Tribology of Hydraulic Pumps

To obtain much higher performance than that of alternative power transmission systems, hydraulic systems have been continuously evolving to use "high-pressure". Adoption of positive displacement pumps and motors is based on this reason. Therefore, tribology is a key technology for hydraulic pumps and motors to obtain excellent performance and durability. In this paper the following topics are investigated: 1. The special feature of tribology of hydraulic pumps and motors. 2. Indication of the important bearing/sealing parts in piston pumps and effects of the frictional force and leakage flow to performance. 3. The methods to break through the tribological limitation of hydraulic equipment. 4. Optimum design of the bearing/sealing parts used in the fluid to mixed lubrication regions.