Improvements in Pneumatic Tyres.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Pneumatic Tyres.
1 JULES EMILE SENECHAL, of 42 Rue Réaumur, Paris, France, Merchant
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 pneumatic tyres of velocipedes have hitherto been made of annular form in
cross section so that they naturally assume a circular form under the internal
pressure of the air.
The pneumatic tyre is usually formed of two separate parts, viz. :-the external
sheath which forms the tread and the air chamber by which the sheath is supported
when inflated.
Pneumatic tyres are also sometimes formed of a single tube of sufficient thickness
to resist the internal pressure.
The defect of these tyres is the liability of the sheath, and consequently of the
air chamber, to be perforated so that the machine is rendered unserviceable.
Many arrangements have been devised to protect the air tube, and if some have
attained that object, it has been at the expense of the elasticity of the tyre.
One single combination consisting of a broad steel ribbon interposed between
the air chamber and the sheath affords the maxinuum of security without impairing
the elasticity of the tyre. But a steel ribbon inserted in a tyre of circular section
has the effect of quickly wearing both the air chamber and sheath by friction
against the edges of the metallic strip.
This invention is designed to obviate these disadvantages by substituting for the
circular form of the inflated tyre which too readily lends itself to perforation, some
other form, and preferably an approximately rectangular or trapezoidal sectional
form. In order to obtain a cross sectional form other than circular, I connect the
opposite sides of the air chamber together by inextensible transverse connections
which limit the lateral expansion of the air chamber and so prevent it assuming
the circular form, as hereafter described and illustrated in the accompanying
drawing forming part of this Specification.
Figure 1 shows for purposes of comparison an ordinary air chamber of circular
section when inflated.
Figure 2 is a similar section of an ordinary tyre having a steel ribbon between
the air tube and sheath, and showing how, by the form assumed when passing over
a stone, the air tube is liable to be cut by the edges of the ribbon.
Figure 3 is a cross section of a tyre of trapezoidal form in section, constructed
according to my invention.
"
Figure 4 shows a modified arrangement in which several air chambers are
superposed so as together to form a tyre of trapezoidal section.
Referring to Figure 1, a represents an inflated rubber tyre. Under the action of
the internal pressure the sectional form of the tyre a when inflated will be circular,
even although this section before inflation were elliptical, oval or of other form. If
inward radial pressure be applied to the inflated tube (Figure 2) supported on the
rim, it will assume the form indicated in said figure and as this change of shape
will occur every time the wheel passes over an obstacle the continual fretting of
the air chamber a and sheath against the edges ed of the metallic ribbon e
interposed between them will cause them to wear, which is more dangerous than the
perforation of the tyre.
The invention consists in means whereby the tyre is prevented from assuming the
ordinary circular form and is caused to take another sectional form preferably
"

page_text: trapezoidal the opposite sides of the air tube being connected together by strips h
of canvas or other inextensible material so as to limit the expansion of the tube in
the lateral direction. The same result is attained by superposing several air
chambers, three for example, as shewn in Figure 4. These chambers or tubes ikl
are of different diameters and united by strips of canvas m cemented thereto so as
to form inextensible transversely extending divisions. These combined air tubes
or chambers communicate with each other by means of orifices and are enclosed
The tread
in a rubber canvas-lined sheath o mounted on the metal wheel rim p.
portion of this sheath is lined with a steel ribbon 7 previously encased in leather,
canvas, or other material in order to avoid liability of cutting by the edges of the
flexible strip. For further security and to obviate the liability of slipping when
wet, the tread of the sheath o may have rivetted or cemented to it an outer band »
of leather, ribbed or other rubber, or other suitable material which is easily
replaceable and protects the sheath from wear.
The air chamber proper whether divided by strips connecting its opposite sides
or composed of superposed tubes in communication by one or more holes will as
well as its sheath retain when inflated the original sectional form adopted whether
rectangular, trapezoidal or other. As the divisions connecting the opposite sides
of the tyre are inextensible the intermediate portions only of the sides can expand
laterally and give the tyre a bellows-like form, and the tread being flat the sheath
and air chamber are not caused to lap round the edges of the steel ribbon so that
all danger of cutting from this cause is avoided and the perforation of the air
chamber is rendered impossible. This new bellows forin and permanently flat tread
of tyre with interposed steel ribbon is superior to all others and possesses great.
flexibility combined with absolute security. Steering can be effected without
dragging on the roughest roads and sharp curves.
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 what I
claim is:
1st. The herein described system of pneumatic tyre for velocipede and other
wheels, made of rectangular, trapezoidal or other sectional form except cylindrical
such that the tread is permanently flat in the transverse direction and retains that
form on passing over an obstacle.
2nd. The herein described construction of pneumatic tyre having its opposite
sides connected together by cross-divisions whether extensible or non-extensible
wholly or in part dividing the air chamber into concentric communicating compart-
ments, substantially as described with reference to Figure 3.
3rd. The pneumatic tyre consisting essentially in the combination of several
superposed extensible or non-extensible air chambers in communication with each
other, substantially as described with reference to Figure 4.
Dated this 22 day of December 1903
J. E.
By A. M. & Wm. Clark,
T
53, Chancery Lane, London, Chartered Patent Agents.