A hinge is a type of 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. Hinges may be made of flexible material or of moving components.
Hinges that are equipped with ball bearings between the hinge knuckles to reduce friction. These types of hinges are designed for heavy duty doors that open to the exterior. They are permanently lubricated..
