Improvements in and relating to door operators

摘要

A drive unit for a remotely controllable operator more especially an operator for garage doors. The drive unit is microprocessor controlled and includes a sensing means 39 to sense deceleration of the driving effect of the drive unit. A microprocessor 40 determines limits indicating positions corresponding to open and closed positions of a door coupled with the drive unit if the deceleration exceeds a threshold, which may be variable. and thereby determines the span of movement of the door. Memory means 41 are provided for storage of the span value whereby the microprocessor can control the duration of operation of the drive unit to move a door coupled therewith between open and closed positions. The drive unit further includes a gearbox for transferring drive from a motor 14 to an output shaft 21. The gearbox has a clutch 23 which is constantly in driven coupling with the motor. The clutch incorporates gear teeth 27 which mesh with a gear 25 coupled with shaft 21. Operating means 31 operable by means 32 external of the gearbox cause clutch 23 to move into and out of engagement with gear 25 such that drive to shaft 21 can be effectively obtained.