Improvements in Locks.
Year: 1887

page_text: Improvements in Locks.
I, FRANZ SPENGLER of 130 Wilhelm Street, Berlin, in the Kingdom of Prussia,
Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention relates to improvements in locks having spring bolts.
To cause the spring bolts to spring back in shutting the lock, a wedge shaped form
has heretofore been given to the projecting or front parts of the bolts. The amount
of friction produced by this between the front part of the bolt and the striking plate
rendered it necessary to give the bolt (or the wedge) a very flat form, the result of
which was that the bolt (or wedge) had to be of correspondingly great thickness in
order to penetrate to a sufficient depth into the striking plate.
In the wedge-shaped bolts a contact takes place, when in the act of shutting, along
a line b d equal to the height of the bolt, between the inclined plane of the bolt and
the striking plate. This contact line, in which the friction takes place, slides, when
the lock is completely shut, upon the inclined plane up to the top fd of the wedge or
bolt, which under the action of a spring, penetrates into the opening of the striking
plate.
By the construction of bolts shown in Figures 1 to 5 of the accompanying
drawing the friction is reduced by the fact that two edges crossing each other
slide one upon the other. The contact, which in constructions hitherto known
took place along a line, takes place in my construction only at one point on the
line a b. For this purpose the bolt has the form of an oblique pyramid c b d a
which is placed in such a manner that only one edge a b slides upon the striking plate.
The details of the construction of the bolt are distinctly shown in Figures 2 to 5.
The slope cba of the top of the bolt, the projection of which falls, in the plan
view Figure 4 on to the line ab may also be a steeper one, that is the front part of
the bolt if it be the same thickness as the ordinary wedge shaped bolt may be made
more projecting, or if the amount of its projection remains the same, it may be
made thinner.

page_text: When the bolt is entirely pressed back into the lock, its lower surface would have
no support in the recess of the lock cramp S.
To avoid this I secure, as shown in Figure 2, a small angle bar w to the interior
side of the lock cramp S, so that the bolt will be carried by this angle bar (see the
position of the bolt marked in Figure 2 in dotted lines). The bolt may, however,
be supported by any other suitable means.
From this arrangement it will be obvious that the above described projecting or
front part of the bolt may be applied to curved bolts as well as to straight ones.
In practice the sharp edges are suitably rounded off.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
In locks especially door locks, the application of a pyramid-shaped projecting part
or head to the spring bolt, so that in shutting the lock the front part or head of the
bolt slides only with a point of one edge upon the striking plate for the purpose of
reducing as much as possible the friction between the said head and the striking plate
and of facilitating the shutting of the lock, substantially as set forth and shown in the
drawing.