In hydraulic drives of self-propelled machines, planetary-rotor hydraulic motors are increasingly used, the rotors of which form a gearbox with internal hypocycloidal engagement. The design methodology of planetary hydraulic motors, determining its performance, is currently virtually absent. The conducted studies established the influence of the design and functional parameters of the rotors of a planetary hydraulic machine on its performance, the kinematics of the contact of the toothed surfaces of the rotors was substantiated. The forces acting in the contact zone of the rotors, the relative rolling speeds and sliding speeds of the toothed profiles were determined. The developed models describe changes in the speeds and sliding coefficients of the toothed profiles of the rotors. The identified criteria for predicting the type of wear made it possible to establish that the contact of the toothed surfaces of the rotors is characterized by the ratio of the sliding speed to the rolling speed. It has been established that for critical φcr and supercritical φ < φcr angles with a ratio of VS/VΣ < 1, an important criterion for the performance of cycloidal rotors is the prevention of possible chipping not associated with fatigue character and, first of all, scuffing. Therefore, to ensure high hardness of the mating surfaces of the inner rotor and the teeth of the outer rotor, it is recommended to use special ball bearing or case-hardening steels with a hardness of the mating surfaces of not less than 59–60 HRC.