How do garage door springs work?

Garage door springs are the part that does the lifting. They store energy when they are wound or stretched, and release it to counterbalance the door, so a heavy door moves with little effort. Clopay's manual puts it plainly: garage doors use springs to balance the door weight, and there are two types, extension and torsion.^[1]

Why a garage door needs springs

Without spring tension, a door is heavy. Clopay says a single-car door may weigh as much as 200 pounds, and some large doors as much as 500 pounds, once the spring tension is removed.^[1] The springs make up that weight so that you, or a small opener motor, can raise it.

The test of a good setup is balance. The CPSC says a properly operating door is "balanced," which means it will stay in place when stopped in any partially open position.^[2] If the springs are weak, worn or uneven, the door drifts down on its own. A severely unbalanced door could unexpectedly crash to the floor, possibly striking someone under the open door.^[2]

Torsion springs

A torsion spring is a coiled spring mounted on a steel shaft above the door opening. The shaft turns drums at each end, and cables run from the drums down to brackets at the bottom corners of the door. As the door lowers, the cables unwind from the drums and turn the shaft, which winds the spring tighter. As the door rises, the spring unwinds and helps lift the panels.

A wound torsion spring holds a great deal of stored energy while the door is closed, which is why the manufacturer's warning is so direct: Clopay's manual says that attempting to remove a torsion spring assembly without proper training and tools may result in an uncontrolled release of spring forces which can cause serious or fatal injury.^[1]

Extension springs

Extension springs run alongside the horizontal tracks, one on each side. They stretch as the door lowers and contract as it rises, pulling on a cable and pulley system that lifts the door evenly on both sides.

They are easy to recognize by their position along the tracks. Clopay says that with the door fully open, most spring tension has been removed, and that extension springs should not be removed or adjusted with the door in the down position.^[1] Even so, they are not something to loosen yourself.

What stays under tension

It is not only the spring itself. Clopay says springs, cables and bottom fixtures are under strong spring tension, and not to attempt to loosen any fasteners on these components, because you could suddenly release spring forces and risk severe injury.^[1] The brackets at the bottom corners of the door are under great tension too.^[1] That is a common way people get hurt: they loosen what looks like an ordinary bolt.

What you can safely do

You do not need to touch the springs to look after them. The CPSC recommends inspecting the door and opener every 30 days.^[2] Watch for a door that is noticeably heavier, jerks, or sags to one side, listen for new noises, and look for gaps in a coil or frayed cable. Keep hinges and rollers lubricated; see how to lubricate a garage door. Then leave the springs themselves, and the cables they connect to, alone.

When to call a licensed pro

For any spring or cable work. That includes replacing a broken spring, adjusting tension, changing the cables or fixing a door that will not hold its position. The CPSC says doors that are not balanced, or that bind or stick, should be serviced by a professional.^[2]

Hiring someone also has a legal side. DPOR's consumer guide says that if the work is valued at $1,000 or more, a valid Virginia Contractor's License is required for the license category in which the contractor is to work.^[3] The same guide says unlicensed contracting is against the law.^[3] Whatever the size of the job, ask any company for its licence number and check it with the Board for Contractors before work starts.

If the door has stopped working, keep clear of it and of the springs until a technician comes. To see what to expect from a repair, read how much garage door repair costs in Virginia and whether it is worth repairing an old garage door.

Browse garage door answers or find garage door services near you. When a spring has broken, describe the job once and local garage door businesses will quote it.