| 摘要 |
852,657. Turntable driving means. BIRMINGHAM SOUND REPRODUCERS Ltd. Feb. 25, 1959 [March 8, 1958], No. 7150/58. Class 40 (2). [Also in Group XXIV] In a change-speed gear for a disc talking machine wherein a multi-stepped wheel 6 on a motor spindle 5 frictionally drives a turntable rim 2 through a rubber - rimmed idler 11 axially shiftable under manual control, the said idler shift is by a cam bar 20 from smaller to larger steps of the wheel 6 and by a return spring 14 from larger to smaller steps, and a motor switch lever 29 simultaneously switches off the motor and transversely disengages the idler from the stepped wheel 6 and, whilst the motor is switched off, retains the idler in its disengaged position but without restraint against axial shift in either direction. The idler 11 is mounted on an arm 16 pivoted by its spindle 15 on a yoke 13 sliding and pivoting on a fixed spindle 12. The free end 26 of a spring 24 which is upwardly biased to hold the cam bar 20 against the motor board engages the top of the yoke 13 and is flanged at 27 to coact with the steps of the cam bar 20 so that rightward cam movement by a hand-control 21 depresses the yoke 13 through the spring end 26 against the return spring 14 which is anchored on the fixed spindle 12 and on the yoke 13, thereby also acting torsionally to engage the idler 11 with the stepped wheel 6 and the turntable rim 2. The lever 29 is moved to close a motor switch 28 against a spring 31 by a hand lever 32 through a rod 33 and a latch lever 34 and has an abutment 39 which, when the switch 28 is open, engages an abutment 17 on the arm 16 to disengage the idler 11 against the spring 14 and to guide the arm 16 for axial shift of the disengaged idler. Alternatively, the latch lever 34 may be actuated automatically on completion of the playing of all the records on an automatic machine by means described in Specification 839,666. The disengagement of the idler prevents deformation of its rubber rim during long rest periods. The idler may be axially shifted in either direction when the motor is switched on, the resilience of the idler rim accommodating the shifts from smaller to larger steps of the wheel 6; further, the risers of the said steps may be tapered to facilitate shift. The spindle 15 is threaded at 40 and has a screw-driver slot 42 for axial adjustment with respect to the yoke 13, the arm 16 being circumferentially retained with respect to the spindle 15 by frictional means comprising a spring washer 41 engaged in a circumferential slot in the spindle 15. The thread 40 permits the arm 16 to pivot freely without materially effecting the vertical adjustment.
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