and the outer covering 3, as and for the purposes
described in the Specification of former Letters Patent granted to me dated
21st September 1891 No. 15952. This special construction of the outer portion of
the tyre therefore forms no part of my present invention.
I am aware that it has heretofore been proposed to use circular metal rings or
strips for securing pneumatic tyres upon wheel rims, but in the case of the rings it
was necessary that they should be made accurately to fit the wheel on which the
tyre was to be placed whereas by my construction I find the tyre may be made to
fit wheels of any size within at least an inch in circumference either way of the
normal size the tyre was designed to fit, and in the case of the strips they were all
furnished with mechanical couplings for the purpose of drawing their ends together
and the application of these couplings required troublesome alterations to the
wheels which has so far prevented these constructions coming into general use.
A further objection to these former constructions is that wheel rims of special
construction are necessary in most cases for such tyres, whereas my improved tyres
can as hereinbefore explained, be applied to any ordinary cycle wheel rim of slight
concavity or to any ordinary vehicle wheel without any alterations thereto
excepting that of drilling a hole in the rim to receive the air valve.
Having now particularly described and ascertained the nature of the said inven-.
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
.
1. Attaching a pneumatic tyre to a wheel rim by causing the outer cover to
become automatically clamped upon the said wheel rim, when the tyre is inflated,
by the automatic contraction in diameter of a circular strip of material that is
rigid transversely flexible longitudinally and practically non-extensible in length,
and which is arranged within a central sheath or channel placed between the air tube
and outer canvas cover at the inner side or periphery of the latter so as to be
subjected to the pressure of the air within the said air tube as set forth.
2. A pneumatic tyre constructed with a circular strip of material that is rigid
transversely and flexible longitudinally but practically non-extensible in length,
arranged centrally and wholly within the tyre between the air tube and outer
canvas cover at the inner side or periphery of the latter and so that its ends, which
are unconnected with external attachments, are free and capable of endways
movement relatively to the sheath or channel in which the said circular strip is
placed, the arrangement being such that when the tyre is inflated the said circular
strip will become automatically contracted in diameter by the action thereon of the
air pressure alone and will firmly clamp the tyre around the wheel rim substantially
as herein described.
3. The improved pneumatic tyres constructed as described and shown for the
purpose specified.
Dated this 20th day of September 1893.