CERTAIN IMPROVEMENTS IN LOCKS AND LATCHES
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by Andrew Sweet at the Office of
the Commissioners of Patents, with his Petition, on the 12th April
1862.
I, ANDREW SWEET, of Hampstead Road, in the County of Middlesex,
Ironmonger, do hereby declare the nature of the said Invention for "CERTAIN
IMPROVEMENTS IN LOCKS AND LATCHES," to be as follows:-
It consists, firstly, in the employment in locks or latches constructed with
levers or tumblers of a toothed pinion (or other equivalent arrangement), the
teeth of which take into corresponding teeth or indentations formed in or
attached to the tumblers or levers, and which by rendering it impossible to
raise the tumblers or levers one by one into the position necessary for allowing
the "stump" or pin (formed with or attached to the bolt). to pass prevent
the picking the lock by pressure, as practised with other locks. The same
principle is applicable also to letter locks having no keys.
Secondly, in the use of a drum or tube capable of revolving on the key pin
and formed to receive the key. This drum or tube is formed with a flat side
or other equivalent figure, which when presented to the tumblers or levers
allows of the bolt being drawn backward from within the door to which the
lock is attached without the use of a key, but which when it is attempted to
pick the lock from without is turned away from the tumblers or levers, and
prevents the drawing back of the bolt until the tumblers or levers are raised
by the proper key into a position which brings a series of notches cut in them
opposite to the stump or pin formed with or attached to the bolt, and allows
of its being drawn backward (as the drum is partially revolved by the key) by

page_text: means of a "false bit" or projection attached to and moving with the drum.
In combination with this arrangement I make use of a shield or guard plate,
which prevents the introduction of a picklock for the purpose of effecting the
withdrawal of the bolt.
Thirdly, in an arrangement for affording additional security in locks wherein
the bolt is withdrawn by means of a handle. In these cases I make use of a
series of tumblers or levers provided with teeth taking into the teeth of a
pinion as first herein described. The tumblers are provided with notches,
which upon their (the tumblers) being moved by the key into a suitable
coincident position, allow a stump or projection attached to a suitable bit or
lever to enter them. The bit or lever referred to carries also a bolt or
projection, which while the stump or projection (previously referred to)
carried by the bit or lever is kept from falling into the notches in the tumblers
prevents the withdrawal of the principal bolt of the lock, but immediately
upon the tumblers being moved by means of the key, so that the whole of the
notches coincide, and permit the stump on the lever to fall into them is
withdrawn from and sets free the principal bolt, which may then be drawn
backward by the handle. This arrangement is applicable to all kinds of lever
locks, whatever may, be the number of bolts.
Fourthly, in a new permutation key, the bits of which are all of one length,
and are capable of being set at various angles, so as to obtain the different
amounts of lift required to operate upon the several levers or tumblers of
the lock.