Before repairing the bearing, the automobile should first check whether the bearing seat bore meets the requirements
(1)Test and repair of bearing
Check and correct the damage of crankshaft bearing in use, mainly including wear, fatigue spalling and burning. New bearings must be replaced during engine overhaul. Before repairing the bearing, it shall first check whether the bearing pedestal hole meets the requirements, and the roundness and cylindrical error of the bearing pedestal hole shall not be greater than 0.015mm. The inspection and correction method is as follows: wipe the bearing seat, install the bearing cover, tighten the fixed bolt or nut according to the specified torque, and check the roundness and cylindrical degree of the seat hole by using the cylinder table. When the roundness and cylindrical degree of the bearing cover exceeds the specified, the bearing cover can be surmounted and welded or adjusted by adding a cushion, and no file is allowed.
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. New bearings should be replaced when the limit is exceeded.
(2) Bearing matching
Currently, the commonly used bearing alloys for crankshaft bearings of gasoline engines are babbitt alloys and high-tin aluminum alloys with a thickness of 0.30 ~ 0.35mm. Besides the standard dimensions, the specifications of the bearings also correspond to the crankshaft journal with the repair dimensions reduced by 0.25mm in inner diameter.