| 摘要 |
632,883. Driving sound-reproducing machines. McDONALD, D. M., and BIRMINGHAM SOUND REPRODUCERS, Ltd. Oct. 21, 1947, No. 28187. [Class 40 (ii)] The mechanism for starting and stopping a gramophone comprises a lever 18, pivoted at 14, and moved in one or other direction by a pick-up arm 6 so as to start or stop an electric driving- motor, or alternatively operate braking mechanism of a spring motor. As applied to an electric motor a plate 13 carrying contact 12 is mounted beneath a second plate 17, the plates 13 and 17 also being pivoted about 14 and being connected to the lever 18 by a connection 19, 20 which allows a small amount of relative movement between the plates and the lever. A pawl 26 is pivotally mounted on the lever 18 about 27 and is biassed by a spring 29. When the pick-up 6 is moved to its outermost position it causes the lever 18 and plate 13 to move the contact 12 between contacts 11 so as to connect a driving-motor 39 to the supply. Movement of the pick-up towards the end of the record causes the freedom allowed by the connection 19, 20 to be taken up between the lever 18 and the plates 13, 17, so that at the end of the traverse the whole lever assembly is moved about the pivot 14 until the edge of the pawl 26 is engaged by a projection 33 which is mounted on the turntable boss and moves the assembly anticlockwise about the pivot 14 to disengage contacts 11 and 12. In the event of the tip 32 of the pawl engaging the projection 33 the pawl pivots about 27 against the bias of the spring 29, the motor being switched off on the next revolution of the turn-table.
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