GB889437A - Improvements in or relating to speed changing mechanism - Google Patents

Abstract

889,437. Change-speed controls. ELECTRIC & MUSICAL INDUSTRIES Ltd. May 2, 1958 [May 2, 1957], No. 14021/57. Class 80 (2). Variable speed gearing for a gramophone turn-table drive comprises a stepped wheel 7 on the shaft of an electric motor and engageable by a wheel 4 mounted on a carrier 8 which is rotatably and slidably mounted on a shaft 9. A spring 5 urges the wheel 4 into contact with a surface of the wheel 7 and with a rim of the turn-table, and a spring 10 urges the carrier 8 downwardly into contact with a pin 19 carried on one face of a disc 17 the otner face of which has pins 18 engageable by a pawl 20 carried by a lever 2. On depressing lever 2 by means of a push-button 1 against the action of a spring 2a, a cam 21 on the lever pivots a lever 22 about an axis 23 so that a pin 24 engages the carrier 8, thus disengaging wheel 4 from the wheel 7 and the turn-table rim. Pawl 20 engages a pin 18 and moves the disc 17 one step, thus altering the height of the pin 19 and hence of the carrier 8. On releasing button 1, spring 5 engages wheel 4 with the appropriate surface of wheel 7. Disc 17 is retained in its various positions by means of a notched member 14 which is fast with the disc and which has a spring 15 engaging in a notch for each position of disc 17. An indicating member 11 has indicia corresponding to the different speeds of the turn-table and is viewed through a window in a base-plate (not shown). In a modification disc 17 is retained in position by a spring-urged lever which bears against the two highest pins 18.