IMPROVEMENTS IN BURGLAR ALARMS
Year: 1884

page_text: I, HERBERT JOHN ALLISON, of the firm of Allison Brothers, Patent Agents, of
52 Chancery Lane, London, in the County of Middlesex, do hereby declare the
nature of said Invention for "IMPROVEMENTS IN BURGLAR ALARMS," 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 burglar alarms designed for application to doors, etc.,
and constructed to automatically release or operate an alarm upon niovement of
the door, or other object upon an attempt to open the same.
The object of my Invention is to provide a simple, cheap and effective device for
this purpose, and among other things to furnish a device applicable to a window in
such a way that both sashes may be left open, but that an attempt to move either
sash after the alarm is set, will result in the release of the alarm mechanism.
To these ends my Invention consists in the combination with a freely-movable
catch or catch bar, adapted to rock on two points or fulcrums removed from one
another, of an aların mechanism whose detent is connected with the bar at a point
between the two fulcrums, so that by the rocking of the bar on either fulcrum the
detent will be operated and the alarm caused to sound.
My Invention consists also in the combination with the upper and lower sashes
in a window of a catch bar or bolt supported on one sash and engaging with the
other, and an aların mechanism whose detent is connected with the catch bar so
that upon the movement of either sash up or down, the alarm will be released.
My Invention consists also of certain details of construction and combinations of
parts that will be specified in the claims, hereto annexed.
In the accompanying Drawings,
Fig. 1, is an elevation of a mechanism embodying my Invention,
Fig. 2, is a plan of the same, a portion of the alarm bell.being broken away in
order to better show the parts,
Fig. 3, is a plan, with the top plate of the alarm mechanism removed,
Fig. 4, shows in vertical cross section a portion of a window with the alarm

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A. indicates the base plate upon which the parts are mounted and which plate is
adapted for attachment to a door, window, or similar object to be protected.
B. indicates a catch bar or bolt adapted to slide on the plate and guided by a
pin L. rising from. the plate through an elongated slot in the bar.
1
A spring K. fixed on the plate and bearing at its ends against the edge of the
bar, serves by entering notches on the edge thereof to hold said bar with its end
projected as shown to enter a suitable socket, or retracted out of engagement with
said socket.
Resting on the bar B. is a movable plate G. supported by or engaging with the
bar at the intermediate portion thereof in such way that if the bar be made to rock
at one end or the other upon the edge of plate A. said plate G. will be raised and
thus caused to release the detent of an alarm mechanism of any suitable kind.
As will be observed the catch bar B. when engaging with a socket will be caused
to rock and raise the plate G. by a movement in either direction, of the support for
said bar or of the socket with which its projecting end engages.
The plate G. is provided as shown with an upwardly extending portion b. from
which extends laterally a plate or arm D. that engages with a detent E. for an
alarm mechanism.
The plate G. b. is guided by sleeves C. connected to the portion b. thereof and
encompassing posts connecting plate A. and a plate M. in which two latter the
arbors of the alarm train of wheels are mounted.
The detent E. is here shown as consisting of a pin which is guided in plate M.
and is held down by a suitable spring as N. so that its lower end tends to enter an
opening F. in a wheel G. for the alarm mechanism, thus locking the latter from
movement.
The arm D. engages with an enlargement on the pin E. and when, the bar B. is
tilted, lifts the pin out of the opening F. thus allowing the alarm mechanism to
rotate so as to sound the alarm.
The spring N. causes the pin to re-engage with the wheel if the pressure
tending to tilt the bar bas been removed.
The alarm movement is of any ordinary or proper construction.
That which I prefer to employ for, the sake of simplicity consists of the main
spring wheel G. the main spring for which is wound up by the handle H. upon
the main spring arbor, and an escapement wheel O. on an arbor carrying a pinion
that engages with the wheel G. The escapement operates the bell hammer in the
usual way. I do not however limit myself to the form or kind of alarm movement,
nor to the particular kind of detent released by the tilting of the bar B. as these
may be varied in many ways.
Fig. 4, shows the application of the alarm to a window.
The plate A. is fastened to the meeting rail of the lower sash, while the end of
the catch bar B. may engage at its projecting end with a socket in the upper sash,
one or more of such sockets being provided so that the upper and lower sashes
may be left open to any desired extent and the alarm will be released upon the
application of an upward or a downward pressure to either sasli.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is:
1 The combination with the freely movable catch bar, adapted to rock upon
either of two fulcrums on the same side of the bar, of an alarm mechanism and
detent therefor, said detent being connected with the bar between its two fulcrums
so that a movement of the bar on either fulcrum will release the alarm.
2nd The combination with the upper and lower sashes in a window,. of the
catch bar mounted on one sash and engaging with the other, and an alarm whose
detent is controlled by said bar, all arranged as setforth so that the alarm. will be
released by a movement of either sash up or down.
3rd The combination of base plate A. the bar B. sliding thereon, the plate G. or
other suitable device adapted to move freely in a plane at right angles to the

page_text: sliding movement of the bar, and resting on said bar over the plate, so as to be
moved in the same direction by the tilting of the bar B. in either direction, and
a detent for an alarm mechanism released by movement of the plate G. and for the
purpose described.
4th The combination of the sliding bar B. the transversely movable plate G.
the detent pin E. and the perforated wheel G³. of an alarm movement.
5th The combination of the catch bar B. pin L. plate or support G. for the alarm
detent and wheel G. controlled by said detent as setforth.
6th The combination of the plate A. spring K. notched sliding bar B. adapted
to work freely in a transverse direction on a pin L. and an alarm controlled by a
connection with the bar B. at a portion thereof which moves upon pin L. when
the projecting end of the bar rises or falls above or below its normal plane.
7th The combination with the sliding bar, working freely in a plane at right
angles to its sliding movement, so that it may rock on either of two pivotal points
on the same side of the bar, and an alarm controlled by connection with the bar
at a portion thereof which moves in the same direction, irrespective of the
direction in which its projecting end moves when the bar rocks.