GB119919A - Improvements relating to Gramophones. - Google Patents

Abstract

119,919. McEwen, J. B. Oct. 24, 1917. Tone - arm joints. - The sound-box is pivotally mounted on a telescopic extension tube of the tone-arm and is constrained by a jointed link and suitable stops, in such manner that, when the sound-box is swung round on changing from lateral-cut to vertical-cut records, the distance between the stylus and the tone-arm pivot remains the same. The sound-box 4 has a curved neck 41, the axis 5 of its outlet being parallel to the stylus bar. The neck 41 has a swivelling connexion to a downwardly-bent tube 3 which telescopes into the tone-arm 1, being guided by a pin 16 and longitudinal slot 17. At the rim of the sound-box outlet is mounted a pin 9 connected by a hinged link 8 to the pin 16. As shown in Fig. 1, the sound-box is in position for playing vertical-cut records. In order to play lateral-cut records, the sound-box is swung through approximately a right-angle around the axis 5. The pin 9 acting as a crank-pin causes the tube 3 to be drawn out from the tone-arm 1, thus placing the stylus at the correct distance from the vertical tone-arm pivot. At the same time the tone-arm is raised slightly on its horizontal pivot 14. A pin-and-slot joint 20, 21 between the parts 1, 11 of the tonearm allows the sound-box to be turned up for changing the needle, &c. The two positions of the sound-box may be determined by the limits of the slot 17, or other stops may be provided. The neck 4 may be locked to the tube 3 by a clamping-screw 18.