Effect of temperature increase on the looseness of connecting rod small end bushing

With the increase on the power density of diesel engine, the looseness of connecting rod small end bushing becomes one of the main faults. In order to solve this engineering problem, the swing friction test bench was utilized to investigate the bushing friction temperature increase under different working conditions. The results show that the highest temperature of the bushing can be close to 300 °C. To further analyze the influence of temperature increase on bushing looseness, bushing looseness tests were carried out at 25 °C, 25 → 100 → 25 °C(Heat from 25 °C to 100 °C, hold for 1 h, and then cool to 25 °C), 25 → 200 → 25 °C, and 25 → 300 → 25 °C. The test results show that the bushing looseness was greatly affected by the temperature increase, especially when the temperature was 25 → 300 → 25 °C. The maximum pressing force of QSn7-0.2 bushing was reduced by 83.9% at 25 → 300 → 25 °C compared with 25 °C. The anti-loosening ability of the bushing can be improved by replacing the CuNi6Sn6 bushing material with higher strength ones as the maximum pressing force of the bushing was higher even though the temperature increased to 300 °C.