| 摘要 |
526,878. Friction gearing; adjusting wireless apparatus. BRITISH THOMSON-HOUSTON CO.. Ltd. Feb. 22, 1939, No. 5906. Convention date, Feb. 23, 1938. [Class 80 (i)] [Also in Groups XXXVI and XL] A mechanical drive for a rotatable driven member comprises a first driving member normally connected in driving relation to the driven member, a second driving member normally disconnected from but connectable in driving relation with the driven member the second driving member having an actuating electric motor connected thereto ; and means responsive to the energization of the motor for displacing axially the driving members thereby changing the driving connection of the driven member from the first to the second driving member. As applied to the drive for a variable condenser or like tuning element 10, the condenser shaft 11 carries a friction gear 12 to the periphery of which friction material 14, e.g., of soft rubber may be applied. The gear 12 may be actuated manually by a friction gear 25 on a shaft 20, provided with a knob 19, the gear being normally kept in contact with the gear 12 by a spring 26. The gear 12, which may be of two diameters 27, 28 to give different ratios of drive, may also be driven by a motor 29 the armature shaft 35 of which carries a coned gear 37 normally out of engagement with the gear 12 but abutting the coned gear 25. With the motor de-energized, the spring 26 urges the cone 25 into engagement with the gear 12, the cone 27 being separated therefrom. When the motor is energized, the armature is moved to the left to bring the cone 37 into engagement with the gear 12, the cone 25 being simultaneously moved out of engagement therewith. The armature does not move into exact alignment with the poles 32, since a slight displacement to the right is necessary to produce axial thrust on the cone 37. Upon de-energizing of the motor the spring 26 quickly causes separation of the gear members 37, 12 so that momentum of the armature does not carry the shaft 11 beyond the desired position. Instead of friction gearing, toothed gearing and clutches may be employed. Further, instead of the gears 25, 37 abutting one another, they may be integral or be connected by linkwork. |
