Nose, Aerial Burst, No. 860 Mk 1, Mk 2, Nose No. 896 Mk 1, Tail No. 867 Mk 1, Tail No. 885 Mk 1, Tail No. 886 Mk 1

 

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Description

The Fuze No. 860 Mk II consists of a body into which is screwed a striker housing and a gunpowder magazine fitted with a percussion cap. Inside the striker housing a compressed striker is retained by three retaining balls. These balls engage a sloping shoulder on the striker and the tapered internal surface of a sleeve surrounding the housing. The sleeve is held against axial movement, while the striker is in the cocked position, by three larger balls, which are located in three upper holes in the striker housing. These larger balls engage the parallel portion of a cone-ended arming pin, which is secured to a boss in the end of a vacuum bellows. The non-pointed end of the striker has a hole into which the pointed end of the arming pin can enter.

One end of the vacuum bellows and a stop plate form the closed end of a cylinder, which passes over the striker housing and abuts against a washer located in a cup. An arming spring is compressed between the cylinder and the fuze body. The vacuum bellows contain a spring, which regulates expansion or contraction of the bellows by atmospheric pressure.

When the fuze is unarmed, the cylinder is held down towards the magazine by an arming screw, which is screwed through an armingvane support carried by a thin outer cover attached to the fuze body by screws.

The arming screw supports an arming vane which is so mounted that it is permitted half an inch of free travel before it locks against the head of the arming screw. Two stop pins, one projecting from the arming-vane support and the other from the arming-vane hub, prevent these two parts from binding together.

The arming vane is protected against damage, premature rotation, and freezing by an arming vane cover bedded against the outer cover of the fuze. The arming-vane cover is fitted over three clips riveted to the outer cover. A vane stop, riveted to the inside of the arming vane cover, prevents premature rotation of the arming vane due to vibration.  A lug is provided on the arming vane cover for attachment to the fuze-setting control link of a bomb carrier.

Four vent holes in the outer cover permit air to escape from inside, thus relieving excess pressure built up inside the fuze while falling after the arming screw has fallen away. The vent holes are covered by adhesive tape on which is written: TO BE REMOVED AFTER FLARE IS FIXED ON CARRIER.

A safety pin is housed in the fuze body between the striker and percussion cap, so that, if the striker should be prematurely released, the safety pin will prevent its firing the cap. The safety pin is held in place by a shear wire in a groove around the fuze body and in a slot in the head of the pin. A spring, housed in the body, is compressed beneath the head of the safety pin. A clip is mounted on the shear wire and can slide along the wire.

The Nose Fuze No. 860 Mk I differs from the Mk II in that the zinc-colored section of fuze is of greater diameter than the rest of the body.

The Nose Fuze No. 896 is the same as the No. 860 Mk II, but a delay element has been introduced between the cap and the magazine. The fuze is designated either A2, A3, or A4, the figure in each case indicating the length of delay in seconds.

The Fuze No. 867 Mk I has no arming vane but is instead fitted with a T-bar, which engages an arming fork on the standard British tail unit.

The Tail Fuze No. 885 Mk I is the same as the No. 867 Mk I, but has a 2-sec. delay.

The Tail Fuze No. 886 has a shear wire to prevent arming at low speeds, and a 1-sec. delay.

See Also

Nothing else to see.

Source(s)

OP 1665, British Explosive Ordnance (1946)