(Fig. 1)

This fuze is of the direct action and graze type with an optional delay of 0.15 seconds. It is used with low velocity equipments as a substitute for the A.Z. 23 (0.15). The design is similar in principle to the latter fuze, but the springs surrounding the centrifugal safety segments and operating the delay shutter are weaker. The fuze may be identified by the stamping "AZ 1" on the flange as illustrated in Fig. 1.

The fuze consists of the following principle components, steel body, light alloy ballistic cap, wooden needle extension, steel needle, creep spring, six light alloy centrifugal seg-ments, a copper covered expanding spring, detent and spring, steel inertia pellet with detonator, plastic holder, delay mechanism, and securing ring.

The body is screwthreaded below the flange for insertion in the shell and is provided with a domed top which is secured by pressing the top of the flange around the side of the dome. The top of the dome is bored centrally in two diameters and bushed to receive the sleeve and needle holder.

The ballistic cap is attached to the fuze body by canneluring it above the flange and tur-ning its lower edge under the flange. The top of the cap is flat and closed by spinning it over a small disc of the same material.

The wooden rod, 2.3 inches long, forms an extension to the needle under the ballistic cap. Its head is housed in the top of the cap and its lower end is accommodated in a steel sleeve above the needle.

The sleeve protrudes from the top of the dome and its forward movement is limited by a flange which bears against a shoulder in the top of the dome.

The needle is secured in a steel holder which is recessed on its underside to form a seat-ing for one end of the creep spring. The other end of the spring is seated on a shoulder in the inertia pellet. On the underside of the holder are six centrifugal segments each pi-voted on a pivot pin.

The segments are kept towards the centre of the fuze by the expanding spring and are so arranged that one, which locks the remainder, is itself locked by a detent with spring which protrudes from the top of the mechanism holder.

The mechanism holder is cylindrical and in two diameters; it is bored centrally to accom-modate the inertia pellet. The top of the holder forms a platform for the centrifugal seg-ments; its underside is recessed to accommodate the delay shutter and to provide a flash channel to the delay filling.

The inertia pellet is bored in three diameters to accommodate at the top the needle and creep spring and, at the bottom the detonator which is secured between a paper disc and a cloth or millboard washer at the top, and two steel washers at the bottom.

The delay mechanism consists of a delay holder, sliding shutter, spring, delay setting plug, thin fixed plate and a screwed securing ring. All these pieces excepting the spring made from light alloy.

The delay holder is provided with two channels, one bored centrally and empty, and the other bored at an angle so that the top is displaced from the centre and the bottom is in communication with the bottom of the central channel. The inclined channel is filled with a pellet delay composition secured by a screwed ring. A recess in the top surface of the holder accommodates a centrifugal shutter which, at rest. masks the central channel; it is retained in this position by a light spring. In flight, movement of the plate is regulated according to the position of the delay setting plug. The setting plug is accommodated in an inclined radial channel in the fuze body and is secured by a screwed ring. The outer end of the plug is slotted for setting purposes and also to serve as an index, and its in-ner end is chamfered to a screwdriver edge. When set for delay action, it retains the shutter in the closed position, when set to non-delay, the chamfered end of the setting plug permits the shutter to slide outwards, under centrifugal action, to unmask the cen-tral channel. A fixed thin plate, with two holes corresponding with the delay and central fire channels, is fitted on the holder and forms an upper bearing surface for the shutter. The holder closes the bottom of the fuze and is retained by a screwed alloy ring.

Before firing. – The neelde is separated from the detonator by the centrifugal segments which are retained in the closed position by their spring. The shutter of the delay me-chanism closes the central fire channel by the pressure of its spring.

To set the fuze for non-delay action, the slot in the index plug is turned to a position parallel to the axis of the fuze thereby permitting the shutter to slide out under centri-fugal action when in flight. For delay action the plug is turned until the slot is positioned at right angles to the fuze axis and in alignement with the stamping "M" and "V 0,5" on the ballistic cap; in this position the plug retains the shutter in the closed position.

On firing. – The detent locking the centrifugal segments sets back, the spring surround-ing the segments expands, and the segments swing outwards one after the other under centrifugal action thus allowing the needle and inertia pellet free movement towards each other. The creep spring, however, prevents creep action. If the fuze is set for de-lay action, the setting plug retains the shutter which masks the central flash channel. If the fuze is set for non-delay action, the position of the setting plug permits the shutter to slide outwards and unmask the central flash channel.

On impact. – The needle is forced on to the detonator by direct action. On graze the inertia pellet carries the detonator on to the needle. The flash from the detonator passes either through the central flash channel or the delay channel according to the setting of the fuze.

Fig. 1