IMPROVEMENTS IN STEAM PRESSURE GAUGES
Year: 1870

page_text: LETTERS PATENT to Edward Joseph Curtin, of No. 32, Ambrose
Road, Clifton Wood, Bristol, in the County of Gloucester, for the
Invention of "IMPROVEMENTS IN STEAM PRESSURE GAUGES."
Sealed the 27th January 1871, and dated the 28th July 1870.
PROVISIONAL SPECIFICATION left by the said Edward Joseph Curtin
at the Office of the Commissioners of Patents, with his Petition,
on the 28th July 1870.
I, EDWARD JOSEPH CURTIN, of No. 32, Ambrose Road, Clifton Wood,
Bristol, in the County of Gloucester, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN STEAM PRESSURE GAUGES," to be as
follows:-
L
My improvements have reference to that class of steam pressure
gauges in which the pressure of the steam causes a hand or pointer to
travel round over a graduated scale on a dial.
My Invention has for its object to ascertain at any time the maximum
pressure of steam that may have been indicated by the gauge, thus

page_text: affording a control over the person in charge of the engine and boilers
to which the gauge is attached.
It consists in providing a supplemental or "check" pointer to the
gauge, which is so arranged as to be readily moved round by the acting
pointer in the direction in which the pressure increases, but which cannot
readily be turned in the contrary direction by the attendant, and is thus
caused at all times to indicate the maximum pressure to which the gauge
has been subjected.
Various arrangements may be employed for actuating the check
pointer in the manner described; thus the acting pointer mây move the
supplemental or check pointer either by means of a stud or finger
upon or carried by the one pointer or the other, or by means of a rack
and pinion, the check pointer being prevented from moving back when
the acting pointer recedes by means of a pawl and ratchet or by any
other similar suitable known contrivance. Such contrivance may be
released by means of a key on unlocking the gauge so as to turn the
check pointer back from the maximum position. Or in certain cases
the Invention may be employed without of necessity arranging the
gauge to be locked.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Joseph Curtin in the Great Seal Patent
Office on the 27th January 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
JOSEPH CURTIN, of No. 32, Ambrose Road, Clifton Wood, Bristol, in the
County of Gloucester, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of July, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Edward Joseph Curtin, Her special
licence that I, the said Edward Joseph Curtin, mý' executors,
administrators, and assigns, or such others as I, the said Edward
Joseph Curtin, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times

page_text: thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN STEAM PRESSURE GAUGES," upon the condition
(amongst others) that I, the said Edward Joseph Curtin, my executors
or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
#
KNOW NOW YE, that I, the said. Edward Joseph Curtin, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, reference being had to the accom-
panying Sheet of Drawings, and to the figures and letters marked
thereon, that is to say :-.
My improvements have reference to that class of steam pressure
gauges in which the pressure of the steam causes a hand or pointer to
travel round over a graduated scale on a dial.
My Invention has for its object to ascertain at any time the maximum
pressure of steam that may have been indicated by the gauge, thus
affording a control over the person in charge of the engine and boilers to
which the guage is attached.
It consists in providing a supplemental or "check" pointer to the
gauge, which is so arranged as to be readily moved round by the acting
pointer in the direction in' which pressure increases, but which cannot
readily be turned in the contrary direction by the attendant, and is thus
caused at all times to indicate the maximum pressure to which the gauge
has been subjected.
Various arrangements may be employed for actuating the check
pointer in the manner described, thus the acting pointer may move the
supplemental or check pointer either by means of a stud or finger upon
or carried by the one pointer or the other, or by means of a rack
and pinion, the check pointer being prevented from moving back when
the acting pointer recedes by means of a pawl and ratchet, or by any
other similar suitable known contrivance. Such contrivance may be

page_text: released by means of a key on unlocking the gauge, so as to turn the
check pointer back from the maximum position. Or in certain cases
the Invention may be employed without of necessity arranging the
gauge to be locked.
On the accompanying Drawing are shewn some of the various
arrangements by which my Invention may be carried into effect.
Figure 1 shews a front elevation of a pressure gauge, in which A is
the ordinary gauge pointer, indicating the pressure on the scale B,
while C is the check pointer upon a separate spindle D for indicating
upon the scale E the maximum pressure which has at any time been
indicated by the gauge.
For this purpose the spindle of the gauge
pointer carries a toothed pinion F imparting motion through an inter-
mediate pinion F¹ to another pinion G upon the spindle D. This latter
pinion is loose on its spindle, and carries a spring pawl, which takes into
a small ratchet wheel (not shewn) fixed on the spindle in such manner
that when the gauge pointer turns to the left (for shewing a reduction in
pressure) it will cause the pinion G to be carried round loose upon the
spindle D, leaving the pointer C stationary (the spindle D being caused
to move with friction for this purpose,) while when the pointer A turns
in the contrary direction to indicate an increase in pressure, it will cause
the pointer C to turn in a similar manner so as to indicate the same
pressure on the scale E. When required to adjust the check pointer the
gauge is unlocked, and the pointer C is moved into the zero or other
position (corresponding with the position of the gauge pointer) by hand
or otherwise.
Figure 2 shews an arrangement in which the check pointer C is loose
upon the spindle of the gauge pointer A, and indicates the maximum
pressure upon the same scale as the latter. The one pointer or the
other carries a projection stud so arranged that when the pointer A
turns to indicate an increase of pressure it carries the check pointer
with it, but when the pointer A recedes upon a decrease of pressure
taking place the check pointer is left stationary. To the check pointer
is attached a disc G with a v groove in its periphery, into which fits
the V edge of the quadrant H turning on the spindle I. The quadrant
is made slightly excentric, so that when the check pointer has been
moved into position for indicating the maximum pressure it is prevented
from receding by the jamming action produced by the quadrant, the
weight of which causes it to press in the groove of the disc G. When
:

page_text: it is required to move the check pointer back for adjustment the quadrant
is raised out of gear either by hand or by turning the spindle I by means
of a key.
Figure 3 shews an arrangement of and mode of actuating the check
pointer similar to the foregoing one; the check pointer C in this case,
however, carries a ratchet wheel J, into which takes a pawl K kept in
gear by a spring L, whereby the check pointer is kept stationary in the
maximum position. For adjusting the check pointer the pawl is raised
out of gear with the ratchet wheel.
Figure 4 shews the same arrangement as above, but with a simple
spring M in gear with the ratchet wheel J, or in place of the ratchet
wheel might be used a disc with a groove on its circumference in which
the spring L is caused to press sufficiently to produce the requisite
frictional resistance.
Figure 5 shews the same arrangement as at Figure 4, with the addition
of a spiral spring N attached at the inner end to a ratchet wheel J, and
at the outer end to the gauge, and so arranged that when the spring M
is released from the ratchet wheel for adjusting the check pointer C the
spiral spring will move back the latter till it comes in contact with the
stud on the gauge pointer A.
Figure 6 shews an arrangement in which the check pointer C is loose
on the spindle of the gauge pointer as before, and has fixed to it a bevil
pinion O, in gear with which is another bevil pinion P on a spindle Q
passing through the case of the gauge, and provided outside with a
button R, so that by turning this button the check pointer may be
moved back for adjustment, the friction of the spindle Q and pinions
being sufficient to keep the check pointer stationary in the maximum
position. The button R is enclosed by mean of a hinged cap S, secured-
by a padlock T, or otherwise.
Having thus described the nature of my Invention and in what manner
the same is to be performed, I wish it to be understood that I in no way
limit myself to the arrangements for carrying the same into practice as
herein-before described, with reference to the accompanying Drawing,
as it is obvious that various other modifications may be adopted without
5 departing from the essential feature of my Invention, but what I claim
as the Invention secured to me under the herein-before in part recited
Letters Patent is, the application to pressure gauges of a check pointer
so arranged as to be readily moved round by the action of the gauge

page_text: pointer in the direction in which the pressure increases, but which will
remain stationary as the gauge pointer recedes so as to indicate the
maximum pressure attained, substantially as herein-before set forth.
In witness whereof, I, the said Edward Joseph Curtin, have here-
unto set my hand and seal, this Twenty-fifth day of January,
in the year of our Lord One thousand eight hundred and
seventy-one.
EDWARD JOSEPH CURTIN. (L.S.)