A word of caution before we begin:
Garage door repairs, often involve replacing garage door hardware that is associated with the spring system, these hardware parts are under high tension and may cause injuries, property damage and even deaths. Replacing garage door springs is very dangerous due to the fact springs are wound and are under high tension. It is not recommended to work with springs or any parts that are under high tension, like drums, cables, bottom bracket and center bearing plate, etc.. A thorough knowledge of garage door interconnection system is critical for safe repairs. It is best to call a professional repair service like Garage Essentials, 208 577-7974.
Torsion springs are designed to counterbalance the weight of the garage door making is easier to lift and close.
Garage door torsion springs are secured to a metal center bearing plate above the center of the garage door, a torsion bar passes through the middle of the springs and connected to the end bearing plates (edge of the garage door).
Torsion springs balance the garage door by applying torque to the torsion bar with drums at each end of the bar. A cable is attached to each drum that extent along the vertical track and is held to the bottom bracket of the door. The torsion spring helps cycle the garage door by process the of counter-balancing.
To illustrate this concept, if your garage door weighs 150 pounds, a spring lift of 150 pounds is needed to lift the weight of the door.
Characteristics that determine the lift and cycle life is determined by coil turns, wire size, length of coil, inside diameter and ratios. Cycle life is how many times the door will open and close before the spring breaks.