Abstract: Guide track assemblies for upward acting doors include substantially linear vertical and horizontal track sections and curvilinear transition sections formed as portions of each of the vertical and horizontal linear sections. The track assemblies are supported, respectively, by mounting brackets which also support a counterbalance mechanism for the door. The curvilinear transition track sections are formed integral with the vertical and horizontal track sections and may have a constant or elliptical radius of curvature, the latter to provide clearance for the guide track assemblies in low headroom installations. The mounting brackets are formed of stamped metal plates which are folded to provide a first flange for attaching the mounting bracket to a structural wall, a support part including a flag portion for connection to the guide track sections and a second flange for connection to a door counterbalance mechanism.

Abstract: A counterbalance system for an upward acting door includes spaced apart wall brackets supporting a tubular shaft for spaced apart cable drums operable to wind counterbalance cables thereon to counterbalance the weight of the door. Torsion springs interconnect the cable drums and spring winder tubes sleeved over the springs and connected to the wall brackets by a winder mechanism including a support plate having spaced apart tabs adapted to register in corresponding slots formed in a wall bracket. The winder mechanism includes a worm gear drive including a ring gear which is connected to one end of the winder tube by an arrangement of radially inwardly projecting key portions in a bore of the ring gear which register with axial grooves formed in the winder tube and are adapted to slide into transverse slots intersecting the grooves. A removable lock pin is engageable with the ring gear or the worm of the worm gear drive.