What are thrust bearings tilting pads?
A thrust bearing is a variation of the rotary bearing, capable of rotating between two components while supporting a primarily axial load. Thrust bearings come in multiple types, tilting pad thrust bearings being one that is capable of transferring high axial loads sourcing from rotating shafts while exhibiting low power loss. Additionally, such bearing types allow for an ease of installation and maintenance, making them advantageous for various applications. In this blog, we will discuss tilting pad thrust bearings, their design, and applications.
In general, tilting pad thrust bearings are composed of a series of pads that are supported within a carrier ring, and all pads can tilt with freedom so that a self-sustaining hydrodynamic film is formed. For the carrier ring in particular, such elements may be a single piece or two halves that are arranged in various locations. For the shafts of thrust bearing tilting pad components, diameters may range from 20 mm to 1,000 mm or more. Additionally, the maximum load that such a bearing can undertake ranges from 0.5 to 500 tons based on its design.
In regard to lubrication, a tilting pad thrust bearing may either have its housing fully flooded, or have oil directed at its thrust face. Additionally, there are two geometric options for such bearings. With the first option, equalizing or leveling links are used, while the other option forgoes such features to benefit gear units and shaft systems where perpendicularity between the centerline of the shaft and the bearing face is guaranteed.
For most tilting pad thrust bearings, flooding the housing with oil is common, relying on an orifice situated on the outlet that ensures flow and pressure regulation. Pressure will typically be set at 0.7 to 1.0 bar, and seal rings are often implemented to prevent any chance of leakage. Despite being a simplistic method for lubrication, flooding the housing causes high parasitic power loss due to the turbulence that occurs at high-speed operations. Generally, a directed form of lubrication is best when sliding speeds surpass 50 meters per second. While directed lubrication can eliminate high parasitic power loss, it can also mitigate bearing temperatures and oil flow. Whether one wishes to use a flooding or direct lubrication method, both can be carried out with the same thrust pads.
The thrust pads themselves may be constructed from numerous materials, common choices including polymeric materials, white metal, and Babbitt. While center-pivoted pads are the most preferable components for bidirectional running, minimum stocks, and foolproof assembly, offset pivots are also a viable option. Offset pivots can be beneficial for a number of applications, offsetting load capacities and mitigating bearing surface temperatures when mean sliding speeds surpass 70 meters per second.
For their application, tilting pad thrust bearings may be found in heavy-duty rotating machinery, assisting in locating rotors and supporting axial loads. Additionally, they may also be found in turbogenerators, high-rotation speed compressors, and other such equipment. If you find yourself in need of a tilting pad thrust bearing, ring thrust bearing, head thrust bearing, floating thrust bearing, key thrust bearing, or other hardware types, let the experts at Click Aerospace help you procure all you require with competitive pricing and rapid lead-times.
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