Core spring system terms
- Torsion spring: A spring mounted horizontally above a closed garage door on a metal shaft, providing counterbalance through torque/twisting force. Most common on modern residential doors.
- Extension spring: A spring mounted above the horizontal tracks on either side of the door, providing counterbalance by stretching under tension.
- Cable: Steel cables connect the springs to the bottom corners of the door, working with the springs to lift and lower the door.
- Drum: A cylindrical part at each end of the torsion spring shaft that the cables wind around as the door opens and closes.
- Winding bar: A specialized tool used by trained technicians to safely wind and unwind torsion spring tension — not a general household tool, and not safe to improvise with substitutes.
- Safety cable: A cable run through the coils of an extension spring that contains the spring if it breaks, preventing it from becoming a projectile.
Balance and cycle terms
- Balance: A properly balanced door stays roughly in place at any point when manually moved with the opener disconnected — the spring counterbalances the door’s weight almost entirely.
- Cycle rating: The number of open-close cycles a spring is designed to handle before reaching typical end-of-life, commonly around 10,000 cycles for standard residential torsion springs.
- Counterbalance: The overall function the spring system performs — offsetting the door’s weight so it can be lifted with minimal force, by hand or by the opener.
Frequently asked questions
What’s the difference between a torsion spring and an extension spring?
A torsion spring is mounted horizontally above the door and provides counterbalance through twisting/torque force; an extension spring is mounted above the horizontal tracks on each side and provides counterbalance by stretching. Torsion systems are more common on modern doors.
What is a winding bar and why can’t I use a regular tool instead?
A winding bar is a specialized tool sized and shaped specifically for safely winding and unwinding torsion spring tension. Substituting a screwdriver or other improvised tool is a well-documented cause of serious spring-related injuries, since the tool can slip under high tension.
Why do extension springs need a safety cable?
If an extension spring breaks, the safety cable running through its coils keeps the broken spring contained rather than letting it fly free under the stored tension — a genuine safety feature, not an optional accessory.