Mounted bearings, sometimes called bearing units or bearing blocks, have a bearing installed in a housing to ease installation and provide additional support for the bearing. They are face or surface mounted in applications where the shaft is perpendicular to the unit. Bearing inserts are used to replace worn or damaged bearings in an existing bearing housing. Collar bearings support high axial loads and limit radial movement. Flanges help ensure that the bearing is flush and provides added rigidity. Pillow-block (Plummer block) bearings attach to a vertical or horizontal surface to support rotating shafts and with light to moderate loads, such as in conveying and other operations where the shaft passes through the bearing. Take up bearings are used to align track and tension conveyor belts.