IMPROVEMENTS IN STEAM-PRESSURE GAUGES
Year: 1881

page_text: LETTERS PATENT to George Furness, of Manchester, in the County of Lancaster,
Brass Founder, and James Robertshaw, of the same Place, Merchant, for an
Invention of "IMPROVEMENTS IN STEAM-PRESSURE GAUGES”
PROVISIONAL SPECIFICATION left by the said George Furness and James
Robertshaw at the Office of the Commissioners of Patents on the 8th July
1881.
GEORGE FURNESS, of Manchester, in the County of Lancaster, Brassfounder,
and JAMES ROBERTSHAW, of the same Place, Merchant. "IMPROVEMENTS IN STEAM
PRESSURE GAUGES."
This Invention relates to improvements in steam pressure gauges employed to
indicate the pressure or variations of pressure of steam, as is well understood.
Previous to this Invention hollow metal tubes or springs, known as the bourdon
springs, have mostly been employed in the construction of such apparatus. The
said springs act to impart motion to the index hand of the gauge.
This arrange-
ment is objectionable on account of the liability of such springs to burst under
high pressures of steam, and when in use for a time are not reliable, as the springs lose
an amount of their resiliency or spring, causing variations in the indications under
the same steam pressure. To remedy these defects, and at the same time to
construct a guage capable of indicating high and low steam pressures, we dispense
with the said spring and employ a diaphragm or plate of metal mounted between
the flanges connecting the guage with the steam pipe. A vertical rod of any
suitable length rests in a hole formed in the top part of the flange and inside the
guage, the end of the said rod resting on the said diaphragmn. A horizontal lever
or rod having its fulcrum to the left or right of the vertical axis of the first named
rod is acted upon by the steam pressure on the diaphragm through the said
vertical rod. On the extremity of the said horizontal rod or lever a short lever is
mounted, which transmits motion from the horizontal lever to a pinion on the axis
of the index finger through a toothed quadrant. The said short lever may be
caused to bear on the horizontal lever by means of a spring if desired; by these
means comparatively high pressures can be recorded and more accurate indica-
tions obtained. The dial face may be either plain or lettered, or the same may be
painted on the glass casing, in which latter case a light inserted between the dial
face and glass casing would display the numerals on the latter, and the indications
read-off at night or in the darkness.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Furness and James Robertshaw in the Great Seal Patent
Office on the 2nd January 1882.
GEORGE FURNESS, of Manchester, in the County of Lancaster, Brass Founder,
and JAMES ROBERTSHAW, of the same Place, Merchant. " IMPROVEMENTS IN STEAM
PRESSURE GAUGES."
The Invention relates to improvements in steam pressure and vacuum guages
employed to indicate the pressure or variations of pressure of steam, as is well
understood. Previous to the said Invention hollow metal tubes or springs,
designated the "bourdon" spring or springs bave ordinarily been employed in
the construction of such apparatus. The steam pressure acting on the tube or
spring causing it to impart motion through the leaves of a pinion to the index
hand of the gauge, or when the steam in the boiler has condensed, indicates the
vacuum. This arrangement is objectionable principally on account of the liability
of the spring or tube to burst under a high pressure of steam, and also on account
of its uncertain action through loss of sensitiveness after being in use for a time
caused by reason of the spring losing an amount of its resiliency, thereby causing
variations in the indications under the same pressure of steam. To remedy these
defects, and to construct a guage capable of indicating comparatively the highest
or lowest steam pressure, we dispense with the said tube or spring and employ in
lieu thereof a metal diaphragm securely mounted between and extending across a
chamber formed within the flanges connecting the guage with the steam pipe. A
vertical rod or spindle is mounted in an opening formed in the boss part or top of
the upper flange, and extends inside the guage, one end thereof bearing on the said
diaphragm. A horizontal lever having its fulcrum to the right or left of the vertical
axis of the first mentioned rod is acted upon by the said rod by the pressure of
steam or the vacuum beneath the diaphragm. Near the end farthest from the
fulcrum of the said horizontal lever an adjustable stud or pin is mounted, carried
by a short arm, one end of which arm is jointed to a quadrant lever, the other end
being forked, through the cheeks of which an adjustable screw passes, a spring
being employed to press down the said arm. Movement is transmitted from the
diaphragm through the said system of levers to a quadrant which acts upon the
levers of a pinion mounted on the axis of the index finger. By these means
comparatively higher pressure can be recorded, and more accurate and reliable
indications obtained. The numerals and letters, painted on a glass dial, mounted
within the guage casing in order that indications may be read off at night, a light
being mounted within or near the dial for this purpose, but if prefered the ordinary
form of dial may be employed.
The
And in order that the said Invention may be more fully understood, we have
caused to be appended hereto a Sheet of Drawings marked with letters of reference,
to which Drawings reference will now be made. Fig. 1 represents a front view
partly in section of a steam guage constructed in accordance with the Invention ;
Fig. 2 represents a side view; Fig. 3 represents a plan of the short arm.
diaphragm a may be plain or corrugated, to increase its acting area, being securely
mounted within and extending across the chamber or space A formed between the
flanges b, c. Within an opening formed in the boss of the flange b a vertical
spindle d is mounted; one end of this spindle rests on the diaphragm a, and the
other end abuts into a vee or other suitably shaped recess formed in the horizontal
lever e.
The lever e, carried by the bracket g, has its fulcrum at f. The adjustable
pin h, formed with a screw-thread and milled button, is caused to bear on the

page_text: lever e in order to transmit motion from the lever e to the quadrant, and to permit
of adjustment. The arm i, jointed at one end to the quadrant lever j, is forked, as
shown in Fig. 3, in order to tighten up by the pin n the screw spindle h when
required. A spring k is employed to bear on and keep in place the forked arm i.
The action of the apparatus is as follows:-The steam pressure acting upon the
underside of the diaphragm a causes the spindle b to be raised to a greater or less
extent, which movement of the spindle lifts the end of the horizontal lever e, and
imparts movement to the forked lever arm i through the adjustable pin h, which
transmits movement to the quadrant j, which quadrant engages with the leaves of
a pinion on the axis of which the index hand m is mounted. Any variation in
the pressure on the diaphragm a is accurately indicated on the dial by the index
finger acted upon through the system of levers, and a comparatively higher degree
of pressure can be recorded than when spring tubes are employed. As the pressure
on the diaphragm diminishes, the pin h will force down the end of the lever e, and
draw back the index hand m, and by adjusting the pin h nearer to or farther from
the fulcrum f, the guage may be made to indicate any amount of pressure. The
arrangement for illuminating the dial is shown by Fig. 2, the numerals and letters
being painted on the glass face n, a light o being mounted in the vicinity of the
guage to permit of readings being taken at night. In using the guage as a vacuum
guage the action of the vacuum formed beneath the diaphragm causes the spindle
to descend, and the index is made suitable to record the amount of vacuum.
Having now described and indicated the nature of the said Invention, and
means for carrying the same into practical effect, we would have it to be distinctly
understood that we claim as secured to us by the hereinbefore in part recited
Letters Patent,-
First. The general arrangement and combination of parts consisting of the
diaphragm a, vertical spindle d, horizontal lever e, and arm i, adjustable pin h
acting on the index dial through the lever quadrant j, for the purpose specified
and as illustrated in the Drawings.
Secondly. The manner and means for illuminating the guage, substantially as
described and as illustrated in the Drawings.
In witness whereof, we, the said George Furness and James Robertshaw,
have hereunto set our hands and seals, this Twenty fourth day of December,
in the year of our Lord One thousand eight hundred and eighty one.
GEORGE FURNESS.
(L.S.)
Signed and sealed by the
I said George Furness and
James Robertshaw
the presence of
in
FERDINAND BOSSHARDT,
HUGH G. GRANT,
Manchester.
JAMES ROBERTSHAW. (L.S.)