Abstract: A system and apparatus for controlling excessive vibration of a rotating shaft at critical speed or when a large imbalance suddenly occurs, comprising an emergency bearing having sufficient radial clearance that it does not normally engage the shaft, and located longitudinally at a portion of the shaft which is sensitive to excessive vibration, and where it will raise the critical speed of the shaft system when additional support is added at that position. The bearing is of inexpensive construction and of such design that it requires no lubrication during the period when the shaft is passing through the critical speed and the bearing is operative.