Hydrostatic transmissions are widely used in the field of mobile machines in construction, mining, agriculture, forestry, both to start working bodies (multipliers) that perform technological operations, and for motion drives. In the first part of the paper, hydrostatic power transmissions and their classification are described, followed by an explanation of the working principles of hydraulic pump and hydraulic motor. In the second part of the paper, the application of the hydrostatic transmission in different mobile machines is presented. The third part represents the most crucial segment, where the calculation to obtain the key parameters for hydrostatic transmission design is presented. Finally, the main components of the hydrostatic transmission are selected.