Cable Ferrule

A cable ferrule is a small metal sleeve slipped over a lift cable end and then crimped flat with a tool, forming a permanent loop or stop. Amarr defines it as "a metal ring or cap that is affixed to a cable so as to form a bottom or loop on the end of the cable."

The lift cable on a sectional door is a multi-strand galvanized steel wire. The bottom end clips to the bottom bracket. The top end winds onto the cable drum. Both ends need a reliable termination that will not loosen or pull through the fitting under repeated load.

Here is how a ferrule is installed. The installer threads the cable end through a hole in the fitting, then loops the end back alongside the main cable. A ferrule is slid over both strands. A crimping tool compresses the ferrule tightly around the wire bundle. The loop cannot pull back through under normal door load.

Ferrule failure is visible before it becomes a cable failure. Look for a crack in the metal sleeve or the crimped end starting to spread apart. Either is a sign the cable needs replacing. A cable that fails suddenly drops the door with full weight and no counterbalance on that side.

Lifting cables carry the door's full weight on every cycle. A 200-pound door loads each cable with roughly 100 pounds of tension per cycle. The top fixture at the top corner of the top section is another cable attachment point and works in the same load path.