GB789761A - Improvements in projectile fuzes - Google Patents

Abstract

789,761. Ammunition fuzes. SOC. TECHNIQUE DE RECHERCHES INDUSTRIELLES -ET MECANIQUES. Sept. 16, 1955, No. 26649/55. Class 9(1) A base fuze for a rifle grenade which is armed by the propellent gases has a body 1- in which a bolt 2 is secured by shear pins 3 to prevent the escape from a sleeve 4 of -a ball 6 latching a striker 5. On launching the grenade, the propellant. gases pass through the tail S and act on a piston 2 extending from the bolt 2. The pins 3 shear and the bolt moves forwards until it abuts a cushion 4<SP>1</SP>, e.g. of lead, stressing a spring 9 as it moves. The gases prevent the return of the bolt 2, until the grenade leaves the rifle when the spring 9 thrusts the bolt against the end 10 of the tail tube. The ball 6 then escapes freeing the striker and arming the fuze for actuation on impact, when the striker moves forward due to inertia to strike a detonator 8. When the grenade is to be discharged by a cartrige fitted with a wad or dummy bullet, the piston 2 has a domed head to reduce the possibility of jamming or deformation of the piston by solid debris from the cartridge. To further protect the piston, filtering orifices for the gases may be provided at the forward end of the tail tube. The fuze may also be mounted in a selfpropelled projectile between the motor and the war-head as in Fig. 5. The base a of the fuze forms the front closure of the motor and supports a partition c which guides the piston 2'. Filter orifices 11 for the gases communicate with a chamber 12, which in turn communicates with the piston chamber 13 through a hole 114, to assist the filtering action. Additional filtering means may be provided comprising a cushion 15 of thin copper, within the motor, a second cushion 16 before the opening 114 and an annular baffle 17 in the chamber 12. A further expansion chamber 18 may be formed in the piston 2'. In Fig. 6 the bolt 27 with integral piston 27<SP>1</SP> is held by a circlip 29 against a ring 24 secured by shear pins 25. Within the bolt is a safety ring, 30 held against the ring 24 by a ball 31 and by a circlip 32 surrounding the striker sleeve 20. On discharge of the grenade, the gases push the bolt 27 against ring 24, the pins 25 shear, and the ring 24 moves towards a washer 34, preferably of lead, and the ball 31 escapes into an annular space 34<SP>1</SP>. As the projectile decelerates, spring 33 pushes the ring 30 forwards and the ball 22 frees the striker. The ring 30 may be replaced by a ring locked by balls housed in the pistoncarrying bolt, which bolt is itself secured by shear pins as in Fig. 2. In a modification of Fig. 5, the chamber 13 has an annular inwardly projecting flange surrounding the piston with small clearance for the piston. A layer of fusible material, such as paraffin wax or tallow, is also placed over the axial passage leading from the propellent chamber to the piston, to prevent unburnt matter entering the fuze and to provide a lubricant for the fuze passages.