Cable Unspooling and Drum Overlap
Metal tension dictates the limits of mechanical movement, and the history documented in the running record long beach garage door springs ahlanart holds shows how many garage failures in Long Beach, CA stem from improper winding. A cable should never bypass the grooves of a drum.
Identifying Cable Unspooling
Watch the winding drum while the door is moving. If the steel cable jumps the track of the drum, it creates a bulge. This happens because the cable has crossed over itself instead of sitting in the grooves. Once the cable overlaps, the diameter of the spool increases. This change in diameter puts uneven pressure on the torsion spring. You will see the cable bunching up near the end of the drum or slipping off the edge entirely. This is not a simple fix. If the cable is tangled, the tension is no longer distributed evenly across the shaft.
The Mechanics of Drum Overlap
A drum is designed to hold a specific amount of cable in a specific pattern. When a door cycles, the cable must sit deep within those grooves. If the cable sits on top of another strand, it is called an overlap. This creates a sudden jump in the door movement. You might hear a loud pop or a grinding sound. This often occurs because the cable was not seated properly during the last spring replacement. The cable must be pulled tight and seated in the grooves before the tension is applied to the system.
Signs of Improper Winding
Look at the drum every time you test the door. If you see a thick section of cable that looks wider than the rest, the winding is wrong. A loose cable will eventually slip out of the groove and bind against the bracket or the wall. This can cause the door to hang crooked. A crooked door puts lateral pressure on the track and the roller sets. If the door does not travel in a straight vertical line, the cable is likely the culprit. Check the drum for any signs of fraying where the cable has rubbed against the metal edge.
Preventing Mechanical Failure
Proper winding requires the cable to be under constant tension. If the door sits open for long periods, the cable might slacken. This slack allows the cable to wander out of its groove. When the opener starts the cycle, the cable snaps back into place incorrectly. This creates the overlap. Maintaining the correct tension on the torsion spring prevents this slack. Always inspect the drum and the cable for any signs of unevenness or fraying. If the cable has jumped, do not attempt to force the door closed. This can cause the cable to snap or damage the drum itself.