A flange bearing is a bearing that is mounted in a cast iron flange. There are three basic flange bearing styles: a round or square, four-bolt flange; a tri-cornered, three-bolt flange; and a diamond-shaped, two-bolt flange. The bearings use one of four bearing styles: ball bearing, plain bearing, needle roller and roller bearing. There also are plastic, bronze and other materials used to manufacture the actual bearing on which the shaft rides. A flange bearing is commonly used to provide support for a shaft that runs perpendicular to the bearing's mounting surface.
Shafts can create problems when high speeds or heavy loads create shaft flex, vibration and axial load or movement. This can be eased with the application of a flange bearing that is located in such a way that it supports the shaft. Depending on the length and speed of the shaft, more than one bearing might be required. Often, the problem dictates which bearing type to use to correct it. Other factors that come into play when choosing a flange-type bearing are cost, available space and the amount of radial force that will be exerted on the bearing by the shaft.
Installation of a ball bearing flange is commonly done at the outer end of the shaft to provide smooth, low-friction rotary movement of the shaft. The extremely small contact patch of the ball in this type of bearing does not support the weight of the shaft, nor does the ball bearing combat linear movement. A plain bearing, also known as a bushing, provides a smooth, flat surface that aids in the control of linear movement by a shaft. This style of flange bearing often contains either an oil-impregnated, bronze or nylon bushing that does not require frequent oiling or greasing to remain operational.
A flange-mounted, needle-type roller bearing provides support against radial loads while also providing a low profile. This type of flange can either have grease applied or be maintenance-free, which does not require grease for the flange to remain operational. Roller bearing flanges provide radial load support and fight linear movement of the shaft. The greater contact patch of the long roller bearing, compared with the ball bearing, allows the roller flange bearing to support the greatest amount of load of all of the flange types. This comes at a cost, with the roller bearings typically costing more than other bearing types.