Mk 7 Mod 1 (Obsolete)

Projectiles used in

Over-all length, inches

Diameter, inches

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Material

Description: This fuze consists of a long, cylindrical body closed at either end by an ogival nose cap and a cylindrical base plug, each threaded into place. The central cavity of the body houses a safety spring, a long percussion rod assembly, a needle striker, a striker retaining sleeve, a detonator, and a ring booster pellet.

The percussion rod is closed at its upper end by a metal cap. The rolled edges of this cap and the safety spring tend to prevent the percussion rod from moving into the upper portion of the body. The long cylindrical portion of the percussion rod is slotted longitudi-nally to allow the eared striker to slide freely within the rod. The ears of the striker are engaged by the striker retaining sleeve, holding the striker permanently fixed. A detona-tor is fixed to the lower end of the percussion rod. In the unarmed position, this detona-tor is not adjacent to the ring booster charge but is encased in a safety chamber in the base of the fuze. Accidental explosion of the detonator in this position would spend itself harmlessly in the expansion chamber, and the booster charge would not be fired.

Operation: The fuze functions entirely on impact, when the inertia of the percussion rod drives the rolled edges of its upper cap past the shoulder of the cap retaining sleeve. The rod then continues into the upper portion of the fuze body, against the force of the safety spring. This action carries the detonator out of the safety chamber, adjacent to the ring booster, and against the fixed firing pin. The initiation of the detonator fires the booster and the main charge.

Rearward motion of the percussion rod during set-back is prevented by the conical shape of the percussion rod just above the striker retaining sleeve.

Figure 80. Point Detonating Fuze Mk 7 Mod 1