Patent GB-127380-A (GB)
Title: Start and Stop Mechanism for Talking Machines.
IPC: G11B17/02
Filed: 1918-05-21
Abstract: 127,380. Marks, E. C. R., (Columbia Graphophone Manufacturing Co.). May 21, 1918. Periodic.-Relates to talking-machines having stop mechanism of the kind in which the machine is arrested when the feed movement of the tonearm ceases or is reduced; and consists in employing two members rotated in opposite directions by the turntable and the tone-arm respectively, the stop device being actuated by a supplemental movement of a third member which is normally rotated by the rotary members. An inward movement of the tone-arm after its manual return to the record rim re-starts the machine. Fig. 1 shows in plan an electrically-driven machine, with the turntable and top-plate removed, and Fig. 5 is a perspective view of the mechanism as applied to a machine driven by a spring motor. A sectorshaped rack 21 secured to the tone-arm engages a pinion 61 connected by a roller-ratchet clutch 49 of a differential gear, the opposite bevel-wheel 66 being driven in the opposite direction by the driving-motor through a slipping clutch 75, 76, During the normal playing of a record, the wheels 49, 66 rotate at equal speeds in opposite directions and the axle 44 of the planet pinion 47 consequently remains stationary. The upper end of this axle 44 supports a pivoted latch 40, which engages a notch 34 in a spring-pressed sliding rod 31 connected to a switch 27, Fig. 1, in the motor circuit, or to a brake lever 83, Fig. 5. When the tone-arm ceases to advance, the wheel 49 is arrested, and the pinion 47 receives a planetary motion causing it to release the latch 40. The planetary motion is limited by the ends of a slot 44<1> in the casing. When the tone-arm is returned by hand towards the starting-position. the roller clutch allows the wheel 49 to remain stationary; while a movement of the tone-arm by hand in the opposite direction, with the motor stationary, causes the wheels 49, 66 to rotate in opposite directions, the wheel 66 being allowed to rotate to the slipping clutch 75, 76 between it and the wheel 73 geared to the motor. In order to re-set the sliding rod 31, the sector 21 carries a pivoted cam 38 pressed by a spring against a stop 39. As the tone-arm is returne to the rim of the turntable, the cam 38 is swung on its pivot by striking a roller 37 on the end of the rod 31, and is then returned, after passing the roller, into contact with the stop 39 by the spring. The tone-arm is then moved inwards slightly so that the cam surface presses in the sliding rod and causes it to be re-engaged by the latch 40, which is raised by the bevelled end of the axle 44, ad. vanced by the rotation of the wheel 49. The differential gear, latch, &c. are housed in a casting 28 which also carries the motor and is secured by bolts to the top plate of the casing of the machine. The shaft 69 of the pinion 72 is driven by a worm 67 on the turntable spindle 12, which is itself driven by a spring or electric motor 10. When a spring motor is employed, the sliding rod 31 acts on an arm 83 connected by a sleeve 84 to a second arm 86 carrying a spring tongue 87. This tongue bears against the lower end of a vertical pin 88 supported on horizontal pivots and carrying friction pads at its upper end. When the sliding rod is released, a spring 92 actuates the arm 83 and causes the friction pads to engage and arrest a motor-driven disk on the governor shaft.