Abstract
Causes and countermeasures for various kinds of hydraulic system failures in construction machinery generated by biodegradable hydraulic oil (bio-oil) are discussed. Previous component analytical methods can prevent all kinds of failures except hydraulic system malfunction, which requires a holistic approach for analysis. Using the Systems Modeling Language (SysML), the cause of malfunctions can be understood, and the most effective countermeasure can be obtained. Integration of a component analysis method and a holistic analysis method for system development is proposed.