| 摘要 |
1297117 Control of DC motors ELLIOT BROS (LONDON) Ltd 16 Dec 1969 [18 Dec 1968] 60128/68 Heading H2J [Also in Division H1] A mechanical drive transmission system, suitable for inching an electric motor drive, for example, comprises an input member driven via a first friction clutch, an output member coupled thereto via a second friction clutch, the input member having stop-limited movement from a datum position in either of two directions against spring bias, and control means whereby the clutches may be engaged to provide limited movement of the output member and disengaged to allow spring return of the input member to its datum position. As shown, motor 13 drives a 180 degree limitation device 21 via reduction gearing 15 and clutch 23 and output is taken via clutch 25 and reduction gearing 17. The device 21 actuates a switch 51 or 53 (according to the direction of rotation) after it has been driven 180 degrees against the bias of a torsion spring (see Division H1). The control is by a double-pole change-over switch 67 (Fig. 4) which is spring-urged to a central off position and energizes motor 13 and clutch windings 23<SP>1</SP> and 251 when manually operated for forward or reverse running. When either switch 51 or 53 is opened the motor 13 stops and clutch 25 is disengaged, but clutch 23 remains energized and prevents the return of device 21 to its datum position. When switch 67 is released clutch 23 frees the device 21 which is then restored by its torsion spring in readiness for a further incremental drive. A brake 63 may be provided to hold the output shaft of clutch 25 when the latter is disengaged. |
