Improvements in Pressure Gauges.
Year: 1894

page_text: Date of Application, 23rd May, 1891
Complete Specification Left, 25th Feb., 1895-Accepted. 11th May, 1895
Improvements in Pressure Gauges.
I, CHARLES FREDERICK WOOD, of 35 Hanby Terrace, Ordnance Road,
Enfield Lock, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to pressure gauges and has for its object to construct an
improved gauge for use in testing the inflation of pneumatic tyres, air cushions, and
like articles which are inflated with air, gas or fluid under pressure.
Hitherto it has been the custom to permanently secure to the vessel a pressure
gauge for indicating the pressure of the air inside the same but such gauges are
usually expensive and costly to manufacture and moreover it is not necessary
that the gauge should be permanently attached to the vessel as the pressure is
generally required to be known only at the time when the vessel is being inflated
and at times when leakage is suspected.
It is an important feature of my invention that no part of the gauge is in
communication with the interior of vessel to which it is to be applied.
According to my invention I provide a simple and inexpensive device which can be
readily applied to any vessel having flexible sides or a flexible side such as a
pneumatic tyre or air cushion or the like, and will then indicate the pressure of air
in the same.
In a modification of my invention I provide for permanently attaching one of my
improved devices to the vessel containing the air under pressure or to the rim of a
wheel for example.
In order that the nature of my invention may be readily understood I will
proceed to describe by way of example one method of carrying the same into
practice.
I provide a tube or cylinder fitted with a piston or plunger adapted to slide up
and down but not to rotate therein. The plunger may be furnished for this purpose
with a stud which projects through a straight slot in the side of the cylinder.
Between the bottom of the cylinder and the piston or plunger I arrange a spiral or
other suitable spring or elastic cushion which tends to force the said piston or
plunger out of the cylinder. In order to move the piston or plunger into the
cylinder pressure must be applied to the end thereof and the greater the pressure
the farther will the piston or plunger be pressed into the cylinder. The cylinder
end is preferably rounded and the plunger is preferably provided also at its end
with a rounded cap or head. The ends however of either may be of any suitable
shape. The slot and stud before mentioned may be dispensed with; in that cas
the tubes would be capable of revolving.
In using my improved device to test whether a tyre is pumped hard enough for
example, the cylinder is held in the hand and the end of the plunger pressed into
the tyre into which it sinks as far as a datum mark at the end or a projection on
the side of the plunger. During this operation the pressure of the air in the tyre
forces the plunger into the cylinder and the distance through which the plunger
moves relatively to the said cylinder varies with the pressure.
This may be
conveniently indicated by marking the side of the slot in which the stud on the
plunger moves as aforementioned and noting the position of the stud when the
datum mark on the plunger touches the tyre.
The end of the plunger may, of course, be held in the haud and the end of the

page_text: cylinder pressed into the tyre, a datum mark being made or a projection provided
on the cylinder end instead of on the end of the plunger.
I sometimes make the piston or plunger move air-tight in the cylinder in which
case I may dispense with the spring using the elasticity of the air confined in the
cylinder to force the plunger out.
The spring or the indications on the side of the slot may be regulated to suit
various pressures.
In a modification of my invention 1 provide for attaching the gauge to the rim.
of a wheel or to any part of the air vessel.
I
may
do this as follows, that is to say, in the case of a wheel rim for example,
the plunger is provided with a head at the end as aforementioned and at a short
distance away from the head I provide a collar or stop. The plunger is passed
loosely through a suitable hole in the rim and is confined therein by the head and
the collar, the head being pressed against the outside of the rim by the air tube of
the tyre and the collar on the plunger being at a short distance from the rim.
When the tyre is to be tested the cylinder of the gauge is grasped and gently
pressed towards the rim the plunger is thereby pushed into the cylinder until the
pressure of the air tube on the head of the plunger is equivalent to the pressure of
the gauge spring in the cylinder. When this is the case any further pressure on
the cylinder will tend to force the plunger through the rim until it is stopped by the
collar. Hence as soon as the collar is seen to move towards the rim the position
of the stud in the slot in the side of the cylinder will indicate the pressure of air in
the tyre.
I sometimes attach the cylinder to the rim in the manner above described instead
of attaching the plunger, and similar methods may be followed in attaching the
gauge to any vessel or to a part of any vessel containing air under pressure.
A further modification of my invention is more especially applicable for use with
pneumatic tyres. In this modification 1 make a hole in the rim to which the tyre
is secured and provide a short rod passing through the hole the end of the rod being
furnished with a head which lies between the tyre or air tube and the rim. The
outer end of said rod may or may not have a head. When the tyre is to be tested
the piston or the cylinder of the gauge is pressed against the outer end of the rod
in the rim instead of being itself pressed against the air tube or tyre. By this
means I avoid securing the gauge to the rim at the same time providing for the
obtainment of an accurate indication. The piston or cylinder of the gauge may of
course be permanently attached to the rod if desired. Said rod may also be used
without the pressure gauge for testing by hand pressure.
In another modification of my invention I attach my improved gauge to the
inflating or valve tube of the tyre or the inflator itself in such a manner that the
pressure of the air therein acts on the piston of the gauge and thereby indicates
the pressure.
My improved device is made in various sizes to suit different purposes and
pressures and will be found cheap and easy to use.
Dated this 23rd day of May 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Pressure Gauges.
I, CHARLES FREDERICK WOOD, of 35 Hanby Terrace, Ordnance Road,
Enfield Lock, Engineer, 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 :-
:
My invention relates to pressure gauges for use in testing the inflation of

page_text: pneumatic tyres, air cushions, footballs and like articles that are inflated with air,
gas or fluid under pressure.
The object of my invention is to provide an inexpensive gauge that may be
applied to an elastic envelope or chamber when the pressure therein is required to
be known, for example when the envelope or chamber is being inflated and at times
when leakage is suspected.
In one form of my invention I provide for permanently attaching the gauge to
the elastic chamber containing the air under pressure, a pneumatic tyre for example,
or to the rim of the wheel on which the tyre is mounted.
In order that my invention may be clearly understood I will now describe the
same with reference to the accompanying drawings, in which,
Figure 1 is an elevation of a pressure gauge constructed according to my
invention, and
Figure 2 is longitudinal central section of the same.
Figures 3 and 4, and 5 and 6 are similar views illustrating modified constructions
of pressure gauges to be hereinafter described.
Figure 7 is a longitudinal central section of the barrel of an inflator or pump
baving a pressure gauge contained therein in accordance with my invention.
Figure 8 is an elevation and
Figure 9 is a central longitudinal section of the valve tube or inflating tube of a
tyre provided on the exterior thereof with a form of pressure gauge to be hereinafter
described.
Figures 10 and 11 illustrate a pressure gauge with means for adjusting the
pressure of the spring contained therein.
Figures 12 and 13 are elevation and plan respectively of a stud or button
hereinafter described.
Like letters denote corresponding parts throughout the drawings.
Referring to Figures 1 and 2 which illustrate by way of example one method of
carrying my invention into practice A is a cylinder, B is a piston or plunger and B' is
an extension thereon forming a piston rod, C is a spring compressed between the piston
and the end of the cylinder. In order to move the piston rod into the cylinder,
pressure must be applied to the end thereof to compress the spring C.
A pin D secured to the plunger or piston B projects through a slit A' in the side
of the cylinder A. A2 is a scale of pressures, experimentally or otherwise
determined, marked off along the edge of the slit A'.
To employ such a pressure gauge for testing the pressure of a tyre, for example,
it is necessary to place between the air tube of the tyre and the conical or
pointed end B³ of the piston rod a plate, stud or button E Figures 12 and 13 of
known area.
When placed in position for use the stem or rod E' of the stud E is passed
through a hole which it loosely fits in the rim of the wheel and the head or plate E²
which is preferably covered with leather or indiarubber is arranged so as to lie on
the air tube of the tyre between it and the rim. The end of the stem E' is
preferably provided with a small indentation or recess E³ for the reception of the
pointed end B of the gauge. To test the pressure of the air in the tyre the
cylinder A is held in the hand and the piston rod B is gently pressed against
the stein E of the stud E. The pressure of the air in the tyre forces the piston
back a certain distance into the cylinder against the pressure of the spring C until
a point is reached at which the air pressure balances the pressure of the spring.
When this state of things is arrived at the pressure per square inch on the
head E2 of the stud E may be read off on the scale A³ on the side of the
cylinder A.
gauge
The use of such a stud obviates the necessity of permanently securing the
to the rim and also prevents any injury being inflicted on the tyre by the point of
the rod B'. At the same time the portion of the stud in contact with the air tube
of the tyre being of known area provides for an accurate measurement of the air
pressure within the tyre.
"

page_text: The stem E may be dispensed with, and the plate E2 may be permanently
attached to the inflated tube. The same device can be used for air cushions,
footballs and the like.
I sometimes dispense with the plate or stud E in which case the end B2 of 'the
gauge is arranged to present a flat or rounded surface which when in use is pressed
into direct contact with the inflated envelope, the pressure in which it is desired to
ascertain.
When I apply the pressure gauge to the outside of the tyre cover, I provide a
bridge piece of thin metal placed over the cover and the ends of which are adapted
to engage with or be held by the sides of the rim. The said bridge piece is
employed to act as a fixed datum. The pressure gauge is passed through an opening
provided in the bridge piece or is used by the side thereof, and when pressed inward
a stationary mark on the gauge is brought opposite the edge of the bridge piece.
At this moment the pressure within the tyre is indicated on the gauge. If found
necessary a similar datum mark may be provided when the gauge is used in direct
contact with the air tube of the tyre.
A scale of pressures may be provided on the rod B₁ instead of on the cylinder as
previously described. The said rod B is in that case preferably made flat as shown
in Figures 3 and 4 instead of cylindrical. The forward end A³ of the cylinder
then acts as a fixed pointer against which the scale on the part B' is adapted to
move.
In a modification of my invention I provide for permanently attaching the gauge
to the rim of a wheel or to any part of the air vessel to be tested.
I accomplish this as follows, that is to say, in the case of a wheel rim, for example,
to the tubular plunger BI fix a short rod B³ having a rounded or otherwise
suitable shaped head B2. The part B³ is passed through a hole provided for it in
the wheel rim and is confined therein between the head B' and the shoulder B*, the
head B2 being pressed against the outside of the rim by the air tube of the tyre,
and the shoulder B being when in its normal position, at a short distance from the
rim of the wheel.
When the tyre is to be tested, the cylinder A of the gauge is grasped and gently
pressed towards the rim, the plunger B is thereby forced into the cylinder until the
pressure of the air in the tyre on the head B2 is equivalent to the pressure of the
gauge spring C in the cylinder A. When this is the case any further pressure on
the cylinder A will only tend to force the part B through the rim until it is
stopped by the shoulder B. Hence as soon as the said shoulder B is seen to
move towards the rim the pressure may be read off on a scale on the tubular
plunger.
I sometimes attach the cylinder of the gauge to the rim instead of the plunger as
above described; similar methods may be followed in attaching the gauge to any
vessel or to a part of any vessel containing air under pressure.
It is an important feature of each of the hereinbefore described forms of pressure
gauge that no part thereof is in communication with the interior of the tyre or
other elastic chamber to which it is to be applied.
In a further modification of my invention I attach my improved gauge within
the barrel of the inflator or pump in such a manner that the gauge indicates the
pressure in the tyre or other inflatable body during the act of inflation.
Figure 7 illustrates this part of my invention. F is the barrel of the pump or
inflator within which is secured a pressure gauge of similar construction to those
previously described. The cylinder A of the gauge which is secured inside the
barrel Fis of rather less diameter than the interior of the said tube F so as to
allow of the free passage of air past the gauge when the pump is being worked to
inflate the tyre or other inflatable body.
A pin D on the piston projects through the slit A' in the side of the cylinder A
and also through a corresponding slit F or opening in the wall of the barrel F..
A curved plate G is secured to the pin D which plate serves as a movable pointer to
indicate pressure on a suitable scale provided on the barrel F.

page_text: When the inflator barrel F is attached to a tyre or other inflatable body it is
obvious that the pressure of the air contained therein and therefore in the barrel F
will act on the piston B of the gauge and drive it forward against the spring C for
a distance depending on the pressure in the inflator barrel or tube F, and moves the
pointer over the graduated scale.
A convenient form of pressure gauge for tyres is that shown in Figures 8 and 9
which gauge acts as a relief valve and may be set to open or blow off when the
pressure in the tyre during inflation or at any other time exceeds a certain desired
amount. H is the valve tube to which the inflator barrel is connected when it is
desired to inflate a tyre, the air from the pump or inflator passing through the
opening H into the tyre. To the exterior of the tube H is secured the pressure
gauge the cylinder A of which communicates with the tube H by means of the
opening or ort H. The spring C is so adjusted by means of the screw I or
otherwise that when the pressure in the tyre exceeds a certain amount, the air will
lift the piston B so far as to uncover the port A' in the cylinder A and thus put
the tube H into communication with the external atmosphere through the ports H*
and A
I may provide as follows for adjusting the pressure at which such a pressure
gauge will open & thus act as a relief valve.
Referring to Figures 10 and 11 which illustrate a modified form of gauge to be
permanently secured to the inflatable body, the spring C is compressed between the
piston B and an adjustable cap J to which latter is secured a pin J', that projects
through a longitudinal slot A³ in the cylinder. The pin may be passed into any
one of two or more notches or recesses A' A' in the side or sides of the slit or
opening A in order to adjust the compression of the spring. A is the air
inlet opening which is put into communication with the interior of the inflatable
body.
I may also apply these or other suitable means of adjustment to any of the forms
of pressure gauges herein before described.
I may so calibrate the pressure gauge that the position of the pin J¹ in each of
the notches A' A' corresponds to a certain known pressure per square inch which
may be marked opposite to the said notches.
My improved gauges are made in various sizes to suit different purposes and
pressures and will be found cheap and easy to use.
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 combination with the inflator tube or its delivery tube of a pressure
gauge placed therein and having an external indicator, for the purpose specified.
2. A pressure gauge constructed substantially as described with reference to
Figures 1 and 2, or to Figures 3 and 4 or to Figures 5 and 6 or to Figure 7, and
operating as, and for the purposes, specified.
3. The combination, with the inflator or with an inflatable vessel, of a pressure
gauge constructed substantially as described with reference to Figures 8 and 9 or
to Figures 10 and 11 and operating as, and for the purposes, specified.
4. The combination with an inflatable vessel of the stud or plate E as, and for
the purposes, specified.
...
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.