Understanding how your window blinds function is essential when performing home repairs, evaluating the need for maintenance or dismantling for remodelling. There are two main types of window blinds: vertical and horizontal. The history of these window treatments is unknown, though literary references and paintings suggest the style was adopted by traders from the Republic of Venice during the early Middle Ages.
Types and Parts
Blinds are raised with two mechanisms: a moving pulley system and a vertical tilt rod. Pulley-system blinds are composed of three parts: slats, cord and locking pulley. Horizontal blinds have slats made of wood, metal, plastic or stiff fabric. Vertical-blind slats are made from heavy material to avoid excess movement.
The tilt-rod system features wood, metal or stiff plastic slats connected by a rigid vertical pole, tilt rod.
The slats are the stiff horizontal components of the blind. Each slat has three holes at either end. A stationary cord runs through the middle hole connecting each slat and forming a ladder-like structure. The other holes house a looped cord which runs through the slats and through a pulley at the top of the blind. This cord is controlled by a pair of long strings that attach directly to the main cord. When the front string is pulled tension is placed on the cord at the back of the slats, pulling the slats up at the back. At the same time the cord slackens in the front, causing the slats to drop forward. Thus, the slats close in a down-facing, overlapping fashion. When the back string is pulled, the cord reverses direction, pulling the front of the slat upward and the back downward. If both strings are pulled simultaneously the cord looped through the slats shortens at both ends, raising the blinds. Raised blinds are held in place by a stiff lever, or ratchet. Blinds are lowered by pulling at an angle that releases the ratchet.
Tilt-rod blinds, or interior shutters, only tilt; they don't have slats that raise and lower. In this design slats are fitted into a rigid frame, connected at either end with straight pins. These pins enable the slats to rotate freely, like a wheel on an axle. The tilt rod is affixed to the centre of each slat with a flexible connector, usually a pair of interconnected eye screws or chain links. When the tilt rod is pulled up or down the slats raise and lower.
Variations on a Theme
There are many varieties of window blinds: Persian, Venetian, Roman, Austrian. All of these window blinds function with a similar pulley system but each has its own additional features that affects the amount of light and air that enter a room. Persian and Venetian blinds are composed of numerous, interlocking slats. Roman blinds have cloth-covered, wide-spaced slats, allowing more light into the room. Austrian blinds feature fabric shades instead of slats. Usually, there are several independent pulley systems in Austrian blinds, enabling you to create a variety of ruched and draped effects.