The present invention relates to a bearing, such as a bearing for rotary shaft, and in particular for a large size rotary shaft mounted in a deformable structure such as for example a ship's propeller shaft.
The primary function of such bearings is to support the shaft by taking the radial stresses, while minimizing the resisting friction pairing.
The conventional bearings which have been designed for installations of essentially non-deformable structure are all ill-suited for the applications cited hereinabove, because they do not support any relative deformations of the hull (hence of the structure) and of the shaft.
According to a conventional system, the part on which is defined the friction surface of the bearing, or at least the part of surface most exposed to stresses, is fractionated or split into bearing elements which are more able to follow deformations than one massive piece. Such split-bearings, when used on large-sized rotating machines, improve the hydrodynamic stability of the lubricating film between the friction surface and the shaft.
According to a known variant, this kinematic effect is achieved by means of cylindrical laminates of radius smaller than that of the shaft, and in particular by producing the bearing in two parts, a first part being in contact with the shaft and a second part opposite thereto, both parts contacting together over a cylindrical surface parallel to the shaft and of smaller radius. Thus, the first part of the bearing which is in contact with the shaft has a degree of mobility with respect to the second part by sliding/rotating, thus permitting an accurate orientation of the contacting surfaces and improving lubrication.
These dispositions, however, only permit deformations of very limited amplitude, and although they are relatively well suited for those cases where the axis of the shaft is off-center, they are completely unsuited for cases of angular variations of the axis (non-alignment).