1. Oil leakage: oil flows out or seeps from the shock absorber during use, in static or working state.
2. Failure: the shock absorber loses its main function during use. Usually, the damping force loss of the shock absorber exceeds 40% of the rated damping force during its service life.
3. Abnormal sound: abnormal sound generated by the interference of parts during the use and operation of the shock absorber (friction sound generated when the damping oil flows through the valve system is not abnormal).