Patent GB-578330-A (GB)
Title: Improvements in or relating to fuze-setting apparatus
IPC: F42C17/00
Filed: 1941-06-18
Abstract: 578,330. Projectile fuze - setters. MOLINS, D. W., HARVEY, V. P., MASON, J. A., POWELL, G. F. W., and MOLINS MACHINE CO., Ltd. June 18, 1941, No. 7728. [Class 9 (i)] [Also in Groups XXXI and XXXVII] Relates to fuzesetters, especially for anti-aircraft use, of the type wherein the gripping-device for the fuze ring is rotatable between a fixed stop and an adjustable stop, the position of which may be continuously varied during the setting operation in accordance with the predictor indications. According to the invention, the driving means of the setter is arranged to be rotated through a constant angle during each setting operation, in the course of which the gripping-device is axially reciprocated to grip the fuze ring, then rotated until contact is made with the adjustable stop, whereupon the rotational drive is declutched, and the device is subsequently withdrawn axially from the fuze and rotated back into contact with the fixed stop. When the rotational drive is declutched, the gripping- device becomes latched to the member carrying the adjustable stop, so that any movement of the latter before the withdrawal of the gripping- device from the fuze is imparted to the fuze ring. The apparatus is electrically driven and a switch is provided for automatically stopping the motor at the end of the cycle ; an operating hand-crank which is used if the motor fails, is controlled by a latch which limits its rotation also to one complete cycle. As shown in Fig. 2, the fuze ring gripping-device 2 is axially reciprocable by a lever arm 51 and is rotated by gearing 28, 29 through the medium of a clutch pawl 36 pivoted at 38 on the driven member 34 which is rotationally fixed on the hollow shaft 30 of the gripping-device. The pawl engages a notch in a member 31 attached to the gear-wheel 29. The adjustable stop (not shown) is carried by a worm-wheel 42 freely rotatable relatively to the shaft 30. The wormwheel is rotated, in order to position the stop, by a worm 63, Fig. 3, and a train of gearing 64 ... 67, by an operator who watches the receiver dial associated with the predictor. The fuze-setter itself is driven by an electric motor 6 through reducing gearing 11 ... 14, of which the wheels 12, 13 are carried by a spring held arm 16 so that, if the setter jams, the wheel 13 will travel up the stopped gear 14 until the driving connection is broken. The gear 14 is mounted on a shaft 9 carrying a cam-drum 19 and two plate cams 59, 60. The cam 24 on the drum rocks a toothed sector 25 engaged with a pinion 26 on the boss of the gear-wheel 28 of the gripper-rotating gear-train. The cams 59, 60 operate the gripper-reciprocating arm 51 through rollers 57, 58 on an intermediate lever 56 and spring 61. A screwed stud 62 enables the arm 51 to be set relative to the lever 56 so as to adjust the axial travel of the gripping- device to accommodate various positions of the fuzes of shells in the loading tray. The cams are set so that rotation of the gripping-device occurs between the out and return axial movements of the device. When an arm 5 on the spindle of the clutch-pawl 36 contacts the adjustable stop on the worm-wheel 42, the pawl is lifted and the drive through the geartrain is stopped. At this, position, however, a latch carried by the worm-wheel 42 engages with the arm 5 and couples the member 34 to the wheel so that, until the return axial movement of the gripping-device commences, any movements of the adjustable stop in accordance with the predictor indications, will cause corresponding rotation of the fuze-grippers 2 and the fuze ring gripped thereby. 3 is the fixed stop which limits the return rotation of the device. Starting and stopping. The starting switch is shown in Fig. 9 and comprises means whereby the switch will be broken at the end of the cycle even if the operator maintains pressure upon the press-stud 20 of the switch, and whereby the switch will be held " on " auto - matically until the end of the cycle. The pressstud bears against one end element 75 of an articulated rod comprising a toggle-linkage 78 'and an'end element 175 carrying the contactmaking members 73. A spindle 71 adjacent the rod carries three radial arms 70, 72, 79. When the stud 20 is pressed to engage the contacts 73, 74, the arm 72 drops into a groove 76 in the rod-element 75 and holds the switch in the " on " position until a stud 69 on a disc 68 on the cam-shaft 9 engages the arm 70 on spindle 71 and lifts the arm 72 out of the groove 76. A spring 77 then moves the rod 75, 78, 175 to the left and breaks the circuit if the pressure on the stud 20 has been relaxed. Otherwise, the third arm 79 on the spindle 71 breaks the toggle 78 and opens the switch. Hand operation. If the electric drive fails, the setter may be operated by a hand-crank 80 applied to the cam-shaft 9. The crank is constrained to make only one revolution at each operation by a stop 81. The crank-arm comprises a spring plunger 82 which engages the stop until the plunger is pressed in by the operator's thumb to align a notch 182 with the stop. During rotation of the crank, the change of position of the operator's hand relative to the crank forces him to release the pressure on the button 83, whereupon the plunger 82 again moves outwards so as to engage the stop 81 on the completion of the cycle.