How Does Your Garage Door Work?
Most residential garage doors are overheads, which roll up on a track and fold up in sectional pieces to get onto the ceiling, or “overhead.” Here is a quick overview on how your overhead garage door functions…
Counterbalance Lifting System
Overhead garage doors open by means of a counterbalance system that uses either a torsion spring system or extension springs to lift the door overhead. In a torsion spring system, one or two tightly wound springs are situated on a steel shaft with cable drums at both ends. This apparatus is typically mounted horizontally along the inside wall just above the garage door. As the garage door comes down, cables attached to the bottom corners of the garage door cause the springs to wind up, “energizing” the garage door opening system by storing tension. Then, when the door is opened again, the springs unwind and the stored tension lifts the door by turning the shaft and cable drums at the ends of the apparatus, the cables attached to the bottom corners of the garage door wrapping themselves around the cable drums.
The other, less common type of counterbalance system involves extension springs. In this type of a system, two springs are attached to cables that run to the bottom corners of the garage door. Then, when the garage door is closed, the springs are stretched instead of tightly wound. Upon opening the door, the tension released by the contracting springs will work to lift the door.
Overhead garage doors are generally made from wood or steel, both of which are durable and reliable materials; however, they can also be made from glass, aluminum, or vinyl. They tend to have a sectional design, with three to eight horizontal panels that can individually travel up the garage door track. This allows the door to come up overhead without swinging outward the way that single panel garage doors of the past have done.
Though the springs actually do most of the heavy lifting for an overhead garage door, these are not the only parts of an overhead garage door system. There are also, of course, the curved side tracks on which rollers attached between garage door sections travel up and down. In the case of an automatic garage door opening system, a curved door arm attached to the inside of the garage door connects to a central overhead rail that runs a chain to the garage door operator (or motor). Automatic garage doors will also have a safety reversing sensor that causes the door to raise should something be detected at the foot of the garage door as it is closing.