CERTAIN IMPROVEMENTS IN LOCKS
Year: 1851

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MICHAEL
LEOPOLD PARNELL, of 32, Little Queen Street, Holborn, in the County of
Middlesex, Ironmonger, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of
Great Britain and Ireland, bearing date at Westminster, the Sixth day of
November, One thousand eight hundred and fifty-one, in the fifteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Michael Leopold Parnell, my exors, adñiors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Michael Leopold
Parnell, my exors, adñiors, and assigns, or such others as I, the said Michael
Leopold Parnell, my exors, adññors, or assigns, should at any time agree with,
and no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "CERTAIN IMPROVEMENTS IN LOCKS;" in which said Letters Patent is contained
a proviso that I, the said Michael Leopold Parnell, shall cause a particular
description of the nature of my said Invention, and in what manner the
same is to be performed, by an instrument in writing under my hand and
seal, to be inrolled in Her Majesty's Iligh Court of Chancery within six

page_text: calendar months next and immediately after the date of the said in part recited
Letters Patent, as in and by the same, reference being thereunto had, will
more fully and at large appear...
NOW KNOW YE, that in compliance with the said proviso, I, the said
Michael Leopold Parnell, have ascertained and set forth the nature of my
said Invention, and the manner of carrying the same into effect, in and by
the following description thereof, reference being had to the Drawings here-
unto annexed, and to the figures and letters marked thereon, observing
that the same letters denote the same parts in all the Figures wherever they
occur.
My Invention refers to that description of locks known as "tumbler" locks,
and consists,
First, of certain arrangements of parts for preventing access to the tumblers
by means of pick locks or false keys.
Secondly, of an improved construction of expanding key; and,
Lastly, of an additional security in connection with the tumblers and bolt.
Figures 1 and 2 represent an "inner" lock with the front plate and what I
denominate the "revolving cap" removed, in order to shew more clearly some
of the parts; and Figure 3 shows the lock with the revolving cap in its place.
The Figures represent the bolt of the lock in three different positions. In
Figure 1 the bolt is fully shot, and the key is in the act of pressing back one
of the "detectors." In Figure 2 the bolt is shot half back, and in Figure 3
the bolt is wholly shot back, and the revolving cap is in the position it would
occupy when the key has been withdrawn. A is the case of the lock, B the
bolt, and the bolt stop, and C the tumblers, all of which parts are of the
ordinary construction. D is the key (shewn likewise in elevation in its con-
tracted state in Figure 4, and in its expanded state Figure 5 (with a portion
of it removed to shew the construction of the bit). It has a moveable bit d
inserted between two cheek pieces d², which project from the pipe of the key,
and the bit is retained between them by a pin 3 passing through the check
pieces and through a slot d' in the bit. E is a cam (shewn detached in
Figure 6) attached to the bottom of the case and having an aperture e' to
admit the pipe of the key; and a portion of the lower part of the bit adjoining
the pipe is cut away (as shewn at d³) to allow the bit to descend over the
narrow part of the cam to the bottom of the case. As the key is turned
round the sliding bit is shot during a portion of the revolution by the operation
of the cam, whereby it raises the tumblers, and having shot out or drawn back
the bolt, the sliding bit in the course of the remaining portion of the revolution
is forced into the recess in the key by contact with an eccentric guard F.

page_text: Attached to the bottom of the case G is what I denominate my "revolving
cap," for preventing picks or false keys from reaching the tumblers.
Figure 7 shows a plan of the under side of this cap; and Figure 8 a section
through the keyhole. The cap is composed of a circular plate g', having a
keyhole g of sufficient length to contain the key in its expanded state. On
the under side is a cylindrical ring g³ (of a radius not exceeding the length of
the key in its contracted state), a portion of which is removed in the wake of
the keyhole; and there is a socket ' at the keyhole, from which two check
picces g extend to the ring. When the cap is in its place the socket and
check pieces extend to the face of the cam, and the ring extends to the bottom
of the case and surrounds the cam. A rectangular notch ", and two indenta-
tions g', are formed in the plate to receive studs in the detecting apparatus, as
will be subsequently explained. The plate g' rests upon and revolves in a
circular ledge in a frame I, shewn detached in Figures 9 and 10, which is
secured to the bottom of the case, and which has apertures to admit the
tumblers and the detectors I, shewn detached in Figures 11 and 12, which last
I shall now proceed to describe. ',, are two levers, turning upon centres ;
and drawn towards the frame II by the springs. From the face of each lever
projects a stud i, and through each stud passes a più , which is pressed for-
ward by a spring, at the back of the lever. A projection 7, from the upper
corner of the levers, limits the range of the levers by coming in contact with
the frame I, which acts as a stop. The operation of this apparatus is as
follows:-Supposing the parts of the lock to be put together, the front plate
will be upon the top of the cap, and the pins will be pressed by their springs
against the front plate, and the springs will be pressed back, as shown by the
dotted lines in Figure 12. If now the proper key be inserted and turned
round, the cap will close the keyhole; and the bit of the key, as it expands;
will press back one of the detector levers, and retain it in that position until
the notch g in the cap is carried past the stud on the detector lever; but if
a false key be inserted, as it cannot enter the lock if longer than the right key
when closed, it cannot act upon the detector levers; and when it has turned
the cap about one fourth round, one of the detector levers will be pressed
forward, and the stud enter the notch in the cap, and one of the pins 2³ will
enter a small hole in the front plate, whereby the cap will be retained in that
position, so that the false key cannot be withdrawn.
I
I now proceed to describe what I denominate my "spring stop," the object
of which is to prevent the tumblers from sticking, in the event of pressure
being thrown upon the bolt. It also acts as an additional tumbler. K (shewn
detached in Figures 13 and 14) is the spring stop, consisting of a radial

page_text: arm, with a returned end, and having a pin projecting from the
face of the returned end, which end is forced down by a spring into one of
two notches 5 cut in the bolt. These notches are so adjusted that the spring
stop and not the bolt stop shall receive any pressure thrown upon the bolt,
and thus the tumblers will always be free to act. The pin must be so
adjusted that it shall be lifted sufficiently high by a tumbler or tumblers as to
raise the returned end completely out of the notch by the time the bolt
stop is in position for passing the tumblers. In the case of "outer locks,"
in which it would not be desirable that the false key should be retained
in the lock, I dispense with the pins and their springs ", and formi the
studs on the detector levers, as shewn at 1, Figure 15; and in lieu of the rect-
angular notch go in the revolving cap, shewn in Figure 7, I remove a portion
of the plate so as to leave too hooks or horns, as shewn at 9, Figure 16. By
this arrangement, if a false key be employed, one of the horns will catch
against one of the studs, and the further revolution of the revolving cap will
be prevented, but the cap may be turned back again and the false key with-
drawn. For door locks requiring to be opened from either side I remove a
portion of the cam, as shewn at ein Figure 17, and I remove a portion of
the upper as well as of the lower part of the bit nearest to the stem of the key,
as shewn at d, Figures 18 and 19. For cabinet locks, in lieu of a cam and
an excentric ward; I prefer to employ an axcentric ring (e) shewn in Figure
20, which fitting into a corresponding notch d', Figure 21, in the bit causés
the bit to advance or recede during the turning of the key. Or, in lieu of
the excentric ring, I employ a plate in which is formed a suitable eccentric
groove, as shewn at es in Figure 22, to receive a stud in the bit, as shown
at d in Figure 23. In respect to the form of the cam, excentric ring, or
groove, I would observe that as it must cease to project the bit during the
time the tumblers are passing the bolt stop, that portion of the cam, eccentric
ring, or groove corresponding to this part of the revolution should be formed
as an are concentric with the keyhole. The construction of the revolving
cap may be varied from those already described, and for small locks I generally
make the caps, as shewn in Figures 7 and 8, the circular plate having a
solid cylindrical boss cast on the under side with a passage for the key, and a
circular recess formed in the lower face, of the depth of the excentric and
sufficiently large to enclose the same and allow the cap to revolve. The ring
may also be dispensed with, retaining only the plate, socket, and cheek pieces.
as shewn in Figures 7 and 8b; or the socket and check pieces may be dispensed
with, retaining only the plate and ring, as shown in Figures 7 and 8°. The cap
may also be formed, as shewn in Figure 7, with the central part of the plate

page_text: removed, but in this construction the keyhole remains open whilst the key is
being turned.
Having thus described the nature of my Invention, and the manner of
carrying the same into effect, I now proceed to define my claims in respect
thereof, observing that I do not limit myself to the precise forms of all the
parts as above described, as they may be modified without departing from the
principle of my Invention.
I claim, firstly, the construction of keys with sliding bits moved inwards or
ontwards by means of an eccentric or eccentrics contained within the lock, as
herein-before described.
Second, I claim, as applied to locks having "expanding bit" keys, the
revolving cap, herein-before described, whether combined or not with the
detecting apparatus herein-before described.
Lastly, I claim the application to tumbler locks in general of the spring stop
herein-before described.
In witness whereof, I, the said Michael Leopold Parnell, have hereunto
set my hand and seal, this Fifth day of May, in the year of our Lord
One thousand eight hundred and fifty-two.