Improvements in Pneumatic Tyres.
Year: 1898

page_text: Date of Application, 23rd Nov., 1898
Complete Specification Left, 23rd Aug., 1899-Accepted, 21st Oct., 1899
PROVISIONAL SPECIFICATION.
Improvements in Pneumatic Tyres.
We, HELLSTERNS SYNDICATE LIMITED, of 158, Leadenhall Street, in the City
of London, E.C., and NOEL PHILIP WENTWORTH BRADY, of 81, Cannon Street,
in the City of London, E.C., Solicitor, do hereby declare the nature of this inven-
tion to be as follows:-
It has been proposed to construct pneumatic tyres with air tubes having
therein a series of elastic compressible chambers communicating with one
another by means of tubes formed or provided with non-return valves, the first
chamber of the series being in communication with the external atmosphere
through a non-return valve and the last chamber with the air tube of the tyre
so that, as the wheel revolves in contact with the ground, the said chambers will
be successively compressed and automatically expanded and air thus caused to
enter the first chamber and to pass thence from chamber to chamber and to
finally discharge into the air tube of the tyre. It has been found impossible
to sufficiently inflate the air tubes of tyres of this kind as heretofore constructed
owing to the chambers being of such a nature that, when compressed as much
as possible, only a comparatively small proportion of the air previously drawn
into them is expelled and that the remaining air, which expands during the
automatic expansion of the chambers, prevents a sufficiently low pressure being
obtained in the chambers to cause air to enter the said chambers. Moreover,
the chambers, which have hitherto been constructed of rubber, have been liable
to become stretched and distorted in use and consequently more
ineffectual.
or less
Tyres of the kind above referred to are described in the Specification of Appli-
cation for Patent No. 24610/97.
Now, according to this invention, the chambers, instead of being more or less
circular in cross section so that a portion of the air space thereof occupies a
position within the rim of the wheel when the tyre is in place, are so constructed
that the whole of the air space is outside or further from the centre of the
wheel than, the outer periphery of the wheel-rim. For this purpose, the exte-
rior of the chamber is made to fit the air tube but that portion which is adjacent
to the rim of the wheel is thickened so that the hollow of the wheel-rim is
occupied by a solid wall. When the chamber is compressed as the wheel
revolves in contact with the ground practically all the air contained therein will
be expelled. The non-return valves are placed as close to the compressible
part of the chamber as is possible.
For the purpose of preventing, distortion, the chambers may be constructed
of india-rubber and an unstretchable fabric such as canvas or insertion cloth
or other suitable material. The fabric may be attached to the inner or outer
surface of the chamber, or the fabric and rubber may be arranged in alternate
connected layers, for instance one layer of fabric may be sandwiched between
two layers of india-rubber, or be otherwise incorporated, it, of course, being
understood that the walls of the chambers are to be air-proof.

page_text: The accompanying drawing illustrates, by way of example, a tyre constructed
according to this invention.
In Fig. 1, 1 is the wheel rim and 2 the outer cover of the tyre. 3, 3 are
the chambers (shown in detail in Figs. 2 and 3) which are connected by tubes 4
fitted with non-return valves 5 and having an air inlet 6. In the left hand
half of Fig. 2 the chamber 3 is shown with fabric moulded into it but it may
be made of rubber only as shown in the other half of the figure.
Improvements in Pneumatic Tyres.
We, HELLSTERNS SYNDICATE LIMITED, of 158, Leadenhall Street, in the City
of London, E.C., and NOEL PHILIP WENTWORTH BRADY, of 81, Cannon Street,
in the City of London, E.C., Solicitor, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:
It has been proposed to construct pneumatic tyres with air tubes having
therein a series of elastic compressible chambers communicating with one another
by means of tubes formed or provided with non-return valves, the first chamber of
the series being adapted to be placed in communication with the external atmo-
sphere through a non-return valve and the last chamber with the air tube of the
tyre so that, as the wheel whilst loaded revolves in contact with the ground, the
said chambers will be successively compressed and afterwards automatically ex-
panded and air thus caused to enter the first chamber and to pass thence from
chamber to chamber and to finally discharge into the air tube of the tyre. It has
been found impossible in practice to sufficiently inflate the air tubes of tyres of
this kind as heretofore constructed, owing to the chambers being of such a nature
that, when compressed as much as possible, only a comparatively small propor-
tion of the air previously drawn into them is expelled and that the remaining
air, which expands during the automatic expansion of the chambers, prevents a
sufficiently low pressure being obtained in the chambers to cause additional air
to enter the said chambers. Moreover, the chambers, which have hitherto been
constructed of india-rubber, have been liable to become stretched and distorted
in use and consequently more or less ineffectual.
Tyres of the kind above referred to are described in the Specification of
Patent No. 24610/97.
Now, according to this invention, the air chambers, instead of being more or
less circular in cross section so that a portion of the air space thereof occupies
a position within the rim of the wheel when the tyre is in place, are so con-
structed that the whole of the air space is outside or further from the centre
of the wheel than the outer periphery of the wheel-rim, so that when the
chambers are successively compressed by pressure against the ground whilst
the tyre is not fully inflated, a larger proportion than usual of the air in such
chambers will be expelled by compression into the air tube or chamber of the
tyre and consequently a larger quantity of air will be admitted to each chamber
on the re-expansion thereof.

page_text: For this purpose the exterior of each chamber is fitted to the air tube of the
tyre which is stretched over it but that portion of the chamber which is adjacent
to the rim of the wheel is thickened so that the hollow of the wheel-rim is
occupied by a solid wall. When the chamber is compressed as the wheel
revolves in contact with the ground, practically all the air contained therein
will be expelled. The non-return valves are placed as close to the compressible
part of the chamber as is possible.
For the purpose of preventing distortion, the chambers may be constructed
of india-rubber and an unstretchable fabric such as canvas or insertion cloth or
other suitable material. The fabric may be attached to the inner or outer sur-
face of the chamber, or the fabric and rubber may be arranged in alternate
connected layers, for instance one layer of fabric may be sandwiched between
two layers of india-rubber, or be otherwise incorporated or combined therewith,
it being of course understood that the walls of the chambers are to be air-proof.
The drawings filed with our Provisional Specification illustrate, by way of
example, a tyre constructed according to this invention, Fig. 1 being a longi-
tudinal section of the rim of a cycle wheel fitted with a pneumatic tyre pro-
vided with compressible air chambers constructed according to this invention,
and Figs. 2 and 3 longitudinal and cross sections respectively of one of the
compressible air chambers.
1 is the wheel rim, and 2 the outer cover of the tyre within which is the air
tube, shown in its inflated condition as a thick black line, such air tube when
not inflated being of less external diameter than the interior of the outer cover.
3, 3 are the improved compressible air chambers arranged at intervals within
the air tube which when not inflated is of less diameter than the exterior of
the chambers so that it has to be stretched over such chambers. Each air
chamber has that side which is next the rim thickened as shown, so that when
the tyre is in place on the wheel rim, the whole of the air space within the
chamber will be outside of or further from the centre of the wheel than the
outer periphery of the wheel rim, indicated by the dotted circle in Fig. 1, as
and for the purpose hereinbefore described. Each chamber is surrounded as
before with a longitudinally perforated ring or collar that is made to fit the
outer cover and the wheel rim and serves to hold the chamber in place within
the air tube and also as a means whereby the external pressure on the tyre when
in contact with the ground can be effectively concentrated on the outer flexible
portion of the air chamber for the purpose of compressing it and expelling the
greater portion of the air therefrom in a direction to finally enter the air tube.
The improved air chambers 3 are connected together as before, by tubes 4 fitted
with non-return valves 5 which may be of any known or suitable kind, the end
tube at the inlet end being connected to an air inlet pipe 6. The mode of opera-
tion of the improved air chambers 3 and non-return valves 5 is similar to that
of the chambers and valves described in the former specification herein before
referred to but the expulsion of the air from each chamber at each compression
thereof, is, as a consequence of the improved construction and arrangement
The wall of each of
herein before described, more complete than heretofore.
In
the improved air chambers may be strengthened in any convenient manner.
the left hand half of Fig. 2, the wall of the air chamber 3 is shown strength-
ened with fabric moulded into it, but it may be made of india rubber only as
shown in the other half of the figure. One or more chambers 3 such as
described may be used in a pneumatic tyre.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, we declare that
what we claim is:-
1. A pneumatic tyre of the kind herein referred to wherein that portion of
the wall of each compressible air chamber that is adjacent to the wheel rim
when in use is thickened so that the hollow of the wheel rim at such part will

page_text: be occupied by a solid portion of the air chamber and the air space of such
chamber will be outside of or further from the centre of the wheel than the
outer periphery of the wheel rim, substantially as described with reference to
the drawings for the purpose specified.
2. A pneumatic tyre having compressible air chambers constructed and
arranged as herein before described with reference to and shown in the drawings
referred to.