Counterbalancing mechanism for an overhead door

Counterbalancing apparatus for an overhead door disposed in an opening defined by a door frame structure, said apparatus comprising:

• a torsion shaft mounted for rotation between first and second fixed supports;
• a torsion spring having a first end fixed to said torsion shaft such that said first end rotates with said torsion shaft but does not move axially along said torsion shaft during raising and lowering of said overhead door, said torsion spring having a second end operatively connected to a winding mechanism for winding said second end with respect to said first end with said door held stationary, said winding mechanism being mounted to one of said first and second fixed supports, said spring being comprised of coils wherein adjacent coils are spaced from one another by a gap when said spring is in an unwound, resting state;
• and being generally defined by the formula:
• a counting mechanism operatively connected to said winding mechanism for counting windings of said spring.

Counterbalancing apparatus for an overhead door disposed in an opening defined by a door frame structure said apparatus comprising:

• a) a torsion shaft;
• b) a torsion spring having a first end fixed to said torsion shaft;
• c) a gear system connected to a fixed mounting structure and operatively coupled to a second end of said torsion spring, said gear system including;
• i) a ring-shaped gear rotatably supported by said mounting structure, said ring-shaped gear being operatively affixed to said second end of said torsion spring such that rotation of said ring-shaped gear rotates said second end of said spring with respect to said first end of said spring;
• and,
• ii) a worm drive gear rotatably supported by said mounting structure and including outer teeth meshing with the teeth of said ring-shaped gear, said worm drive gear being mounted with respect to said ring-shaped gear between et position in which an axis of rotation of said worm drive gear extends approximately vertically and a position in which said an axis of rotation of said worm drive gear extends inwardly at approximately 45.degree. with respect to said door opening;
• and
• a counting mechanism operatively connected to said ring-shaped gear for counting rotations of said ring-shaped gear.

Counterbalancing apparatus for an overhead door comprising:

• a torsion shaft mounted for rotation between first and second roller bearings held by respective first and second fixed sheet metal supports disposed at opposite ends of said torsion shaft;
• a winding mechanism including a ring-shaped gear engaging a worm drive gear and each mounted for rotation to said first fixed support;
• a torsion spring receiving said torsion shaft, a first end of said spring being rigidly affixed to said torsion shaft for rotation therewith and a second end of said torsion spring being affixed for rotation with said ring-shaped gear;
• and,
• first and second drums rigidly affixed to opposite ends of said torsion shaft for rotation therewith, said first drum at least indirectly bearing against said ring-shaped gear so as to bear a thrust load of said torsion spring when said torsion spring is in a wound state.

Counterbalancing apparatus for an overhead door disposed in an opening defined by a door frame structure, said apparatus comprising:

• a torsion shaft mounted for rotation between first and second stationary supports;
• a torsion spring having a first end fixed to said torsion shaft so as to allow rotation with said torsion shaft;
• a winding mechanism connected to a second end of said torsion spring for winding said second end of said torsion spring with respect to said first end with said door held stationary, said winding mechanism being mounted to said first stationary support;
• and,
• a counting mechanism operatively connected to said winding mechanism for counting windings of said torsion spring and providing indication of a number of said windings.