Improvements in Pressure and Vacuum Gauges.
Year: 1888

page_text: COMPLETE SPECIFICATION.
Improvements in Pressure and Vacuum Gauges.
I, JOHN JACKSON, of Suffolk House, 5 Laurence Pountney Hill, in the City of
London, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to he particularly described and ascertained in
and by the following statement:-
My invention relates to pressure and vacuum gauges of the kind or class in which
the indications are effected through the medium of a flexible or elastic diaphragm,
and my said invention comprises various improvements hereinafter set forth.
In the accompanying drawings I have shown how my said invention can be
conveniently and advantageously carried into practice.
Figure 1 is a front elevation of one form of my improved pressure or vacuum
gauge, the dial and other parts being removed.
Figure 2 is a vertical section on the line x, x, Figure 1.
Figure 3 is a vertical section on the line y, y Figure 2, showing the indicating
mechanism.
Figure 4 is a plan of the lower part of the casing of the gauge, showing also the
diaphragm hereinafter described.
Figure 5 is a sectional elevation illustrating a modification of my said invention.
Like letters indicate corresponding parts throughout the drawings.
A is the upper part and A' the lower part of the casing. B is a frame carrying
the indicating mechanism hereinafter described, and secured in the said casing by
screws or otherwise. C is the pointer or indicator.
The said pointer or indicator C is fixed on a spindle a carried in suitable bearings
in the frame B. A pinion is formed or fixed on the spindle a and is geared with a
toothed quadrant e, a suitable spring b₁ being connected with the said spindle a to
retain the indicator or pointer C normally at zero.
The toothed quadrant c is pivoted at d to the frame B and is provided with guides e
in or between which is adapted to slide a nut f screw carried in suitable
bearings e¹ in the guides e passes through the said nut f, which is correspondingly
screw-threaded. The screw 9 is, moreover, provided with a head g¹ having holes g² in

page_text: which a pin or rod can be inserted to turn the said screw and thereby adjust the
nut f. A rod is coupled or pivoted at h¹ to the nut f. The lower extremity of the
said rod fits into a hole in a rod j connected to the diaphragm k by a ball-and-
socket joint at k¹. The rod his retained in the said hole by ineans of a set-screw j.
It will be seen from the foregoing description that I arrange the indicating
mechanism of the gauge in the frame B so that it is entirely supported by the said
frame and can be very readily inserted and secured in, or removed from the casing
with the said frame as a whole and separate or distinct device. The removal of the
mechanism can, moreover, be effected without the necessity for taking the said
mechanism to pieces or detaching any part of the same from the said frame.
It will also be seen that, by means of the adjusting screw g and the nut f herein-
before described, the gauge can be accurately adjusted with great facility.
The diaphragm k is preferably made of steel and is corrugated as shown; it is
fitted into a recess in the lower part A¹ of the casing and is held or clamped in
place between the two parts of the casing by means of screws 2 which unite the said
parts. Or the two parts of the casing are united by screw-threads as shown in
Figure 5, one part being screwed into the other and the diaphragm thus tightly
clamped between them and the two parts being securely held in position by a
counter-sunk screw ³ or otherwise. The parts of the casing may, however, be
otherwise united if desired. Moreover it is not essential that the diaphragm should
be fitted in a recess in one or the other part of the casing. I sometimes provide for
simply clamping the diaphragm between annular ribs or projections on the two parts
of the casing.
By making the diaphragm smaller in diameter than the parts of the casing between
which it is to be secured and clamping it between the said parts as above described,
I obviate the necessity for weakening the diaphragm by boring holes therein.
Moreover I am enabled to make perfectly tight metal to metal joints between the
diaphragm and the two parts of the casing without the application of excessive force
to the screws or bolts uniting the said parts, I can, therefore, dispense with India-
rubber or similar packing or jointing material.
The improved arrangement of the diaphragm also increases the flexibility thereof
and diminishes the quantity of metal required in the said diaphragm.
I prefer to place a second or supplementary diaphragm m of copper or similar
material beneath the steel diaphragm k for the purpose of protecting the latter against
injury by moisture. This supplementary diaphragm is sometimes corrugated to
correspond with the diaphragm k.
I usually form the lower part A¹ of the casing with a narrow annular rib or
projection A upon which the diaphragm will rest and against which the said
diaphragm will be clamped. I thus provide for diminishing the force required to
tighten the joints between the diaphragm or diaphragms and the two parts of the
casing.
I prefer to construct the upper part A of the casing of cast iron and the lower
part A¹ thereof of gun-metal or similar material, thus obviating the liability to rust of
the part of the casing below the diaphragm. The parts above the diaphragm not
being subjected to the action of the fluids under pressure, are not liable to rust and
can therefore be advantageously made of cast iron.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I wish it understood that
I claim :-
First. The frame having the indicating mechanism arranged therein, and adapted
to be secured in the casing by screws or otherwise, substantially as, and for the
purpose, set forth.
Second. The combination, with the toothed quadrant, of the guides, the nut and
the adjusting screw, substantially as, and for the purpose, set forth.
Third. A corrugated diaphragm made without bolt-holes and clamped between the
two parts of the casing, substantially as, and for the purposes, set forth.

page_text: Fourth. The combination, with the corrugated steel diaphragm, of a supplementary
corrugated or other diaphragm of copper or similar material, as, and for the purpose,
above specified.
Fifth. The construction of the casing with a rib or projection A², as, and for the
purpose, above specified.
Sixth. The improved casing having its upper portion formed of cast iron and its
lower portion of gun-metal or similar material, as, and for the purpose, above
specified.
Seventh. The improved pressure or vacuum gauge consisting of the parts
constructed and combined substantially as described with reference to the
accompanying drawing.
Dated this 22nd day of June 1888.
JOHN JACKSON.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.