Journal Bearings

High- or low-pressure, oil-lubricated journal bearings are normally used in specific applications and have advantages over rolling-element bearings.

• Relatively inexpensive
• Lower running friction
• Higher loading capacity.
• Relatively smaller
• Have a large support damping

Due to clearances between bearing surface and the shaft journal, non-contacting sensors are required to provide information about shaft hydro-static and hydro-dynamic behaviour relative to the bearing. Uneven oil pressures in the bearing clearance can induce vibrations (oil-whip and whirl) and various configurations of journal bearings are available to reduce these effects.

Due to different orthogonal-axes bearing stiffness the sensors are mounted in pairs, at 90º to each other in the radial plane, to determine the shaft's static position and dynamic movement during rotation. This configuration allows analysis of the shaft's orbit during rotation to provide information and trace the source of problems. The orbit shape reveals load direction, existence of unbalance, bent shaft, misalignment, rubbing, oil-induced vibrations or other problems.