The utilisation of on-board transmissions has witnessed a surge in popularity within the domain of heavy-duty vehicles. This study undertakes a comprehensive analysis of the kinematic and power performance of an on-board transmission, which is predicated on the principle of a power adder employing two planetary mechanisms. In order to achieve the stated objective, a methodology was employed that enabled the determination of the ranges of change in the transmission output speed and the range of hydrovolumetric gear power to the total transmission output power for various combinations of two planetary mechanisms. This further provides practical recommendations for the use of circuit combinations in the on-board HMCVT. The result of the study is the establishment of the relationship between the kinematic and power indicators of the onboard HMCVT, which consists of two planetary mechanisms, and the structural change in the connections of the component planetary mechanisms.