Improved Method and Apparatus for the Detection of Punctures in Pneumatic Tyres.
Year: 1896

page_text: Date of Application, 15th May, 1896
Complete Specification Left, 15th Feb., 1897-Accepted, 8th May, 1897
Improved Method and Apparatus for the Detection of Punctures in
Pneumatic Tyres.
I, RALPH WINNINGTON LEFTWICH of 125 Kennington Park Road London
Surrey Physician do hereby declare the nature of this invention to be as
follows:-
The object of my invention is to facilitate finding the seat of a puncture. For
this purpose, I attach a small metal box to the air pump, in common use for inflating
pneumatic tyres. The box communicates with the barrel of the inflator. The box
is then charged with some substance capable of producing visible vapour or smoke,
such as smouldering brown paper. The pump, attached to the tyre, is then worked
in the usual way and as the tyre becomes inflated, the smake or vapour issuing
from it will indicate the position of the puncture.
3000
Improved Method and Apparatus for the Detection of Punctures in
Pneumatic Tyres.
I, RALPH WINNINGTON LEFTWICH, of 125 Kennington Park Road, in the
County of Surrey, M.D. 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 an improved method and apparatus for the detection of
punctures in pneumatic tyres by the injection of smoke into the air tube under a
pressure which will cause it to issue at the puncture and so enable the situation of
the latter to be readily located. According to this invention a charge or cartridge
of material which will fume or burn with emission of smoke is placed in what is
hereinafter termed a smoke chamber, so connected with the pump that by means
of the latter the smoke produced by the charge can be forced into the air-tube
through the air-valve of the tyre, in the manner in which air to inflate the tyre is
supplied thereto.
Preferably the pump and smoke-chamber are combined in a single appliance
such as is hereinafter described and the charge to produce the fume or smoke may
be of a form and constitution such as are presently indicated.
The accompanying drawing illustrates in longitudinal central section an air-pump
fitted with a smoke-chamber according to this invention.
A is the pump barrel; B is the smoke chamber attached thereto at a point near
to one end of the pump the nozzle C' being at the end of the piston rod C which
is tubular. The pump-barrel head is perforated at A2, the perforation affording
communication between the interior of the pump-barrel and that of the smoke-
chamber B.

page_text: The piston rod is provided with a piston C2 having leather packing C³ arranged
(as is customary in such pumps) to permit the contents of the cylinder to pass
from the smoke-chamber end of the pump-barrel to the other end whilst the piston
is travelling towards the smoke-chamber, but on the other hand preventing any
flow of fluid past the piston when the latter is required to expel through the piston-
rod, in returning, the contents of the barrel.
Bare bars extending across the inner end of the smoke-chamber B to prevent
the charge hereinafter described from being passed too far into it. B is a lid or
cover which has a central perforation B³ and fits closely upon the outer end of the
smoke chamber, from which it is readily removable, to admit of the insertion of a
charge of smoky combustible such as a cigarette D, which is indicated in position
therein by chain lines. It is desirable that the cigarette should fit fairly closely
the interior of the chamber B in order that as much as possible of the air drawn
through the chamber should pass through the cigarette.
The lid or cover B2 can be provided with a bayonet-joint slot B' and the wall of
the smoke-chamber with a pin B' to enter the slot, the arrangement constituting a
bayonet-joint; but the interior of the flanges of the lid or cover B' and the exterior
of the chamber B can be screw-threaded to enable the lid or cover to be readily
secured in place or removed therefrom, or other means for like purposes can be
adopted.
To use the apparatus for smoke-testing a tyre, the nozzle C is connected with
the air valve of the tyre and the lid or cover B2 of the chamber B is removed; a
charge such as a cigarette of tobacco or other fuming or combustible material is
placed in the smoke chamber B and ignited, the lid or cover B³ is replaced and the
pump piston C2 is reciprocated. When the piston C2 moves away from the closed
end As of the barrel A the smoke or fumes generated in the smoke-chamber B
will enter the pump barrel by way of the perforation A2, passing the piston C³ as
hereinafter described; on the return of the piston C2 the smoke thus admitted to
the barrel will be expelled through the nozzle C¹ into the tyre through the non-
return air valve of the latter and will issue at the puncture or punctures, so as to
give an indication of their whereabouts which will be readily visible in the same
stroke. Air is drawn through the perforation B³ and through the cigarette D into
the barrel A by way of the perforation A. The smoke, which during the expulsion
of the contents of the barrel as aforesaid has from the smoke-chamber B followed
the piston and filled the space around the piston rod between the piston and cover
of the pump barrel, will be allowed by the packing C³ to pass from one side of the
piston to the other during the return stroke to be expelled, like the preceding
charge, in the next stroke, together with any further supply of smoke which may
have entered the pump barrel from the smoke-chamber, and so on until the
cartridge is burnt out.
The combustible charge employed may conveniently be a cigarette as described;
but it need not be filled with tobacco; a fuse can be inserted in it if desired to
afford a convenient means of ignition. As a combustible mixture, charcoal with
lamp black, saltpetre and orpiment are found to give good results if ground and
mixed together and filled into a tubular casing. For example the relative pro-
portions by weight, in which these ingredients can be employed are :-

page_text: 2. The employment substantially as and for the purpose described of a charge
or cartridge of material which will fume or burn with the emission of smoke in a
chamber such as B.
3. The combination and arrangement of parts constituting the complete appliance
for the testing of pneumatic tyres substantially as described and illustrated in the
accompanying drawings.
D
RALPH WINNINGTON LEFTWICH.
Boult & Wade,
Agents for the Applicant.
RALPH WINNINGTON LEFTWICH.
Boult & Wade,
Agents for the Applicant.