Patent GB-473282-A (GB)
Title: Improvements in or relating to clockwork time fuzes
IPC: F42C9/04
Filed: 1936-04-06
Abstract: 473,282. Projectile fuzes. SCHENK, E. H., and INDUSTRIAL COMMODITIES DEVELOPMENT CORPORATION. April 6, 1936, No. 10144. Convention date, Sept. 25, 1935. [Class 9 (i)] A clockwork fuze according to the invention comprises a compression spring motor 9 in the hollow body of the fuze, a compound rotor 21 axially slidable in the said body and adapted to be driven by the said motor, and a clockwork mechanism within said rotor. In the form shown, the time release mechanism is analogous to that described in Specification 473,284, and the compression spring motor 9 is constructed and adapted to be compressed by inertia at the moment of discharge as described in Specification 473,283, except that the front ball bearing is now axially slidable in the fuze body. The compound rotor 21 is attached to central shaft 16 of the spring motor and these parts are mounted between a rear ball bearing 44 and a front ball bearing 18. Normally, the rear race 45 of the rear ball bearing is supported by the spring 46 of a striker 47, and the rotor is locked against rotation relatively to the setting cap 4 by balls 42 seated in recesses in the rotor and guided by longitudinal slots 42A in the cap. On discharge, the rotor sets back, the balls 42 come opposite radial holes 43 and escape into these by centrifugal force. At the same time a thimble 74 over the top ball bearing also sets back, and centrifugal segments 76 open out behind a shoulder 77 in the setting cap 4. The rotor sets back until the ball race 45 abuts against the top of the striker 47 and spikes 63 on the fuze body are empaled into the bottom plate of the rotor. When acceleration is over, the spring 46 returns the rotor forward until the shoulder 77 arrests the centrifugal segments 76, whereby the spring 46 remains stressed for operation of the striker, and the operation of the clockwork begins. An internally toothed gear-wheel 23 is rotatably carried by the rotor and has ears 23A in engagement with the slots 42A, whereby the wheel is keyed to the fuze cap 4. The first pinion 22 of the clockwork is in mesh with the gear-wheel 23 and the last pinion 26 is fast with the escapement wheel 27, which co-operates with a cylinder 28 on the spindle 30 of the balance 29. The top end of this spindle is attached to the lower end of an axially disposed flat hair-spring 34 guided by a tube 37 within the motor shaft 16. Near its upper end, the hair-spring passes through a slot in a plug 35 in a hollow grub-screw 36, and the end of the spring fits into a slot 31 in the nose piece 7. The plug 35 can rotate within the grub-screw 36 when the nose piece 7 is rotated, and this serves to adjust the initial position of the cylinder 28 and torsion of the spring ; after this adjustment, screws 38 are tightened to lock the nose piece 7 against displacement. The grub-screw 36 permits the effective length of the spring to be adjusted before the nose piece 7 is inserted. When the rotor sets back. at the moment of discharge, the end of the spring 34 leaves the slot 31, but is still held against rotation by friction between the plug 35 and the grub-screw 36. The setting cap 4 is normally retained in the fuze body 1 by screws 40A having projections 40 fitting into a circular groove in the setting cap to permit its rotation. The graduations are marked on flanged steel bands 3, 6 which are, mounted on the fuze body and cap 4 respectively and are formed with internal sharp teeth adapted to be pressed into an internal lead washer 71 to fix the setting cap to the fuze body after the cap has been rotated to set the time of the fuze. The timing ring proper of the fuze is constituted by the flange 60 at the bottom of the rotor. This flange has a notch 59, which, at the appointed time comes opposite a centrifugal lever 54, allowing this lever to rock outward to bring about the release of the striker. Normally, the lever 54 is held at safe by a lug 62, which is moved out of locking position when the cap is rotated from the zero position. Thereafter, the rim 60 holds the lever until the notch 59 comes opposite the lever. The pivot 55 of the lever is mounted in a slot 56, which allows the lever to set back with the rotor and afterwards move forward again. The lever 54, when released by the notch 59, swings out and releases a ring 53, which is driven round by a spring 72 and releases trigger balls 51, thereby allowing the striker to be driven against the percussion cap in a pellet 64, which is followed by a booster charge 65. The pellet 64 is held in place during flight by a creep spring or shear wire after release by centrifugal bolts 67 themselves released by an inertia bolt 68, so that if impact occurs before the appointed time the pellet 64 strikes the firing pin 47 by virtue of its momentum.