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3. Bearing Inspection and Maintenance

Turbine Bearing Maintenance

Turbine bearing maintenance is a critical task for ensuring the safe and stable operation of the unit. It primarily involves inspecting, measuring, cleaning, and assembling radial bearings, thrust bearings (thrust bearings), and bearing housings to ensure clearances, contact surfaces, and tightness meet specifications.

1. Macro Inspection:

1) Inspect the bearing shell alloy layer (e.g., Babbitt alloy) for peeling, cracks, scratches, or uneven wear.

2) Contact impressions between bearing shells and journal surfaces should be uniformly distributed along the axial direction.

3) For thrust bearings (thrust bearings), inspect the alloy layer of thrust bearing shells and the load-bearing surfaces on their backsides to ensure no indentations or wear.

2. Radial Bearing Clearance:

1) Top clearance is commonly measured using the lead wire method (lead wire diameter slightly exceeds clearance value). Top clearance equals the average thickness of the top lead wire minus the average thickness of the lead wire at the center plane.

2) Side clearance is measured using a feeler gauge inserted to a depth of no less than 1/4 of the journal diameter.

3) Thrust bearing clearance: Use the shaft-pushing method. Mount a dial indicator on the rotor shaft end and push the rotor back and forth. The maximum axial movement represents the thrust clearance.

3. Bearing Tightness: Measure using the lead wire compression method. Place lead wires on the bearing shell top and spherical shell center plane. After tightening, measure the difference in flattened lead wire thickness.

4. Cleaning, Trimming, and Assembly

1) Cleaning: Thoroughly clean the bearing housing with kerosene and white cloth, ensuring no cracks, oil leaks, and unobstructed oil supply holes.

2) Trimming: Slightly scrape worn bearing surface contacts with a scraper; grind and trim oil seal gaps if too small to ensure proper fit with journal arcs. When bearing pillow blocks have poor contact, grind and scrape the blocks, then use red lead powder to verify contact area (requiring >70%).

3) Assembly: Reassemble in reverse order of disassembly. After assembly, recheck clearances to ensure thrust bearing blocks swing freely and anti-rotation pins are securely fixed.

1-1. Inspection and Disassembly of the Front Thrust Bearing