An extension spring counterbalance system consists of a pair of stretched springs running parallel to the horizontal tracks. The springs lift the door through a system of pulleys and counterbalance cables running from the bottom corner brackets through the pulleys. When the door is raised, the springs contract, thus lifting the door as the tension is released. Typically these springs are made of 11 gauge galvanized steel, and the lengths of these springs are based on the height of the garage door in question. Their lifting weight capacity can best be identified by the color that is painted on the ends of the springs.
A torsion spring counterbalance system consists of one or two tightly wound up springs on a steel shaft with cable drums at both ends. The entire apparatus mounts on the header wall above the garage door and has three supports: a center bearing plate with a steel or nylon bearing and two end bearing plates at both ends. The springs themselves consist of the steel wire with a stationary cone at one end and a winding cone at the other end. The stationary cone is attached to the center bearing plate. The winding cone consists of holes every 90 degrees for winding the springs and two set screws to secure the springs to the shaft. Steel counterbalance cables run from the roller brackets at the bottom corners of the door to a notch in the cable drums. When the door is raised, the springs unwind and the stored tension lifts the door by turning the shaft, thus turning the cable drums, wrapping the cables around the grooves on the cable drums. When the door is lowered, the cables unwrap from the drums and the springs are rewound to full tension.
Carriage: These doors mimic the look of doors found on old carriage houses in the days of horses and buggies. Because of their rustic look, they are often favored in the West and Southwest of the United States. The doors swing open like oversized French doors and hang from jambs on hinges. With their unique look, they create an area of visual interest for your home and are quite energy efficient. The downside is they require a considerable amount of clearance to work properly. Because most carriage garage doors are largely composed of wood, you may need to replace deteriorating or rotting door materials. The average cost for carriage garage door repairs is $133.