GB593243A - Improvements in or relating to reduction gearing - Google Patents

Abstract

593,243. Intermittent toothed gearing. STANDARD TELEPHONES & CABLES, Ltd., FIELDING, E. C., LUKEY, R. W., and SEATH, E. G. May 25, 1945, No. 13119. [Class 80(i)] [Also in Group XXXVIII] An intermittent toothed reduction gear of the " Geneva mechanism " type comprises a driving shaft 1 with an eccentric 4 which oscillates a follower plate 8 having a pin 9 at one side guided in a fixed slot 10 and a pin 11 at the other side which engages with peripheral castellations in a castle plate 7 to move this plate one castellation in the opposite sense from that of the shaft 1 for each revolution of the shaft. In an application to radio equipment for tuning a multi-turn inductance or capacitance to any of a number of predetermined frequencies one such gear unit is provided for each of the required positions of the shaft 1, all the units being driven off this shaft. Each unit has a disc 3 fixed to the shaft with a V-notch 12 in its periphery and a disc 6 secured to the driven plate 7 freely mounted upon a hub 2 on the shaft and having a notch 13 in its periphery. Adapted to engage with the notches 12, 13 when they are in line is a peg 14 on a lever 15 pivoted at its other end at 16 and urged towards contact with a cam 20 by a spring 18. The shaft 21 of cam 20 and the shaft 1 are both driven by electric motors through electromagnetic clutches (not shown). To select any required position of the shaft 1 the motor driving the camshaft 21 is started and run until a roller 19 on the appropriate lever 15 falls into a notch in the corresponding cam 20. This movement of lever 15 operates electrical contacts (not shown) on members 22 and 23 which stop the motor and start up the driving motor of the main shaft 1. Rotation of shaft 1 continues until the notches 12 and 13 are in line when the peg 14 drops into these notches and in doing so effects a dis-engagement of the electromagnetic clutch and stops the driving motor. Thus the shaft 1 is turned a definite number of turns determined by the driven disc 6 of the operative gear unit and a portion of a turn determined by the V-slot in the disc 3, the discs of each unit being initially set to give the desired operation to be selected by cams 20. An auxiliary shaft may be geared to the main shaft 1 to operate an indicator and also to operate contacts to reverse the motor drive at either extremity of the shaft operation.