Roll-up Garage Door System
Tension Spring System (Shown on a Single Sectional Garage Door)
This system consists of a pair of stretched springs which are running parallel to the horizontal tracks. This is only used on Single Garage Doors.
The spring lifts the door through pulleys and counterbalance cables running from the bottom corner brackets through the pulleys. When the door is raised, the springs contract and thus lifting the door as the tension is released.
Torsion Spring System (Single or Double Garage Door)
This system consists of one or two tightly wound up springs on a Torsion Tube with Cable Drums at both ends. The entire apparatus mounts on the headroom above the garage door and has three supports (a Center Bearing plate with a Steel Bearing and two End Bearing plates at each end.
The Springs consist of 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 Torsion Tube. Steel Lifting Cables run from the Bottom Lifting 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 Torsion Tube, thus turning the Cable Drums, wrapping the Lifting 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.