Vestnik MGTU (Dec 2018)
Fishing vessels' rolling bearings reducers of diesel-reducer units: The diagnostics' results
Abstract
In marine power plants with medium-speed diesels, diesel-reducer units (DRU) being a combination of diesel, gearbox, shaft-generators and other aggregates that can be driven from DRU have become very popular. The basis of the DRU is the main gearbox, which serves to transfer torque to the gross line with a reduction in the speed and drive of the variable speed and alternating current generators (usually with an increase in the speed of rotation in the gear stage). Structural schemes where for the drive of shaft generators, hydraulic pumps, etc. a separate gear reducer is used driven from the main gearbox or directly from the engine have found application as well. The greatest number of revealed defects is associated with the rolling bearings that are part of the gearbox bearing assemblies, as experience in the application of non-dismantling diagnostics for the determination of the technical condition of the DRU gearboxes has shown. For diagnostics of rolling bearings, the method of vibration diagnostics is used based on the spectral analysis of the envelope of the high-frequency component of the vibration signal. The paper presents kinematic schemes of DRU of six types of fishing vessels' gearboxes with the designation of the main elements included into them. The features of the work on reducers' diagnostics have been described; the analysis of rolling bearing diagnostics for each type of gearbox has been carried out; the number of revealed defective bearings and their location in the gearbox have been indicated. Conclusions have been made about the possible causes for the rolling bearings' failure: increased speed of gear shafts, an unsuccessful design scheme, inadequate initial load capacity of the bearing or its incorrect installation leading to deformation of the bearing outer ring, axial displacement or skewing of the rings.
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