Patent GB-777779-A (GB)
Title: Improvements in and relating to a safety arming mechanism for fuzes
IPC: F42C15/18
Filed: 1955-06-06
Abstract: 777,779. Projectile fuzes. ROSSELET, J. June 6, 1955 [June 8, 1954; Sept. 11, 1954; Sept. 11, 1954; May 25, 1955; May 25, 1955], No. 16124/55. Class 9 (1). Safety mechanism for arming a fuze comprises a spindle 1 mounted axially of the fuze in plates 3, 5, the spindle being hollow to allow the passage of a striker 7. A weight arranged to rock about an axis perpendicular to the spindle 1 comprises two arms 8, 9 rigidly connected by stays 10, 11, the arm 8 being rigid with a spindle 12 mounted in a bearing 14 and the arm 9 being rigid with a spindle 13 mounted in a bearing 15. Movement of the weight is controlled by a spring 16 coiled round the spindle between the arm 8 and bearing 14. Escapement mechanism connecting the spindle 1 and the weight comprises a wheel 19 rigid with the spindle 1 and a sector 20 rigid with the spindle 13. A driving spindle 21 to rotate the spindle 1 is fixed at one end to the bearing 2 and at the other to a ferrule 22 rigid with the spindle 1 and is wound by means of the bearing 2. The striker is held by a slotted bolt secured by a member 25 rigid with the plate 5. When the spindle 1 has turned through a predetermined angle, the bolt comes into line with a port in the member 25 and is urged outwardly by centrifugal force, thus freeing the striker and arming the fuze. Two spring blades 30, 31 act as stops for the rocking weight. The wheel 19 intermittently engages the sector 20, so that the rotation of the spindle is controlled by the oscillations of the weight. When the mechanism is fitted in the fuze of a rotated projectile, after firing, the locking springs 30, 31 are forced outwards by centrifugal force and release the weight which is then oscillated by its spring 16 and releases the spindle 1, which after a predetermined rotation allows the bolt to escape and free the striker. The locking bolt may be replaced by a lever rigid with an arm, the lever and arm being pivoted at their junction, so that a cam follower at the free end of the arm travelling on a cam rigid with the spindle 1 causes the lever to swing out after a predetermined rotation of the spindle and thereby releases the striker. Fig. 6 shows a modified radially sliding bolt 51 locked by a cam 54 on a spindle 55 parallel with the spindle 1 and carrying a toothed wheel 56 driven by a pinion 57 on the spindle 1. Thus as the spindle 1 rotates the cam 54 also rotates, and allows the bolt to move outwards thereby freeing the striker 53. Instead of a sliding bolt, an inertia-actuate mass may be used to block the mechanism, Fig. 10, the mass 82 being held in the locking position by a spring 83. A plug 85 screwed into the casing 81 forms a housing for a detonator and primer. After firing a projectile containing the mechanism, the mass 82 sets back by inertia and uncovers ports 89, 90 thus releasing the springs 30, 31 which hold the rocking weight. Two compound rocking weights may be used, the plane of one being perpendicular to the other, so that the centrifugal torques on the weights, which tend to damp out the oscillations, compensate each other. The compensating weights may be discs symmetrically loaded or with symmetrically placed apertures or the weights may be carried by cross-shaped supports. In an alternative arrangement, Fig. 19, the spindle 201 housing the striker, carries a wheel 219 engaging a sector 220 as in Fig. 3. The rocking sector is mounted on a pivot 213 bearing against an attachment screw 229 and rigid with a pinion 221 which meshes with a wheel 222 freely mounted on the spindle 201. A spring 223 maintains the oscillations of the wheel 222. In Figs. 21 and 22 the central spindle 403 carries a cam 405 followed by the nose 413 of a lever 406 pivoted at 407 and ending in a projection 408 which locks a bolt 410 beneath the striker 404. After a predetermined movement of the spindle 403, the nose 413 enters a recess 415 in the cam and further movement of the spindle turns the lever 406 thereby releasing the bolt 410, which then uncovers the passage 417 between the striker and a primer 418. The bolt may be a flat plate arranged to swing in its own plane when released. The modified bolt of Fig. 24 has a primer recess 427 communicating through ports 428, 429 with an annular space 430 in a detonator carrier 426 when the bolt is in the locking position. On release by the cam follower, the bolt moves to bring the primer into line with the striker. In the modified cam 502 of Figs. 28, 29 the recess 504 has two shoulders 508, 508<SP>1</SP> to engage a plug 509 guided by a ring 510 rigid with the lower plate of the mechanism. A port 512 in the ring 510 allows entry of the cam follower, while a second port 513 allows outward movement of the plug 509. Not until the plug escapes, can the nose 413 engage the recess in the cam. The stationary ring may have a single opening permitting both escape of the plug and entry of the cam follower.