Hydrostatische Fahrantriebe für mobile Arbeitsmaschinen

Hydrostatic drive transmissions have been introduced for many kinds of mobile machinery, as they offer improved productivity and comfort and as they contain a high potential for automatic control strategies including engine control. The paper deals with a review and updated fundamentals. After historical remarks follows a list of relevant machinery and a survey on structures of "direct" transmissions. Further alternatives are possible by the principle of external power split. Some general fundamentals, design rules and typical efficiencies are presented for both. Modern hydrostatic power split transmissions achieve almost the same efficiency level as high efficient multi-speed power shift transmissions (without hydrodynamic torque converter). Some hydrostatic transmissions, which are in series production, are discussed. Direct hydrostatic drives are rather typical for construction machinery, self propelled harvesters, fork-lift trucks and most other mobile machinery, while hydrostatic power split transmissions are mass-produced mainly for tractors.