Abstract: In order to study the rear mount bracket bolts loose and the crack of the flywheel housing for a heavy vehicle, a strength analysis is conducted on the flywheel housing, and the assembly torque of the suspension support bolts is recalculated, at the same time, the friction coefficient, axial force, and surface quality of the support bolts are tested. The result shows that surface quality of mount bracket is poor, and axial clamp force can′t resist external load leads, the mounting bolts gradually loosen during the use of the vehicle, which leads to fatigue cracking of the flywheel housing. Therefore, the quality rectification of the surface quality of the feet was carried out, after the full verification of the market, the fault is finally solved, which provides ideas for the solution of similar problems.

Key words: Threaded connection; Flywheel housing; Friction coefficient; Axial force; Surface quality

摘要： 为研究某车型发动机后悬置螺栓松脱和飞轮壳开裂问题，对发动机飞轮壳进行了强度 分析，重新计算悬置支脚螺栓装配扭矩，同时对螺栓的摩擦系数、轴向力和支脚表面质量进 行了检测。结果表明，支脚表面质量较差导致了螺栓轴向力不足，引发了螺栓松动，进而导 致飞轮壳疲劳开裂。因此对支脚表面进行质量整改，经过市场充分验证，故障得以解决，给 类似问题的解决提供了思路。

关键词: 螺纹连接；飞轮壳；摩擦系数；轴向力；表面质量