Bombs used in

Fuzes used with

Over-all length

Width of fuze body

Material of construction

The sensitive Manzolini Fuze screws into the bomb body and forms the nose of the bomb. It is protected by the aluminum cap, which is retained by the vane cap. This latter screws into the brass adapter in the fuze cover. Two projections on the outer face pro-ject through corresponding holes in the cap and prevent the latter from rotating as the vane cap unscrews.

When the vane cap has unscrewed and has fallen away, the fuze cap is released and is forced off the fuze mainly by the rush of air acting on the projections. This is also assis-ted by the pressure of the strip springs within the cap. Each of the three strips has a brass claw which passes through one of the three equally-spaced holes in the body and holds the collar in position. A strong spring in the upper part of the fuze presses out the brass claws so that the strip springs bear hard against the cap.

After the cap has been forced off, the pressure of the strong on the steel collar, acting on the curved surfaces of the claws, ejects them completely, and the strips fall away. The steel collar then sets down and is pressed hard against the rubber rings, completely masking the fuze and preventing the entrance of sand, grit, or water.

When the bomb strikes the ground, the brass cup-shaped piece and the inertia sleeve set down. The former is cushioned by the spring, while the latter is slit in six places around the upper edge to allow it to pass the slight ridge on the cylinder. The three steel balls, which are equally spaced circumferentially, can then move outwards and free the pistons.

Under the action of the strong spring, the piston rises through the light oil in the cham-ber. The arming delay thus obtained allows the bomb to come to rest before the fuze is completely armed. Until the piston has moved upwards, the three equally-spaced balls prevent relative movement of the two cylinders.

When the piston has completed its travel, the balls roll inwards and the two cylinders are free to move relative to each other. The fuze is then completely armed. The two spacers at each end of the fuze allow lateral movement of the two cylinders, which results in the cylinders approaching each other.

Thus any jar will overcome the light spring in the base of the fuze and will cause the up-per cylinder to move down in the lower cylinder until the three pairs of steel balls come opposite the annular slot into which they then move outwards. This free the striker which, moving under the compression of its spring, impact the detonator.

A modification includes a device which will cause detonation after lapse of a certain pe-riod if the bomb has not already been detonated by vibration or interference. The diffe-rence in the piston is 0.6 cm shorter; the piston travel is shorter; the striker spring is 2 cm short; and the inertia sleeve is slit in ten pieces instead of six. The devive consists of a steel holder in which slides the hollow cylinder. The closed end of the cylinder car-ries a short projection which passes through and locates the aluminum shear strip. Above the holder sits the steel cover having eight slits in the vertical rim end enclosing the strong steel spring.

The operation of this device proceeds as follows: On impact, the cover sets down and the projection on the rim engages in the annular groove and so locks itself to the holder.

The spring within this enclosure then exerts a pressure on the shear strip through the movable cylinder. At the end of a certain period (60 to 80 hours), the strip shears and, since the projection bears in the plug, an appreciable jerk is communicated to the cylin-der to operate the fuze.

Figure 71
"Manzoline" Fuze