Torsion Spring Counterbalance
By Huu Khanh Nguyen · Updated October 28, 2026 · sectional-door, counterbalance, torsion-spring, cable-drum, clopay, hormann, amarr, garador, normstahl, sommer
A torsion spring shaft with cable drums that balances a sectional door, mounted over the lintel or at the rear of the tracks.
Parameters
| Name | Default | Unit |
|---|---|---|
| Door width | 2438 | mm |
| Door height | 2133.6 | mm |
| Shaft or track height above the door top | 330 | mm |
| Shaft position | front | |
| Backroom beyond the door height | 457 | mm |
| Track depth behind the door plane | Math.min(doorHeight + backroom, 3813) | mm |
| Springs | 2 | |
| Spring length | 597 | mm |
| Spring wire diameter | 5.715 | mm |
| Spring inside diameter | 50.8 | mm |
| Shaft diameter | 25.4 | mm |
| Cable drum diameter | 101.6 | mm |
| Spring windings | Math.round(springLength / springWire) - 1 | |
| Depth | (shaftPosition == 'rear' ? trackDepth : drumDiameter / 2 + 3) + 149.225 - Math.min(0, (shaftPosition == 'rear' ? trackDepth : drumDiameter / 2 + 3) - (springInsideDiameter / 2 + 1.02 * springWire)) | mm |
| Height | (doorHeight + shaftOffset) + Math.max((drumDiameter / 2) + (shaftPosition == 'rear' ? 3 : 0), (springInsideDiameter / 2 + 1.02 * springWire)) | mm |