Improvements in Base Fuses for Projectiles.
Year: 1888

page_text: Date of Application, 12th Dec., 1888
Complete Specification Left, 6th Sept., 1889-Accepted, 12th Oct., 1889
PROVISIONAL SPECIFICATION.
Improvements in Base Fuses for Projectiles.
I, THORSTEN NORDENFELT of 53 Parliament Street, in the City of Westminster,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has for its object improvements in base fuses for projectiles.
In this base fuse the pellet, which by striking upon a patch of fulminate
ultimately fires the charge and bursts the projectile, is restrained in the following
manner, so that the explosion cannot take place until after the projectile has leit
the gun.
A
The pellet is contained in a chamber at the fore end of which the fulminate
patch is situate. In the wall of this chamber there is a hole and there is a
corresponding cavity in the side of the pellet. steel ball of suitable size is
lodged partly in the hole and partly in the cavity. So long as the ball occupies
this position the pellet is held fast in its place and cannot approach the patch of
fulminate. The hole however communicates with another chamber in the shell of
the fuse and this contains a bolt capable of sliding in a longitudinal direction. The
bolt however is locked in its place by a pin screwed into it and through the wall
of the chamber.
This chamber is open in rear and when the gun is fired the pressure in the
gun forces the bolt to move, the end of the locking pin being shorn off. This
brings a pocket or cavity in the side of the bolt opposite to the ball and then
(with the requisite delay) the ball passes into the pocket and the pellet becomes
free to act on the impact of the projectile with the object.
COMPLETE SPECIFICATION.
Improvements in Base Fuses for Projectiles.
I, THORSTEN NORDENFELT, of 53 Parliament Street, in the City of Westminster,
Civil 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 has for its object improvements in base fuses for projectiles.
In this base fuse the pellet, which by striking upon a patch of fulminate
ultimately fires the charge and bursts the projectile, is restrained in the following
manner, so that the explosion cannot take place until after the projectile has left
the gun.
The pellet is contained in a chamber at the fore end of which the fulminate patch
is situate. In the wall of this chamber there is a hole and there is a corresponding
cavity in the side of the pellet. A steel ball of suitable size is lodged partly in the
hole and partly in the cavity. So long as the ball occupies this position the pellet
is held fast in its place and cannot approach the patch of fulminate.
The
hole however communicates with another chamber in the shell of the fuse
and this contains a bolt capable of sliding in a longitudinal direction. The
bolt however is locked in its place by a pin screwed into it and through the wall
of the chamber.
This chamber is open in rear and when the gun is fired the pressure in the gun
forces the bolt to move, the end of the locking pin being shorn off. This brings a
pocket or cavity in the side of the bolt opposite to the ball and then (with the
requisite delay) the ball passes into the pocket and the pellet becomes free to act on
the impact of the projectile with the object.

page_text: DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal section of a base fuse constructed in accordance with
my invention.
Figure 2 is a transverse section on the line 2, 2, in Figure 1.
Figure 6 is also a transverse section but with the parts in the position they occupy
after firing.
Figure 4 is a longitudinal section and Figure 5 is a transverse section of the
fuse body.
a is the pellet, it is cylindrical in form and furnished in front with a point a¹.
The pellet is lodged in a central longitudinal cavity in the fuse body which is closed
in front by a screw plug b. In the plug b there is a hole for the passage of the
point a¹ and over the hole in a cavity in the plug is a patch of fulminate & which is
kept in place by a small perforated cover plate 6. The edges of the cavity are
burnished over to retain the cover plate. c is a bolt also approximately cylindrical
in form; it is lodged in a cavity in the fuse body parallel to that which contains
the pellet.
The two cavities, namely the pellet cavity and the bolt cavity com-
municate by a passage in which a ball d is lodged; this passage is drilled through
from the side of the fuse body and then the outer end of the hole is closed by a
screw plug e. The ball dis partly received into a cup like recess in the side of
the pellet a and partly it occupies the passage between the cavities. The ball is
kept in the passage by the bolt c and this is held by the pin f which is screwed into
the body and its end projects into a hole in the bolt. Behind the bolt is the copper
and
between the ring and the gas check thero is a thin wax wad i. At there is a lead
ring washer. In the side of the bolt c is the recess o¹. The fuse is screwed into the
base of the projectile and as already stated when the gun is fired the bolt c is driven
forward the end of the pin f being shorn off. This brings the recess into position
to receive the ball and the ball falls into it leaving the bolt c free to pass to the fore
end of its cavity in the fuse body when the flight of the projectile is checked on
impact. The point a¹ then strikes the fulminate and the flash which results passes
through the holes in the cover 62 to the bursting charge.
gas check g. The bolt cavity is partially closed in rear by the screw ring
This fuse is very certain in its action and also safe; the pellet cannot move so
long as the ball is retained in place by the bolt; but when the bolt has been thrust
forward in firing the pellet is free, even if the-ball does not of its own accord pass
into the pocket in the bolt for the pellet in its advance can drive the ball back.
The fuse also is easily constructed and put together.
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
1. A base fuse substantially as described in which the pellet is locked by a ball
entering a hollow in its side; such ball being kept in place by a bolt which in
firing the gun becomes shifted in such manner as to release the ball as herein
set forth.
2. A base fuse substantially as described and represented by the annexed
drawings.
Dated this Fourth day of September 1889.