Year: 1896

page_text: I BENJAMIN HOWARTH THWAITE of 29 Great George Street Westminster
Civil Engineer do hereby declare the nature of this invention to be as follows:-
This invention relates to a novel method of applying air pressures to the wheels
of cycles or other vehicles. In my invention I prefer to employ two tubes to both
of which I apply an air pressure, but of varying intensity. The outer tube which
constitutes the tread or actual tyre has a higher pressure than the inner one, which
only comes into actual useful service in periods of emergency.
I subject both tubes to a continuous pressure of air, each of the tubes has an
independent air inlet attachment for the purpose of reinflation, and each tube has
its own non-return valve.
In the initial charging of the tubes with a pressure of air, I first attach the air
inflating pump or other character of pneumatic pressure container to the inlet of
the inner tube and allow sufficient air to enter as will expand this inner tube until
it commences to inflate the outer tube to a condition of partial hardness, just
sufficient to permit the cycle or other vehicle to be used in case of puncture of the
outer tube. After the inner tube has been inflated to the degree described, then
the air pump or other inflator is detached therefrom, and is then applied to the
inlet of the outer tube, the air is then introduced to the outer tube until it is
inflated to the usual condition of hardness required. The high pressure necessary
for this compresses the inner tube, reducing its diameter until it occupies a con-
siderably less cross sectional area than does the outer tyre and whilst in this
condition of compression, and also owing to the high dilation of the outer tube, the
inner tube is not in contact with the inside surfaces of the outer tube, as air under
high pressure intervenes between the inner and outer tubes, so that should the outer
tube be pierced or punctured the inner tube is not affected.
Immediately the puncture occurs the air surrounding the outer tube would escape
and the inner tube whose outside surface is relieved from the outer compression
due to the previous inflation of the outer tube, would expand, and the outer tube
would slightly contract, and a sufficient rigidity of tyre would be re-established to
permit the cyclist to repair the puncture of the outer tube at his leisure. It is
obvious that by inflating the inper tube he may obtain any degree of hardness, (as
the conditions would be exactly those of the present tyres) in the usual manner.
Any well known detachable outer tyre now employed as a single tube would serve
the outer tube purposes of my invention. Instead of two separate air inlet equip-
ments I may combine both the outer and inner equipments in one piece, with
separate attachments for the inflator connection and separate valves.
I may employ two inner tubes arranged figure 8 ways, and also having separate
valves and inlets, so that if by some extraordinary accident one of the inner tubes
should collapse or be punctured, the other one comes into play for the emergency
period. For ordinary purposes, I prefer to limit myself to the following variation
of pressures: inner tube to be compressed from 15 lbs. to 20 lbs., the outer tube

page_text: from 25 to 35 lbs., but I do not intend to be confined to any fixed range of pressure
variation.
When I provide two separate air inlet attachments, I make the one for inflating
the outer tube project further than that for inflating the inner one, or vice versa :
so as to permit of immediate identification.
11
T
G
I BENJAMIN HOWARTH THWAITE of 29 Great George Street Westminster
London 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 relates to a novel method of applying air pressures, to the wheels
of cycles, or other pneumatic tyred vehicles. In my invention I prefer to employ
two tubes, to both of which I apply an air pressure, but of varying intensity. The
outer or cover tube, which constitutes the tread, or actual tyre, has initially a
higher pressure than the enclosed one, which only comes into actual useful service
in peroids of emergency.
I subject both tubes to a continuous pressure of air; each of the tubes has its
own independent air inlet attachment for the purpose of reinflation, and each tube
has its own non-return valve. In the initial charging of the tubes with a pressure
of air, I first attach the pump or air inflating apparatus to the inlet of the enclosed
tube, and allow sufficient air to enter as will expand this enclosed tube until it
commences to inflate the outer or cover tube to a condition of partial hardness, or
just sufficient to permit the cycle to be used in case of puncture of the outer or cover
tube.
After the enclosed tube has been inflated to the degree described, then the air
pump or other inflator is detached therefrom, and is then applied to the inlet of
the outer or cover tube. The air is then introduced to the outer or cover tube,
until it is inflated to the usual hardness required. The high pressure for this,
compresses the enclosed tube, reducing its diameter, until it occupies a considerably
less cross-sectional-area than does the outer or cover tube, and whilst thus com-
pressed, should a puncture occur in the outer or cover tube, the air enclosed therein,
and compressing the inner tube would escape, and the enclosed tube, being relieved
of this compression, would expand, and the initial rigidity of tyre (established
when inflating the enclosed tube), would permit riding to be continued, and the
repair to the outer cover tyre effected at leisure. It is obvious that by further
inflating the enclosed tube any degree of hardness may be obtained.
Any cover tyre, now employed as a single tube tyre would serve the outer or
cover tube purposes of my invention, and tyres made on the "Dunlop." principle,
would only require to have the outer cover made airtight, and fitted with an
independent valve, to be available for use on my system.
I may employ two inner or enclosed tubes arranged figure 8 ways, and having
separate valves and inlets, so that in the event of one being injured by puncture or
otherwise, the other one comes into play for the emergency period.
Before referring to the diagrams illustrating my invention, I wish it to be
understood that I do not intend to be confined to the employment of the exact
details shown therein; as these may be modified without involving a departure
from the true intent and meaning of my said invention.

page_text: Fig. 1 shows a broken longitudinal section of one application of my invention,
and Fig. 2 is a cross section thereof. Both figures shew the position of the enclosed
tube under the influence of external compression, Figure 3 shews the position
taken up by the enclosed tube A when the compression influence has been removed.
The actual treading part, or outside tyre B, shown in the diagrams, is the
"Fleuss" type of single tube or cover tyre shewn adapted to my system.
The inlet valve C supplies the outer or cover tube B, and the valve D the
enclosed tube A. I may combine the two valves in one, but usually prefer to keep
them distinct and separate, and opposite to each other in the rim of the tyred
wheel. To identify the respective valves, I make one slightly longer than the
other.
In applying my differential pressure system of air supply, I first apply the pump
or inflator to the valve D, by which I inflate the inner or enclosed tube A to a
condition that makes the wheel rideable; I then attach the inflator to the valve C,
and supply air to the outer cover tube B, this causes a compression influence on the
enclosed tube A as shown in Fig. 2, reducing its cross sectional area in a relative
degree to the differential pressures. When the outer cover B is pumped to a
condition of hardness advisable for continuous riding, the effect of the compression
on the enclosed tube A is shown in Figure 4 which is a copy of a radiograph of a
tyre to which my system was applied. On puncturing the outer or cover tube B,
the air in the space escapes, and the enclosed tube, relieved from the compression
influence, expands, and presses against the inner surface of outer cover tyre B, as
shown in Figure 3, permitting the rider to continue his journey without even dis-
mounting, and to repair the punctured outer or cover tube at his convenience.
In all the Figs. except Fig. 3 the enclosed tubes A are shown under the influence
of comparative pressures, and before puncture has removed the compression
influence from the inner or enclosed tube A.
In order to keep the enclosed tube A in a safer position as regards immunity
from puncture, than it might otherwise assume, I slightly stretch it on to the
bottom of the outer or cover tube or tyre, in first placing it in position.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same may be performed, I declare that what I claim
is described as follows-
First. The system of multiple and independently air inflated pneumatic tubular
tyres substantially as shewn and described.
Second. The method of initially inflating and dilating the enclosed tube, followed
by the application to the outside surface of such enclosed tube of a superior air
pressure by which the said enclosed tube is reduced in cross sectional area until
such time as the superior outside air compressional influence is withdrawn.
Third. The employment of an enclosed tube with its own independent valve, to a
detachable and air inflated cover tyre of the "Fleuss" or similar type, such
enclosed tube being subjected to the inflation and deflation treatment described in
Claim Second.
Fourth. The method of providing the outer "Fleuss" type of tyre and its
enclosed tube with distinctive and easily identified air pressure inlet and valvular
attachments substantially as shewn and described.