Base Detonating Fuze Mk 23 Mod 0 (Obsolete)

Projectiles used in

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Delay, second

Description: The fuze is composed of three major parts: the head, the body, and the nose cap. The fuze head assembly contains the firing pin, firing pin detents, and two locking balls behind the firing pin. In the assembled position, the point of the firing pin does not protrude from the head. The body contains the detonator plunger, which is spring-loaded downward toward the firing pin by a very heavy firing spring. The firing train – consisting of the sensitive primer, the secondary primer, the delay element, the detonator, and the booster elements – is contained within the detonator plunger. Plunger alignment is maintained by pins in the plunger stock. The nose cap contains the ball re-tainer, ball retainer detents, and locking balls. The spring-loaded plunger is held up by the locking balls, which are, in turn, held in by the ball retainer. The ball retainer is pre-vented from moving because of the ball retainer detents.

Operation: When the projectile is fired, centrifugal force causes the firing-pin detents and ball-retainer detents to be moved outward against their springs. When the firing-pin detents have moved out, the firing pin moves forward because of creep, and the locking balls drop into the space left by the forward movement of the firing pin and will be held outward by centrifugal force, thus locking the firing pin in the forward position. The ball retainer is prevented from moving forward under influence of creep, because of the anti-creep spring behind it. On impact, the ball retainer moves forward until stopped by the nose, and is locked in this position by three split ring segments engaging a shoulder at the end of the body this forward movement of the ball retainer and are projected out-ward. When the force of impact has diminished sufficiently to permit the firing spring to propel the plunger to the rear, the sensitive primer in the base of the plunger is thrown down on to the firing pin. When the plunger moves down, it brings the booster lead-ins and lead-outs in line, and the plunger is locked in the rear position by three split ring segments in a manner similar to the ball retainer. When the sensitive primer is fired, the gas from it fires the percussion primer. The flash from the percussion primer passes through and around the baffle and ignites the delay pellet. This defers ignition of the de-tonator for 0.02 second. The detonator then fires the booster elements.

Remarks: This fuze will detonate on thin plate and on water impact.

Figure 108. Base Detonating Fuze Mk 23