FIELD: mechanical engineering. SUBSTANCE: dividing circuit that connects rotation of a tool with rotation of a blank and circuit of longitudinal feed connecting rotation of the blank with longitudinal movement of the tool are provided with hydraulic step motor output shafts of which are connected with the spindle of the blank and the screw of the longitudinal feed and generators of hydraulic pulses each of which controls one step hydraulic motor. The transmission ratio of each circuit depends on the ratio of the hydraulic pulses produced by generators and supplied to the step hydraulic motors. The transmission ratio is defined by a relationship presented in the invention description. EFFECT: enhanced reliability. 1 dwg
