Improvements in and connected with Apparatus for Inflating and Deflating Pneumatic Tyres.
Year: 1891

page_text: Date of Application, 24th Dec., 1891
Complete Specification Left, 22nd Oct., 1892-Accepted, 26th Nov., 1892
PROVISIONAL SPECIFICATION.
Improvements in and connected with Apparatus for Inflating and
Deflating Pneumatic Tyres.
I DAVID ABERCROMBIE of Brooklands in the County of Chester, Gentleman
do hereby declare the nature of this invention to be as follows:-
My invention relates to apparatus for inflating and deflating pneumatic tyres and
regulating the pressure in the same, and has for its object to secure greater
expedition, precision and safety. The improvement consists in the use of a safety
valve loaded by means of a spring or other convenient mechanical means so as to
give way when a certain definite pressure is reached. The safety valve is placed
in communication with a chamber at the back of the back-pressure valve which
communicates with the tyre and retains the compressed air therein. The chamber
is also fitted for the application of the inflating pump thereto so that the compressed
air is discharged from the inflating pump into the chamber, and thence by way of
the back-pressure valve into the tyre.
By this arrangement when the pressure in the chamber has reached the point to
which the safety valve has been set the latter gives way and the air in the tyre
cannot be further.compressed.
Also when the chamber is by the attachment of the force pump thereto or by
other means closed from .communication with the external atmosphere, any excess
of pressure of air in the tyre may on the back pressure valve being forced.from its
seat, be relieved by the safety valve. The latter may also in such case by
releasing the load on the safety valve be used as a deflating valve.
The safety valve and its communication with the chamber may form part of the
inflating pump.and be attached or withdrawn therewith, or the safety valve.may be
placed directly in communication with the tyre at any convenient.position. In such
case the safety valve is arranged to be put out of action when not required by the
use of an air tight cap.or.other convenient mechanical means.
Dated this 23rd day of December 1891.
DAVID ABERCROMBIE.
COMPLETE SPECIFICATION.
Improvements in and connected with Apparatus for Inflating and
Deflating Pneumatic Tyres.
I, DAVID ABERCROMBIE, of Brooklands, in the County of Chester, Gentleman,
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 apparatus employed in inflating and deflating.pneumatic
tyres, and its object is to allow any desired air pressure to be readily obtained
whilst at the same time minimising the risks of such tyres bursting through
excessive air pressure.
In carrying this invention into effect a safety valve is combined either with the
inflating valve with the pump or with the tyre so that an excess of air can not be
forced into the-tyre, or alternatively, should such an excess of air be forced into
the tyre or should an excessive air pressure be otherwise, set up it is automatically

page_text: And in order that my invention may be more clearly understood I have hereto
appended a sheet of drawings reference to which is hereinafter made, similar letters
being used to indicate similar parts where they occur in the different figures.
Figure 1 represents in section a combined inflating valve and safety valve, the
safety valve being between the inflating valve and the tyre.
Figure 2 illustrates in section a combined inflating and safety valve in which the
.safety valve is placed between the inflating valve and the pump.
Figure 3 shews the combination of a safety valve with the pump nozzle.
Referring to the figures A indicates a back pressure valve which may be of the
usual pattern. As shown in Figure 1 the valve casing B has an opening C between
the valve A. and the tyre D, which opening is ground or otherwise furnished with a
seating for a valve E. This valve is held down by means of a spring F which
may be adjusted by the screw G so as to allow the valve to lift and the air to
escape upon any predetermined pressure being reached in the tyre. The casing H
of the safety valve may be open to the atmosphere so as to allow free escape of the
air or may be provided with a cap or plug by means of which the escape of air can
at any time be prevented.
As shewn in Figure 2 the safety valve E is placed at a point between the back
pressure valve A and the pump attachment J. In this arrangement the safety
valve is operated only during the process of inflation. Upon the desired pressure
being obtained any further air which may be forced in from the pump will not enter
into the tyre but will merely lift the safety valve and escape, thus obviating all risk
of bursting the tyre through excessive pressure. In the form shewn in Figure 1
however not only is this danger similarly obviated, but owing to the safety valve
being in communication with the tyre any excess of pressure arising from heat or
other causes is instantly released. In both cases however, the safety valve may be
covered or closed with a cap so as to prevent any escape of air.
In the modification illustrated by Figure 3 the safety valve is shewn as forming
part of the pump nozzle. This nozzle may consist of a bifurcated tube in one
branch of which K the safety valve E is contained. The flexible tube from the
pump is attached to the branch L, the safety valve E in this case as in Figure 2
being only operative during the pumping. As before, the valve may at any time
be rendered inoperative by the addition of a screw cap.
It is perfectly obvious that any other form of nozzle may be substituted for the
bifurcated tube, for instance the right angled tubes shewn in Figures 1 and 2 may
be employed, and vice versa these latter may be substituted by the bifurcated tube.
Many other forms of casings for the valves may however be used.
In another modification which does not need an illustration, the safety valve
may be independently and directly in communication with the tyre, being attached
thereto in a manner similar to that employed in attaching the ordinary inflating
valve.
If the inflating valve employed is not of the deflating class the air within the
tyre can be released at any time by opening the safety valve.
It will be perfectly obvious that the loading of the safety valve may be accom-
plished by many other forms of spring than the helical one hereinbefore
described.
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. As an accessory to a pneumatic tyre the combination with the inflating
devices of a safety valve constructed and arranged substantially as and for the
purpose hereinbefore described with reference to the accompanying drawings.
2. Apparatus for regulating the pressure of air in pneumatic tyres constructed
arranged and operated substantially as herein before described with reference to the
accompanying drawings.

page_text: 3. The combination with a pneumatic tyre of a safety valve furnished with a
cap or other similar closing device substantially as and for the purpose herein-
before described.
Dated this 4th day of October A.D. 1892.
WILLIAM E. HEYS,
Agent for the Applicant.