For reliable operation in high-speed and medium- to high-load applications, tilting pad thrust bearings are the preferred choice due to the increased support area to accommodate axial loads and utility to adjust to varying conditions during operation. Their overall load capacity is determined by the generated oil temperature, and to control this several design features can be selected, including material choice, bearing size, pivot configuration and lubrication scheme. To further optimize bearing reliability and to meet API requirements, a self-equalizing system can be incorporated to accommodate tolerance and alignment variances.
Creation of a convergent wedge profile is achieved through the pad geometry, clearance and movement capability of tilting pad bearings. When the shaft begins rotating, the lubricant’s adhesive effect on the shaft acts to pull the lubricant into the gap, which narrows in the direction of rotation. Pressure develops in the fluid film to create a running clearance between the stationary and rotating surfaces. Effective monitoring of bearing operation is critical to machine reliability. This is typically achieved through temperature monitoring using either RTDs or thermocouples. An additional option is to monitor the thrust load, which is particularly useful through the design and testing phase of any machine. Traditionally, load is measured through the use of load cells embedded in the thrust pad. John Crane has developed a patented solution that monitors load through the use of temperature-compensated strain gauges. This unique design provides a wider application range for thrust load monitoring and is an effective solution for development testing and ongoing field monitoring.