The number of sections ranges from 3 to 7 or more depending on the style and height of the door.
The Residential Garage Door usually has 4 sections up to 7' high and 5 sections up to 8' high. A typical 1-car garage door is normally 8'- 9' wide and a 2-Car door from 15'-18' wide with 16' being the most common.
The Door is lifted by a counterbalance spring system, which can either be a Torsion system as shown in the diagram, or an Extension system where the springs stretch out along the Horizontal tracks on either side of the door. The Extension system is typically used where the headroom is too low to accommodate the Torsion system.
Garage Door Springs can cause serious injury and should only be serviced by a Professional Technician.