Abstract The dynamic behavior of hydro-static transmission (HST) systems is studied experimentally and theoretically to formulate a linearized mathematical model of the HST system and a recursive identification model is then proposed. A computer-controlled test rig is developed and the system state responses are measured. The results obtained from the experimental work and the linearized models are used to build a recursive identification model in order to identify the system under study. Furthermore, comparisons among the experimental, simulated, and identified results are presented. These results show that recursive identification models are powerful tools that can be used for the identification and analysis of HST. Finally, parameter variations of the volume displacement and the motor torque are introduced to the system in order to study their effect on pressure and hydraulic motor speed. Keywords Recursive identification methods . Auto-regressive moving average (ARMA) . Hydro-static transmission (HST)