Fig. 23

This fuze is screwed into the base of the shell on a copper washer and is secured by a fixing screw.

It consists of a body, detonator holder, needle pellet, creep spring and gaine.

The body is of steel, varnished black, threaded externally and formed with two recesses at the base to take a key for screwing into the base of the shell. Internally it is recessed and threaded to take the gaine and detonator holder. Two inclined grooves are cut in the body near the base, these lead into a lateral recess in the body into which the safe-ty balls move after the shell has left the bore.

The aluminium needle pellet with steel needle is housed inside the detonator holder. The pellet contains two polished nickel steel safety balls which are carried in a recess at the bottom of the pellet. The function of the safety balls together with the creep spring is retain the pellet in a safe position before firing.

The gaine is of steel, varnished black. It contains the detonator and exploder and is screwed into the upper end of the fuze body against the detonator holder.

Action. – Before firing the needle pellet is kept from the detonator by the creep spring and the two safety balls. The latter, when the fuze is at rest lock the pellet to the deto-nator holder.

After firing the effect of set back keeps the pellet held against the fuze body.

On deceleration after the shell has left the bore the pellet tends to creep forward over-coming the resistance of the creep spring. This movement is assisted by the safety balls which, acting under centrifugal force, are caused to ride up the inclined planes in the de-tonator holder into of the lateral recess in the body. The forward pressure of the safety balls on the pellet having ceased the creep spring reasserts itself and returns the pellet to its original position, this movement locks the safety balls in the recess in the body. The pellet is now held from the detonator only by the creep spring. On impact the pellet is carried forward on to the detonator overcoming the spring. The flash ignites the deto-nator in the gaine which in turn detonates the bursting charge of the shell.

Fig. 23