Base Detonating Fuze Mk 2 Mod 0

Projectiles used in

Over-all length, inches

Diameter of body, inches

Diameter of head, inches

Threaded length, inches

Threads

Material

Description: This fuze consists of two major parts: (1) a tracer head, threaded ex-ternally to screw into the base of the projectile and containing the tracer primer and py-rotechnic components; (2) the fuze body which houses the Sempler striker and carrier unit, the primer-detonator tube, the safety coil, the centrifugal bolt assembly, and the booster charge.

In the unarmed position, the striker, which is pivoted in the striker carrier, is held in the offset position by a pair of centrifugal lock bolts. These bolts are housed in the stri-ker carrier and engage the hole in the weighted end of the striker. Also, in the unarmed position, the detonator is separated from the booster charge safety is provided by en-casing the detonator in a small expansion chamber surrounded by a heavy steel safety coil. Accidental explosion of the detonator will expand itself in the chamber and against the safety coil, and will not penetrate past the gate bolts sufficiently to fire the booster.

Operation: When the projectile is fired, the tracer primer functions and ignites the tarcer element in the base of the fuze. Centrifugal force causes the centrifugal lock bolts and the centrifugal gate bolts to move outward against their springs. This provides free access between the detonator capsule and the booster charge, and unlocks the pivoted striker. Since the striker is heavily weighted on its lower end, centrifugal force causes the striker to rotate around its pivot and align the striker point with the primer. On im-pact, the striker carrier moves forward aganst its spring, bringing the striker against the primer, which fires the delay element and the detonator. The flash from the detonator passes by the open gate bolts and initiates the booster charge, firing the projectile.

Remarks: Because of the shape of the striker, the force of the initial acceleration prevents centrifugal force from producing alignment while the projectile is still in the bore of the gun. When acceleration ceases, centrifugal force revolves the pivoted striker to the armed position.

Figure 100. Base Detonating Fuze Mk 2 Mod 2