IMPROVEMENTS IN KEY GUARDS, APPLICABLE ALSO TO THE SHANKS OF KNOB LATCHES
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at
the Office of the Commissioners of Patents, with his Petition, on
the 15th September 1869.-A communication from abroad by
Max Emanuel Berolzheimer, of the City, County, and State of
New York, United States of America.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN KEY GUARDS, APPLICABLE ALSO
TO THE SHANKS OF KNOB LATCHES," to be as follows:-
This Invention relates to improvements in locking or securing the
keys of locks against the efforts of burglars to enter by turning the keys
while on the outside of the door by means of nippers thrust in the
keyhole and fastening on the shanks of the keys, or by any other means.
The said improvements are also applicable to the shanks of knob
latches.
The said improvements consist in the application to the front plate of
the lock, or to a front plate attached to the door, or in the application
to the door without the plate at the inside of the room of guard latches
pivoted thereto and provided with notches, recesses, or slots (either one

page_text: or more) of any angular form, and arranged to swing upon the shanks
of the keys immediately in front of the said face plates, where the said
shanks are shaped in cross section to correspond with the notches or
slots so as to be taken into them, and be by them by reason of the said
angular form prevented from turning while the said guards are so resting
upon the said shanks. In the case of the guards having two or more
slots or notches divided by a projection between them the key or knob
shanks will have holes to receive the said projections, the sides being
made plane to correspond with the sides of the said notches.
The Invention also consists in an arrangement of sliding notched or
recessed guards adapted to receive the plane sided shanks of the keys
or knobs and to hold them against turning.
The Invention also consists of an arrangement whereby the key and
knob shank guards may serve also as key hole guards for covering the
key holes to prevent the insertion of wires for throwing the guards off
the key or knob shanks, the said guards being made broad enough to
cover the key holes and to be moved over them when engaging the
shanks; and to prevent the guards from being forced away from over
the key holes they are provided with catches which swing through
slots in the lock plate and catch behind them at the edges of the said
slots to hold them. In all cases the shanks of the keys and knobs are
arranged for the reception of the guards when the bolts or latches
are shot, and the bits of the keys are turned away from the holes to
prevent the same from being thrown back in any way.
In the different views of the accompanying Drawings I have repre-
sented several modes of carrying out the Invention.
Figure 1 is a face view of the inside of the lock or lock plate (or
may be a plate on the door, the lock being enclosed) showing a
rectangular section A of the key shank, and a pivoted key guard B with
two notches or recesses, and a central projection C passing through
a hole in the shank of the key. Also a pivoted catch G for the guard
to prevent throwing off the guard by wires from the outside thrust
through the key hole.
Figure 2 represents a side view of the key showing the plane side,
against which one wall of the slotted key guard bears to prevent
turning, the opposite side bearing similarly against the other wall of
the slot.

page_text: Figure 3 represents a plan view of the key showing the grooves a
in each side for the reception of the walls of the slot or notch in
the guard, also the hole 6 in the same for the reception of the pro-
jection C.
Figure 4 represents a side elevation of a guard B, with only one notch
and cross section of the shank A of rectangular form fitted to the same.
Figure 5 represents a plan view of the shank fitted to the guard, as
represented in Figure 4, with grooves a in the sides for the reception
of the walls of the guard.
Figure 6 represents a side view of the guard and cross section of the
shank when arranged without the grooves a in the sides for the walls
of the slot of the shank.
Figure 7 represents a similar view when the shank is rhomboidal in
cross section.
Figure 8 represents a triangular shaped shank and similarly shaped
notch or recess with a central projection taking into a hole in the
shank.
Figure 9 represents a sliding guard D provided with guides E forming
a dovetailed, or it may be, any other formed groove which will hold it
in place. This guard has a recess or notch in the end, which receives
the flat sided shank F into it when moved towards the said shank, as
represented in the Drawing, the said slotted end engaging at the same
time under a cap D'.
Figure 10 represents the guard B arranged to cover the key hole when
engaged with the shank, for which purpose it is caused to swing against
the under side of the key or knob shank, when the shank of the key
projects from the top of the key hole in the usual way, but if the
elongated key holes are arranged in any other direction from the part
through which the said shanks project the guards will be arranged
accordingly. To hold these guards up to the key shanks when arranged
under them, and also to prevent them from being forced away by pressure
from without, I provide catches G for engaging through slots H behind
the lock plates at the edges of the slots. These catches are pivoted to
the guards B at K, and may be turned on the pivots to be passed through
the slots H when the guards are turned into the position for engaging
the key shanks. These guards B are disengaged from the shanks and
turned around on their pivots out of the way when the lock bolts are

page_text: to be thrown back for opening the doors. These catches G may be
applied to all the guards B, whether engaging the shanks from above or
below, and they may also be applied to the sliding guards D, either
in connection with the caps D' or not, and connected to either end of
the said slides.
Figure 11 is a section through the lock plate showing the transverse
arrangement of Figure 10. When the guards B are arranged to serve
as key hole guards also the ordinary key hole guards may be dispensed
with. These said key guards are equally applicable also to the knob
latch shanks under all the modifications herein described, as represented
in Figure 1, where the guard G is shown in dotted lines as engaging
the said shank. The said guard G for the knob shank may, if preferred;
be pivoted on the same pin that serves as the pivot of B.