Abstract: 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.

Abstract: An improved brake drive apparatus having a brake surface formed in a portion thereof and a brake assembly interposed generally between and connected to an input drive assembly and to an output member, the output member being rotatingly driven via the input drive assembly in the driving mode of the brake assembly and the brake assembly being positioned in the braking mode for preventing rotation of the output member in response to a torque applied at the output member. The brake assembly includes: a brake ring connected to and rotatingly driven via the input drive assembly; a first and a second brake shoe element, each having a portion engageable via a portion of the brake ring; a driven cam connected to the output member and disposed generally between the first and second brake shoe elements; and at least one brake roller disposed generally between the brake shoe elements and the driven cam.

Abstract: An improved apparatus for opening and closing door members and the like such as elevator doors and garage doors, for example, wherein the driver rotatingly drives a driver shaft coupled to a driven shaft via a ball drive assembly, the ball drive assembly not only coupling the driver and the driven shafts so the driven shaft is rotated at a reduced rate of speed, but also cooperating to provide a portion of a torque control for sensing obstructions in the door member path of travel and automatically stopping or reversing the opening or the closing of the door member. The ball drive assembly has a relatively low moment of inertia, which facilitates faster stopping of the door member travel, and the internal friction of the ball drive assembly is greater than a pulley-belt type of coupling, for example, thereby increasing the amount of force required to move the door member from a stopped position.