IMPROVEMENTS IN INSTRUMENTS OR GUAGES FOR MEASURING AND INDICATING THE PRESSURE AND VACUUM OR DIFFERENCES OF PRESSURE AND THE DRAUGHTS OR BLASTS OF FLUIDS
Year: 1871

page_text: tion of "IMPROVEMENTS IN INSTRUMENTS OR GUAGES FOR MEASURING AND
INDICATING THE PRESSURE AND VACUUM OR DIFFERENCES OF PRESSURE AND
THE DRAUGHTS OR BLASTS OF FLUIDS."-Partly a communication from
abroad by Bernhard August Schäffer and Christian Friedrich Buden-
berg, persons resident at Buckau, near Magdeburg, in the Kingdom
of Prussia.
ealed the 1st September, 1871, and dated the 15th March 1871.
PROVISIONAL SPECIFICATION left by the said Joseph Knowles Broad-
bent at the Office of the Commissioners of Patents, with his Petition,
on the 15th March 1871.
I, JOSEPH KNOWLES BROADBENT, of the City of Manchester, in the
3 County of Lancaster, Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN INSTRUMENTS OR GUAGES FOR MEASURING
AND INDICATING THE PRESSURE AND VACUUM OR DIFFERENCES OF PRESSURE AND
THE DRAUGHTS OR BLASTS OF FLUIDS," the result partly of a communication
made to him from abroad by Bernhard August Schäffer and Christian

page_text: exterior of the bellows, so that should there be any slight leakage it will
not affect the correctness of the indications. In place of the bellows an
inverted cup may be used like a gasometer scaled with mercury.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Knowles Broadbent in the Great Seal
Patent Office on the 13th September 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
KNOWLES BROADBENT, of the City of Manchester, in the County of
Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of March, in the year
of our Lord One.thousand eight hundred and seventy-one, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Joseph Knowles Broadbent, Her special
license that I, the said Joseph Knowles Broadbent, my executors,
administrators, and assigns, or such others as I, the said Joseph Knowles
Broadbent, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
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 Inven-
tion for "IMPROVEMENTS IN INSTRUMENTS OR GAUGES FOR MEASURING AND
INDICATING THE PRESSURE AND VACUUM OR DIFFERENCES OF PRESSURE AND THE
DRAUGHTS OR BLASTS OF FLUIDS," the said Invention is the result partly
of a communication to me from abroad by Bernhard August Schäffer
and Christian Friedrich Budenberg, persons resident at Buckau near
Magdeburg, in the Kingdom of Prussia, and partly of Invention and
Discovery made by me, upon the condition (amongst others) that I, the
said Joseph Knowles Broadbent, by an instrument in writing under
my hand and seal, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be per-
formed, 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.
NOW KNOW YE, that I, the said Joseph Knowles Broadbent, do
hereby declare the nature of the said Invention and in what manner the

page_text: same is to be performed, to be particularly described and ascertained in
and by the following statement, and the accompanying Drawings, (that
is to say) :-
Firstly. The Invention relates to arrangements applicable to guages
for measuring and indicating the pressure or vacuum or difference of
pressure of fluids when small fractions or variations of pressure are
required to be shown more accurately, and consists in gearing the
mechanism of the hand for the general index with the mechanism of a
hand to show the fractions or divisions, which latter hand may make
one complete revolution for each unit or division of the general or unit
index, the fractional hand being at zero when the general hand has
completed each unit.
Secondly. It relates to means to be employed in combination with
pressure or vacuum guages for showing the maximum degree of pressure
or vacuum within any period after an adjustment, and consists in using
a moveable dial which is carried along in one direction only by the
indicator mechanism of the guage and is left and remains stationary
when the indicator mechanism moves back from its maximum. The
maximum dial is locked or scaled up and may be arranged to show
through an opening in the front of the ordinary dial, or so as only to be
seen when the enclosing case is unlocked, or there may be two such
dials, one seen through the glass face of the guage and one not seen
until the cover is unlocked, and both may be locked or sealed up if
required.
Thirdly. It relates to means for measuring small pressures or vacuums,
applicable more particularly for measuring and indicating draughts in
furnaces, flues, and mines, and also the pressure of blasts, and for other
purposes. It consists in employing two discs connected together at
their edges by leather or other similar suitable material, so that one
disc can move towards the other like a pair of bellows; one disc is fixed
in a suitable case, the other is connected with a spring of suitable
strength adjustable by a screw. The spring is connected with one arm
of a bell-crank lever having a slot in it for an adjustable joint pin, the
other arm of the lever is formed into a toothed sector which gears with a
small wheel on the axis that carries the hand of the index. The interior
of the bellows is connected by a pipe with the furnace flue or chamber,
the draught of, in, or through which is to be measured and the
atmosphere has free access to the exterior of the bellows, and thus should

page_text: there be any slight leakage it will not affect materially the correctness of
the indications. The apparatus may be made with two pairs of bellows
(or a double pair of bellows) arranged and connected so that the pressure
caused by a current or draught entering the orifice of a tube facing it
may pass into one pair or division of the bellows, and the vacuum caused
by the same current or draught passing across the orifice of a tube may
act exhaustively upon the other pair of bellows, the joint action of the
two being indicated by the mechanism.
Fig. 1 is a sectional view; Fig. 2 a front view of the index face of the
guage, and Fig. 3 is a view with the back of the guage removed,
illustrating the first part of the Invention.
;
a is the general index hand, and a¹ is its axis; is the fractional index
hand, and is its axis, and both axes have bearings in the plates c.
and c d is the axis of a wheel d' which gears with a pinion a² upon
the axis (a) of the general index haud (a). This wheel dis connected
with the pressure tube (a) or diaphragm, as the case may be, by any
ordinary mechanism and receives oscillating movements as the pressures
increase and diminish. This wheel or another wheel on its axis gears
with a pinion e¹ on another shaft e having bearings in the plates c and c¹
and upon this shaft (e) there is a wheel e' that gears with a pinion
on the axis b¹ carrying the fractional index hand (b). The last-named
pinion (3) gcars with a wheel f¹ upon a shaft f having bearings in
brackets cand c³ secured to the side plate c¹. There may be any
required number of wheels and pinions between the axis for the general
index hand and the fractional hand, but they must be so calculated as
to give the required proportion of movement between the two, but it is
necessary to remove the effect of "play" in the gearing and for this
purpose spiral springs are used which when wound up have sufficient
tension to overcome the friction of the gearing, these springs being
connected one a³ with the shaft a', the other f with the axis f¹ of the
wheelf, both springs being arranged so that they will be wound up or
tightened when the general index hand (a) begins its movement from
zero, the springs bringing back the gearing or keeping the same sides
of the teeth in contact with each other during the back movement of
the index hands. When the movements of the general index hand are
not uniform the shaft d may be geared to the shaft e by a fine jointed
chain similar to those used in watches. One end of the chain being
attached to a wheel having a variable periphery and secured upon the

page_text: .
shaft (d) and the other end attached to a drum secured upon the
shaft e.
This arrangement being somewhat similar to that between the
main spring drum and fusee barrel of a watch except that the part
acting in place of the fusec will only make a part of a revolution and
its surface upon which the chain winds will be made irregular in form
in proportion to the varying movements of the general index hand (a).
The chain will be kept tight by the spiral spring or springs f and a³.
Fig. 4 is a front view, and Fig. 5 a section illustrating the second part
of the Invention. a is the hand of the index on a shaft a having
bearings in the plates c and c¹. The mechanism for actuating the
shaft a¹ being of any ordinary kind is not shewn. There is an arm a²
secured upon the shaft a¹ which as it rotates comes in contact with a
pin 6 in a moveable disc or dial having bearings in the fixed dial
as shewn, and carries it along and leaves it when the shaft turns back.
There is a whole in the face of the fixed dial d through which the move-
able dial can be seen. The moveable dial can be set by opening the
frame (e) carrying the glass face which is hinged to one side of the
casing of the guage and turning the disc by means of the milled
collar (62) in front of the fixed dial. If required a dial 63 may also be
arranged at the back of the guage casing by causing the shaft a¹ to pass
through its bearing which is screwed in to project so that its exterior
will form the bearing of the disc as shown. An arm
shaft (a) is made to act upon a pin in the disc b³; 6 is a pointer
referring to the index upon the dial; g is an hinged cover which may
be locked or scaled up as desired.
upon the
Fig. 6 is a plan view and Fig. 7 a vertical section on the line AB,
Fig. 6, of one modification, and Fig. 8 is a vertical section showing
another modification illustrating the third part of the Invention.
a is the casing standing or secured upon feet, the guage as arranged
being intended for use only when the dial plate is in a horizontal
.position. b and b¹ are circular discs of tin plate connected together by
calf skin leather 62 cemented upon rims round each disc, and further
-secured by hoops 6³ of tin plate, as shewn. The lower disc b is secured
by a screw to the bottom of the casing, as shewn, and there is a short
branch pipe soldered to the lower disc into which a junction pipe (65) is
screwed through the casing which forms the connection between the
gúage and the furnace, fluc, chimney, passage, or chamber, the draught
in or through which is to be measured and indicated. The upper and

page_text: moveable disc b₁ of the bellows has a central stem 6° soldered to it which
passes through a hole in a flat spring c secured to a beam d³ which
passes across and is secured in the casing. This spring c sustains the
weight of the moveable disc, there being a pin 6' passing through the
stem at the upper side of the spring, and this spring is also drawn down-
wards by the action of a draught diminishing the pressure in the interior
of the bellows, and thus its tension measures the force of the acting
draught, and the corresponding movement in the spring is com-
municated to the index hand (g). The screw c¹ is for adjusting the
spring, and its movement is transmitted by a link c jointed to its end
and to one end of a lever d having its fulcrum at d; the other end of
this lever is jointed with a link d² also jointed with a stud e¹ that is
adjustable in the arm of a bell-crank lever e having its fulcrum or axis
at e. The movement of the spring may be transmitted to the bell-
crank lever directly. One arm of this bell-crank lever carries a toothed
segment that gears with a small pinion upon a vertical axis f, as
shown, upon which axis the index hand g is secured. A fine spiral
spring is connected with the axis f so that it will be wound up when
the index hand moves from zero; this keeps the same sides of the teeth
in contact and removes the effect of play between the teeth. When the
guage is at zero the side of the slotted arm of the bell-crank lever e
rests upon the hook projection (d*) from the cross beam, and the index
hand rests against the pin ¹ in the dial plate. The dial may be divided
to show inches and fractions of an inch of a column of water, and along-
side this division the corresponding velocity of draught may be marked
in feet per second, so that the extent of the draught will be shown in
force and velocity at the same time. Space or a small hole is left so
that the atmosphere may have free access to the interior of the casing,
and consequently to the exterior of the bellows.
Fig. 8 is a section showing a modification with double bellows in
which the upper and lower disc (6' and b) is fixed, and a middle disc b*
which separates the two is moveable, and it is connected with the
spring c by a cross piece 6%, the two ends of which are jointed to
studs (6) upon opposite sides of the disc. The upper bellows is supposed
to be connected through the branch with the pipe by acted upon by the
draught and producing pressure, and the lower bellows through the
branch with the pipe 65 in which the draught produces vacuum, so that
both pressure and vacuum tend to depress the middle disc 6*, and their
joint force is indicated by the index hand.

page_text: I have now particularly described the nature of the said Invention,.
and the mode in which it is to be carried into effect, and claim as
secured to me by the in part recited Letters Patent,-
Firstly. The combination and arrangement of gearing and springs for
working general and fractional index hands in guages for measuring
and indicating pressure and vacuum, substantially as herein-before
described.
Secondly. Transmitting motion between the shafts for the general and
fractional index hands through a jointed chain combined with springs
for keeping the same stretched, substantially as herein-before described.
Thirdly. The arrangement of a moveable dial to show maximum
movements in pressure or vacuum guages, substantially as herein-before
described.
Fourthly. The combination and arrangement of bellows, spring, and
index hand for measuring and indicating draughts or pressures, sub-
stantially as herein-before described.
In witness whereof, I, the said Joseph Knowles Broadbent, have
hercunto set my hand and seal, this Twelfth day of September in
the year of our Lord One thousand eight hundred and seventy-
one.
JOSEPH KNOWLES BROADBENT. (L.S.)