Continuous hinges are also known as piano hinges; piano hinges could have taken their name from one of two sources. Some contend that piano hinges are so named because of their resemblance to piano keyboards. The more common contention is that they are named after one of their most common applications. Nearly all pianos are affixed with piano hinges; they are used to facilitate the opening and closing of panels and keyboard covers.
Continuous hinges can be found in many applications outside of uses in pianos. Tool boxes, equipment cases, instrument cases and compartments in utility trucks and fire trucks or often fitted with continuous hinges. Folding wall partitions, electrical enclosures, doors and other equipment involved in managing or securing spaces can make use of continuous hinges.
Continuous hinges are essentially expansions on simple butt hinge designs. Butt hinges are composed of two machined plates called leaves that are joined by a pin. Continuous hinges are distinct from butt hinges only because of their length. Common continuous hinge manufacturing lengths are six and eight feet, though they can be cut to any necessary length. Continuous hinges are valued because they evenly distribute the weight they bear; this reduces the kind of stress at individual points that is created when several small hinges are used.
When used in outdoor electrical enclosures, continuous hinges can contribute to a higher degree of weather resistance, as they cover areas through which moisture could pass into the enclosure. There are two main continuous hinge configurations: gear and pin. Continuous hinges that are joined by pins are the most common configuration. They are simple and inexpensive compared to geared continuous hinges.
Geared hinges involve specially designed, interlocking gears in order to allow for motion. The gears, like the knuckles or barrels of pin hinges, are connected to flat plates. Geared continuous hinges are advertised as longer lasting than pin continuous hinges, so investment in a geared continuous hinge may be wise if the hinge is applied in a setting where it will be used constantly.