Time and percussion fuze for Schneider
75mm field guns
|
Schneider time & percussion fuze.
It was composed by : body (1), core (3), time fuze
mechanism (7), top composition ring (9), bottom composition ring (2), cover
(5), screw (19) and percussion fuze mechanism (15). |
|
|
The body
(1) was made of aluminium and had a stem screwed into the shrapnel head.
The upper part of the stem was cylindrical in shape and supported the two
rings of the time mechanism, the bottom of them being
attached on a slot (20) of the stem cap. The interior of the stem was
bored and threaded to receive the core (3) of the fuze. The magazine (21) at
the bottom of the core was filled with fine grain black
powder and connected with the slots of the bottom ring by a horizontal channel
with a vertical hole, filled with a tubule of pressed black powder. |
|
|
The
external end of the channel was closed with a plug
(4). At the bottom the stem was closed with a bronze
cap (22) with a hole in the middle to transmit the fire. The
hole was closed by a copper plate. The
core (3) was made of bronze and contained
the time and the percussion mechanisms. It was screwed
in the stem and had a ring nut on the top to screw the fuze cap (5). On the inside it was divided in two stages by a bar. The
time fuze mechanism (7) was
contained in the upper level and was composed by
firing pin (6), percussion spring (7) and percussion cap (8), contained in a
copper box. The
top (9) and the bottom (2) composition rings were both of aluminium. The bottom ring was mobile and was housed in the stem cap, a broadcloth disc being placed
between them. A groove was formed in the under side
for the time composition of pressed black powder (10). The walls of the
groove were coated with red brass, to avoid that the
charge was in contact with the aluminium. At the beginning of the groove
there was a hole filled with a tubule of pressed black powder and a
horizontal vent hole (11) for the
passage of the gas when the fuze burnt. The
top ring was
fixed and lay on the bottom ring, a broadcloth disc being placed
between them. A groove was formed in the under side
for the time composition, with a hole (23), as in the bottom ring. That point
was connected with upper stage of the core by an inclined
channel of red brass (12), fixed in the stem of the fuze and filled with
black powder. That channel transmitted the fire from the percussion
cap to the upper part of the time mechanism. The percussion
fuze mechanism (15) was contained in the lower stage of the core and was
composed by : needle (13) screwed in the core bar; little safety spring (14);
firing pin (15), carrying the percussion cap (16) and having on the axis a
channel filled with a tubule of pressed black powder; retracting girdle (18);
great safety spring (17); two springy segments (24). The firing pin lay on a cardboard disc (25), supported by the stem
cap. The cap (5) was screwed on
the stem and along with the creep spring (19) caught
the bottom ring of the time fuze mechanism. A hole (26) was
drilled on it, to centre the fuze when the shrapnel was put into the
fuze setter. The cap was kept in place by a stirrup
spring, placed in the core of the fuze. Two plugs
(20a) were screwed on the external surface of the
stem cap and of the bottom ring of the time fuze mechanism
to join the fuze setter. The lower part of the bottom ring was graduated in
meters to be set by hand with the fuze wrench, according with the lines (T)
engraved on the stem cap. Krupp time & percussion fuze.
It was similar to the Schneider fuze, even if the internal arrangements were
slightly different. The body was made of aluminium and was
screwed into the shrapnel. It supported the graduated ring, where were
mounted the two rings of the time percussion mechanism and the fuze cap.
Inside the core was double-banked, the upper level containing the time
mechanism and the lower level the percussion mechanism. |
|
|
As
a whole, the Krupp shrapnel was composed by : – time mechanism : body with
graduated ring (a), time composition rings (b), cap (c), time pellet (d),
safety pillar (e), detonating cup (f), top needle (g), base plug (h), fine
grain black powder magazine (i); – percussion mechanism : holder
(k), mount (l), percussion pellet (m), safety pillar (n), detonating cup (o),
bottom needle (p), retracting girdle (q), spiral spring (r). |
|
|
Operation of the time fuze.
When the gun was fired, the firing pin of the time
fire mechanism came back by inertia, compressed the percussion spring, strike
the ignitable substance in the percussion cup (8), which created a flash. The
flame was transmitted to the channel (12) and to the
powder of the top ring of the time fuze mechanism. Then it went through the
hole in the bottom ring, was transmitted to the
powder of the bottom ring, went through the hole in the stem cup and ignited
the fine grain powder of the stem magazine. Finally
it went through the central tube of the shrapnel, reached the powder chamber,
ignited the bursting charge the and the shrapnel burst. When
the top ring of the time fuze mechanism was set at 0, the vertical holes on
the fuze cap, on the top ring and on the bottom ring were
lined up and directly connected with the powder stored in the stem magazine.
Thus the shrapnel burst just after it left the
muzzle. Turning the bottom ring of the time fuze mechanism,
its hole moved away from the other two holes and thus the fire was
transmitted by the powder contained in the grooves of the two parts of the
time fuze mechanism : the more the top ring was turned (i.e. the more the
holes were distant), the more the transmission of fire took time. However the grooves of the time fuze rings were not
perfectly circular, but there was a sort of gap, called bridge. When the top
ring was turned so that the bridges were in front of
the holes (with the line on the graduated ring on T), the fire could not be
transmitted and the fuze was ready to be employed for percussion fire. Operation of the percussion fuze.
When the gun was fired, the retracting girdle of the
percussion mechanism dropped back and fell on the firing pin. Thus the great
safety spring was bent, but the retracting girdle could not went back, since
it was held on the firing pin by the springy segments :
the firing pin with percussion cap was then kept away from the needle only by
the little safety spring. When the shrapnel hit the target, the impact caused
the firing pin and the retracting girdle to snap up against the percussion
cap, after compressing the little safety spring. The ignitable substance in
the percussion cup (16), created a flash, the flame was transmitted to the
central tube of the shrapnel by the hole in the firing pin, reached the
powder chamber, ignited the bursting charge and the shrapnel burst. |
|
|
|
|
|
1. Position of the rings with
fuze set at 0 2. Position of the rings with
fuze set for time firing 3. Position of the rings with fuze set for percussion
firing |
|
|
К fuze toggle Т fuze cap with its hole в |
г
top ring with its hole а д
bottom ring with its hole б |
|
T&P Fuze |