Abstract: A door operator unit includes a drive motor connected to a speed reduction differential planetary gear drive mechanism having a drive unit output shaft. An electromagnetic brake is interposed the motor output shaft and the planetary gear drive mechanism and is releasable when energized to allow rotation of the motor output shaft and the drive unit output shaft. A first ring gear is normally held stationary by mechanism including a release block and is operable in response to disengagement of the release block to permit rotation of the drive unit output shaft when the brake is engaged to allow manual opening and closing of the door by way of an auxiliary drive shaft drivingly connected to the ring gear. A torque limiting clutch may be interposed the operator unit output shaft and a second ring gear of the differential planetary gear drive mechanism.

Abstract: A door operator unit for opening and closing an upward acting or horizontally moveable door includes a drive motor connected to a speed reduction differential planetary gear drive mechanism having a drive unit output shaft for connection to further door drive mechanism. An electromagnetic brake is interposed the motor output shaft and the planetary gear drive mechanism and is releasable when energized to allow rotation of the motor output shaft and the drive unit output shaft. A first ring gear of the planetary gear drive mechanism is normally held stationary by a release block and is operable in response to disengagement of the release block to permit rotation of the drive unit output shaft when the brake in engaged to allow manual opening and closing of the door by way of an auxiliary or manual drive shaft connected through a gear train to the ring gear.

Abstract: A door operator unit includes a drive motor connected to a speed reduction differential planetary gear drive mechanism having a drive unit output shaft for connection to a further door drive mechanism. An electromagnetic brake is interposed between the motor output shaft and the planetary gear drive mechanism and is releasable when energized to allow rotation of the motor output shaft and the drive unit output shaft. A first ring gear of the planetary gear drive mechanism is normally held stationary by a release block and is operable in response to disengagement of the release block to permit rotation of the drive unit output shaft when the brake in engaged to allow manual opening and closing of the door. A torque limiting clutch may be interposed the operator unit output shaft and a second ring gear of the differential planetary gear drive mechanism.