An Electric Alarm for Pressure Gauges.
Year: 1894

page_text: Date of Application (in United Kingdom), 24th Apr., 1894
Complete Specification Left, 24th Apr., 1894-Accepted, 14th July, 1894
COMPLETE
SPECIFICATION.
An Electric Alarm for Pressure Gauges.
I, William HENRY BRADT, of Troy, New York, United States of America'
residing at No. 415 Tenth Street, 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 :-
Fig. 1 of the drawings is a plan view of the face of a common form of pressure-
gauge provided with my improvements a portion of the case and dial being broken
away to show the testing apparatus.
Fig. 2 is a cross-section of the same taken on the broken line 2-2, in Fig. 1.
Fig. 3 is a view in elevation of the testing-finger removed.
Referring to the drawings, A represents a well-known form of pressure-gauge
having an index A¹ operated by a Bourdon-tube A' and intermediate links in the
usual manner, a portion of the tube and one of the links A3 being shown in Fig. 1.
B is an electric battery which may be of any known form; and C is an electro-
magnetic signal bell located in the battery-circuit.
A line-wire B' connects one pole of the battery with the gauge-case at B', and
with the case and index-pinion A forms a continuous connection between the
battery and the index, the index forming the movable electrode of the circuit-
closing mechanism.
The other electrode is formed by the contact-hand D insulated from the index
and having its end offset to form a contact-finger D' in the path of the index.
The contact-hand is pivoted concentrically with the index, upon a sleeve D'
inserted in the central aperture in the dial D³, surrounding the index-pinion.
The sleeve is provided on its inner end with a shoulder D' abutting on the under
side of the dial, and its outer end is screw-threaded to receive and fit the similarly
threaded clamping-nut D by means of which the contact-hand is securely clamped
to the dial.
The dial, with its contact-hand secured thereto, is insulated from the case of the
gauge and the index by means of the washers D* of rubber or other insulating
material between which the dial is clamped by the screws S which secure the dial
to the case.
A binding-post E is secured in an aperture in the case-wall by the nut E¹ on its
inner end, the post and uut being insulated from the case by the insulating
sleeve E' and washer E'.
The inner end of the post is connected by the conductor E with the dial, and
the outer end by the line-wire B' with the remaining pole of the battery, whereby
the contact-hand D is connected through the dial and intervening conductors with
such pole of the battery, and forms the fixed electrode of the circuit-closing
mechanism.
When the gauge-pressure has caused the index-operating mechanism to move the

page_text: index into engagement with the contact-hand, the circuit will be closed by the
contact of the electrodes, and the alarm signal will be rung.
By loosening the clamping-nut D the contact-hand may be oscillated on the
sleeve D' to assume any radial position on the dial, and may be locked in such
position by the clamping-nut.
By thus varying the position of the contact-hand, the alarm will be given when
the pressure reaches any predetermined degree.
By employing two of such contact-hands arranged with their contact-fingers on
opposite sides of the index, I can combine in the same gauge both high-pressure and
low-pressure alarms.
Electrical pressure-alarms as heretofore constructed have been regarded with
distrust and suspicion by many on account of their uncertainty of operation at
critical times.
This is frequently caused by the failure of the battery current and by the
electrodes becoming corroded or coated with oil, dust or other matter which
prevents the contact of the electrodes.
The latter is frequently the case when the gauge-pressure reaches its alarm-limit
at infrequent intervals.
I have shown a device which can be easily applied to an alarm-gauge, by means
of which the electrodes can be brought into contact at frequent intervals to close
the circuit for testing the battery, and remove and prevent any accumulation of
dust or other substance upon the electrodes.
A finger F is loosely inserted in an aperture in the case-wall of the gauge, and
secured therein by the shoulder or flange F¹ on the finger which bears upon the
outer side of the wall, and the pin F passed through an aperture in the finger on
the inner side of the case, as shown in the sectional portion of Fig. 1.
The inner end of the finger projects interiorly of the case transversely of the end
of the Bourdon tube, and the outer end of the finger is provided with an operating
handle F projecting exteriorly of the case.
The finger fitting loosely in the case-wall aperture, may be oscillated by means
of the handle F' to act as a lever and force its inner end against the tube, moving
the tube and other index-operating mechanism of the gauge and producing the
same results upon such mechanism and the index as when the tube is subjected to
internal pressure.
A sufficient movement of the finger will thus cause the index to indicate the
alarm-degree of pressure and thereby cause a contact of the electrodes, whereupon
the alarm will be sounded if the apparatus is in working order.
The handle F being accessible from without the gauge-case, the testing operation
can be repeated very frequently without inconvenience.
Besides testing the battery-current, the frequent contact of the electrodes tends
to prevent accumulations of dust and other substances thereon, keeping their contact
surfaces clean and in an operative condition.
The form of the testing-finger may be varied as desired to adapt it to different
constructions of gauge, it only being necessary for the finger to be engageable with
the index-operating mechanism within the gauge-case and accessible from without
such case.
Having now particularly described and ascertained the nature of my said
invention and in what mauner the same is to be performed, I declare that what
1 claim is:
1. In a circuit-closing device for gauges, the combination with the gauge-case
and dial insulated therefrom, of the gauge-index in electrical connection with the
case, a contact-hand pivoted concentrically with the index in electrical connection
with the dial and offset into the path of the index, a clamp for locking the contact-
hand in adjusted positions, and means for connecting the case and dial with the
respective poles of an electric battery having an electro-magnetic alarm signal ·
in circuit, substantially as described.

page_text: 2. The combination with an electric battery having an electro-magnetic alarm-
signal in circuit, of a pressure-gauge having its index electrically connected
with one pole of the battery, a sleeve inserted in the central aperture in the
dial of the gauge having one end screw-threaded and having a shoulder on the
other end abutting on the dial, a contact-hand pivoted upon the sleeve and.
insulated from the index, an electrical connection between the other pole of the
battery and the contact-hand, and a clamping-nut on the threaded end of the sleeve,.
substantially as described.
3. The combination with a gauge having electrodes arranged to be brought into
contact by the movement of the index-operating mechanism, of a lever fulcrumed
upon the case-wall of the gauge and engageable with the index-operating mechanism.
interiorly of the case, and an operating handle on the lever projecting exteriorly.
of the case, substantially as described.
Dated uns 200 uay or smaren 10
WILLIAM H. BRADT.
H. D. Fitzpatrick,
70, Wellington Street, Glasgow, Agent..
WILLIAM H. BRADT.
H. D. Fitzpatrick,
70, Wellington Street, Glasgow, Agent..