Improvements in Automatic Alarm-locks.
Year: 1890

page_text: Date of Application, 21st July, 1890-Accepted, 10th Jan., 1891
COMPLETE SPECIFICATION.
Improvements in Automatic Alarm-locks.
I, EDMUND BARDTHOLDT, Engineer of Würzburg, in the Kingdom of Bavaria and
German Empire, 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 :—
This invention relates to a lock which operates an alarm at the slightest attempt to
open it unauthorisedly and has the advantage as compared with other similar locks
that it cannot be injured by any such attempt as it operates the alarm signal at the
first turning of the key whether the same fits or not.
The disadvantages in similar locks hitherto known are that many parts are broken
in a forcible attempt to open the lock thus preventing even the rightful person
opening the same, at the same time such breakage causes expensive repairs.
In order that my invention may be the better understood I now proceed to describe
the same in relation to the drawings hereunto annexed and to the figures marked
thereon.
Figures 1 to 4 show the lock in various positions.
Figure 5 shows diagrammatically the arrangement of the electrical circuits for
several such locks.
In the box or casing of the lock is situated a bolt 1 and a cog wheel 2, operated by
the movement of a key inserted through the lower or upper key-holes respectively.
On this cog-wheel 2 is raised the boss 3 with a recess 4. The bolt moves through
the front of the casing and is guided by the pin 5. It carries the tooth 8 pivotted*
at 7. The normal position of this tooth 8 is secured by the pin 9 and the spring 10.
The upper side of the bolt has a recess 11 into which enters the sliding stop 13.
To the latter is connected a jointed lever 14 carrying a counter-weight 16 which is
pivotted on the pin 15 of the bolt 1. This counter-weight endeavours to lift the
sliding stop 13 out of the recess 11 and in a corresponding position to press it into
the recess 4 of the boss 3.
On the pin 17 is situated a spring 18 which by means of the weight 19 attached to
it, presses on the pin 20 situated on the sliding stop 13.
If as soon as the lock is locked and secured by the rotation of the cog-wheel 2
with the boss 3 (see Figure 1) an attempt is made to open the lock through the
lower key-hole, the bit of the key lifts the spring 18 and the weight 19, but the
sliding stop 13 remains in its position in the recess 11 of the bolt and keeps
the same locked, as the cog wheel 2 with the boss 3 has not been put in the right
position, that is to say, the recess 4 of the boss 3 has not been placed over the
sliding stop 13.
When the key is turned further it operates the tooth 8 (Figure 3) and thus
rotates the contact lever 6 pivotted on 21 so as to break the circuit of the battery
influenced by this contact lever whereby the alarmı bell is rung.
If however through the upper key-hole, the recess 4 of the boss has been turned so
far as to be above the sliding stop 13, the bit of the key, when the lock is being
opened through the lower key-hole lifts the weight 19 by means of the spring 18 and
releases the sliding stop 13 which is lifted by means of the counter-weight 16
connected to the jointed lever 14 into the recess 4 of the boss 3 (see Figure 4).
When the counter-weight 16 is descending, a projection of the lever 14 is pushed
behind the moveable tooth 8 which is therefore secured in its position so that when
the key is turned further the bolt is engaged and joins the movement. The lever of
the alarm arrangement therefore remains in its original position as to tooth 8 and
does not make any rotary movement. The alarm signal is thus not operated.
On the axis of the cog-wheel may be arranged a disc with numbers on it,

page_text: which being visible from the outside indicates to the proper person by means of a
number the position of the cog-wheel 2, which is required to allow of the lock being
opened. This disk is adjustable with regard to the cog-wheel 2 so that the numbers
may be changed as desired.
It will thus be seen that all the locks in a house may be alike but can only be
opened by the person knowing the corresponding numbers.
The control over all doors of a building may be effected from a central position,
say from the room of the porter or other officer. In such room may be situated an
indicating plate with as many numbers as there are locks, or doors to he controlled.
The electric arrangements serving this purpose are shown in Figure 5; where the
numbers 1, 2, 3, 4 (at the left hand side of the figure) represent different doors cach
fitted with an alarm lock, connected by means of an electrical battery and conducting
wires with the corresponding numbers of an indicating plate, and alarm bell arrange-
ment, in the porter's room represented at the right of the Fig. 5.
If an unauthorised person attempts to open any of the doors, the alarm bell is
operated in the porter's room, the corresponding number to the door, which is being
tampered with, appears on the indicating plate, and the porter knows at once where
to go to.
The use of this invention will be easily understood from the above, but it may be
mentioned that the lock may be operated from the inside and outside with equal oase
and that the electrical control may be suspended from the inside.
This invention may also be used if desired for call signals, by connecting the
electrical circuit in the different rooms with an ordinary push contact which also
operates the alarm bell and indicating plate in the porter's room.
Instead of a rest battery (that is a battery where the electrical circuit is normally
closed and the alarm bell only operates when the circuit is interrupted) an ordinary
battery may be used, that is, a battery whereby the alarm bell is operated when the
electrical circuit is closed; in this case the construction is altered so that if an
unauthorised person operates the lock, the contact lever receives such a rotation as to
close the circuit and operate the alarm signal ;-this arrangement is not shown in the
drawing.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed I declare that what
claim is :-
1st. An automatic electrical alarm lock in which a tooth 8 is moved by the key,
such footh 8 operating by a lever 6 the alarm apparatus the bolt retaining its position,
unless prior to the operation of the lock by the key, the sliding-stop 13 is brought
into a corresponding position of a recess 4 on a cog-wheel 2, which will then permit
the operation of the lock substantially as and for the purposes described.
2nd. The construction and arrangement of an automatic alarm lock substantially as
and for the purposes described.
Dated this 21st day of July 1800.
FELL & WILDING,
1, Queen Victoria Street, Agents for the Applicant.