Springs are the heart of a balanced rolling door. Without them, the door is too heavy to lift manually and the motor works too hard. Here's what to know about rolling door springs.
There are two main types: torsion springs and tension springs.
Torsion Springs
Mounted on the shaft above the door. They twist as the door closes, storing energy. When you open the door, the stored energy helps lift it. Torsion springs are inside the barrel or mounted on brackets at each end of the shaft. In rolling doors, the spring is often a helical coil wound directly on the shaft.
Tension Springs
Mounted on each side of the door, running vertically along the tracks. They stretch as the door closes. Tension springs are more common on sectional overhead doors than rolling doors, but some lightweight rolling doors use a tension spring assist.
For most rolling doors, especially electric ones, torsion springs are the standard. They are contained within the door assembly, don't take up wall space, and distribute the balancing force more evenly.
What Makes a Spring Good
Material: Spring steel, properly heat-treated. Chinese standard 60Si2Mn or 55CrSi is good. Cheap springs use lower-grade steel and fail early. A good spring should last 10,000 to 20,000 cycles. A cheap spring might fail at 3,000 cycles.
Cycle life rating: This is how many times the spring can operate before it breaks. A door that opens and closes 4 times a day needs 1,460 cycles a year. A 10,000-cycle spring should last about 7 years. A 20,000-cycle spring, about 14 years. For commercial doors that cycle 50 times a day, you need high-cycle springs or you'll be replacing them every few months.
Galvanized coating: Rust is the enemy of spring steel. A good spring has a zinc coating to protect it. Electro-galvanized is okay. Hot-dip galvanized is better.
Size and calculation: The spring must be matched to the door's weight, height, and drum configuration. A spring that's too strong makes the door hard to close. One that's too weak makes it hard to open. This calculation should be done by the manufacturer or a qualified technician, not guessed.
Brand matters: Names like Century Spring, Lesjofors, and local premium manufacturers produce consistent quality. No-name springs from small workshops are a gamble. The price difference is not big enough to justify the risk.
When to Replace Springs
If the door is hard to lift manually. If the motor sounds strained. If the door is unbalanced. If the springs show visible rust, gaps between coils, or if the torsion spring has a broken coil.
Spring replacement is dangerous. The stored energy in a wound torsion spring can cause serious injury. If you don't know what you're doing, call a professional.