A MECHANICAL FUSE
Year: 1885

page_text: We PAUL PFUND of Rolle, Switzerland, Major of Engineers in the Swiss Army,
and ALBERT SCHMID, Civil Engineer of Zurich, Switzerland do hereby declare the
nature of our invention for "A MECHANICAL FUSE }} to be as follows:-
The construction of this mechanical fuse has the purpose to produce the explosion
of mines, not only by a direct frontal shock or collision, but also by shocks or by
tractions produced in an oblique direction. This fuse is specially adapted for
military purposes, as for example, sea and land torpedoes.
This improved fuse is constructed as follows:
There is a cylindrical percussion bolt with a needle guided by a disc secured in
a suitable socket on which a half-cylindrical piece is screwed and guides the upper
part of the bolt. A spiral spring is interposed between the bolt and the disc in the
socket. The upper part of the percussion bolt is provided with a groove above
which is a cone the rim of which is salient, and is retained by the nose of a trigger
which pivots on a pin. The upper extremity of a trigger is cylindrical as well as
a fixed piece and between both there is a loose cylindrical plug with a groove or
recess with which engage the inwardly bent extremities of the fixed cylindrical
piece and the trigger. A caoutchouc or India rubber ring causes the nose of the
trigger to catch under the rim of the cone above mentioned and keeps it in place.
A bell or hollow cone is fitted on the prolongation of the plug and held fast by a
screwed contact-button.
•
An arming and disarming box has a flange or ring provided with holes placed
opposite to each other for fastening strings or wires. The box itself has two
helicoidal grooves of revolution guided by screw heads which are screwed in the
socket of the fuse.
By this means the arming and disarming box can be screwed up or down from a
sheltered position, in its upper position the release of the trigger is prevented so
that no explosion can take place, while in its lower position, the trigger can be
moved sufficiently to disengage the pecussion bolt which by the tension of the spring
drives the needle into a percussion cap or cartridge and produces the explosion of
the mine or the like.

page_text: Any contact, shock or traction, on the contact-button changes the position of the
plug, the top part of the trigger is moved and disengaging the percussion bolt
causes the explosion.
The spiral spring is bent with a hollow pin introduced from below, driving back
the fixed disc with the percussion bolt until the trigger clicks.
.
In adapting this mechanical fuse to sea-torpedoes the bell having the only purpose
to prevent the rain to penetrate inside the fuse, is omitted as well as the flange on
the disarming box, which in this case can be fastened by a screw or the like, until
the fuse is to be used.'

page_text: We PAUL PFUND of Rolle, Switzerland, Major of Engineers in the Swiss Army.
and ALBERT SCHMID of Zurich, Switzerland, Civil Engineer do hereby declare the
nature of our invention for "A MECHANICAL FUSE and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-.
The object of this mechanical fuse is to produce the explosion of mines not only
by a direct frontal shock or collision but also by shocks or by tractions produced
in an oblique direction. This fuse is specially adapted for military purposes as for
example for sea and land torpedoes.
The mechanical fuse is shown in the annexed drawings in which Figure 1
represents a longitudinal section Figure 2 a cross section upon line A B of Figure 1,
Figure 3 the arming and disarming box, Figure 4 the ring by which the fuse is
connected to the mine. Figure 5 a plan. Figure 6 is a sectional view of this fuse
fitted to a shell.
The same letters refer to the same parts in all figures.
The cylindrical percussion bolt a with the needle b is guided by the collar c in
the socket d on which the half cylindrical piece e is screwed and guides the upper
part of bolt a. A spiral spring v is interposed between the piece e and the collar c.
The upper part of the percussion bolt a is provided with a groove fabove which is
the conical end g the rim of which projects so as to engage with the nose k of the
trigger which pivots on pin h. The upper extremity of the trigger i has the
same cylindrical shape as the fast piece e and between both there is a loose
cylindrical plug m with a conical recess in which seize the inwardly curved
extremities of the fast piece e and the trigger i. An india rubber ring t causes the
nose k of the trigger i to catch under the rim of the cone g and keeps it in place.
The bell is fitted on the prolongation of the plug m and held fast by contact
button o which is screwed on as shown.
The arming and disarming box p Figure 3 has a flange or collar q provided with
holes placed opposite to each other for fastening strings or wires. The box p itself,
has two helicoidal grooves r of revolution guided by the screw heads 8 which are
screwed in the socket d.
By this means the arming and disarming box p can be screwed up or down from
a sheltered position in its upper position the trigger i is prevented from unlatching
so that no explosion can take place while in its lower position indicated by dotted
lines Figure 1 the trigger can be moved sufficiently to disengage the percussion
bolt a which by the tension of the spring v drives the needle b into a percussion
cap or cartridge and produces the explosion.
i'
A blow on the contact button o drives in the plug m the conical upper part
whereof forces out the end of trigger i thus disengaging the percussion bolt a and
causing the explosion.
To reset the apparatus the spiral spring is compressed by means of a hollow
pin introduced from below driving back the collar c with the percussion bolt a until

page_text: the trigger clicks under the influence of spring v the nose k sliding over the conical
head g and the apparatus is set again as in Figure 1.
In adapting this mechanical fuse to sea torpedoes the bell n which only serves
the purpose of preventing the rain from penetrating inside the fuse is not wanted
as well as the flange on the disarming box which in this case can be fastened by a
screw or the like until the fuse is to be used.
The working of the fuse shown in Figure 6 is similar to that of Figure 1 but
the length is reduced by altering the shape of the coiled spring v which when
compressed lies flat as shown, and when the bolt is shot assumes the conical shape
as indicated in dotted lines.
The safety pin w engages with a groove x in the collar c so that the bolt cannot
be shot until the pin is withdrawn, A cross section of this pin w is shown in
position on the right of the collar c.
.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed we declare that what
we claim is
1. In a mechanical fuse the combination with a bolt a which carries the needle b
and whose forward movement is effected by the spring which encircles it of a
trigger having a nose adapted to engage with the head g for the purpose of
holding back the bolt and to release said bolt upon being forced outwards by the
plug m the whole constructed and operating substantially in the manner specified.
2. In a mechanical fuse the combination with the bolt a having a head g of a
movable trigger i the nose whereof is adapted to engage with said head g and
hold back the bolt a and to be disengaged therefrom by the movement of the
plug m substantially as specified.
3. In a mechanical fuse the combination with the piece e which carries the
movable trigger i of the plug m adapted to move in a recess in said piece e and
force out the trigger i substantially in the manner specified.
1