Each garage door spring system is different depending on the door's size and weight, application and brands. Each spring type has its own particular features and every door would have a particular number of springs. Though, all spring systems do the same job and work along with garage door cables. Cables and springs are interconnected since the door needs the good cooperation of both parts in order to move.
Since torsion and extension springs are installed in a different way, they also have different supportive parts and are connected with cables in a different way, too. The hidden energy of springs and the amazing strengths of cables are the two things which ensure the movement of the overhead door. If either of them loses some of their power, the door would suddenly be too heavy to be lifted and would place a lot of strain on the garage door opener.
The spring/cable system is vital! Knowing a few basic things about how these two garage door parts work will give you an idea on how the door moves and why it is important to keep both springs and cables in exceptional condition. Torsion springs move around a shaft, which is connected at both sides with the cable drums. When the spring moves, its power is transferred to the drum through the shaft which pulls the cable up. The cable wraps and unwraps around the drum depending on the status of the door and stretches all the way to the bottom of the door where it connects with a bracket.
In the case of extension garage door springs, which are installed at the two sides of the door parallel and also above the horizontal tracks, the cables still connect with the bottom brackets but go through pulleys. One end of each spring is attached to a pulley with a pulley fork and the cable goes over this pulley and is attached on one end with an s-hook to the track. On the other end the cable goes above a second pulley and straight to the bottom bracket. When the door opens, the extension springs contract and the cables are pulled to open the door.