我厂试生产的 EQ140型五吨民用车,自1977年开始先后在海南岛及云南保山地区进行使用试验,先后共发现十根曲轴在第五、六连杆轴颈油孔处产生与轴线成45°方向裂纹,后又经台架扭转共振疲劳试验,其结果,与道路上出现的破坏特征相似,可见曲轴开裂原因是发动机经常在扭转共振转速下运行而产生的扭转疲劳破坏。为解决这一问题我们采用了在曲轴 I plant trial production of EQ140 five tons of civilian vehicles, has been in Hainan Island in 1977 and has conducted tests in Baoshan District of Yunnan Province, has found a total of ten crankshaft in the fifth, six-pin shaft journal hole with the axis into 45 ° direction crack, and then by the bench torsional resonance fatigue test, the result is similar to the damage characteristics of the road, crankshaft cracking can be seen due to the engine often operating under torsional resonance speed torsional fatigue failure. To solve this problem we adopted the crankshaft