What is a Cable Drum?
A grooved cylindrical spool mounted at each end of the torsion bar that the lifting cable winds around.
Cable drums are cylindrical spools with precisely machined grooves that guide the lifting cables as they wind and unwind during door operation. They are mounted at each end of the torsion bar (the shaft that holds the torsion springs). As the torsion springs release energy and the torsion bar rotates, the cables wind around the drums, lifting the door evenly. The grooves in the drum ensure the cable wraps in an orderly spiral — if a drum is damaged or the cable comes off the drum, the door will hang crookedly or bind in the tracks. Cable drums are sized to match the height of the garage door (standard, high-lift, or vertical-lift configurations). Worn or cracked drums should be replaced in pairs along with the cables.