Door opening apparatus for large overhead doors

摘要

A structure for mounting and apparatus for opening, closing, and locking a large, overhead door is adapted for buildings constructed on terrain which is not level and having floor and overhead structures that conform to the terrain. A sloping overhead truss spans a door opening and includes a widened faceplate along the length of its span to accomodate mounting a large overhead opening door along a horizontal line between vertical columns. A combination manual and automatic electrically powered door opening apparatus includes a counterweight, a coil chain and sheave for manual operation which is interchangeable with an electrically powered motor for automatic operation, all connected to a common lift cable which applies substantially vertical lifting force to the lower edge of the door for opening. Bias means for causing initial folding of door sections for opening, and locking apparatus for resisting folding of the door sections to prevent opening are also provided.