GB878571A - Improvements in or relating to sound reproducing machines - Google Patents

Abstract

878,571. Change-speed friction gears. FOSTER-MALLARD Ltd. Oct. 23, 1959 [July 25, 1958], No. 24016/58. Class 80 (2).. In a gramophone having a constant-speed electric motor driving the turntable through a stepped driving wheel engaged by a rubbertyred friction wheel engaging the rim 11 of the turntable, the friction wheel is moved axially of the stepped wheel by a rocking lever and ramp means. As shown in Figs. 1 and 2 two friction wheels 16 are employed, and a stepped driving wheel 17 is mounted on the shaft of a reversible electric motor and drives the turntable through either one of the wheels 16, depending on its direction of rotation, the drive being transmitted through the wheel which tends to be drawn more firmly into engagement with the wheel 17 and turntable rim. This enables records supported above the turntable to be played on their undersides before being dropped on to the turntable, the pick-up being provided with an upwardly extending stylus as well as a downwardly extending stylus. The wheels 16 are carried by arms 14 urged inwardly by a spring 15 and journalled on a sleeve 19 slidably mounted on a spindle 13. Sleeve 19 is urged upwardly by a spring 21 and downwardly by a lever 22 having a forked end engaging a groove 24 in the sleeve and pivoted at an intermediate point between lugs 23 struck from a base plate 10. The free end of the lever engages an inclined portion 32 of a slide bar 29 which is guided in a slot 34 in the base plate and pivoted to a member 27 fast with a spindle 26 rotated by a knob 25. A blade spring 36 engages notches in the member 27 to locate it in the positions corresponding to the steps of the wheel 17. In the modification of Figs. 4, 5 a friction wheel 40 is engageable with a stepped driving wheel 49 on the shaft of a non-reversible electric motor, the wheel 40 also engaging the turntable rim, and a wheel 41 engages the turntable rim and engages the wheel 49 through an idler 52 to provide reverse drive. The wheels 40, 41 are carried by arms 42 pivoted to arms 43 pivotally mounted on a pin 44 carried by a lever 45 rotatable about a horizontal pivot 46 and urged upwardly by a spring 53. The lever 45 is moved downwardly by a slide bar 54 having an elbow 61 engaging the upper surface of the lever and an end notched to engage the edge of a ramp 59 formed in the base plate. Slide bar 54 is pivoted to an arm 56 rotatable about a pivot 57 by means of a lever 58 above the base plate 47. The wheels 40, 52 are thus adjusted to the appropriate step of the driving wheel 49 by adjusting the slide bar 54. To transmit drive through the appropriate wheel, a plate 65 is mounted on the lever 45 so as to turn about the pin 44 and to slide longitudinally of the lever, and has pins 66 engaging the arms 43. The plate 65 is slid longitudinally of the lever by a pin 69 engaging an arcuate slot 72 in the plate and so connected to means for starting and stopping the machine that when the machine is stopped the plate is slid towards the pivot 46 and the pins 66 move the arms 43 to lift the wheels 40, 41 off the turntable rim. Rocking the plate about pivot 44 brings the appropriate friction wheel into contact with the rim, in the longitudinally outermost position of the plate.