| 摘要 |
An improved apparatus for opening and closing door members wherein the door member is connected to an output shaft, the rotation of the output shaft opening and closing the door member. A brake drive assembly is connected to the output shaft and constructed such that a torque applied at the output shaft causes the brake drive assembly to be conditioned in the braking mode. A ball drive assembly is connected to the output shaft and constructed such that the output shaft is rotated in response to the rotation of a portion of the ball drive assembly. |
