Improvements in Pneumatic Tyres.
Year: 1897

page_text: Improvements in Pneumatic Tyres.
I, JOHN WILLIAM MCDOUGALL, of Napier, in the Colony of New Zealand,
Journalist, 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 that class of pneumatic tyres which have an inner
tube for inflation purposes and a protective cover to withstand wear and tear.
The principal advantage of such form of tyres is that they can be easily detached
from the rim of the wheel for repair, and being in two parts, the protective cover
when worn can be replaced by a new cover which can be used with the old inner
tube.
A further advantage is that in case of a small puncture, the inner tube may be
inflated without fixing the same upon the rim of the wheel and their submerging
the same in water when the bubbles caused by the escaping air will show the
position of the puncture.
These tyres, however, have the disadvantage that the repairing or covering patch
must necessarily be fixed upon the outside of the inner tube, and thus the act of
inflating after repair tends to and in many cases immediately forces off the patch.
To obviate this difficulty tyres known as tubeless tyres have been designed,
that is tyres which are not of closed circular section, but when removed from the
rim of the wheel partake more or less of the shape of a flat band. They are
usually fixed to the rim of the wheel by lugs, wires, or other contrivances and'
when so fixed may be inflated and form pneumatic tyres.
These tubeless tyres, however, have the disadvantage that they cannot be inflated
except when in position upon the wheel rim, and although it is easy to take a
tyre of this class off the wheel and repair a puncture still there is great difficulty
in finding the puncture, as the water test cannot be used.
By the present invention these difficulties are removed, as I provide an inner
tube which is not of closed circular section and can therefore be opened out when
removed from the wheel and patched from the inside. Though my tyre is not
of closed circular section it may be folded and fastened as to be practically so and
may be inflated when removed from the wheel. Thus the water test may be
applied and when the puncture is found the tube may be repaired from the inside.
A further advantage of my form of tube is that it may be so strengthenede

page_text: Figure 7 is a section of the same when opened as a flat band.
Figure 8 is a section similar to Figure 6, but provided with a strengthening
thickness to resist wear and tear.
Figure 9 is a section of a tyre when closed and showing another method of
fastening.
Figure 10 is a section of the same when opened as a flat band.
Similar letters refer to similar parts.
7
Referring more particularly to Figure 6 the band (a) is folded upon itself to
form the secondary chamber (a) or this secondary chamber may be formed sep-
arately and attached to the band as shewn by dotted lines (a²) on Figure 7. (b)
is a strengthening band of calico, canvas or other suitable material and (c) is
another similar band (d) is a non return valve of ordinary construction which
will allow air to pass from the secondary chamber (a) into the tyre but prevents
its return. (f) is the ordinary air admission nozzle and valves to which the
force pump may be applied and through which air may be forced into the cham-
ber (a). (g) is a hole of sufficient size to pass over the nozzle (f³). (h & h¹) are
hooks and eye respectively. If the band as shewn on Figure 7 is folded upon
itself and fastened it will present the form shewn on Figure 6. Air may then be
forced through the nozzle and valve (f) into the chamber (a¹) whence it cannot
pass until the pressure is sufficient to raise the non-return valve (d) and the force
required to open the said valve may be regulated by adjusting the screw cap ().
It is so regulated that there shall always be sufficient pressure in the chamber (a¹)
to force the surfaces (a³) into close juxtaposition and make an airtight joint, so
that the air cannot escape when it passes from the chamber (a) to the tyre, but
the tube remains inflated. The action of the restraining band (c) assists in effect-
ing the result since it prevents the chamber (a¹) expanding equally in all directions,
but the expansion is mainly downwards, that is towards the rim of the wheel. If
desirable the surfaces (a³) may be lubricated with soft soap or other suitable
lubricant which will help to make the joint airtight.
"
To deflate the tyre the valve (d) may be raised by passing a wire or the like
through the nozzle (5) until the air has escaped.
Figure 8 is a view similar to Figure 6 with a strengthening thickness (a³) to
resist wear and tear and is thus a tyre complete in itself.
i
On Figures 9 and 10 the fastening is effected by two bands (e and e¹) of rubber
or the like, pierced at intervals to receive screws (2) or other. fastenings. The

page_text: bands may have flat surfaces as shewn on Figure 9 or corrugated as shewn at (e³)
Figure 10, and such surfaces may be lubricated or otherwise prepared to make an
airtight joint. Air cannot escape when pumped into the tube, owing to the two
bands (e and e¹) being forcibly clamped together and to the close juxtaposition of
the two surfaces (a³). The dotted lines on Figure 9 shew how the secondary
chamber (a) may be applied if desired and used with any of the fastenings des-
cribed herein.
Referring now to Figures 1 and 2 the joint is made by the small compression
tubes (and f) tightened together by the lace (2) and hooks or studs (f). The
manner in which the lacing is effected is shewn on Figure 5.
The surfaces of the tubes may be lubricated as before described to form a joint.
Figure 3 shews the bands (e and e¹) so placed that they may be bolted together
by bolts (e) having square necks (e) to prevent them, from turning whilst the
nuts (e) are being screwed thereupon.
On Figure 4 the bands (e and e¹) are grooved to receive a packing ring (e) which
may be made of india rubber, metal, or other suitable material, the fastening being
effected by the lace (2) and studs (f³).
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:—
1. In combination with the rim, a tyre having overlapping surfaces to form a
joint and a compression chamber or bands for making an airtight joint, such tyre
being capable of being inflated when removed from the rim of the wheel, sub-
stantially as described.
2. In combination with the rim, a tyre having overlapping surfaces to form a
joint and a compression chamber or bands and restraining bands for making an
airtight joint, such tyre being capable of being inflated when removed from the
rim of the wheel, substantially as described.
3. In combination with the rim, a tyre having overlapping surfaces to form a
joint and a compression chamber or bands and restraining bands for making an
airtight joint, an admission tube leading into the secondary chamber and a non-
return valve leading from the chamber into the interior of the tyre, the valve of
said chamber being arranged to hold a greater pressure in the chamber than in
the tyre, such tyre being capable of being inflated when removed from the rim
of the wheel, substantially as described.
4. In combination with the rim, the tyre capable of being inflated when removed
from the rim and having a ring fitting between the meeting edges of the fasten-
ing bands to form a joint when compressed by lacing or by screws, substantially
as described.
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