Hinge Hinge A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation: all other translations or rotations being prevented, and thus a hinge has one degree of freedom. Hinges may be made of flexible material or of moving components. In biology, many joints function as hinges like the elbow joint. There are many types of door hinges. The main types include: Other types include: Since at least medieval times there have been
Geared continuous hinge the door’s weight over the entire door length rather than concentrated on two or three spots as with butt or pivot hinges. The gears allowed fluid movement as the door opened and closed. Baer's patent expired in 1985. He sold his company to a national manufacturer in 1989. With the sale, and with other companies beginning to manufacture geared continuous hinges, the market soon went from regional to national. Later the hinges were tested to verify their endurance. In 2004, a geared continuous hinge earned 60 minute Ballistic Resistance and Forced Entry certification from the United States Department of State