Improvements in Preumatic Tyres for the Wheels of Vehicles.
Year: 1896

page_text: Date of Application, 19th June, 1896-Accepted, 15th Aug., 1896
COMPLETE SPECIFICATION.
Improvements in Preumatic Tyres for the Wheels of Vehicles.
We, THOMAS ALFRED HEARSON of Coopers Hill, Englefield Green, Surrey,
Professor of Engineering and WILLIAM MENZIES, of Englefield Green, Surrey,
Architect, 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:-
Our invention consists of an improved construction of a compound tube which is
intended to form the air tight lining of a pneumatic tyre for the wheels of vehicles
whereby a reserve airtight lining is provided and carried in such a way as to be
protected from the risk of injury by puncture.
The compound air tube is so constructed as to contain two annular compartments
each being continuous in itself but separated from the other by an air tight
diaphragm, and each being capable of separate inflation.
Thus if the outer compartment, that furthest from the hub of the wheel, is
inflated and the other is open to the atmosphere the diaphragm will be pressed close
against the portion of the outer surface of the compound tube which lies in contact
with the rim of the wheel.
The diaphragm being within the protection of the hollow rim of the wheel and
remote from the road will be free from a liability of being punctured.
If the outer compartment should becoine deflated on account of the outer
surface of the compound tube being. punctured the construction is such that air
can be forced through a separate valve into the compartment within, which will
then be blown out to lie in contact with the outer. surface of the compound tube
and thus re-inflate the tyre.
The compound air tube when in use is enclosed within a covering which is
inextensible or only slightly so.
This covering may consist partly of the rigid rim of the wheel and partly of a
flexible sheath attached to and detachable from the rim or the flexible inextensible.
sheath may completely and permanently envelop the tube.
Now our invention consists of the manner in which the compound air tube is
constructed which is such that each compartment forms an endless airtight tube to
which an inflating valve of the construction in ordinary use may be attached in:
the usual way by pinching the rubber of which the tube consists between the
enlarged head of the valve stem and a washer tightened by a nut which is
particularly described by reference to diagrams.as follows:-
The compound tube is first made in a straight length in one of the two following,
ways:-
(a) A sufficiently long and wide strip, of unvulcanized rubber is wrapped around
a mandril nearly two times so as to leave a, portion of the circumference of the
mandril with a single thickness only of rubber on it and the two edges of the
width of the strip are attached to the surface of the rubber adjacent by (so called)
"welded" joints. The section of the compound tube thus formed is as shewn in.
Figure 1 in which I, is the diaphragm by which the inner or reserve compartment is
provided, and O, is the surface of the outer compartment in ordinary use, J₁ and
Kare the welded joints.
The diaphragm I₁ is drawn somewhat crumpled to separate it from O₁.
() An unvulcanized strip of rubber is wrapped around a mandril to form a
simple single tube and outside this is wrapped a second strip of rubber of some-
what less width so as to nearly but not entirely embrace it and the edges of the
second strip are welded to the surface of the previously formed tube..

page_text: The section of the compound tube thus formed is as shewn in Figure 2, in-
which I and O, are the sections of the inner and outer compartments and
J, and K, are the welded joints.
In both methods of construction the shorter length from J to K has only a single
thickness of rubber.
This and the width of the joints are when in use placed within the protection
of the metal rim of the wheel.
A straight compound tube having been made as previously described a sufficient
length to surround the periphery of a wheel is taken and the ends are joined up to
form an endless tube in one of the following ways.
(c) The compound tube is first valefnized. Then at the ends a portion of the
compound tube which would form the outer compartment is removed if it has not
been omitted in the previous manufacture.
Next a short length of vulcanized rubber tubing X the internal perimeter of
the section of which is equal to the external one of the compound tube is threaded
over one end to be used in a manner to be afterwards described.
Then the portion of the compound tube which is to provide the inner or reserve
compartment is joined up by a cemented joint in the following manner.
A piece of tinned plate or other fairly stiff and fairly flexible miterial is bent
to form a short tube T of about the diameter of the compound tube Figure 3, an
open joint being left through which the rubber tube in a collapsel condition may
be inserted into or removed from the interior.
One end of the compound rubber tube is threadel through the tube T and a
short portion of its length is turned outwards and stretched around the outside of T
in such a way as to expose a portion of the innerinost surface of the compound
tube. Over this is stretched the other end of the compound tube as shewn in
Figure 4.
The letters OI TJ relate to the same parts as are indicated in Figures 1, 2
and 3.
The surfaces S, and S, are then prepared for cementing together by rubbing off
the outer smooth coating of sulphur and chalk.
After smearing the surfaces with rubber solation the surface S, is folded back
on to the surface S, and the whole allowed to remain for a sufficiently long time
for the joint to mature.
The tube T is then withdrawn and the joint of the compound tube will be as
shewn in Figure 5, the inner or reserve compartment being made continuous and
airtight.
A piece of woollen cloth or other similar material W is then wrapped around the
joint and inserted for a short distance between the outer and inner surfaces O and I
for purposes to be afterwards explained and to keep the cloth in place some rubber
solution is applied between a portion of its surface and the tube.
The valve for inflating the inner chamber should then be affixed in the ordinary
way the stein being passed through the single thickness of rubber between J and K
in Figures 1 and 2.
The short length of rubber tubing X previously referred to which was threaded
over the compound tube is now brought into place to bridge the gap between the
two ends of the outer compartment of the compound tube and the inner surfaces
at the ends of X are cemented to the exterior surface of the compound tube, the
surfaces being duly prepared.
By inflating the inner compartment the surfaces required to bo cemented can be
kept tightly pressed together until the joints are matured.
The piece of tubing X which is thus made to form a portion of the outer
compartment of the compound tube will locally completely surround the inner
compartment.
The stem of the valve for inflating the outer compartment is secured to the
tube X in the usual way as shewn in Figure 6.
At the place where the attachment is made the tube X is reinforced by a

page_text: rubber washer R being cemented to it. The stem of the valve can be inserted
from the inside of X and securely attached before threading it on the compound
tube.
The piece of woollen cloth W being porous will serve the purpose of preventing
the rubber from tightly closing the air passage through the valve stem so that the
outer compartment may always be capable of being readily deflated. It will also
prevent any rubber solution which is used in making the joints of X from getting
between 0 and 1 and thus ensure that they are not stuck together.
(d) The two ends of the compound tube may be joined up in a somewhat.
modified manner so as to avoid making a cemented joint at one end of the tube
piece X and to substitute for it a welded joint or dispense with a joint entirely
when the construction is as shewn in Figure 2 by making the piece X in one with
the piece O which forms the outer compartment of the compound tube.
In these cases the compound tube together with X are vulcanized together.
For the purpose of making the cemented joint for the inner chamber as
previously described the end X of the compound tube can be folded back by being
turned inside out and the remainder of the operation completed as before-
described.
(e) The compound tube may be manufactured in another manner as follows:-
An ordinary rubber tube of single thickness is made and vulcanized the length
being a little more than sufficient to wrap twice round the periphery of the wheel
of which it is to form a portion of the tyre.
This tube is turned inside out for a little more than half its length the split
tube T having previously been threaded over it so that the section of the tube as
turned back over T is as shewn in Figure 7. Over this is stretched the uninverted
end E₁ of the tube as in Figure 7 and the surfaces S₁ and S, after preparation are
cemented together by doubling back a second time a portion of the tube as is.
shewn in dotted lines in the lower half of Figure 7.
After the joint is matured the portion of the tube which was turned inside
out is reinstated in its normal attitude and the tube T withdrawn when the
section of the compound tube at the joint will be as shewn in Figure 8.
The second end E, of the tube must now be cemented to the outside of the
portion of its own tube which it wraps.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that being
acquainted with the fact that other inventors have proposed the construction of a
compound tube with two compartments we claim only
The methods of manufacturing the compound tube substantially as described
and the use of a compound tube so made for the pneumatic tyre of the wheel of a
vehicle.
D.
ليمي
1000
T. A. HEARSON.
WILLIAM MENZIES.