The fuze, which weighs 2 oz. 0 3/4 dr., is used in the 3.7 cm Pak (anti-tank gun) H.E./ Tracer shell described in Pamphlet No. 6 and is of aluminium alloy with a body tapering towards the flat topped nose. The tip of the fuze is red and the stamping "3,7 cm Kpf.Z. Zerl.P." on the side of the body, is also coloured red. The fuze is of the direct action type and includes a safety device which is released by the disintegration of a pellet of gunpowder. The detonator which ignites the powder pellet also ignites a delay compo-sition which connects with the magazine of the fuze and provides a self-destroying ac-tion when direct action does not occur.

The direct action mechanism is contained in a central recess in the body and consists of an aluminium hammer supported by a steel pellet which is integral with the needle. The needle pellet is supported by a centrifugal bolt which protrudes from a radial channel in the body. The hammer consists of a circular disc with a stem which passes through a guide screwed into the body recess. The recess is closed at the top by a thin brass disc and has a hole at the base for the stem of the needle which enters a guide in the maga-zine adapter.

The brass centrifugal bolt is slotted at its inner end to fit round the stem of the needle and has a collar formed round its centre which limits its inward movement. A stem formed on its outer end bears against a pellet of gunpowder contained in an aluminium perfora-ted capsule attached to the inner side of the closing plug of the radial channel. The cap-sule is cylindrical with a concave wall with perforations equally spaced around it. The inner end of the capsule, which bears against a lead washer supported by a shoulder in the radial channel, has a hole in the centre to receive the stem of the centrifugal bolt. The screwed closing plug carrying the capsule has a lightly closed vent at its centre for the escape of pressure when the powder is ignited. Two inclined flash channels connect the radial channel with a recess containing a detonator and needle assembly.

The recess containing the detonator with its spiral supporting spring and screwed needle is displaced from the centre of the fuze. The two inclined flash channels connecting the recess with the radial channel are located one near the top of the recess and the other near the bottom. An additional inclined flash channel, also near the bottom of the recess, connects with the channels containing the delay composition for the self-destroying action.

The delay composition for the self-destroying action is contained in two vertical channels with a transverse connecting channel. The flash channel from the detonator recess leads into the closed lower end of the first vertical channel. This channel is filled from the up-per end with delay composition and closed at the top by a plug which is machined to correspond with the tapering body of the fuze. Near the top of the channel a transverse channel containing pressed gunpowder leads into the upper end of the second vertical channel which also contains delay composition and is open at the base where it is in contact with a circular disc of pressed gunpowder carried in a recess in the top of the magazine adapter.

The magazine adapter screws into the underside of the body and carries a magazine si-milar to that to the A.Z. 39, as described in Pamphlet No. 4. The circular recess in the top of the adapter has a cylindrical projection in the centre which is drilled to form a guide for the needle. The pressed pellet of gunpowder contained in the recess is in the form of a washer to fit over the needle guide.

Fig. 11

On acceleration the igniferous detonator in the displaced recess sets back on the needle. The flash from the detonator passes through the flash channel to the powder pellet in the radial channel and to the lower end of the delay filling in the first of the vertical channel. When the pellet in the radial channel disintegrates the bolt is thrown outward by centrifugal force leaving the needle held off the detonator in the magazine by the creep action resulting from deceleration. On impact the needle is driven in by the hammer and pierces the detonator in the top of the magazine. During flight the burning of the delay composition in the first vertical channel is transmitted by the gunpowder in the transverse channel to the delay composition in the second vertical channel. When direct action does not occur before the composition burns to the base of the second channel the disc of gunpowder confined in the top of the magazine adapter is ignited and explo-des and thus initiates the detonation of the magazine.