(Fig. 5)

This fuze, which consists of a slightly modified le.Jgr.Z. 23 n.A. with the addition of a wooden striker extension rod and nose bush to fit into the ballistic cap, is used in pro-jectiles with ballistic caps. It is being replaced by the Hbgr.Z. 35, also descirbed in this pamphlet.

It is designed to function on impact through a wooden extension rod or on graze and has an optional delay of 0.15 seconds.

The fuze consists of an aluminium body, needle, needle holder, creep spring, centrifugal segments, expanding spring ring, detonator pellet, detonator collar, delay mechanism and a magazine.

The body is in three sections, to facilitate the assembly of the mechanism which are screwed together and secured by spinning.

The nose section is bored centrally in two diameters to form a chamber at the base to accommodate the neelde holder, and above it, a recess to accommodate a wooden rod forming an extension to the striker. The top of the recess is coned outwards. Externally at the bottom it is screwthreaded for insertion in the centre section. The steel cylindrical needle holder is bored centrally in two diameters to receive the steel needle. The needle is secured in the holder by turning the metal at the top of the boring over the head of the needle. The underside of the holder is recessed to form a bearing for one end of the creep spring which surrounds the stem of the needle.

The centre section is bored centrally in two diameters, screwthreaded internally at the top to receive the nose section and externally at the bottom for insertion in the base section. The chamber formed in the top houses five brass centrifugal segments each pi-voting on a pin. The segments are surrounded by an expanding spring ring which, at rest, prevents the needle and detonator pellet moving towards each other to fire the detona-tor. The lower chamber houses the detonator pellet.

The detonator pellet is of steel, cylindrical in shape, and smaller in external diameter at its forward end; it is bored centrally in three diameters to form an internal flange sepa-rating two chambers. The upper chamber receives the base end of the creep spring and the point of the needle, and the lower chamber the detonator. The detonator is retained in the pellet by a light alloy plug with central fire channel. The plug is secured by a steel pin. The base of the plug is coned and located in an iron inertia collar. Paper washers are inserted between the plug and detonator.

The base section of the fuze body is bored, centrally to form chambers for the collar, delay holder and magazine, and radially to accommodate the delay mechanism. It is screwthreaded internally at the top to receive the centre section and externally at the base below the flange for insertion in the shell. The chamber at the top houses an iron inertia ring rustproofed by some process which leaves a matt surface. The ring is square in section and coned internally at the top to match the coned portion of the plug in the detonator pellet. The diameter of the ring is considerably less than that of the chamber which houses it. The ring is centred by five upturned lugs of a rustproofed steel washer which fits closely at the bottom of the chamber. The chamber at the bottom houses the delay holder above a magazine which closes the base of the fuze.

The delay holder is an aluminium pellet with a central flash channel, and another channel, displaced from the centre, filled with delay composition. Both channels are in communi-cation with the magazine filling and there is an inclined channel between the delay com-position and the centre of the fuze. A recess in the top surface of the holder accommo-dates a centrifugal shutter. The delay composition, in a similar fuze, consisted of sulphur 9.2 per cent, potassium nitrate 72.6 per cent, charcoal 18.2 per cent.

The magazine is screwthreaded externally and contains a perforated pressed pellet of gunpowder. A flash hole in the base of the magazine is closed by a paper disc inserted below the pellet.

The central flash channel in the delay holder may be closed or opened by an optional delay mechanism. The delay mechanism consists of a setting plug, centrifugal bolt, spiral spring, plate and screwed ring. The setting plug is tubular steel closed at one end and has a slot on the outside which serves as a setting index. The plug is retained in the fuze body by the steel screwed ring. The cavity in the plug houses a cylindrical steel centrifugal bolt and spiral spring. When the fuze is set to non-delay, a slot, cut diametri-cally across the mouth of the cavity, receive a centrifugal copper shutter that slides in a recess in the top surface of the delay holder and unmasks the central fire channel. A brass plate with holes bored to correspond with the delay and central fire is placed on the holder and forms an upper surface for the copper plate.

The neelde is separated from the detonator by the centrifugal segments, which are re-tained in the closed position by the expanding spring. The shutter of the delay mecha-nism closes the central fire channel by pressure from the centrifugal bolt. This position is maintained whether the fuze is set delay on non-delay. The delay channel is always un-covered.

To set the fuze for non-delay action, the slot in the setting plug is turned to a position in prolongation with the axis of the fuze to the marking "O" on the fuze body, thereby bringing the slottered recess in the plug opposite the shutter. For delay action the set-ting plug is turned at right angles to the axis of the fuze to the marking "M" and "V" on the fuze body, and in this position the plug prevents movement of the shutter during flight, so closing the central fire channel.

The centrifugal segments swing outwards one after another, and the surrounding spring expands. During deceleratin only the creep spring prevents the detonator pellet carrying the detonator on to the needle. The centrifugal bolt of the delay mechanism moves out-wards compressing its spring, and the plate under centrifugal action slides into the plug and opens the central flash channel.

When set to delay, the plug prevents the shutter sliding under centrifugal action and the central fire channel remains closed.

By direct action the extension rod forces the needle directly on to the detonator. On graze, the detonator pellet is carried forward on to the needle, or it may be forced on the needle by a sideways movement of the inertia collar. The flash from the detonator passes either through the delay channel or through the central channel to the magazine, according to the setting of the fuze and thence to the gaine in the shell.

Fig. 5