Patent GB-791826-A (GB)
Title: Improvements in or to double-acting percussion fuse provided with a safety device for projectiles
IPC: F42C9/04
Filed: 1956-04-17
Abstract: 791,826. Ammunition fuzes. ELLIS, L. S. E. (Anstalt Mineral'co). April 17, 1956, No. 11672/56. Class 9(1) A clockwork controlled direct action percussion fuze intended for unrotated projectiles, and having safety means for preventing accidental operation during transport and preventing premature operation after firing, comprises a toothed locking member adapted to be released by the clockwork after a given time to bring a slot in the member into alignment with a plunger and an inertia block carrying a primer and thus arm the fuze for operation on impact. The clockwork b is held in the fuze body a by an elastic washer c<SP>2</SP> bearing against the cap c. Within the frame, b<SP>1</SP>, b<SP>2</SP>, b<SP>3</SP> of the clockwork is housed a toothed rack d formed of superposed plates held together by a rivet d, and each provided with a key-hole slot d<SP>3</SP> through the narrow part of which extends the plunger i having a shoulder i' engaged by the rack. The rack meshes with a pinion e of a gear train f, g, the gear g being an escapement wheel co-operating with a lever h integral with a balance-wheel h<SP>1</SP>, Figs. 1 and 2, pivoted about the plunger. The plunger i extends into a piston j supported by a spring k which counter-balances the air-pressure on the piston. The rack d is held against the action of its spring d' by a pin l having a ball-and-socket joint in a piston m, Fig. 5, supported by a spring n. The upper end of pin I engages one arm h<SP>2</SP>, Fig. 2, of the balance-wheel to prevent the wheel oscillating and so locks the rack. The block o carrying the primer o<SP>2</SP> is supported by a plug o<SP>3</SP> and held by a spring o<SP>4</SP> so that the block contacts the rack d. A metal tongue p obturating the flash passage leading from the primer o<SP>2</SP> to the detonator (not shown) is housed in a washer q, and locked by a pin s parallel with the plunger and held in the locking position by the rack d. Before using the fuze a cap u covering the piston j is removed. On firing, the pin l and piston m set back due to inertia compressing the spring n and releasing the balance-wheel which is then oscillated by spring d<SP>7</SP>, the rack d and gearing f, g. The pin l swings aside and the rack moves until the enlarged end of the key-hole slot is aligned with the shoulder i<SP>3</SP> of the plunger. A spring p<SP>2</SP>, then displaces the obturator p driving the locking pin s upwards so that it engages the slot in the rack, a flash opening p<SP>4</SP> in the obturator is then aligned with the primer. The fuze can then operate by a blow on the piston j driving the plunger against the primer or the primer may be carried against the striker by the inertia of the block o. In a modification a toothed sector is used instead of a rack The pin s locking the obturator p may be rigid therewith and extend into a cavity in the plug o<SP>3</SP>, so that the plug o<SP>3</SP> locks the pin s. After the toothed sector has brought the eye of the slot into line with the plunger and inertia block, the spring of the obturator through the pin s may displace the block and free the obturator to clear the flash passage. The pin l locking the balance may be a split pin and may be rigid in the piston m.