Abstract: An electronically controlled brake apparatus (10) for tractors. The apparatus (10) having:—devices (11, 12, 13a, 13b, 15, C1, C2) for producing and distributing compressed fluid;—a device (14) for braking and steer-by-braking (SBF) the tractor; and—compressed-fluid modulating devices (18, 19, 24, 25) for activating tractor brakes (21, 23, 27, 29). The modulating devices (18, 19, 24, 25) are connected electrically to a brake-control electronic central control unit (CNT). And the apparatus (10) also has a device (DS) for supplying high-pressure fluid to the rear modulating devices (24, 25) and selecting the maximum pressure of the fluid supply to the rear modulating devices (24, 25), depending on the function to be performed.