(Fig. 34)

This fuze has been encountered in connection with the 25 mm. H.E./T ammunition des-cribed elsewhere in this pamphlet.

The fuze is in four main parts – the nose and body which are of brass, the shutter holder which is of nickel-plated brass, and the magazine which also constitutes a gaine is of du-ralumin.

The nose is drilled centrally, the bore being enlarged and threaded at the base for at-tachment to the body. It is closed by a copper diaphragm rolled into the head.

The body is machined externally at the top to provide the thread for the attachment of the nose. Internally an annular groove is cut leaving a central boss which is drilled through and constitutes a striker guide. Centrally, a transverse hole is drilled to carry the centrifugal bolt. It is threaded at one end to receive the closing plug, and has a center-ing boss for the bolt spring at is closed end. A hole is drilled centrally on the lower axis of this compartment and provides a channel for the striker needle. The plug is secured by stabbing and covered with white paint. The centrifugal bolt is cylindrical, having a de-pression at one end to carry the retaining spring and being stepped and slotted at the other to carry the end of the striker shaft and the steel needle. The striker is a headed duralium shaft carrying a blued steel needle. This has the typical Japanese wedge-sha-ped joint. No support spring is fitted to the striker. At the base, the body is bored to re-ceive the shutter holder, and tapped internally to receive the magazine.

The shutter holder is in the form of a cup fitting in the upper portion of the base cavity of the fuze. It has a widened bore at the top and carries therein the detonator plug. At the bottom it is drilled centrally to provide a flash channel, anti carries the shutter pivot and stop pin. The detonator plug is of nickel-plated brass and retains the detonator by rolling the rim of the former on to the rim of the latter. The detonator itself comprises a copper shell and closing disc containing 0.93 grs. of a Mercury fulminate, Potassium chlo-rate, and Antimony sulphide, composition. (Analysis figures are not available).

The shutter is an oval brass plate notched on one side to engage the stop pin, and pivo-ted at one end. A blind hole is drilled transversely in the side opposite to the stop pin. The detent spring is inserted in this hole together with the detent bolt. The head of this bolt presses against the side of the shutter holder and the compression of the spring re-tains the shutter against the stop.

The shutter holder is retained in the body of the fuze by insertion of the magazine and suitable washers.

The magazine-gaine is of duralumin and is threaded externally for attachment to the base of the fuze and internally to receive the brass closing plug. The latter carries at the top an 0.93 gr. perforated powder pellet. The magazine contains a 12 gr. pellet of pres-sed T.N.T. with a central pressing of 2.5 grs. lead azide. The charge is covered by a se-ries of washers as follows: one white paper, one open weave fabric, one perforated cardboard, and at the top white paper.

Fig. 34

In the safe condition the striker needle is held clear of the detonator by the centrifugal bolt, and the flash channel is closed by the shutter.

On firing the striker will set back against the centrifugal bolt and lock it in position, at the same time the shutter sets back on the base of its holder and remains closed.

In flight the centrifugal bolt opens and the striker remains "floating" over the detonator, at the same time the shutter opens against the spring-loaded detent.

On impact the striker driven on to the detonator, flash is boosted through the perforated powder pellet and actuates the magazine filling and to that of the shell.