Patent GB-561931-A (GB)
Title: Improvements in or relating to detonating mechanism for aerial bombs, pyrotechnic devices and the like
IPC: F42C5/02
Filed: 1941-10-06
Abstract: 561,931. Fuzes for bombs. HEBARD, H. C., and IMBER RESEARCH, Ltd. Oct. 6, 1941, Nos. 12902 and 14210. [Class 9 (i)] A detonating device for bombs, pyrotechnic devices and the like comprises a striker normally restrained from movement by mechanical means which are released at a predetermined height above sea level by an aneroid device responsive to changes in atmospheric pressure. The fuze comprises a casing 1 fixed to a nose 3 having an internal fixed sleeve 5 with two sets of apertures 10, 19 containing balls 11, 18, respectively. Mounted to slide on the fixed sleeve, is a sleeve 15 having one end 16 internally tapered to an angle greater than the angle of friction between the sleeve and the balls 11 and the other end internally chamfered to engage the balls 18, so that the sleeve is normally held stationary by engagement with the two sets of balls. The balls 11 normally restrain a spring-pressed striker 4 against endwise movement towards a detonator 8 while the balls 18 coact with a tapered rod 20 secured to one end of a bellows 26 having an internal spring 27, the other end of the bellows being formed by disc 28 forming one end of a casing 31 adapted to be pressed bodily downwards within the outer casing by a spring 30. The air in the bellows is reduced in pressure and the disc 28 normally contacts with a screw 32 mounted in a nut 33 fixed to the casing and adapted to be rotated therein by a wind vane 34; a spring mounted cap 36 normally protects the wind vane and a stop device 48, 49 determines the inward adjustment of the screw 32. A limiting stop 35 is also provided in the base of the casing 1 and a hand-removed screw safety pin 40 is interposed between the striking pin and the detonating cap. The angle of taper of the rod 20 is equal to the angle of friction between the rod and the balls 18, so that the rod can be withdrawn from between the balls without effort on operation of the bellows due to increased air pressure. As the bomb is taken up with the aircraft, the decrease of pressure acting on the bellows causes the tapered pin 20 to be pressed upwardly' so that the balls 18 press against the cylindrical part of the pin. After the stop pin 40 and the cap 36 have been removed, the bomb is released and the wind vane rotates to release the screw stop 32 which falls off, thus allowing the spring 30 to press the bellows casing bodily downwards against the stop 35 and arm the bomb. As the bomb descends, the pressure of air inside the casing and on the outside of the bellows increases, so that the bellows contracts and the pin 20 is drawn downwardly until the balls 18 abut against the conical portion 15 of the pin 20 and finally slide inwardly radially by the pressure of the spring 13 and firing pin 14 on the balls 11 and tapered portion of sleeve 15, so that the sleeve is released and moves downwardly releasing the restraining balls 11 and consequently the firing pin, so that detonation occurs. According to the first Provisional Specification the movable sleeve coacting with the retaining balls is attached directly to the bellows device and is operated thereby to release the restraining means. Specification 561,894 is referred to.