Abstract: Bearing arrangements are described which enable rotation about a vertical axis with a very extended diameter bearing, for example 20 meters diameter. A usually stationary base supports a rotating member, e.g. on a fluid cushion. Separately, a ring of radially adjustable arcuate surface support pads on an outer member acts against a cylindrical surface of an inner member. The adjustability of the radially movable support pads enables them to increase their thrust at parts of the circumferences of the bearing relative to others. This enables considerably smoother running to be achieved, both to compensate for the difficulties of producing complete circularity with a bearing diameter of substantial size, and for varying direction lateral loadings, e.g. as experienced by a vertical axis wind-driven turbine.