摘要 |
An operator (10) for moving in upward and downward directions a sectional door (D) having a counterbalancing system (30) including a drive tube (31) interconnected with the door including, a reversible motor (40), a drive shaft (50) selectively driven in two directions by the motor, a drive gear (61) freely rotatably mounted on the drive shaft, a driven gear (65) mounted on the drive tube and operatively engaging the drive gear, a disconnect assembly (70) having a spool (71) rotatable with the drive shaft and movable into and out of engagement with the drive gear for selectively connecting and disconnecting the motor and the drive tube, and an actuating mechanism (80) normally maintaining said spool in engagement with the drive gear and biasing the spool out of engagement with the drive gear when released to permit independent movement of the door. |