In January 2011, Kingsbury's Repair & Service Division, located in the Philadelphia suburbs, received a request from a major German pump manufacturer to design retrofit bearings for two pumps that had originally been fitted with a competitor's bearings. The original assemblies were self-contained radial bearings with fixed profile thrust faces installed in a flange-mounted housing. Taper-land bearings typically have about half the load capacity of tilt-pad bearings (1.75 MPa vs. 3.50 MPa), and in this particular case, the fixed profile thrust bearings were not capable of handling the larger than anticipated axial loads exerted by the pump.
To alleviate the problem, Kingsbury's sales engineers proposed our CH and C bearing assemblies, which feature not just tilt-pad thrust bearings: the units are equalized as well, assuring that the axial load is evenly distributed across the entire active face of the bearing. The tilt pads themselves are in turn fitted with spherical supports, allowing for significant misalignment capability. The key to the unit's success is the oil circulator, within which the collar rotates in order to create a slight amount of pressure in the oil supply system. There is sufficient pressure from the oil circulator to lubricate not only the non-drive end journal bearing, but also the drive-end unit on the opposite side of the pump. After the oil lubricates both journal bearing assemblies, it returns to the non-drive end unit, where it passes through a heat exchanger for cooling by water before recirculating in the bearings. Given the low ambient temperatures in winter, Kingsbury also opted to install thermostatically-controlled heaters in the oil bath to prevent untoward changes in the lubricant's relative viscosity.
|Back side of thrust shoe, showing spherical support that allows the shoe to pivot 360°. The shoe's greater freedom to tilt permits a thicker film of oil to develop, which in turn increases the load capacity and reduces the operating temperatures.|
|Cutaway view of CH assembly, showing location of thrust and journal bearings, oil circulator and seals.|
|Base Ring assembly, with shoes removed to show leveling plates. The leveling plates distribute the load evenly around the bearing by adjusting the position of the shoes so that all can be loaded.|