IMPROVEMENTS IN PRESSURE-GAUGES
Year: 1885

page_text: I, JOHN JACKSON, of 8 Frederick Place, Gray's Inn Road, in the County of
Middlesex, Manufacturer, do hereby declare the nature of my invention for
"IMPROVEMENTS IN PRESSURE-GAUGES to be as follows:-
My invention relates to pressure-gauges of that class wherein the steam or other
fluid acts upon a spring through the medium of a diaphragm of india-rubber or
similar material. And my said invention comprises various improvements as
hereinafter specified.
In gauges of the above named class, it has been customary to employ a volute
spring acted upon directly by the diaphragm, which was consequently liable to
considerable wear and tear, and required frequent renewal. But in my improved
gauge, the diaphragm bears against the smooth rounded end of a rod or spindle,
which is acted upon by a spiral spring and is connected with a rack which gears
with a pinion on the axis of the hand or pointer. The said rod or spindle and the
spring are enclosed in a hollow cylinder or casing, and the rod or spindle is
provided with a disc or collar fitting into the cylinder or casing or with other
suitable means for guiding it therein.
I prefer to make the said cylinder or casing with a cross-piece which fits the
interior surface of the box or case of the gauge and is secured thereto by screws.
When the gauge is constructed in this manner the said box or case is made circular
and without any projecting pieces, and can, therefore, be turned in a lathe to
finish it.
A bracket is attached to the said cylinder or casing and extends into the box or
case. This bracket carries the hand or pointer and its axis and pinion. These
parts are unattached to the back of the box or case and will not be affected by
vibration of the same, nor be liable to injury by blows received thereby.
I make the aforesaid rod or spindle with a stop or projection, which, when the
parts are in their normal position, and the pointer is at zero, rests against the end
of the hollow cylinder or casing or against a stop or projection provided thereon.
This stop prevents or diminishes the pressure of the spindle upon the diaphragm,
when the gauge is not in use.

page_text: In constructing pressure-gauges, it is customary to provide for a slight move-
ment of the rack before the pointer begins to move from zero; But, by reason of
the peculiar construction of my gauge, this is rendered unnecessary, and the pointer
in my gauge is arranged to move from zero immediately the pressure exceeds the
ordinary atmospheric pressure.
My gauge, moreover, possesses the advantage over those heretofore used, that, by
merely substituting one spring for another, I can alter a gauge from one scale to
another, the spring being unattached to the other parts. Furthermore, in my
gauge, the highest pressure for which it is intended can be exceeded to a con-
siderable extent without affecting the action of the parts. And, if desired, I can
make my gauge in such a manner that the pointer will make two revolutions
instead of only one, as in the gauges heretofore made.
Dated this 92nd dow of Insu
1005

page_text: I, JOHN JACKSON of 45 Southampton Buildings, London, 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 has for its object improvements in pressure gauges.
Fig. 1 of the accompanying drawings shews a sectional elevation of the
mechanism of a pressure gauge constructed according to my invention and Fig. 2
an external elevation thereof.
The following is a description of my invention :-Instead of the ordinary volute
spring I employ a spiral spring a mounted upon a rod b (hereafter termed the
plunger) terminating in a smooth rounded base (c) which presses against an elastic
diaphragm d fitted in an annular recess e formed in the base of the gauge-The
upper end of such rod is connected with a rack f working in a guide g and gearing
with a pinion h on the axis of the pointer i-The plunger is enclosed in a
cylindrical or other suitable casing j furnished with a disc or collar k or its
equivalent which serves to guide the plunger in its travel-The plunger is furnished
with a cross piece which fits into the box of the gauge and is secured thereto by
screws or otherwise.
A bracket m is attached to the top of the casing This bracket carries the
pointer together with its axis and pinion.
The upper end of the plunger is furnished with a stop or projection n--which
when the various parts are in their normal position and the pointer at zero, rests
either against the top of the casing itself or against a suitable projection provided
thereon-Such stop serves to prevent or diminish the pressure of the plunger upon
the diaphragm when the gauge is not in use.
All the parts of the mechanism of the gauge are separate and detached from the
box of the gauge and are not therefore liable to be injuriously affected by its
vibration or by any shock which it may sustain as the gauge is worked direct by
the plunger through the cylinder or casing in which the spiral spring is fitted-
The flange of the plunger acts on the spring and the flexible diaphragm-the latter
being thoroughly protected by the manner in which it is fitted in the base of the
gauge,
A set screw o Fig. 2 prevents the plunger either from twisting or pressing
against the diaphragm thus causing the gauge to start without any back lash.
Another advantage is that owing to the spring being perfectly independent of
the other parts of the mechanism either a stronger or weaker spring as desired may
be readily substituted for the existing spring wherewith the gauge is fitted.
A further advantage is that the highest pressure for which the gauge is intended
may be considerably exceeded without injuriously affecting its action.

page_text: Having thus particularly described the nature of my said Invention and in
what manner the same is to be performed I declare that what I claim is
Fitting a pressure gauge with a spiral spring a plunger b with rounded base c
flexible diaphragm d fitted in an annular recess e in the base of the gauge cylinder
or casing collar k or its equivalent cross piece --bracket m-stop n and regulator
set screw o all constructed arranged combined and fitted substantially in the
manner and for the purposes herein before specified.