EMPLOYMENT: Mechanical nose fuze with self-destroying arrangement for 3.7-cm Pak H.E. shells. (See fig. 566.)

DATA:

Over-all length: 1.75 inches.

Maximum diameter: 1.25 inches.

Threaded length: 0.437 inch.

Number of threads: 5 RH.

CONSTRUCTION: The fuze is of aluminium alloy with a body tapering towards the flat topped nose. The tip of the fuze is red and the stamping, "3.7-cm Kpf.Z.Zerl. P." on the side of the body, is also red. The fuze is of the direct action type and includes a safety device which is released by the disintegration of a pellet of gunpowder. The detonator which ignites the powder pellet also ignites a delay composition which connects with the magazine of the fuze and provides a self-destroying action when direct action does not occur.

The direct action mechanism is contained in a central recess in the body and consists of an aluminium hammer supported by a steel pellet which is integral with the striker. The striker pellet is supported by a centrifugal bolt which protrudes from a radial channel in the body. The hammer consists of a circular disk with a stem which passes through a guide screwed into the body recess. The recess is closed at the top by a thin brass disc and has a hole at the base for the stem of the striker which enters a guide in the maga-zine adapter.

The brass centrifugal bolt is slotted at its inner end to fit around the stem of the striker and has a collar formed round its center which limits its inward movement. A stem formed on its outer end bears against a pellet of gunpowder contained in an aluminium perfora-ted capsule attached to the inner side of the closing plug of the radial channel. The cap-sule is cylindrical with a concave wall with perforations equally spaced around it. The inner end of the capsule, which bears against a lead washer supported by a shoulder in the radial channel has a hole in the center to receive the stem of the centrifugal bolt. The screwed closing plug carrying the capsule has a lightly closed vent at its center for the escape of pressure when the powder is ignited. Two inclined flash channels connect the radial channel with a recess containing a detonator and striker assembly.

The recess containing the detonator with its spiral supporting spring and screwed striker is displaced from the center of the fuze. The two inclined flash channel conneting the re-cess with the radial channel are located one near the top of the recess and the other near the bottom. An additional inclined flash channel, also near the bottom of the recess, connects with the channel containing the delay composition for the self-destroying ac-tion.

The delay composition for the self-destroying actions is contained in two vertical chan-nels with a transverse conneting channel. The flash channel from the detonator recess leads into the closed lower end of the first vertical channel. This channel is filled from the upper end with delay composition and closed at the top by a plug which is machined to correspond with the tapering body of the fuze. Near the top of the channel a traverse channel containing pressed gunpowder leads into the upper end of the second vertical channel which also contains delay composition and is open at the base where it is in contact with a circular disk of pressed gunpowder carried in a recess in the top of the magazine adapter.

The magazine adapter screws into the underside of the body and carries a magazine si-milar to that of the A.Z. 39. The circular recess in the top of the adapter has a cylindri-cal projection in the center which is drilled to from a guide for the striker. The pressed pellet of gunpowder contained in the recess is in the form of a washer to fit over the needle guide.

ACTION: On acceleration the igniferous detonator in the displaced recess sets back on the striker. The flash from the detonator passes through the flash channels to the power pellet in the radial channel and to the lower end of the delay filling in the first of the ver-tical channels. When the pellet in the radial channel disintegrates, the bolt is thrown out-wards by centrifugal force, leaving the striker held off from the detonator in the ma-gazine by the crep action resulting from deceleration. On impact, the striker is driven in by the hammer and pierces the detonator in the top of the magazine. During flight, the burning of the delay composition in the first vertical channel is transmitted by the gun-powder in the traverse channel to the delay composition in the second vertical channel. When direct action does not occur before the composition burns to the base of the se-cond channel, the disk of gun-powder confined in the top of the magazine adapter is ig-nited and explodes and thus initiates the detonation of the magazine.

Figure 566 – 3.7-cm Kopfzünder Zerl.P.