tailieunhanh - Bearing Design in Machinery Episode 1 Part 2

Tham khảo tài liệu 'bearing design in machinery episode 1 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | only axial loads. A combination of radial and thrust bearings is often applied to support the shaft in machinery. Bearing Classification Machines could not operate at high speed in their familiar way without some means of reducing friction and the wear of moving parts. Several important engineering inventions made it possible to successfully operate heavily loaded shafts at high speed including the rolling-element bearing and hydrodynamic hydrostatic and magnetic bearings. 1. Rolling-element bearings are characterized by rolling motion such as in ball bearings or cylindrical rolling-element bearings. The advantage of rolling motion is that it involves much less friction and wear in comparison to the sliding motion of regular sleeve bearings. 2. The term hydrodynamic bearing refers to a sleeve bearing or an inclined plane-slider where the sliding plane floats on a thin film of lubrication. The fluid film is maintained at a high pressure that supports the bearing load and completely separates the sliding surfaces. The lubricant can be fed into the bearing at atmospheric or higher pressure. The pressure wave in the lubrication film is generated by hydrodynamic action due to the rapid rotation of the journal. The fluid film acts like a viscous wedge and generates high pressure and load-carrying capacity. The sliding surface floats on the fluid film and wear is prevented. 3. In contrast to hydrodynamic bearing hydrostatic bearing refers to a configuration where the pressure in the fluid film is generated by an external high-pressure pump. The lubricant at high pressure is fed into the bearing recesses from an external pump through high-pressure tubing. The fluid under high pressure in the bearing recesses carries the load and separates the sliding surfaces thus preventing high friction and wear. 4. A recent introduction is the electromagnetic bearing. It is still in development but has already been used in some unique applications. The concept of operation is that