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The goal of the present study was to develop a new legform impactor that accurately represents both the impact force (i.e., force between the leg and impacting mass)and leg kinematics in lateral impacts simulating car-pedestrian accidents. In its development we utilized the knee joint of the pedestrian dummy called Polar-2 (HONDA R&D) in which the cruciate and collateral ligaments are represented by means of springs and cables, the geometry of the femoral condyles is simplified using ellipsoidal surfaces, and the tibial meniscus is represented by an elastomeric pad. The impactor was evaluated by comparing its responses with published experimental results obtained using postmortem human subjects (PMHS). The evaluation was done under two conditions: 1)impact point near the ankle area (bending tests),and 2)impact point 84 mm below the knee joint center (shearing tests). Two impact speeds were used: 5.56 m/s and 11.11 m/s.

Anybody knows that contamination in oil is always harmful to hydraulic and lubricating systems. Contaminants inevitably exist in the oils of hydraulic and lubrication systems and cause tribological problems. In order to prevent such tribological problems due to contaminants, various oil cleaners have been developed and applied to hydraulic and lubricating systems. They have greatly contributed to improving the reliability of the systems. Since sophisticated hydraulic systems with proportional valves or servo valves, which are sensitive to oil contamination, became popular, fine filters like 3 micron or 1 micron are additionally used. However contamination problems have been revived. The authors have investigated the causes of hydraulic and lubricating problems and found that polymerized oil oxidation products were as harmful as solid particles. They are of molecular size and cannot be removed by mechanical filtration.