GB831176A - Multiple speed phonograph turntable drive mechanism - Google Patents

Abstract

831,176. Change-speed friction gear. EASY WASHING MACHINE CO. Ltd. March 25, 1958, No. 9617/58. Class 80 (2). The rim 17 of a gramophone turntable 1 is driven from a stepped motor spindle 11 through a friction idler disc 16 rotating upon a shaft 19 carried by an arm 18, pivoting upon an idler support 21 fast with a rotatable pin 22 moved axially to establish a ratio shift by turning a knob 30 fast with a cam body 25 having a stepped cam 26 engaged by the end of the pin, the cam body also having a series of cam recesses 32 . . . 36 engaged by the end 39 of a lever 38 pivoted about a stud 37 on a supporting frame and engaging at its other end an arm 41 depending from the idler support 21, the arrangement being such that on turning the knob 30, the cam recesses 32 . . . 36 act to turn the lever 38 which, through the arm 41, pivots the idler support 21 and withdraws the friction idler disc from the stepped motor shaft, the stepped cam 26 then effecting axial movement of the pin 22 to position the idler disc opposite a new step on the motor spindle 11. The friction idler disc 16 is normally biased to engage the motor spindle 11 and the turntable rim 17 by a spring 24, and the lever 38 is biased to engage its end 39 in the cam recesses 32 ... 36 by a spring 42. A spring 28 surrounds the pin 22 and biases it to engage the stepped cam 26. The cam recess 34 is of lesser depth than the adjacent recesses, so that when the end 39 of the lever 38 engages therein, the idler disc 16 is held away from both the motor spindle 11 and the turntable rim 17, corresponding to a neutral position of the gear. The friction idler disc 16 is held upon its supporting shaft 19 by a C-spring allowing axial adjustment of the idler disc to compensate for variations in manufacturing tolerances.