Improvements in Pneumatic Tyres.
Year: 1894

page_text: Date of Application, 24th Apr., 1894-Accepted, 30th June, 1894
Improvements in Pneumatic Tyres.
I JOSEPH GEORGE MOOMY, of No. 132 East 12th Street in the City of Erie,
in the County of Erie, and State of Pennsylvania, United States of America,
Inventor, 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, that is to say :-
This invention relates to pneumatic tyres, and consists in certain improvements
in the construction thereof, as will hereinafter be fully described and pointed out
in the claims.
The invention is illustrated in the accompanying drawings as follows:
Fig. 1 shows a transverse section of the tyre in place on the rim, and a deflated
inner tube therein.
Fig. 2 is a side elevation of the inner tube.
A, marks the rim of the wheel; B, the casing; b, the binder flaps thereon ;
D, the binder; and C, the inner tube.
The inner tube is made of such length that in its inflated condition, (not shewn)
its outer periphery will just fit snugly against the inner side of the outer periphery
of the tyre casing. It is so constructed as to be substantially inelastic longitudinally,
but has its full expansibility transversely.
Where the tube as commonly constructed is elastic both longitudinally and
transversely, its longitudinal circumference increases with inflation, and whatever
force there is to this tendency is sustained by the binder or the outer periphery of
the casing; and when the tube is made inexpansible both longitudinally and
transversely, as is the case where canvas is used in its construction, it is very
difficult to make it of the proper size to fit snugly and smoothly in the casing.
By making the tube inelastic longitudinally, the tendency of the tube to increase
in the longitudinal circumference as it is inflated is obviated, and the force
sustained by the tube itself, so that the binder is relieved of this strain; and
as the outer circumference of the tube cannot increase with inflation, the expansion
of the tube with inflation must be inwardly, and the flaps and the inner periphery
of the casing are pinched between the rim of the wheel and the inflation force of
the inner tube, so that the inflation of the tube, instead of straining the binder,
re-enforces it to some extent; and as the tube can fully expand transversely it fills
when inflated the casing completely and smoothly.
A further advantage of this construction is that it is less liable to creep in the
casing, for, as it is inelastic longitudinally, to move at any one point, it must move
throughout its circumference, and as the tube is expanded by its inflation trans-
versely against the casing, the frictional contact is so strong as to make its
movement next to impossible. With the ordinary tube, it being expansible
longitudinally, when there is a tendency at any point, caused by the tread or otherwise,
to creep, the longitudinal elasticity of the tube at that point allows it to move in
the direction of the tendency, and the tube as it becomes normal, will have moved
its position slightly in the direction of the movement of the initial point.
To make a tube having the qualities hereinbefore described, I mix a fibre
(preferably raw cotton, carded or uncarded) with the rubber. This mixture is then
calendered, care being taken to always run it in the same direction. This process
makes the finished material substantially inelastic lengthwise, that is, in the
direction it has been passed through the calenders. The explanation of this effect,
is that the process of calendering undoubtedly brings the bulk of the fibre to one
general direction. This leaves the material in the transverse direction substantially

page_text: free from the influence of the fibre, so that the rubber in this direction has nearly
its natural elasticity. In making the tube, the material is so placed that the
inelastic direction is lengthwise of the tube. In the drawing the dots in the cross
section of the tube marked c¹ indicate the fibres in cross section, and the dash
lines in Figure 2 indicate the general direction of the bulk of the fibre.
This makes a tube that is substantially inexpansible longitudinally and expansible
transversely.
By adding a raw fibre to the material from which the tube is made, the tube is
also made much less penetrable than is the case with rubber alone or rubber with a
woven fabric. Of the fibres known to me, I prefer ordinary cotton fibre, on account
of its well known impenetrable quality when in its unwoven state.
This quality
seems to be enhanced in connection with the rubber.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
An inner air tube, for pneumatic tyres, constructed as and having the properties
Dated this 24th day of April 1894.
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, and 6, Victoria Street, Nottingham,
Agent for the Applicant.