IMPROVEMENTS IN LOCKS AND LATCHES
Year: 1872

page_text: LETTERS PATENT to Theodore Kromer, of Neustadt, in the Grand
Duchy of Baden, but at present of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for the Invention of
Sealed the 18th March 1873, and dated the 5th October 1872.
PROVISIONAL SPECIFICATION left by the said Theodore Kromer at
the Office of the Commissioners of Patents, with his Petition,
on the 5th October 1872.
I, THEODORE KROMER, of Neustadt, in the Grand Duchy of Baden,
but at present at No. 20, Southampton Buildings, Chancery Lane, in
the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN LOCKS AND LATCHES," to be as follows:-
My improvements have reference to the construction of locks and
latches for which Letters Patent were granted to C. D. Abel, bearing
date the 28th November 1870, No. 3115, being a communication to him
from me.

page_text: My improvements consist, firstly, in making the pins of the key to
such locks with conical or tapering recesses at their ends, and in making
the front ends of the grooved sliding pins of the lock conical or tapering,
so that on inserting the key into the lock the pins of the latter enter
with their conical ends into the conical recesses in the pins of the key.
The conical recess of each pin of the key is made of a different depth and
taper, so that the ends of the sliding pins (which are all made with the
same amount of taper for one and the same lock) enter the recesses to
varying depths, by which means the construction of a false key and
picking of the lock thereby is rendered very difficult.
Another improvement consists in providing in the body of the lock
beneath each sliding pin a recess containing a pin, which is pressed
upwards by a spring so as to catch into the false and real grooves or
notches of the sliding pins. By this means the sliding pins are made to
work in their recesses with a considerable amount of friction, whereby
it is rendered very difficult, if not impossible, to feel when the latch falls
into the real notches of the sliding pins in attempting to pick the lock.
Another improvement has reference to the construction of the sliding
bolt and its mode of operating in combination with the hinged latch of
the lock. The latch is constructed without the projections described in
the Specification to the before-mentioned Patent, it having simply an
inclined front face. The sliding bolt has at its tail end a spring stud,
which, when the latch is in its raised or locked position projects in front
of the inclined face of the latch, and thus prevents the bolt from being
slid back from its locked position. On the latch being caused to fall
into the unlocked position its upper face is below the spring stud, and
the sliding bolt can consequently be shot backwards. The sliding bolt
has furthermore an inclined projection on its under face, which, on the
backward motion of the bolt presses against the inclined end surface of
the latch, and thus raises the same up out of the notches of the sliding
pins, so as to allow these to spring forward into the locked position. As
the latch is thus raised up the before-mentioned spring stud is pressed
upward thereby, and on the sliding bolt being again slid forward into the
locked position the spring stud after passing the end of the latch again
springs down in front of the same, thus locking the bolt as first
described.
In order to keep the latch raised out of the notches of the sliding pins
Conilitate the infundation of th

page_text: key for unlocking, the spring stud of the sliding bolt is by preference
formed with an inclined face, which is made to press against the inclined
face of the latch by means of a spring acting on the sliding bolt.
Another improvement consists in adapting the before described
improved lock or latch to act as a combination lock or latch, opening
without the use of a key. For this purpose the front ends of the sliding
pins are extended so as to project through the holes in the case, and the
projecting ends are formed with small knobs, whereby the sliding pins
can be moved outwards or inwards by hand. As the before-mentioned
spring pins beneath the sliding pins will by springing into the notches
of the latter retain them in any position into which they are slid by
hand, it will be seen that the operator, knowing the position of the real
notch relative to the false notches in each of the sliding pins, can readily
bring each of these successively with their real notches in correct position
for unlocking by counting the number of times that the spring pins
catch into the notches of the sliding pins while he is drawing these out;
and by occasionally changing the positions of the several silding pins
(the real notches of which have different positions in each pin) the
picking of the lock will be rendered very difficult.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Theodore Kromer in the Great Seal Patent
Office on the 25th March 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, THEODORE
KROMER, of Neustadt, in the Grand Duchy of Baden, but at present of
No. 20, Southampton Buildings, Chancery Lane, in the County of Mid-
dlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of October, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Theodore Kromer, Her special
license that I, the said Theodore Kromer, my executors, adminis-
trators, and assigns, or such others as I, the said Theodore Kromer,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during

page_text: the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN LOCKS AND LATCHES," upon the condition (amongst others) that
I, the said Theodore Kromer, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the
suid Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Theodore Kromer, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, reference being had to the accom
panying Sheet of Drawings, and to the figures and letters marked
thereon, that is to say :-
My improvements have reference to the construction of locks and
latches for which Letters Patent were granted to C. D. Abel, bearing date
the 28th November 1870, No. 3115, being a communication to him
from me.
My present improvement on such locks is represented on the accom-
panying Drawings, in which Fig. 1 shews a front view of the lock with
the cover plate removed, shewing the sliding bolt in the unlocked
position; Fig. 2 shews the sliding bolt and latch in the locked position;
Fig. 3 shews a section on line X, X, Fig. 1; Fig. 4 shews a section on
line Y, Y, Fig. 1; Figs. 5 and 6 shew respectively a plan and a section
of the key; and Fig. 7 is a similar section to Fig. 4, shewing a modified
construction of the notched or grooved sliding pins to adapt the lock for
use as a combination lock without a key.
One part of my Invention has reference to the construction of the
notched sliding pins and key.
The sliding pins a (Figs. 3 and 4) are formed with a tapering or conical
projection a' on their front ends, which when the pins are in the forward
or locked position are situated in holes b' of small diameter formed in
the projection of the casing b, as shown at Fig. 3. The pins e of
the key c (Figs. 5 and 6) are formed with tapering or conical recesses at

page_text: their front ends, as shewn, which, when the key is inserted into the lock
for pushing back the sliding pins, fit on to the tapering ends a' of the
latter. The recess of each key pin is made of a different depth and taper,
so that the ends of the sliding pins (which are all made of the same
length and taper for one lock) enter the recesses of their respective key
pins to varying depths. By this arrangement it is rendered very difficult
to ascertain the distance to which the sliding pins have to be pushed in
order to bring all the deep or real grooves or notches thereof into position
for unlocking, and it is also rendered very difficult to take a proper
impression of the key for the purpose of making a false key, and thus
the probability of the lock being picked is rendered very remote.
Another part of my Invention consists in providing in the casing of
the lock below each sliding pin a pin d (Fig. 4) fitting into a recess in
the casing, and pressed upward by a spring d' so as to catch with its
upper
end into the false or real grooves or notches of the sliding pin a.
By the action of these spring pins in catching into and pressing against
each groove of the sliding pin as this is slid back for the purpose of
bringing the real groove into position for unlocking it is rendered very
difficult, if not impossible, to feel when the hinged latch e falls with its
knife edge e¹ into the real groove of the sliding pin in attempting to pick
the lock.
. Another part of my Invention has reference to the sliding bolt f
(Figs. 1 and 2) of the lock, and its mode of operating in combination
with the hinged latch e. The latch, instead of having the projections
upon its outer end, described in my before-mentioned Patent, is simply
provided with an inclined face e². The sliding bolt has on its lower
face a spring stud, which, when the latch e is in the raised or locked
position, and the bolt fis also in the locked position as at Fig. 2, projects
in front of the inclined face of the latch, and thus prevents the bolt f
from being slid back from its locked position. On the latch e falling
into the unlocked position (shewn in dotted lines at Fig. 2) by the
introduction of the key, its upper face is just below the spring stud f',
and the sliding bolt can consequently be slid back into the unlocked
position by means of the lever and handle at g. The sliding bolt fis
furthermore provided with a stud or projection f, which on the back-
ward motion of the bolt presses against the inclined end face e of the
latch, and thus raises the same up so as to allow the sliding pins a to
spring forward into the locked position. As the latch is thus raised up

page_text: the spring stud ƒ¹ of the bolt ƒ is pressed upward thereby, as shewn in
Fig. 1, and on the bolt being again slid forward into the locking posi-
tion the spring stud after passing the end of the latch e again springs
down in front of the same, thus locking the bolt as before described.
In order to keep the knife edge e' of the latch e raised out of the false
notches of the sliding pins when in the locked position, so as to facilitate
the pushing back of the sliding pins by means of the key for unlocking,
the spring stud is by preference formed with an inclined face, as shewn,
which is made to press against the inclined face of the latch e, so as
to raise it by means of a spring h fixed to the casing of the lock, which
tends to press the bolt backwards when in the locked position, as shown
at Fig. 2. In this case, after the introduction of the key for unlocking
the bolt must first be pressed slightly forward against the action of the
spring by means of the handle at g, in order to free the latch e from
the pressure of the stud, whereupon the latch will fall into the unlocked
position, and the bolt can then be slid back.
Another part of my Invention consists in adapting the above described
lock to act as a combination lock, opening without the use of a key.
For this purpose the springs to the grooved sliding pins a are dispensed
with, and the front ends of the sliding pins are extended, so as to project
through the holes b' of the casing, as shewn at a³, Fig. 7, and the pro-
jecting ends are provided with knobs whereby the pins a can be slid
backwards and forwards by hand. As the spring pins d by springing
into the grooves or notches of the sliding pins a will act as ratchets in
retaining them in any position into which they are moved by hand, it
will be seen that the operator knowing the position of the real groove
or notch relative to the false grooves in each of the pins a can readily
bring each of the latter successively with their real grooves in correct
position for the knife edge of the latch e to enter them for unlocking
by counting the number of times that the spring pin catches into the
grooves while he is moving the sliding pins.
The relative positions of the sliding pins a (the real grooves or notches
of which have a different position in each pin, as described in my before
mentioned Patent) may be changed at will by removing the back plate i
of the casing, so that a number of different combinations, depending on
the number of sliding pins in the lock may be obtained, whereby the
picking of the lock will be rendered as difficult as in any other known
construction of combination locks.

page_text: Having thus described the nature of my Invention, and in what
manner the same is to be performed, I claim,―
First. The notched or grooved sliding pins à with tapering or conical
ends a operating in combination with the key c with pins c¹, having
conical or tapering recesses, substantially as and for the purposes herein-
before described.
Second. The spring pins d operating in combination with the sliding
pins a, substantially as and for the purposes herein-before described.
Third. The sliding bolt f, with spring stud f', and stud or projection f³,
operating in combination with the hinged latch e with inclined face e³,
substantially as and for the purposes herein-before described.
h
Fourth. The spring operating in combination with the sliding bolt f,
spring stud f, and hinged latch e, substantially as and for the purposes
herein-before described.
Fifth. The notched or grooved sliding pins a, with projecting ends a³
passing through the casing of the lock, operating in combination with
the spring pins & so as to constitute a combination lock without a key,
substantially as herein-before described with reference to Fig. 7 of the
Drawings.
In witness whereof, I, the said Theodore Kromer, have hereunto
set my hand and seal, this Seventeenth day of March, in the year
of our Lord One thousand eight hundred and seventy-three.
THEODORE KROMER. (L.8.)