The present invention relates to a turn system actuated by hydraulic cylinders, applied to the four wheels of sugar-cane harvesters, wherein the harvester (80) comprises a rear axle (23) and a front axle (24), with wheel assemblies (9) associated to the axles (23, 24), wherein the rear axle (23) and the front axle (24) have a turn system, the one of the rear axle (23) being actuated by means of a double-action rear hydraulic cylinder (1) and that of the front axle (24) being actuated by means of a double-action front hydraulic cylinder (11), the hydraulic cylinders (1, 11) receiving a flow of oil through at least one flow divider (61) connected to an ortibrol (65) actuated by means of a steering wheel (60) of the harvester (80), the flow of oil received by the flow divider (61) being proportional to a factor related to the turn of the steering wheel (60), the turn system enabling the turn of the wheel assemblies (9) in amplitude ranging from 0.5 to 40 degrees, to the right or to the left, with respect to the longitudinal axis of the harvester (80).