EMPLOYMENT: Nose fuze for the 3.7-cm Stielgranate (3.7-cm Rodded Bomb) fired from the 3.7-cm Pak. (See fig. 561.)

DATA:

Over-all length: 1.875 inches.

Maximum diameter: 1.187 inches.

Threaded length: 0.25 inch.

Number of threads: 7 RH.

CONSTRUCTION: The fuze is of aluminium and has an ogival body with a hole at the nose through which the cylindrical striker protrudes. The body is screw-threaded for in-sertion in the grenade and has an internal circumferential recess below the striker to per-mit the expansion of the coiled spring in flight. The striker carries a needle surrounded by a spiral spring which is held between the under-side of the striker and a cup-shaped re-tainer. The retainer has a central hole for the needle and has a step formed near the the front end around which a length of flat spring is coiled. The coiled spring is retained by a cylindrical arming ferrule with an internal groove near its base end. A stirrup spring is held between the retainer and the detonator holder. The detonator holder is screwed into the base of the fuze and carries an igniferous detonator in a perforated screwed plug. The holder is secured in the fuze body by a set screw.

ACTION: On acceleration the arming ferrule in the fuze sets back over the stirrup spring which engages in its groove and retains it clear of the coiled spring. During this period the coiled spring is held by the set-back of the striker, and propellant gases, entering the flash hole in the screwed closing plug at the base, ignite the delay pellet. During flight the coiled spring is expanded into the annular recess in body by centrifugal force, thus leaving the striker with its needle supported only by the striker spring.

On impact, the striker is driven in and the needle pierces the igniferous detonator of the fuze. The flash from this detonator initiates the detonator in the grenade, which in turn, brings about the detonation of the bursting charge.

REMARKS: This fuze is also used in the German H.E. Rifle and Hand Grenade "Gewehrgra-nate Spreng".

Figure 561 – A.Z. 5075, A.Z. 5075 M.K.