(Fig. 2)

The fuze, as indicated by the letters "Nb" in the abbreviated desgination, is intended for use in smoke shell but has also been found in H.E. shell for the anti-tank equipment 7.5 cm Pak 40. The deep olive green painting of the exterior distinguishes this fuze, lar-gely of moulded plastic with a steel casing, from the aluminium fuze of the same desig-nation which is described with the 7.5 cm smoke shell in Pamphlet No. 4.

The fuze body consists of a thin steel ogival casing attached by spot welding to an inner cylindrical steel casing both of which cover moulded brown plastic. The ogival casing has a hole at the top for the wooden hammer. The hole is closed by a brass disc overlapped by the casing. The cylindrical casing is inserted from the base of the ogival portion and attached about half way up the interior. The lower part of the cylinder protrudes and is screwthreaded for insertion in the shell. The plastic interior is in two parts. The larger part, forming the centre of the body, is shaped to accommodate the graze and direct action mechanism and has an interior screwthread in the lower portion to receive the moulded plastic base plug. The smaller part of the plastic interior is in the form of a collar which surrounds the cylindrical casing within the ogival portion.

The fuze mechanism consists of a steel graze pellet carrying an igniferous detonator below a needle fitted to an aluminium pellet. The needle pellet is recessed at the base and is held away from the graze pellet by a creep spring and by five pivoted centrifugal segments. The segments are held in engagement with a shoulder on the graze pellet by a spring in the form on an expanding ring and are pivoted on the top of the plastic base plug. The plug is recessed and fitted with an aluminium liner to contain the graze pellet and has a flash hole at the base.

The coil of the expanding spring ring is enlarged and the segments swing clear of the graze pellet by centrifugal force during flight. The needle pellet is then held in the for-ward position by the "creep" resulting from decelearation and is protected from air pres-sure by the brass sealing disc in the top of the fuze. Forward movement of the graze pellet is prevented by the creep spring.

On graze, the graze pellet sets forward, overcoming the creep spring, and impinges the detonator on the needle. With suitable impact the needle is simultaneously driven to-wards the graze pellet and direct action is obtained. The flash from the detonator passes through the flash channel in the detonator plug, and through the flash hole in the base of the fuze to the gaine beneath. The recess in the base of the needle pellet is appa-rently designed to fit over the top of the graze pellet and thus prevent the flash being expended in the wrong direction.

Fig. 2