(Fig. 3)

The fuze has a combined graze and direct action with an optional delay of 0.15 second and is used in H.E. shell of equipments as follows:–

The designation "A.Z. 23" is stamped above the flange of the aluminium body diametric-ally opposite to the optional delay setting plug. The period of delay is stamped adjacent to the plug in the form "V. 0,15". To obtain delay the slot in the head of the setting plug is set coincident with the index marks lettering "M" and "V". For action without delay the plug is set to the "0" index.

The weight of the fuze is 15 oz. 6 drs. The dimensions are shown on the drawing.

The aluminium body of the fuze is in two parts. The head portion, which is screwed to the lower part, is solid and tapers towards the nose. A channel is formed through its centre to accommodate the wooden hammer and the needle pellet. The channel is closed against air pressure at the top by a brass disc which is secured by a brass collar fitted around a step formed in the nose of the fuze. The head is secured to the lower part by a fixing screw.

The lower portion of the body is tapered above the flange to correspond to the head and is screwthreaded below the flange for insertion in the shell. Near the top it is reduced in diameter and screwthreaded to receive the head and is recessed to accommodate the graze pellet. Another recess, formed in the base, contains the delay holder with a shut-ter and is screwthreaded to receive the magazine. The two recesses are connected by a central flash hole and, in inclined flash channel. A radial channel for the optional delay assembly leads from the exterior to the lower recess.

The aluminium needle pellet, fitted with a steel needle, is supported above the graze pel-let by a creep spring and by five centrifugal aluminium segments pivoted on the top of the lower portion of the body. The segments are held between the base of the needle pellet and a shoulder on the graze pellet by an expanding spring ring.

The graze steel pellet carries an igniferous detonator supported by a perforated screwed plug.

The delay holder consists of a cylindrical aluminium pellet with a flash channel through the centre and a second channel, displaced from the centre, which contains a delay fil-ling and coincides with the inclined flash channel from the recess containing the graze pellet. A slot formed in the top of the holder to receive the shutter extends to just bey-ond the central flash channel. At the outer end of the slot the holder is recessed to re-ceive the inner end of a centrifugal bolt forming part of the shutter. A tin disc with per-forations corresponding to the channels in the holder is inserted above the holder.

The shutter assembly consists of a copper plate attached to a cylindrical bolt and is contained in the delay setting plug with a spiral spring which tends to retain the shutter in a position to close the central flash channel. The width of the shutter is greater than the diameter of the centrifugal bolt.

The delay setting plug is recessed from the inner end to accommodate the centrifugal bolt and the spiral spring and has two slots to receive the sides of the shutter projecting beyond the bolt. The outen end of the setting plug is closed and has a groove for the setting key. The plug is retained in the fuze body by a screwed securing ring which en-gages a flange on the plug but does not prevent it being turned in setting.

The magazine contains a pressed perforated pellet of gunpowder weighing approximately 2 drams and has flash hole in the base closed by a paper disc.

Before loading, the fuze is set for delayed or non-delayed action by means of the setting plug.

During flight the coil of the expanding spring ring is enlarged and the segments swung clear of the graze and needle pellets by centrifugal force. The needle pellet is then held in the forward position by "creep" whilst the graze pellet is held back by the creep spring. The action of the shutter is governed by the setting plug. With the plug set to "0", the slots at its inner end are aligned with the projecting sides of the shutter and permit the centrifugal bolt to move outwards, taking with it the shutter and exposing the central flash channel in the delay holder. With the plug set in alignment with the "M" and "V" markings, the slots in its inner end and are not in a position to receive the protruding sides of the shutter. The movement of the shutter and bolt is thus prevented and the shutter remains closed.

On graze, the graze pellet moves forward, compressing the creep spring, and impinges the detonator on the needle. With suitable impact, the hammer and striker pellet are dri-ven in as the graze pellet moves forward and a more rapid action is obtained.

The flash from the detonator ignites the delay composition in the delay holder through the inclined flash channel and, if the shutter has opened, at the same times passes through the central flash hole and explodes the powder pellet in the magazine. With the fuze set for delay action, the central flash hole is masked by the shutter and the explo-sion of the magazine filling is brought about by the delay composition.

Fig. 3