Patent GB-124755-A (GB)
Title: Improvements in and relating to Stop Mechanisms for Talking Machines and the like.
IPC: G11B17/02
Filed: 1919-03-24
Abstract: 124,755. Columbia Graphophone Manufacturing Co., (Assignees of Hinckley, F. C., and Skane, J. F.). March 23, 1918, [Convention date]. Periodic - A gramophone brake-lever 52 is operated either manually or by the continued rotation of the turntable after the sound-box has ceased to advance across the record. The brake cannot however become operative in any case until a certain number of revolutions have occurred after starting the record. Fig. 2 is a plan view with the motor plate removed and with the turntable 3 and tone arm 7 shown in dot-and dash lines. The vertical portion 8 of the tone-arm extends through its socket and is frictionally connected at its lower-end to an arm 11, the movement of which is limited by a slot 16. The advance of the tone arm during are. production thus tends to move the arm 11 into contact with the left hand edge of the slot 16. The point of the arm 11 bears against a lug 29 on a second arm 26 pivoted to the motor board at 27 limited in its. rooking movement by a slot 30, and having its point 31 in operative relation with a pin 37 on a disk 32. The turntable spindle 2 is geared by a pinion 41 to a second pinion 40 which carries a pin 39 and thereby advances the toothed disk 32 clockwise one tooth for each revolution of the pinion 40. The brake lever 52 is pivoted on a pin 51 and carries a brake block 58 engaging the governor disk 60 or other rotary member. A spring arm 54 on the brake lever lies in the path of a pin 36 on the toothed disk 32. When the brake is released to start a record, the pins 36, 37 lie respectively just beyond the points of the arms 54, 31 so that the disk 32 makes a complete revolution (corresponding to a considerable number of revolutions of the turntable).before the pins 36, 37 are brought into operative position in front of the arms 54, 31. At this stage, a large tooth or cam 38 on the disk 32 lies adjacent to the driving-pin 39. The next rotation of the pinion 40 would cause the pin 39 to ride down the curved back of the cam 38 and give a larger clockwise movement to the disk 32 sufficient to apply the brake by the pin 36. The advance of the tonearm, however, rocks the arm 26, and its point 31 gives a short anti-clockwise movement to the disk 32, thus preventing the driving-pin 39 from operating the cam 38. The disk 32 thus has a to- and-fro movement so long as the tone-arm is advancing. When this advance ceases, the driving- pin 39 engages the back of the cam 38, and the pin 36 applies the brake. The pinion 40 is carried on a pivoted spring-controlled arm 43 to permit it to withdraw from the disk 32 should the driving- pin 39 jam against the cam 38. The spring arm 54 on the brake lever prevents sudden application of the brake, and permits the pin 36 eventually to pass beyond it. The brake lever has a lug 63 which is pressed by a spring 70 against one side of a slot in the hand-control lever 65. The whole of the stop mechanism, excepting the arm 11, is mounted on the underside of the motor-plate which is hinged along one edge to the top plate of the machine to enable it to be lifted. This may be effected without disconnecting any part of the stop mechanism. When the motor-plate is lowered, the lug 29 passes into operative position opposite the point 17 of the arm 11, and a cover-plate 25 fits between the forks of a bracket 4 on the tonearm socket.