Roll-up door counterbalancing apparatus and method

摘要

The disclosure sets forth an apparatus and method for counterbalancing a roll-up door. A first threaded shaft is concentrically disposed around a torsion shaft and a spring is also disposed around the torsion shaft. The spring has a first end and a second end. The first end of the spring is secured to a first anchor plate that is threadably mounted to thread onto the threaded shaft. The second end of the spring is fixed relative to the torsion shaft. When the threaded shaft is rotated, the first anchor plate moves along the threaded shaft, thereby longitudinally stretching the spring a predetermined distance. A first stop prevents the movement of the first anchor plate along the threaded shaft beyond a predetermined position so that further rotation of the threaded shaft winds the spring thereby applying a predetermined counterbalancing torque on the torsion shaft.