Inventors:
Jakhim B. Popper - Kiryat Motzkin, IL
Riza E. Murteza - Oklahoma City OK
Assignee:
LSB Industries, Inc. - Oklahoma City OK
International Classification:
F16D 1104
F16H 1306
E05F 1502
E05F 1500
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.