How to choose crankshaft bearings

**How to Choose Crankshaft Bearings** Home > Bearing Knowledge > How to Choose Crankshaft Bearings Source: China Bearing Network | Time: July 4, 2014 After the crankshaft has been repaired and its size grade determined, it is essential to match the appropriate bearing grade. Bearings are typically available in four standard sizes: 0.00mm, 0.25mm, 0.50mm, and 0.75mm. Choosing the right bearing is crucial for ensuring smooth operation and longevity of the engine. When replacing a bearing, consider the following key factors: 1. **Select Based on Journal Size** Match the bearing grade according to the grinding size of the crankshaft. The same grade of bearing should be used to ensure proper fit and function. 2. **Check Bearing Length** When installing a new bearing into the housing, both the upper and lower halves should extend slightly above the bearing seat surface by 0.03–0.05mm. This ensures a tight fit between the bearing and the housing. To check the length, install the bearing cap and tighten one bolt to the recommended torque. Insert a 0.05mm thick gasket between the other end cover and the bearing seat. If the torque reaches 10–20 N·m and the gasket cannot be removed, the bearing length is correct. If it can be removed easily, the bearing is too long. If the torque is not reached, the bearing is too short and needs to be replaced. 3. **Ensure Proper Lubrication** The backside of the bearing should be free of oil spots and have a surface roughness of Ra 0.8μm. If the lubrication pattern is poor, the bearing may not seat properly. If the pattern is too low, it can be corrected with a sharp mill. If the pattern is damaged, the bearing should be replaced entirely. 4. **Check Elasticity and Noise** After placing the bearing in the housing, ensure that its curvature is slightly larger than that of the housing bore. This allows for proper elastic contact and better heat dissipation. To check for noise, tap the opposite side of the bearing. A dull sound indicates poor alloy-to-base plate contact, and the bearing should be replaced. 5. **Verify Clearance Between Bearing and Journal** Measure the clearance between the bearing and the journal using a micrometer. The difference between the two measurements gives the clearance. For connecting rod bearings, apply a thin layer of oil, mount the rod on the journal, and tighten the bolts to the correct torque. Then, manually rotate the rod—there should be a slight resistance but no play. For main bearings, apply oil to both the journal and bearing, tighten the bolts, and turn the crankshaft by hand. There should be a noticeable resistance, indicating proper clearance. 6. **Ensure Coaxiality of the Housing Bore** The centerline of each main bearing must align with the others. To check this, remove the bearing cover and lift the crankshaft. The contact areas of the bearings should be uniform. If there is a significant difference or if one bearing does not make contact, the housing bore may need repair or the bearing should be selected again. --- **Related Bearing Knowledge** - How to Anneal Thrust (Positioning) Bearings for High Carbon Chromium Bearing Steel - Discussion on the Detection Method for INA Plastic Bearing Noise - Analysis of Methods for Dealing with Overheated Imported Bearings This article is sourced from China Bearing Network. Please cite the source when sharing. Previous: Application Example of Long-Life Rolling Bearings Next: Layout Characteristics and Effect of Thrust Bearings

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