Flange mounted bearings are used when the shaft axis is perpendicular to the bearing mounting surface. They incorporate a sealed bearing that is preassembled into a flanged housing. The housing contains a precision ground surface perpendicular to the bearing axis and two, three or four mounting holes, depending on the style. The bearing can be unbolted and removed, which makes bearing replacement easier and faster than traditional rotary bearings that must be press fit into a housing. Flange mounted bearings can also support heavy loads, which protects the shaft from deflection, which could cause vibration or other damage.
Two-bolt flange mounted bearings are diamond shaped and have two holes for mounting bolts, one on each side of the bearing. A line drawn through the axis of the mounting holes forms a straight line that runs through the axis of the bearing.
Three-bolt flange mounted bearings have three mounting holes, either arranged radially around the bearing axis at 120 degrees from each other, or on a triangular flange that is offset from the bearing axis.
Four-bolt flange mounted bearings have four mounting holes, located radially around the bearing axis. Four-bolt flanged bearings typically have round or square housings.