Correction of shaft misalignment

In the previous part, the author explained how the detection, location and analysis of faults play a vital role in the field of rotor dynamics. This article discusses how shaft misalignment can be another cause of vibration due to reaction forces generated in the shaft couplings.

Vibration monitoring 101

Vibration monitoring is one of the primary condition monitoring methods used in detecting faults in rotating machines. Experience has shown that shaft misalignment and rotor unbalance are the main sources of vibration in rotating machines. Due to advances in engineering and materials science, rotating machinery is becoming faster and lighter, as well as being required to run for longer periods of time. As a result, detection, location and analysis of faults play a vital role in the field of rotor dynamics.

Evaluation Of a High Speed, Light Load Phenomenon In Tilting-Pad Thrust Bearings

This paper discusses a newly found high speed, light load hydrodynamic tilting-pad thrust bearing phenomenon. The phenomenon was first witnessed on centrifugal compressors operating above 10,000 rpm. Testing results have shown that in high speed, light load applications, thrust bearing babbitt temperatures are much higher than expected at low load conditions, and then drop to expected levels as the thrust load is further increased.

A Study Of Parameters That Affect Pivoted Shoe Journal Bearing Performance In High-Speed Turbomachinery

Journal bearing pad temperatures, oil flow requirements, and power losses can impose limitations on the design and operation of high-speed turbomachinery. Over the past few years, the authors have conducted extensive tests and studies of parameters that affect pivoted shoe journal bearing performance.

Test Results Comparing the Effect of Reverse Rotation on Offset Pivot Journal Bearing Pad Temperatures

Babbitt temperatures in pivoted shoe bearings can be significantly reduced by offsetting the pad pivots in the direction of rotation. However, reverse rotation can occur in certain types of machinery under temporary or adverse conditions. The offset is then in the wrong direction and it becomes important to know if the bearing can withstand the reverse rotation operating conditions without damage. This paper compares pad temperature data from tests of a 152.4-mm, 60 percent offset bearing in forward and reverse rotation.

Journal Bearing Vibration and SSV Hash

Peculiar, low-frequency, radial vibrations have been observed in various turbomachinery using tilt-pad journal bearings. Unlike discrete subsynchronous spikes that often indicate a serious problem, the vibrations are indiscrete and of low frequency and amplitude. The low level shaft indications have raised concern in witness tests of critical machinery, even in cases that comply with American Petroleum Institute (API) limits, owing to uncertainty regarding the cause and nature of the vibrations.

Special Design Features To Increase Rated Load Or Reduce White Metal Temperatures

Choosing the right bearing is easy, once you know how. To help, this article outlines the steps to take. It includes guidelines for bearing selection and curves for estimating power loss and oil flow requirements.

Directed-lubrication Bearing, LEG® By Kingsbury, Inc.

Design Notes:
The following guidelines for assigning load capacities to tilt-pad fluid film thrust bearings take into consideration theoretical analyses, field experience, and actual test results.

Current issues regarding unusual conditions in high speed turbomachinery

The hydrodynamic bearing is a remarkable device, capable of supporting extaordinary loads at high speeds for decades with little or no wear. However, there are a number of factors, including lubricant contamination, misalignment, vibration and other undesirable operating conditions, that can degrade bearing performance.

High Thrust Bearing Temperatures Due to Varnish

Why is my thrust bearing running hot?

When you hear this question, it is natural to think that there is something wrong with the thrust bearing. This is not always the case. Bearing performance information can give you the symptoms of what is wrong with your machine or in this case the lubricant.

Turbulent Transition in Tilting Pad Journal Bearings

Tilting pad journal bearings can operate under a wide range of conditions of speed, load, load angle, oil temperature, and oil viscosity. Each one of these variables has an effect on the oil film, and an influence on whether the film is laminar, turbulent, or in transition. Other parameters affect the film as well including geometry such as the bearing diameter, length, clearance, preload, the number of pads and their orientation.

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