Cutaway model of a Hungarian 34M base fuze. This fuze was used in the 21cm 33/34M Concrete piercing shell. It was screwed into the baseplate of the projectile.
The fuze body (1) and booster body are made of steel. In the base of the fuze body an aluminium cap is screwed housing the brass primer carrier (2). Opposite to the primer carrier, the aluminium firing pin carrier (3) is placed. The firing pin and primer are held apart by six locking balls (4) -placed around the firing pin-, which are held in inward position by a sheet steel spring bushing with six longitudal spring fingers (5). An inertia bushing (7) is kept in upper position by a spring (6). The inside of the inertia bushing has a groove on the inside.
On top of the of the firing pin carrier (3) the safety slider housing (9) with the safety slider (10) is placed.
Functioning of the fuze:
Upon firing of the projectile, inertia moves the inertia bushing (7) backward, riding the spring (6). The groove on the inside of the inertia bushing hooks behind the fingers of the bushing (5). As the acceleration of the projectile decreases, the spring will push up both bushings (5&6), releasing the locking balls (4) which are thrown outward by the centrifugal force. The primer carrier (2) can now move into the firing pin, kept apart by a weak spring only.
Upon impact, inertia will throw the brass primer carrier (2) forward into the firing pin. The flame travels upward through the channel of the firing pin carrier (3) into a second heat sensitive firing cap with a pellet of black powder ( 8 ) above it to amplify the flame of the primer (2).
After firing, the slider with the detonator (10) slides the detonator (red) into the centre line of the fuze, closing the explosive chain. Two spring loaded centrifugal locking pins are placed around the slider, allowing the slider to move after firing (11), one inertia activated pin (12) locks the slider in it’s working position.
In top of the safety slider housing a strong detonator (13) is placed which will explode the main booster (14) of the fuze.
Regards, DJH
The fuze body (1) and booster body are made of steel. In the base of the fuze body an aluminium cap is screwed housing the brass primer carrier (2). Opposite to the primer carrier, the aluminium firing pin carrier (3) is placed. The firing pin and primer are held apart by six locking balls (4) -placed around the firing pin-, which are held in inward position by a sheet steel spring bushing with six longitudal spring fingers (5). An inertia bushing (7) is kept in upper position by a spring (6). The inside of the inertia bushing has a groove on the inside.
On top of the of the firing pin carrier (3) the safety slider housing (9) with the safety slider (10) is placed.
Functioning of the fuze:
Upon firing of the projectile, inertia moves the inertia bushing (7) backward, riding the spring (6). The groove on the inside of the inertia bushing hooks behind the fingers of the bushing (5). As the acceleration of the projectile decreases, the spring will push up both bushings (5&6), releasing the locking balls (4) which are thrown outward by the centrifugal force. The primer carrier (2) can now move into the firing pin, kept apart by a weak spring only.
Upon impact, inertia will throw the brass primer carrier (2) forward into the firing pin. The flame travels upward through the channel of the firing pin carrier (3) into a second heat sensitive firing cap with a pellet of black powder ( 8 ) above it to amplify the flame of the primer (2).
After firing, the slider with the detonator (10) slides the detonator (red) into the centre line of the fuze, closing the explosive chain. Two spring loaded centrifugal locking pins are placed around the slider, allowing the slider to move after firing (11), one inertia activated pin (12) locks the slider in it’s working position.
In top of the safety slider housing a strong detonator (13) is placed which will explode the main booster (14) of the fuze.
Regards, DJH
