Although a broken cable is a common problem with garage doors, there is not much that can be done to prolong the life of a cable. As with springs, there are different types of cables that can be found on a garage door.
1. Torsion Cable - This is the most common type of cable, which can only be found and used on a torsion spring setup. There are a few reasons why a torsion cable breaks. Sometimes the bottom loop has rusted out, and the pull of the tension from the door causes the loop to open up. A torsion cable can also break if the cable is rubbing against the door or tracks during operation. While the door is in motion, the cable is actually being stripped. Another way torsion cables break is from an imperfection found in the cable drum (another part that works in conjunction with the torsion cables). This frays the cable, and like a thread unraveling, the torsion cable will also begin to unravel.
2. Extension Cable - These are much longer than torsion cables. Like torsion springs, there is no routine maintenance that can help prolong the life of an extension cable. They can break by rusting out the bottom loop, or by fraying due to improper motion from bad pulleys. They can also become frayed from the extension spring losing tension, causing the spring to add weight to the cable. This causes the cable to droop over the sharp edges on the tracks. When cables are directly in contact with the extension springs, they may be harmful or even fatal.
When a cable breaks on one side the tension is only being held on the opposite side, leaving the door crooked. In most cases the door will become jammed when attempting to move the door either all the way up or down. CHANGING CABLES ON A TORSION SETUP IS VERY DANGEROUS AND SHOULD ONLY BE PERFORMED BY A TRAINED PROFESSIONAL.