Torsion or tension springs: what your sectional door uses
Torsion springs sit on a shaft above the opening and twist to lift the door; tension (extension) springs stretch alongside the tracks or in the side frames. Many standard domestic doors use tension springs, while larger, heavier and timber doors and doors with a pass door usually use torsion springs. Both store a lot of energy and should only be worked on by trained engineers.
How the springs work
A sectional door is balanced so that the springs carry most of its weight. As the door closes, the springs are loaded; as it opens, they give that energy back. A balanced door should stay roughly where you leave it part-open.
How to tell which you have
Look above the opening. A steel shaft with coiled springs on it means torsion springs. Springs running beside the horizontal tracks or within the vertical side frames are tension springs, often with safety devices that catch a broken spring.
How long do springs last?
Springs are rated in cycles. Several manufacturers rate theirs at about 25,000 cycles, which at four cycles a day is many years, while some standard springs are rated lower. In everyday use many springs need replacing after something like eight to twelve years.
Replace in pairs
Two springs on the same door have done the same work, so when one breaks the other is often close behind. Replacing both, and checking the cables, saves a second visit.
Why not DIY?
Torsion springs are wound with winding bars and can release suddenly; tension springs can snap and whip. Either can cause serious injury, and a door that loses its balance can fall. Please leave spring work to an engineer.
Sources
- Manufacturer data on spring cycle ratings and spring systems for domestic sectional doors
This guide gives general information, not legal or professional advice. Rules change; check with your council or a qualified adviser for your situation.