Winding Cone

A winding cone is the die-cast fitting at the winding end of a torsion spring, nearly always located on the right side of the spring as you face the door from inside. It is pressed onto the spring's end coil and secured with two set screws that bite into the torsion shaft. The cone's outer face has two or four holes drilled through it at equal intervals. A technician inserts steel winding bars into those holes one at a time to rotate the spring incrementally, adding or removing tension.

The winding cone is what makes field-tensioning possible without specialized machine tools. A spring manufacturer ships the spring with zero turns of tension; the installer slides it onto the shaft, clamps the stationary cone at the opposite end to the center bearing plate, and then winds the required number of turns through the winding cone using hand bars. The correct turn count depends on the spring's IPPT (inch-pounds per turn) rating and the door's weight.

What distinguishes the winding cone from the stationary cone:

The winding cone rotates with the spring coils during winding and does not connect to a fixed structure. The stationary cone sits at the other end of the spring and anchors rigidly to the center bearing plate, preventing that end from turning at all. During normal door operation, the spring twists along its length between these two fixed points.

For example, a standard residential spring for a 200-pound door might require 7.5 turns of winding. A technician counts each quarter-turn with each bar movement to hit that number accurately, because under-wound springs fail to lift the door fully and over-wound springs put dangerous stress on the shaft and end brackets.

Safety context: A wound torsion spring stores enough energy to cause severe injury if a winding bar slips or the cone set screws fail during winding. This is the one garage door component that industry guidance consistently reserves for trained technicians. Most winding cones are zinc die-cast, though some heavy-duty commercial springs use steel cones to withstand higher torque loads.