Improvements in Pressure and Vacuum Gauges.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in Pressure and Vacuum Gauges.
I, JOHN JACKSON, of Suffolk House, 5 Jaurence 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 be particularly described and ascertained in and by
the following statement:-
My invention relates to pressure and vacuum gauges wherein an arbor or spindle
carrying an index or pointer is arranged to be rotated, or partially rotated by the
movement of a bent tube, a diaphragın or the like for the purpose of indicating the
measurements upon a scale or dial.
My said invention is applicable to gauges of various kinds or classes such for
instance as those of which the "Bourdon" gauge and the "Schaeffer" gauge are types.
Heretofore in most gauges the said arbor or spindle has been connected with the
bent tube or other actuating part of the gauge by means of a segmental rack or
toothed quadrant geared with a pinion fixed on the said arbor or shaft. This method
or manner of connecting the parts is open to various objections; for instance the
friction and weight of the said segmental rack and pinion are considerable and
interfere with the free movement of the index or pointer, thus impairing the accuracy
of the indications; moreover, when the said rack and pinion are damaged, the gauge
cannot be repaired without machine work; therefore at sea or in places where the
requisite machinery is not available, the gauge is useless should the rack and pinion
be broken or otherwise rendered inoperative.
According to my invention 1 disponse with the rack and pinion, and I substitute for
the said rack one or more arms or lovers, and I connect the said lever or levers with
the said arbor or spindle by means of one or more cords or ribbons of silk or other
suitable material wound partially around suitable drums or pulleys formed or fixed on
the said arbor or spindle, so that motion will be communicated from the bent tube,
diaphragm or the like to the index or pointer. I usually provide a spring or a small
weight for effecting the return movement of the index or pointer when the pressure is
reduced or removed. I can, however, provide for the return of the index or pointer
by the reaction of the bent tube or diaphragm, if desired.
In the accompanying drawings I have shown how my said invention may be
conveniently and advantageously carried into practice.
Figure 1 is a front elevation of a "Bourdon "
improvements applied thereto, the dial being removed.
Figure 2 is a horizontal section on the line
pressure-gauge having my present
Figure 1.
Figure 3 is a vertical section on the line y y, Figure 2.
Figures 4 and 5 are views similar to Figure 3 showing other forms or modifications
of uy invention.
Figure 6 is a front elevation of a diaphragm pressure-gauge having my present
improvements applied thereto, the l being removed.
Figure 7 is a section on the line ', Figure 6, and
Figure S is a vertical section on the line y y', Figure 7.
Liko letters indicate corresponding parts throughout the drawings.
A is the casing; B is a bracket firmly secured within the said casing for supporting
the measuring and indicating mechanism. C is the index or pointer and D is the
arbor or spindle carrying the same.
a is an arm or lever which is pivoted at a¹ to the bracket B and is coupled, by
means of a suitable adjustable connection, to the bent tube, or other actuating part of
the gauge. is a cord of silk or other suitable material which is attached at one end
to the arm or lever a, and is wound partially around, and attached at its other end to
a pulley c formed or fixed on the spindle D.
Referring to Figures 1. 2 and 3 E is the bent tube whereby the measurements aro

page_text: effected. The free end of this tube.is coupled, by means of an adjustable connection
similar to that described in the Specification of former Letters Patent granted to me
and dated 29th April 1890, No. 6573, with a rod a² forming an extension or tail-piece
of the arm or lever a.
d is a coiled or "hair" spring, secured at one end to the bracket B and at its other
end to the spindle D. This spring serves to return the said spindle and the index or
pointer towards the zero point when released by the backward movement of the
lever & due to any reduction of pressure.
It will be readily understood that, when the free end of the tube E is raised by the
pressure therein, the lever a will be turned about its pivot a' and will, through the
medium of the cord b, partially rotate the spindle D and index or pointer C, the said
cord being unwound from the said spindle and the spring d at the same time more or
less uncoiled. As soon as any diminution of pressure takes place in the tube E, the
reaction of the spring & will effect the return movement of the index or pointer C
through a corresponding angle.
It is evident that, with my improved connection between the index or pointer C and
the actuating portion of the gauge, there will be a very small amount of friction,
inasmuch as there are no heavy moving parts or gearing, and there is no slip of the
cord on the pulley c but only a simple unwinding of the said cord therefrom and
winding of the same thereon. The only practical resistanco to movement of the index
or pointer is due to the hair spring d, which may be a very weak spring, as it has only
to overcome the inertia of the said index or pointer and to effect the return movement
thereof. I sometimes substitute for the hair spring, a spiral spring d, Figure 4,
attached at one end to the cord and at its other end to an extension B of the
bracket B. Or I can employ any other suitable spring for effecting the return of tho
index or pointer or a weight suspended from a cord wound upon a drum or pulley
formed or fixed on the spindle D. Or I provide the lever a with an additional arm a³,
Figure 5, and employ two cords 'one of which extends from the arm a and is
wound partially around the pulley c, and the other of which extends from the arm a
and is wound partially around another pulley formed or fixed on the spindle D. Or
instead of two pulleys I can use a single pulley having two grooves. I find it
advantageous to provide one of the arms a or a³ with a spring a to which one of the
cords or bis attached and which can yield when necessary to prevent undue
stretching of the cords and consequent increase of friction.
In Figure 4 I have shown an improved form of the adjustable connecting device
described in my said former Specification. The rod or tail-piece a is screw-threaded
and a nut e is fitted thereon and is coupled by the link to the bent tubo or other
actuating part of the gauge. A lock-nut el is screwed upon the rod a to retain the
nute in position thereon. The link is connected with the nut e by a screw so that
it can be readily disconnected to permit the turning of the said nut upon the rod a² to
effect the desired adjustment.
In some instances I substitute for the nut e a sliding piece which is moved or
adjusted and held in position upon the rod or tail-piece a² by means of a back-nut and
lock-nut screwed upon the said rod or tail-piece one on each side of the said sliding
piece.
In the modification of my invention illustrated in Figures 6, 7 and 8 the extension
or tail-piece a³ of the lever a is coupled by an adjustable connection with the
diaphragm of the gauge so that any movement of the said diaphragm will, through
the medium of the lever a and cord b produce a corresponding movement of the index
or pointer C.
It is obvious that instead of the silk cord, I can employ a thin metal ribbon or a
cord or ribbon of any other suitable material for the purpose above specified.
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
claim -
First. A pressure or vacuum gauge wherein the required movement is transmitted

page_text: to the index or pointer from the bent tube or other actuating part of the gauge,
through the medium of one or more cords or ribbons wound around or partially
around the arbor or spindle of the said index or pointer.
Second. The combination of an arm or lever coupled by means of an adjustable
connection with the bent tube or other actuating part of a gauge, a cord or ribbon of
silk, or other suitable material connecting the said arm or lever with the arbor or
spindle of the index or pointer, and a spring or weight for effecting the return
movement of the said index or pointer, substantially as, and for the purposes, set
forth.
Third. An adjustable connecting device of the kind described in my said former
Specification constructed with a screw-threaded rod or tail-piece (a) and one or more
nuts adjustable theroon, substantially as described with reference to Figure 4 of the
drawings, for the purpose above specified.
Fourth. The modification of my invention wherein I employ two cords wound
partially around the pulley or pulleys in opposite directions, substantially as described
with reference to Figure 5 of the drawings for the purposes above specified.
Dated this 6th day of August 1890
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.