Pull-down staircases give access to the attic without taking up valuable floorspace. They can be installed relatively easily and require minimal maintenance, because the staircase itself is made up of only a few simple parts.
Almost all pull-down staircases are attached to a door panel, by brackets and springs. The door panel fits tightly into an opening in the ceiling that is framed out with headers, but it's the springs that are responsible for the pull-down mechanism of the stairs. Just like they sound, they spring back into tight coils, holding the stairs tight against the header. There are several spring mechanisms on most pull-down staircases, including springs, spring brackets and spring assembly. Some manufacturers use cables in place of springs on the pull down mechanism, in which case there will be cable holders as well.
Brackets provide the supports for the staircase, to hold it steady. Typically, there will be several brackets, at the top of the stairs, where the stairs are hinged, and along the sides to provide support as you climb up and down. Angle brackets attach the staircase to the door panel that hides the staircase once it is folded back up into the ceiling. The door panel may have a chain or a a rope pull depending on the manufacturer. Some manufacturers use drums on both the door panels and the headers so that the mechanism closes easily.
The hinges allow the stairs to fold up, so several sets are needed as each section of the stairs will have a pair. These can be piano hinges or section hinges.
The stairs themselves are made up of long side pieces called stiles, and then the wood or metal stairs or the treads, as they're sometimes called. Most pull down staircases have ladder rods that give additional support. There are also stair stringers, the boards that support the end of the steps.
Some staircases have handrails, and handrail posts to attach them to the staircases. All staircases will be attached to the headers, which are made up of well sides and well ends, and which may feature a header guide frame. There may be a catch lock which can be used to lock the stair sections in place when they're folded up. Others may have door frame runners and frame spacers.