DESCRIPTION. This fuze can be distinguished by the markings and by the raised boss on the fuze head. It is otherwise similar in appearance to the (67) fuze. (See fig. 188.)

The clockwork mechanism completes its run in three periods: during descent, for about 1/2 second; on impact, for about 5 seconds; after disturbance, for about 1 second.

The mainspring of the fuze is wound around a stud and engages a release pin, tending to force the driving wheel in a clockwise direction. This driving wheel, mounted on a boss, carries two projecting pins and has a slot through which the arming rod passes into the lower fuze casing. One sector of the driving wheel is toothless.

The balance wheel controls the running speed by the action of the two pellet bosses on the escapment. Attached to one of these bosses is a small spring (not shown) which bears against the arming rod and so locks the mechanism until the arming rod is with-drawn during descent.

An inertia spring is anchored by a srew and carries on its free end a stop pin projecting from a weighted boss. A lossely mounted inertia block is supported by a length of spring steel held in place by a stud.

The striker assembly,  containing a striker spring striker, and cap, is identical to that of the (41) fuze. The striker is held cocked by the detent spindle, on which is mounted the striker detent lever, which is prevented from rotating by the restraining arm.

OPERATION. The safety pins or wires are reeved through the holes in the studs on the top of the fuze head and also through the holes in the arming rod. These are removed before the bomb is loaded in the container.

On release from the container, the vanes rotate and withdrawn the arming rod from the fuze body, freeing the balance wheel. This allows the clock mechanism to run until the release pin comes against the inertia spring stop pin.

On impact the inertia moves downwards, clearing the release pin. The clock mechanism then restarts until the stop pin comes up against the nib on the inertia block. This leaves the fuze in a fully armed condition.

Any subsequent shock will displace the lightly balance inertia block, disengaging the nib from the stop pin. The clock mechanism then begins its final run.

After running for about 1 second, the toothless sector of the driving wheel comes into line with the pinion the escapement which therefore ceases to control the running speed of the clock. The driving wheel continues to run with increased momentum until the re-lease pin hits the restraining arm and disengages it from the striker detent lever. The compressed striker spring is then free to force the striker into the cap and explode the bomb.

REMARKS. 1. The (70) B/1 is identical to the normal (70) B, except for minor modifica-tions in the clockwork mechanism.

Figure 188 – (70) B Clockwork Antidisturbance Fuze