Patent GB-133877-A (GB)
IPC: G11B17/00
Abstract: 133,877. Fletcher, T. Feb. 6, 1919. Driving; speed, regulating; feedmotions; tone-arm joints. - Relates to phonographs of the kind in which the turntable is driven by a movable friction pinion in such a way that the record travels at a uniform speed under the stylus, and consists primarily in providing means for adjusting the pressure of the friction pinion on the turntable. Fig. 1 is a plan of the mechanism, and Fig. 3 is a sectional elevation. The motor M drives through bevel gear 4 a shaft 5, which is geared to a transverse shaft 6 by bevel gearing 7. The friction pinion 1 has a sliding feather connexion to a shaft 10 which is driven from the shaft 6 by spur gearing 8, 9. The shaft 10 is mounted in a frame 33 pivoted on the shaft 7 and operable by a vertically-movable handle 35 to place the pinion 1 in driving contact with the underside of the turntable, or to remove it therefrom. The vertical portion of the handle 5 has a retaining rack 36 formed on it co-operating with a spring catch on the casing, and the horizontal member 34 is resilient. The turntable spindle 19 is connected by bevel gearing 20, 21, 23 to a shaft 24 carrying two spur pinions 25, 26 of different size. Spurwheels 27, 28 are axially movable on their shaft 29 by a handle 30, thereby enabling the shaft 29 and feed-screw 16 to be driven at either of two speeds, according to the pitch of the record grooves. A half-nut 15 mounted on a carriage 11 engages the feed-screw 16. The carriage 11 is pivoted on, and slides along, a rod 12, and is connected to the grooved hub 18 of the pinion 1 by a forked member, in such a way that when the pinion is lowered away from the turntable, the nut 15 is raised out of engagement with the screw 16. The tone-arm T is secured to a plate 48 hinged on, and sliding along, a rod 43, and the plate 48 is resiliently connected to a half-nut 46 engaging a feed-screw 44 driven by bevel gear from the shaft 29. Alternatively, the nut 46 may be mounted on an arm and engage the screw 16. The tone-arm projects downwardly through the plate 48 and enters loosely the mouth of a flexible and telescopic tube 50 by which the sound is con. veyed to the horn S. The upper portion of the tube 50 slides on guides 43. When it is desired to play records requiring a constant angular velocity, the feed-screw 16 is disconnected at the clutch 31 operated by a handle 32, and the friction pinion 1 is removed from engagement with the turntable. A bevel pinion 51 driven through gearing 54, 55 from the motor shaft 5 is piaced in engagement with a bevel wheel 52 on the turntable spindle 19 by means of a hand-lever 53. To prevent strain on the turntable, a loose supporting pinion 56 is provided on the side of the spindle opposite to the pinion 1, and the spindle is supported in a ball bearing near its upper end, and in a laterally-adjustable ball footstep bearing at its lower end. The machine may be automatically arrested at any desired point by providing an arm 59 on the tone arm, which at the desired moment engages an adjustable stop 58 on a slidable spring- controlled rod 57. When this rod is moved axially, it releases a latch to operate the stop gear. The carriage 11 may be returned to starting position by a hand-lever 38, 41.