Improvements in Detachable Pneumatic Tyres.
Year: 1895

page_text: This print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c. Act, 1883), as allowed
by the decision of the Comptroller General of the 19th day of June 1897.
Date of Application, 7th Mar., 1895-Accepted, 4th May, 1895
COMPLETE SPECIFICATION (AMENDED).
Improvements in Detachable Pneumatic Tyres.
near
WILLIAM EDWARD CROWTHER 88 Sandy Lane Chorlton-cum-Hardy
Manchester, Science and Art Teacher, 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 :-
The principal object of my invention is the construction of a pneumatic tyre
which whilst having a firm connection with the rim when inflated may be easily and
quickly detached when required.
The tyre is constructed with a separate inner air-tube and an outer cover to
which latter alone my invention applies.
In constructing my improved outer cover 1 make use of one or more plys of
fabric cut out of the piece on the cross and I powerfully stretch the separate strips
of material so that the warp and weft threads may be brought to acute angles
with each other. Whilst in this condition the fabric is proofed with rubber
solution.
When making up the cover I insert in the material along each edge a flat band
formed of thin wire, preferably of spring steel, crimped into zig-zag form. The
fabric is wrapped over the band and may be secured to it by sewing through
between the wires. After the bands of zig-zag wires are secured in each edge of
the strip a portion of one edge is taken, clamped in between slips of metal with
about half its width projecting and is turned over into continuous hook form.
After one edge has been so treated the other edge is dealt with. in the same way
except that the turning over is towards the opposite side of the fabric so that in
transverse section the strip with its wired edges has the form of an elongated S.
The outer covering of rubber is then affixed in the usual manuer.
Instead of placing the band of zig-zag wire in the strip in its flat form it may
first be turned over into hoop shape and enveloped in the fabric afterwards.
The air tube may be entirely enclosed within the improved cover by hooking
together or engaging the turned over edges and when the tyre is inflated it will
expand considerably in tranverse section and shorten greatly and powerfully in
length owing to the oblique position of the threads in the fabric. The range and
strength of this action are sufficiently great to ensure the firm retention of the tyre
upon any hollowed rim without the aid of cement or other fastenings whilst the flat
bands of zig-zag wire being springs may tend to maintain a sufficient hold on the
rim to prevent the tyre coming off if accidentally punctured and deflated whilst
running. If the springs of the edging should be deemed insufficient for this
purpose I may put in the fabric adjacent to the edging an auxiliary zig-zag spring
wire.
Instead of using bands formed of zig-zag wire a narrow band of plain flat wire,
preferably with the ends turned over or thickened may be placed loosely in a

page_text: pocket formed along each edge of the cover, the pockets being so set and arranged
that each band will be turned back towards the centre of the cover, one towards the
outside and the other towards the inside so that two continous and oppositely
turned hook edges will be formed as in the previously mentioned construction.
Each flat band should be secured to its pocket at the central point of its length and
the pockets should be cut away somewhat near the valve and the ends left open.
The air tube can be secured within the cover by hooking together the reversely
turned edges and the whole tyre placed on a hollowed rim. As inflation takes
place, the tyre, shrinking into the rim, causes the ends of the steel bands which
cannot shrink to project from the pockets and to approach the valve stem and so
pass underneath or between the plates with which it is fitted. When the valve is
screwed home to the rim the plates nip the ends of the bands and so secure the tyre
mechanically to the rim.
When the zig-zag wire hooking edges are employed a single wire, flat or round,
lying loosely in a pocket near one of the edges, may similarly be used to effect a
mechanical engagement of the tyre with the rim or the method may be readily
adapted to any form of cover which shrinks under inflation and has sliding wires
in its edges. Instead of using the valve stem to centre the nipping plates upon a
special screwed stem with plates may be applied to the rim diametrically opposite
to the valve.
In the accompanying sheet of drawings
Fig. I shows a portion of the edging band of crimped wire and Fig. II is a cross
section of the strip of fabric showing the wire enwrapped in each edge and turned
over into hook form.
Fig. III is a cross section showing how the hooking edges are engaged so as to
form a complete envelope for the air tube.
Fig. IV gives two views of a portion of the plain flat wiro which may
alternatively be used along each edge of the strip as shown by the cross section
Fig. 5.
Fig. VI shows how the edges may be engaged with each other.
Fig. VII, a longitudinal section at the valve shows the thickened ends of the
flat wires a nipped between the plates b and c on the valve stem as described.
Figs. VIII and IX show the use of a single flat wire, a, in conjunction with the
zig-zag wire hooking edges, a pocket being formed on the outside of the outer
edging to hold the wire, the thickened ends being nipped after inflation between
plates b and c by the screwing of the valve to the rim.
In Figs. VII and VIII the curvature of the rim is not shown.
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 I am aware
of Stubb's Specificatious 21989 of 1891 and 15163 of 1892 in which zig-zag wire
edging bands are mentioned and claimed for the purpose of engaging or hooking
the cover directly to the rim.
I make no claim to such application nor do I claim the wire edging either per se
or as applied to a tyre cover generally.
I am also aware that bands have been used lying loosely in pockets along the
edges of the cover, such bands being gathered round the rim by the process of
inflation and I do not claim that method of shrinking a band around a rim but
what I claim is,
(1.) The use of the zig-zag wire hook edging herein described for the purpose of
attaching the edges of the tyre cover together as described and illustrated in the
drawings.
Dated this Sixth day of March 1805.