Patent GB-475093-A (GB)
Title: Improvements in clockwork time fuzes for projectiles
IPC: F42C9/04
Filed: 1936-02-11
Abstract: 475,093. Projectile fuzes. LASSERRE, J. Feb. 11, 1936, No. 4134. Convention date, Feb. 11, 1935. [Class 9 (i)] A clockwork mechanism and its casing 3, Fig. 1, is rotatably arranged in the fuze as a unit, the driving spring 2c being interposed between the casing and the fuze body, and the last pinion 3d of the clockwork mechanism engaging a crown wheel 2a on the setting cap 2, so that the clockwork unit follows the rotational setting of the cap before the projectile is discharged, and the spring becomes operative during flight to rotate the clockwork casing back, but not the cap. The cap 2 has slits 2l, Fig. 6, in the part fitting into the fuze body 1 to provide elastic friction, and is held to the fuze body by a segment 2j lodged in grooves in the cap and the fuze body, and by a grub screw 1b. The spring 2c is a helix attached at the rear end to a ring 2b in the cap 2, and is compressed by its inertia when the shot is fired. A washer 2e attached to the front end of the spring, and a piston 2d over the washer help with their inertia to compress the spring ; and at the end of this compression, the washer is caught by hooks 4b on a ring 4 provided with studs 4a in engagement with spiral grooves 3c in the tubular stem 5 of the clockwork casing. The discharge also causes an inertia lock to release the balance of the clockwork. During flight, the spring expands and drags the ring 4 forward, and the studs 4a cause the rotation of the clockwork casing under control of a dead beat escapement having a balance 8b on a central spindle connected to a torsion blade spring 6 extending up the centre of the tubular stem 5. The upper end of the spring blade fits in a sleeve 5c, which is guided by a slot 5e in the stem 5, and can be adjusted longitudinally by means of a nut 5a before the clockwork is put in the cap 2 behind a closing disc 2i. The clockwork casing is mounted between ball bearings 2h, 1j, and cushioned by a spring 1k. The balance 8b is supported by a spring 8g, Fig. 11, and provided with a flange 8c which recoils into a recess 8f in the clock-work casing to absorb the shock of discharge. When the clockwork casing sets back on discharge against the spring 1k, spikes 1a on the fuze body are impaled in the flange 3f of the clockwork casing and thus prevent rotation of this casing until acceleration is over and the casing has been returned to its forward position. In the normal zero position of the fuze, Fig. 1, a finger 2m on the cap 2 locks a centrifugal trigger 1e which holds the spring striker 1c cocked. The trigger carries a roller situated within the flanges 3f of the clockwork casing opposite a notch 3g therein. When the cap and clockwork casing are rotated to set the fuze for the desired time, the finger 2m leaves the trigger le but this is then held in place by the flange 3f. At the appointed time during flight, the notch 3g comes back in line with the roller 1f, the trigger escapes by centrifugal force, and the spring striker which carries a percussion cap strikes a firing-pin 3e on the clockwork casing. The flash from the percussion cap passes through a channel 1r to the main detonator 9. Another percussion cap 1m is provided in a momentum pellet 1l to strike a central firing- pin 3i on the clockwork casing on impact. The momentum pellet is locked by centrifugal bolts until the projectile is discharged and is held back until impact by a spring 1p.