This fuze was introduced for use with common lyddite shell, in the Land Service, for Coast Defence guns, Q.F., 12-pr. to 4.7-inch inclusive. In the Naval Service with the B.L., 4-inch, Q.F., 12- and 14-pr., 4-inch and 4-7-inch.
This fuze, as existing stock is used up, will be superseded by the D.A. Impact, No. 45, fuze.
Description.The fuze consists of the following parts :Body, bottom plug, percussion holder with detonator, screw collar, steel plug and shearing pin, safety cap and securing pin.
Body.The body is generally similar to the Fuze, percussion, D.A. Impact, No. 13, Mark IV, but longer, and the lower part of the body is not screw-threaded. It is bored out from the bottom to form a magazine and screw-threaded for the bottom plug. The fuze body is also bored out from the top to take the percussion holder, a central channel forming a communication between the percussion chamber and the magazine of the fuze ; this channel is filled with loose " com*position exploding," stemmed in, and retained in position by a disc of thin white paper secured with shellac.
A disc of tinfoil is shellaced into a recess in the bottom of the percussion chamber.
The magazine of the fuze contains a pellet of " composition explod*ing," compressed under a pressure of 2 tons per square inch ; the bottom is closed by a solid screw plug, covered on the inside with a disc of shalloon and coated on the underside with Pettman's cement.
Percussion holder.The percussion holder screws into the top of the fuze. Suspended in this holder by means of a steel shearing pin is a steel plug with a needle point ; this needle point is directly over a detonator.
The detonator contains four grains of fulminate of mercury ; it fits into a brass collar screwed into the underside of the percussion holder.
A brass disc placed on top of the holder, and spun into position, ,prevents the ingress of damp into the fuze.
Safety cap.The safety cap is of manganese bronze, and has two " T " shaped slots cut in the flange to engage with two brass pins in the head of the fuze.
Securing pin.The safety cap is retained in position by means of a securing pin passing through it and the side of the head of the fuze.
The later issues had a slot cut across the head of the cap and then painted red to show the direction in which the securing pin must be withdrawn.
Action.At the last moment of loading the securing pin and safety cap are removed. The fuze is quiescent in all its parts till direct impact takes place, when the steel plug is crushed in, shearing its steel pin, and carrying its needle point on to the detonator. The explosion of the detonator fires the loose " composition exploding "