IMPROVEMENTS IN LOCKS AND LATCHES
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Matthew Andrew at the Office
of the Commissioners of Patents, with his Petition, on the 11th
September 1869.
I, MATTHEW ANDREW, of Melbourne, in the Colony of Victoria, but at
present residing at Birmingham, in the County of Warwick, Gentleman,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
LOCKS AND LATCHES," to be as follows:-
My Invention consists of the improvements herein-after described in
constructing and arranging the parts of locks and latches whereby the
mechanism of locks and latches is much simplified, and the said locks
and latches are consequently manufactured more economically, and are
less liable to get out of order than locks and latches of the ordinary
construction.
In making a combined lock and latch according to my Invention. I
construct and arrange the parts as follows:-The latch bolt is situated
at the bottom end of the vertical arm of a crank lever, the horizontał
arm of said the lever being situated immediately above the follower fixed
on the spindle of the latch. The said crank lever turns upon a centre,
which may be in the upper corner of the lock case, the said arms of the

page_text: lever being respectively parallel to one of the vertical and one of the
horizontal sides of the case when the lever is in its normal position. By
turning the knob of the latch spindle the follower raises the horizontal
arm of the crank lever and withdraws the latch bolt. The centre on
which the latch bolt turns may be one of the screw pins by which
the plate of the lock case is fixed. The lock bolt consists of a flat bar
having the usual head for entering the staple and recess for the key to
engage in. The rear end of the bolt terminates in a cross piece of a
length equal to the depth of the lock case, the ends of the cross piece
. bearing respectively against the top and bottom of the lock case during
the motion of the bolt, and serving to guide and preserve the parallelism
of its motion. The bolt and cross piece have the general figure of the
letter T. Projections on the top and bottom of the lock case limit the
motion of the said cross piece and bolt. Or the cross piece may have a
length suitable to enable it to work between the said projections, in
which case the forward motion of the bolt is limited by a stop on the
head of the bolt. On the bolt near its front end is a pin on which one
or more levers or tumblers turn. These levers have the figure of the
letter T, and by the motion of the key are raised to the height required
to permit their ends to pass the projections on the lock case. On the
withdrawal of the key the levers descend, and their ends engage against
the said projections. The said levers thus fix the bolt in its shot or
withdrawn position until by the action of the key they are raised to the
required height to permit the ends of their cross pieces to pass the
projections. The upper halves of the cross pieces both of the bolt and
levers may be dispensed with, and the ascending motion of the levers
limited as well as the guiding of the bolt effected by one of the screws
used for fixing the lock plate. This screw is in this case passed through
the lock plate into the back of the lock at the required point above the
bolt. The latch and tumblers fall into their normal positions by the
action of the force of gravity when they are not acted upon by the
follower and key respectively, but in order more effectually to secure
their return to their normal positions they may be operated upon by
springs made to press them in the required directions.