Analysis of Hydro-Mechanical Transmission—An Illustration for Training and Research of Automotive Engineering in China

Split torque and split speed drives are analyzed with Transmission “Functions representing speed relation between input and output derived using pump-motor displacement ratio as controllable variable. Variation of hydraulic, mechanical horse power shares and circulation with such a ratio is studied. Influence of mechanical and volumetric efficiencies of hydraulic branch on the over-all efficiency can be shown in a mathematic formula which indicates that hydro-mechanical drive has an efficiency up to 10% higher than purely hydraulic transmission as verified by experiments.