Bearing inspection and replacement

1) check and correction of bearing hole crankshaft bearing damage in use, mainly wear and fatigue spalling and burning fuse. When the engine overhaul, new bearing must be replaced. Before the replacement of bearings, should first check whether the bearing hole accords with a requirement, bearing hole of the roundness and cylindricity error is not more than 0.015 mm. Check and correction of the method is: wipe bearing seat, mount bearing cover, according to the specified torque tighten the retaining bolt or nut, dosage of cylinder table check hole of the roundness and cylindricity in excess of the prescribed, can be in surfacing welding processing or padded adjustment on both ends of the bearing cover, are not allowed to file repair the bearing cap.

Check the bearing wear method as shown in figure 2 to 16, the journal and bearing oil clean, cut plastic line clearance gauge as same as the width of the bearing length, and then on the crank pin, make them parallel to the shaft centerline, carefully mount bearing cover, tighten nut torque according to regulations, then carefully remove the bearing cover, plastic line clearance gauge on the packet in some measure, measure flattened plastic wire, the width of the widest part clearance values are obtained. More than limit new bearing should be changed.

2) bearing selection at present, the petrol engine crankshaft bearing bearing alloy with babbitt and commonly used plastic aluminium alloy, alloy layer thickness of 0.30 ~ 0.35 mm, the specifications of the bearing in addition to the standard size, and according to the narrow diameter 0.25 mm for the repair of one class size and corresponding crankshaft journal, in order to choose when to repair.