GB887256A - Fuze for underwater explosive charges - Google Patents

Abstract

887,256. Depth charges and fuzes therefor. MENYA Y VIEYRA DE ABREU, J. April 6, 1960 [April 6, 1959], No. 12182/60. Classes 9(1) and 9(2). A hydrostatic fuze for a depth charge comprises a head part 7 housing safety elements together with a detonator and having a tubular extension 13 to which is screwed a casing 17 housing an annular booster charge 16 surrounding a firing pin 18. The fuze extension 13 is screwed into an axial socket in the depth charge. Within the tube 13 is the detonator 21, 22 suspended from a piston 26, which is immobilised by balls 33 protruding from transverse bores 31 under the influence of springs 30 surrounding the stems of locking bolts 28. A cap 8 covering the head 7 is used to set the fuze for operation at a given depth and is secured by balls 25 pressed into a groove 24 by springs 9 compressed by screws 10. Within the cap are cam surfaces 27 which bear against the bolts 28 and, as the cap is rotated, vary the pressure on the balls 33. To prevent rotation of the cap, a ball 25 with its spring may be replaced by a screw sufficiently long to engage the groove 24. An inertia safety device 5 bears against balls 3, housed in openings in the piston, and forces them against a shoulder 4 to immobilise the piston. When the mass 5 is forced downwards by hydrostatic pressure on its upper surface, the balls 3 are freed. During transport a safety spring 2 is threaded through a ring on the mass 5 and openings in the piston 26 to prevent accidental release of the mass. Before launching the depth charge, the cap 8 is rotated to the required setting indicated by a scale on the rim of head 7. A closure 1 is then removed and the safety pin 2 withdrawn. As the charge sinks, the pressure on the mass 5 unlatches the balls 3 and, when the downward thrust on piston 26 is sufficient to overcome the inward pressure on balls 33, the piston moves downwards carrying the detonator against the pin 18 after rupturing a diaphragm 19. To prevent premature movement of the mass 5 due to shock waves produced by adjacent explosions a valve may be arranged above the mass in such a way that the shock wave closes the valve and prevents the ingress of liquid to the depth charge. The valve is restored to the open position by a spring when the excess pressure on the valve ceases.