GB1318830A - Two-speed drive - Google Patents

Abstract

1318830 Two speed drive; valves G N KLOTSVOG 19 Aug 1971 38882/71 Headings F2D and F2V A two speed drive for a valve closure comprises an electric motor drive through a worm and worm wheel to provide a high speed at low torque and a drive through an epicyclic train, which may be by a separate electric motor, to provide a high torque slow speed drive to complete closure of the valve. A motor 2 drives a shaft 4, Fig. 2, on which a worm 6 is splined and resiliently held by a spring 7. A worm wheel 9 through a planetary union 10, Fig. 1, and gear-wheel 11 drives an output shaft 13 without an epicyclic gear effect. A second motor 3, Fig. 1, drives an eccentric shaft 15 on which is freely mounted the planet 10 to provide a drive 15, 10a, 9a, 10b, 11a to the gear 11, when the worm-wheel 9 is held. In use the motor 2 drives the output shaft 13 at high speed through the worm 6 and Worm wheel 9 until the torque rises sufficiently to overcome the spring 7 allowing the worm 6 to move towards a washer 8 closing contacts 16 which switch off the motor 2 and switch on the motor 3 which then drives the output shaft 13 with high torque to complete closure of the valve at which time the torque is sufficient to move the worm 6 further to release contacts 16 and close contacts 17 stopping the motor 3 and restarting the motor 2 to return the worm 6 to its starting position. A reverse procedure applies for opening the valve using contacts 18 and 19. A known manual stand-by regulator using contacts 22 is provided.