Improvements in Air-tubes for Distending Pneumatic Tyres.
Year: 1897

page_text: Date of Application, 26th Feb., 1897-Accepted, 8th May. 1897
COMPLETE SPECIFICATION.
Improvements in Air-tubes for Distending Pneumatic Tyres.
I, SPENCER ROLFE of Clarence House, Teddington, in the County of Middlesex,
Engineer, do hereby declare the nature of this invention and in what manner
the same is to he performed, to be particularly described and ascertained in
and by the following statement :-
This invention relates to improvements more especially applicable to one form of
those pneumatic tyres described in the patent granted to Robert William Thomson,
and entitled " An improvement in carriage wheels, which is also applicable to other
rolling bodies"; numbered 10,990, and dated the Tenth day of December 1845.
Referring to the said Thomson's specification on page 3, line 25 and following,
wherein it is stated that the form of his invention therein especially referred to can
be carried into effect "by tyeing the tubes across at distances of two or three feet
apart, so that each tube shall be divided into a number of separate air-tight
compartments." This form of air chamber for pneumatic tyres has been found to
be objectionable, and hence the chambers as described in the aforesaid Thomson's
specification, lines 28 and following:-" (or instead of the preceding modes of
construction, the belt may be formed of separate and distinct sections, as shewn
in Figures V. and VI., each section having its own air pipe (P) ;)" would have
entirely replaced the air tube formed into compartments by tyeing, had it not been
for the difficulty of charging and maintaining each chamber properly distended,
the air charge having to be introduced through a separate conduit for each
chamber.
I will now proceed to describe my invention with reference to the accompanying
drawings in which :-
Fig. 1 is a longitudinal section of one chamber of my improved pneumatic
tyre.
Figs. 2 and 3 are sections of alternative methods of coupling the chambers
together.
Fig. 4 is a section of a portion of my improvements, whereby I render
pneumatic tyres self-inflating and indicating various forms of valves which can
be used in such.
Figs. 5 and 6 are sections of additional forms of uniting valves.
Fig. 7 an additional form of inlet and safety valve.
Referring more particularly to Fig. 1;
A is the air chamber, constructed of elastic material, (Thomson's Fig. V.) having
at its ends junction tubes BB; such being shown upon the ends; in which case the
junction is formed as in Fig. 2; or the connecting tubes may be in the position
shown at C C, in which case the union is effected within the felloe of the wheel as
shown in Fig. 3, an inlet or deflating opening is formed at D, such being necessary
in the case of an ordinary tyre to one chamber of the series only, forming the
complete tyre, whilst they are necessary for each chamber when self-inflating.
The chambers may be two or more in number forming the circumference of the
wheel.
Fig. 2 A A are adjoining chambers joined by the metal or ebonite nipple E,
through which is forined a passage of a diameter varying with the purpose to
which the tyre is to be applied, as hereinafter referred to.
The junction tubes B B are inverted from the position shown in Fig. 1, upon the
CD

page_text: introduction of the nipple, by which means the internal air pressure tends to make
the joint more secure.
In Fig. 3 AA represent two adjoining chambers, and C C the junction tubes,
carried through corresponding holes in the felloe of the wheel and united by a
nipple E as described above.
In order to render tyres of the above named construction, self-inflating ;
I proceed in the manner indicated in Fig. 4, in which A A are the air chambers
united in one of the ways above described, the junction nipples in this case being
replaced by valves shown at F in Figs. 4 5, and 6. These valves are of such a
form as to be double ended, that is to say they reverse their action upon being
themselves reversed. Through the central opening of each chamber (shown at D
in Fig. 1) an inlet valve is provided; sach inlet valve being arranged to act also
as a safety valve when required as shown in Fig. 7. The inlet valves shown on
the drawing have been varied in order to indicate different forms of such, and are
marked thereon in Figs. 4 & 7, G1, G2, G3, G4, G5, and G6, but I do not
confine myself to the use of those shown on the drawing. In all cases these valves
communicate with the air chamber through a hole in the felloe provided for the
purpose and they may be used for inflation by the ordinary method when
desirable, and may be used for deflating by the use of a piece of wire and may also
contain a plug of cotton, glass, or silicate wool for excluding dust.
The action is as follows:-The pressure acting upon the chamber which is the
lowest at the period under consideration compresses such chamber ejecting a portion
of the contained air into the adjoining chambers at either side, the return of such
air being prevented or retarded by the valves contained in the junction nipples.
Upon the revolution of the wheel the succeeding chamber in the direction of
rotation is compressed, the air discharged being delivered to the chamber in advance.
whilst the chamber previously compressed is expanding and drawing in an additional
supply of air through the inlet valve. This action is continuous, the amount of
inflation being dependent upon the compression of the chambers, and the elasticity
with which they resume their original form, the latter in some cases being promoted
by the higher vulcanization of the material or by internal spring or springs.
With reference to the nipples marked E in Figs. 2 and 3, I find that by a due
adjustment of the size of the passage through them, that the advantages of the
resistance of a tyre composed of distinct chambers, as described in Thomson's
specification above referred to, may be maintained, whilst the disadvantages of the
independent charging of each chamber with air, and their variable inflation, are
entirely done away with. I therefore proportion the size of the orifice through
the nipples to the special purpose for which the tyre is intended. The nipples
shown in the drawing at E E, and intended for use where the ordinary method of
inflation is employed, may be curved or of any suitable form.
I enclose my air tubes of the form indicated in Figs. 1, 2, and 3, or when
arranged for self-inflation, in a cover of any usual construction or material.
I do not claim the inflation of a tube with, or without an external covering such
having been fully described in Thomson's patent above referred to.
I do not claim an air tube for pneumatic tyres formed of independent uncon-
nected chambers, or compartments, such having been described in Thomson's patent
above referred to.
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 what I
claim is :-
1. The connection of the chambers or compartments of the air distending
tube of pneumatic tyres substantially in the manner, and for the purposes set
forth.
2. The control of the elasticity of the chambers of such air tubes, by the control
of the movement of the air from chamber to chamber in the manner substantially
as set forth.

page_text: 3. A chambered air tube of which any chamber being injured can be quickly
and readily replaced and united to the adjoining portions as herein set forth.
4. The means adopted for rendering chambered air tubes self-inflating substan-
tially as herein described.
5. The use of connecting nipples containing a valve, such being self-reversing in
the manner and for the purpose substantially as herein described.
6. Inlet, safety, and deflating valves as herein set forth.
Dated this Trantsirth day of Febru 1897