Depth Charge Pistols Mks XIX and XX (Service)

Description: The pistol and valve units are separated by a distance tube. The valve body is internally threaded to receive the valve cover, which is drilled centrally and tap-ped to accommodate the valve spindle. To the top of the valve spindle is fixed an arming fork, which engages a similar fork on the end of the reach rod of a standard British tail unit. On the lower end of the valve spindle is a shoulder to which is fitted a beveled rub-ber washer, secured to the shoulder by a cotter pin and fitting into the lower valve body. The valve cover screws into the valve unit and is held in place by a set screw.

On the lower end of the distance tube is located the pistol assembly. The cover of the pistol body is threaded to the distance tube and is held into the pistol body by a locking ring. Around the sides of the pistol body are six water-entry ports, extending through the distance piece, which fits into the rubber diaphragm. The diaphragm is loca-ted between an inner and an outer sleeve. In the inner sleeve are two holes containing retaining balls, which engage and retain the spring-loaded striker. The striker spring rests on a shoulder on the lower end of the striker, and on the outer sleeve, so that as the diaphragm expands and the sleeve move apart, the striker spring is compressed. The de-tonator carrier is threaded to the lower end of the pistol body.

Operation: When the depth charge is dropped, the safety wire is pulled and the arm-ing fork is rotated by the reach rod and the vanes. After about 11 revolutions of the va-nes, the valve spindle has threaded the valve down onto the shoulder of the valve body, thus closing the valve and preventing water from entering the distance tube. After the depth charge enters the water, the water enters the water-entry ports in the top of the valve unit, and passes through the pimer tube. The water then enters the entry ports on the side of the pistol body and passes through the distance piece, causing the rubber diaphragm to expand. This moves the inner and outer sleeve apart. At the depth of 20 - 24 feet the sleeve have traveled sufficiently to allow the retaining balls to be cammed out into a shoulder in the outer sleeve. The compressed striker spring then forces the striker into the detonator.

Figure 145 - Depth Charge Pistol Mk XIX or XX