Thrust bearings are designed for side or axial loads, and cannot handle much radial load at all. The rolling element in a thrust bearing can be a ball, needle or roller. Thrust bearings come in both metric and inch sizes. Dimensions to consider when searching are the bore, the outside diameter and the overall width. Operating specifications to consider when searching for thrust bearings are rated speed, static axial load, and dynamic axial load. RPM for a bearing running in oil is going to be higher than one running in grease. The static axial load is the maximum axial load a bearing can withstand while stationary without suffering permanent damage. The dynamic axial load is the maximum axial load a bearing can withstand while revolving without suffering permanent damage.