Counterbalancing mechanism for an overhead door

摘要

An overhead door apparatus utilizing a torsion spring counterbalancing mechanism. The counterbalancing mechanism includes a worm drive ring-shaped gear winding mechanism for setting the appropriate torque or number of winds in the spring. A counting mechanism is provided to indicate to the installer the number of winds being given to the spring. Means are also provided for accommodating spring growth and contraction during winding and unwinding using the winding mechanism and during normal raising and lowering of the door. A spring clip gear retainer is disclosed for preventing rotation or creep of the worm drive gear and spur gear during normal raising and lowering of the door. A second embodiment is disclosed allowing more universal interchangeability of components between the left and right sides of the door system, easy snap-in assembly, and including a telescoping spring cover. Each embodiment includes a spring winding counter.