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Depth charge fuze No.895A Mk.1 , British, WW2

pzgr40

Well-Known Member
Premium Member
On the BOCN homepage one can see a series of fuzes on a shelf. All of them I could identify, exept the cutaway model in the back corner…. Until…I was reading the British bombs fuzes book by Peter Voss and found out it was a No.895 depth charge fuze.

I asked on the BOCN whose it was, and with some help (thanks) found out the present owner, who was willing to sell it (thanks Mick).

After receiving it I found out it most probably was a factory cutaway model as it was an exactly 90 degrees cutout, and cut exactly to the centerline.
Regretfully the cans of paint were present in those days allready, attempting to change the cutaway surfaces into a colourfull piece of contemporary art.

Time had regretfully degraded the latex rubber bellow, which fell apart into a sand like powder. To my luck I had kept the 90 degrees cut out piece of bellow from the DCP Mk.XX, which I could now use as a replacement bellow, solving the biggest problem with repairing the cutaway model.

At the same time I started investigating what fuze it was exactly; it appeared to be the ‘hydrostatic fuze No.895A Mk.1’, meant for the ‘100 Lb AS (Anti Submarine) bomb Mk.VI’ only. The letter ‘A’ meant that the fuze had a factory depth setting of 18 feet (5,5 mtrs) that cannot be adjusted. To mark this ‘A’ type fuze, the top cover was painted red. Mk.1 means an extra spring in the fuze housing has been added later on.

In fact there are three types of this fuze No.895:
*Fuze No.895A (Mk.1), for the 100 Lb AS bomb MkVI, red top cover, depth setting 18 feet (5,4 mtrs).
*Fuze No.895B, for the 25Lb AS bomb type 1 Mk.1, blue top cover, depth setting 22 feet (6,7 mtrs).
*Fuze No.895C, for the 600Lb AS bomb Mk1, green top cover, depth setting 30 feet (9,1 mtrs).

This does not seem very deep, but one should realize that the time between discovery of a U-boat from an airplane, diving towards it and bombing was relatively short, giving the U-boat ample time to dive. Therefore, a submarine attack was mostly on the surface, either in the initial stage of diving, making these depth setting suitable for a kill.

The entire fuze housing is made of Duralumin, an alloy of copper and aluminium, which can be easily cast and machined. Only some of the inner mechanism parts are steel made.

Functioning of the fuze:
On the outside of the fuze body three water inlet holes (1) are placed on the circumference, at 120 degrees each. This allows water to enter the bellow (2). If the water enters the bellow it will expand as the bomb sinks deeper due to the water pressure, pushing the steel ring (3) which is connected to the firing pin retaining bushing (4) both upward. The firing pin (5) is kept in locked position by two balls (6) which fall into a groove in the firing pin (5) and two holes in the firing pin retaining bushing (4). If the steel ring (3) and the firing pin retaining bushing (4) have been pushed upward to a certain degree, both steel balls (6) will be able to move sideways into a reces machined in the base flange (7), releasing the firing pin (5). A hook (not visable in picture, see drawing part No.4) is machined to the firing pin retaining bushing (4), connected to the rotating safety shutter (8 ). In safe position the firing cap (9) in the safety shutter is rotated 90 degree out of line with the firing pin (5), when the steel ring (3) and the firing pin retaining bushing (4) both move upward, the hook rotates the safety shutter (8 ) 90 degrees anti clockwise to place the firing cap (9) in line with the firing pin (5), just prior to release of the firing pin. The firing cap is than also in line with the booster (10).
In top of the fuze body, a mechanism is placed, consisting of a spring (12) loaded sleeve (11) with a groove in top, into which two steel balls (13) are placed. This mechanism is meant to prevent the fuze from being activatd when the bomb would land tail first on the waves (backward), throwing the firing pin (5) backward through inertia, releasing the steel balls (6) and activating the bomb prematurely. If the bomb falls backwards, the sleeve (11) is thrown backward by inertia, pushing the steel balls (13) inward, preventing the firing pin (5) from upward movement.
On top of the top cover a safety piston (14) is installed through which a wire is installed when the bomb is placed in the bomb rack. When dropping the bomb the wire is retracted , allowing the piston to move backward, pushed by the firing pin when it moves backward on activation by waterpressure.

Dimensions of the fuze No.895A Mk.1:
Complete length o.a. :183,8mm
Diameter fuze body : ø73,8mm

All together an interesting addition to my collection of British WW2 depth charge fuzes and pistols that got a nice place in the glass case.

Regards, DJH
 

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  • Pict.05 - DC fuze No.895A Mk.1 before and after repair.jpg
    Pict.05 - DC fuze No.895A Mk.1 before and after repair.jpg
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