A hydrostatic rotary bearing with angled surface self-compensation

A design for a low profile hydrostatic rotary bearing is presented that utilizes a new type of self-compensation that allows a large number of bearing pockets to be present with only a few precision round parts, thus allowing high hydrostatic averaging with relatively low design complexity. A key feature of this design is that it does not use capillaries or orifices or a complex network of passageways to route fluid. The design consists of five easily assembled round parts which can be manufactured by cylindrical grinding. A seal is incorporated which prevents fluid leakage and creates a closed system. The theory of operation is discussed along with manufacturing considerations. Tests show that the rotary bearing has high stiffness, and achieves a high degree of averaging, resulting in a radial error motion of 0.05 mum from components ground to an accuracy of only 2.5 mum. (C) 2002 Elsevier Science Inc. All rights reserved.