Modeling and simulation of a hydrostatic transmission with variable-displacement pump Original Research Article

The S-matic power split drive of Steyr Antriebstechnik is a drive box for vehicular drive systems which combines the advantages of hydrostatic and mechanical transmission. This paper is concerned with the mathematical modeling of the hydrostatic unit of the drive box with special emphasis on the swash-plate mechanism of the variable-displacement pump. For reasons of reliability no measurement device is planned for the variable swash-plate angle. Therefore, a simple discrete on-line simulator for the swash-plate angle is derived by simplifying gradually the mathematical model on the basis of physical considerations.