The most common complaint by operators of rotating machinery is high vibration. The second most common complaint is high bearing temperature. High bearing temperature is almost always associated with a high dynamic or static radial load; such a load can be caused by process conditions, various mechanical factors, coupling malfunctions, or misalignment. Radial loads and misalignment have similar symptoms; in fact, misalignment usually produces high radial loads in one or more bearings. Thus, the diagnosis of both of these malfunctions uses closely related techniques. For that reason, we will study both malfunctions in this chapter.