Year: 1898

page_text: Date of Application, 31st Mar., 1898-Accepted, 30th July, 1898
one end of which there is a plate which is fastened on to the door while the other
is provided with a specially constructed locking piece which can be fastened into
a lock situate on the door jamb by simple insertion even when there is no one in
the house and the opening of the door can be effected by the proprietor of
the house by means of a key from the outside, by pushing the door open to the
extent of the chain.
The accompanying drawings shews a method of executing the object of the
application.
Figure 1 illustrates the chain with plate and locking piece.
Figure 2 the lock front view.
Figures 3 & 4 the lock in section and
Figure 5 the key.
The plate 6 is by means of screws nails or the like c fastened to the door or other
suitable object. From the holdfast d rivetted into this plate there hangs a chain a
with a locking piece f at its other end which locking piece is provided with a
wedge shaped projection e which can be inserted into a lock intended for it. The
lock is fastened to the door jamb and consists of a covered-in casing y in which
the catches or tumblers i actuated by springs h are arranged to revolve on pins k.
When the lock is closed the catches or tumblers i are parallel at a fixed distance
which is defined by a stop-pin o. Between the catches or tumblers i is the guide /,
for the introduction of the key, fastened in the wall of the lock case next to the
door jamb. The key for locking the door has two wards diametrically opposite
to each other. With this arrangement in locking the catches or tumblers i are
simultaneously and equally forced apart. These catches or tumblers are attached
to the front wall of the casing and are so arranged that there is a space between
them and the wall of the casing next to the door jamb, in which space the inserted
locking piece takes up its position. When the catches or tumblers i are closed
the locking piece cannot possibly be drawn out as the angles n of the projecting
part e hook behind the catches or tumblers i after the fashion of an arrow-head.
The insertion of the projecting piece e into the lock can be accomplished even when
the catches or tumblers i are closed with the exercise of slight pressure in which
case the catches or tumblers i are forced apart in consequence of the wedge and
arrow shape of the projecting piece e. The catches or tumblers i fly back into
their closed position when the projecting piece e with the hooks n is forced through.
The advantage of this safety chain is that it can be easily opened from outside
by the owner of the house by means of a key.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is;
CLAIM.
A safety chain characterised by having on its free end a hook-piece or the like,
which can be put into a lock firmly fixed on the door or door frame, and can be
made fast automatically or with the help of a key while it can be loosened only by
means of a key.
Dated this 30th day of March 1898.
OTTO DEMKE.
By George Barker,
Agent for Applicant, 77, Colmore Row, Birmingham.