Improvements in Automatic Spring Bolts for Folding Doors.
Year: 1895

page_text: Date of Application, 12th Jan., 1895--Accepted, 16th Feb., 1895
COMPLETE SPECIFICATION.
Improvements in Automatic Spring Bolts for Folding Doors.
I, MORITZ BUROW, Locksmith, of 40 Lothringer Strasse Berlin, in the Empire
of Germany, do hereby declare the nature of my invention and in what manner
the same is performed to be particularly described and ascertained in and by the
following statement:―
The present invention consists of an automatically operating spring_bolt for
folding doors, which only acts to lock the doors when both are shut. The said
bolt slides horizontally and not vertically as heretofore.
And in order that the present invention may be more easily understood reference
is had to the accompanying drawing in which similar letters denote similar parts
throughout the several views:
Fig. 1 being a vertical cross section through the bolt casing,
Fig. 2 a vertical longitudinal section through the retaining roll,
Fig. 3 a vertical longitudinal section through the bolt and bolt casing showing
the retaining roll in cross section.
Fig. 4 a similar section to Fig. 3 showing the bolt in position to retain the doors
closed and
Fig. 5 a plan of the device seen from underneath.
g is the bolt casing secured within the door at the top and bottom of the same,
is a roll mounted in a roll-casing in which it vertically moveable, said roll
being adapted when depressed by the inclined end of the bolt to enter a recess
in the floor or door frame at the top and bottom of the said door, and thus retain
the latter in position. The bolt has horizontal stem h and is horizontally guided
in the casing g by means of a guide pin e fixed in the said casing. The stem his
provided with a spiral spring which tends to actuate in a direction to depress the
roll. The end of the stem projects out of the door as shown in Fig. 3, at the
edge of the said door which contact with the edge of the second folding door when
the two are closed, said stem being pressed inward by the second door when the
same is closed onto the first.
The device operates in the following manner:
When both the doors are open they may be opened and closed freely, a slight
push being sufficient to raise the roll against the pressure of its spring when the
second door does not hold it closed. When however both doors are closed in
position and locked they will be retained securely by the rolls which engage in
their respective orifices in the door frame and floor.
Instead of the roll r a vertical pin may be arranged in the floor, and the end of
the bolt r may be pointed or inclined at both sides, so as to close behind the pin
when the door is closed and to be retained in position behind said pin when the
second door is properly closed against the first. In this case a suitable lateral
orifice must be made in the casing g to enable the door to close and open over
the pin.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is performed 1 declare that what I
claim is:
1. The combination of a horizontally sliding bolt having two inclined plates
at its inner end and having a stem projecting at the contacting edge of the door
and a pin arranged in the door frame or floor behind which said bolt engages

page_text: under the action of a spring and is retained by the clused wing of the said door
substantially as described.
2. A device of the description covered by Claim 1 by which the said sliding
bolt operates to depress or actuate a vertically moveable roll to engage depressions
in the floor or door frame substantially as described.
Dated this 12th day of January 1895.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.