Patent GB-647219-A (GB)
Title: Improvements in automatic shaft positioning apparatus
IPC: H03J5/22
Filed: 1947-10-21
Abstract: 647,219. Toothed gearing; stopping rotary members in predetermined positions; securing members on shafts. COLLINS RADIO CO. Oct. 21, 1947, No. 28137. Convention date, Oct. 29, 1946. [Classes 80(i) and 80(ii)] [Also in Group XXXVIII] An electric remote controlled shaft positioning device, e.g. a radio tuner, comprises a plurality of selectively operable shaft stopping units each including a pair of oppositely rotatable members whose conjoint rotation to a mutual stopping position determines the positioning of the shaft. Selection is effected by operating a rotary switch 112, Fig. 5, to the desired one of four settings. A relay 115 is thereby energized over the gapped-disc switch 60 to energize the power motor 119. The motor driven shaft 17, Figs. 1, 2, drives through worm gearing 18, 19, gears 104, 106, 105 and a lost motion device 107, e.g. as described in Specification 635,758, [Group XXXVIII], a drum 47 carrying four helically arranged notches 49. The motor also drives through further worm gearing 21, 22, Fig. 2, a limit switch 23 which closes contacts 124, 125 before the gapped disc switch 60 driven with the drum 47 opens the relay circuit as the selected notch 49 reaches the operative position to reverse the motor. A shaft 16 connected to the power drive through a friction clutch 20, and locked against rotation by a ratchet 24, 25 during forward rotation of the motor, now rotates in the clockwise direction, Fig .2. The drum 47 remains at rest because of the lost motion connection 107 and the operative drum notch permits the associated lever arm 38-41, pivoted at 42, to be rocked by its biassing spring 54, Fig. 2, to mesh the gear 30 carried thereby with the corresponding gear 26-29 driven by the shaft 16. The drive is thus transmitted through gear trains 26, 30, 43, 75 and 26, 30, 43, 70, 74, Figs. 3, 4, to drive, in opposite directions, the gears 74, 75 of the stopping unit A, B, C or D selected by the operative lever 38-41. Rings 94, 96 rotatable respectively with the gears 75, 74, Figs. 3, 4, each carry a single lug 95, 97 through which gear wheels 99, 101 are stepped in opposite directions. The gears 99, 101 are mounted diametrically on a disc 89 rigid with the turning shaft 82 and each gear has a single tooth 100, 103 of double width which when engaged by the associated driving lug locks therewith. The first of the gears 99, 101 to be locked in this way causes the disc 89 and therefore the turning shaft 82 to rotate therewith until the second gear is locked when the gear 89 is locked against rotation in either direction in the selected position of the turning shaft and the friction clutch 20 slips. The motor 119 continues to run until the limit switch opens the motor circuit at switch contacts 124, 125, a lost motion device being provided in the limit switch drive to ensure selective setting of the shaft 82 as above described before the motor circuit is broken. The discs 89 of the stopping units A-D are held frictionally between rings 87, 88 splined to the turning shaft by a thumbnut 93 which is released for presetting of the discs 89.