Over-all length

Maximum diameter

Thread diameter

This fuze is a clock-mechanism arming type with a centrifugal safety bolt holding the firing pin and detonator apart. The fuze body is brass; the striker and centrifugal are alu-minum; the detonator holder and clockwork mechanism are brass.

The clockwork mechanism has a train of four wheels, each consisting of spur and pinion, and a balance wheel oscillator. The nose of the fuze, drilled through its center to take the striker and aluminum connecting rod, is closed against air pressure by a brass disc. The safety bolt forks at the inner end to provide two arms which pass under a collar of the firing pin to prevent the pin from moving towards the detonator. A recess to engage a detent is located on the underside of the bolt, and a hole in the center of one side en-gages the stem of the spring-loaded centrifugal locking bolt. In the opposite side of the safety bolt, a toothed rack is emmeshed with the first spur of the clockwork escapement mechansim. The detonator holder is kept in position by a creep spring.

On acceleration, the detent sets back, forcing the spring past the shoulder in the sleeve, withdrawing the spring past the shoulder, and withdrawing the stem from the recess in the safety bolt. The spring then engages the detent and prevents the detent from re-turning to a forward position. Centrifugal force causes the locking bolt to move out-wards. The safety bolt is then held only by clockwork mechanism. On deceleration, wheels separate, and the centrifugal bolt moves outwards under control of the clockwork escapement mechanism. When the fork portion of the bolt clears the collar, the firing pin is held apart from the detonator by a creep spring. On impact, the firing pin and detona-tor move together.

Figure 212
Percussion Nose Fuze O.BO. 34/37