Hydraulic motor (1; 201) for a vehicle wheel, comprising: - a hydrodynamic element having: i) cells (Ai), ii) pistons mounted so as each to slide in a respective cell (Ai), defining a variable-volume chamber therein, and iii) ducts that lead into the cells in order to communicate with the chambers, - a reaction element (6; 206) comprising an annular cam (7; 207) on which an active face of each piston acts, - a front bearing and a rear bearing, by way of which, at least indirectly, the reaction element and the hydrodynamic element are rotatable with respect to one another about an axis of rotation, - a support (8; 208) rotationally linked to one of the elements (6; 206), the other element being designed to be rotationally linked to a vehicle wheel, - an oil distributor (9; 209) that rotates as one with the reaction element (6; 206) and brings the ducts selectively into communication with an oil supply line (18; 218) and oil return line (19; 219) depending on its angular position relative to the hydrodynamic element, and - a brake (12; 212) mounted functionally between the two elements (2, 6; 206) in order to selectively prevent said rotational movement, the brake (12; 212) having at least one first braking surface rotationally coupled to the hydrodynamic element, and a second braking surface rotationally coupled to the reaction element (6; 206), characterized in that each piston is mounted radially with respect to the axis of rotation, and in that the hydrodynamic element is secured to a collar which surrounds the oil distributor and bears, on its radially outer face, means for rotationally coupling to the at least one first braking surface, the brake (12; 212) thus being disposed around the distributor (9; 209). - a hydrodynamic element having: i) cells (Ai), ii) pistons mounted so as each to slide in a respective cell (Ai), defining a variable-volume chamber therein, and iii) ducts that lead into the cells in order to communicate with the chambers, i) cells (Ai), ii) pistons mounted so as each to slide in a respective cell (Ai), defining a variable-volume chamber therein, and iii) ducts that lead into the cells in order to communicate with the chambers, - a reaction element (6; 206) comprising an annular cam (7; 207) on which an active face of each piston acts, - a front bearing and a rear bearing, by way of which, at least indirectly, the reaction element and the hydrodynamic element are rotatable with respect to one another about an axis of rotation, - a support (8; 208) rotationally linked to one of the elements (6; 206), the other element being designed to be rotationally linked to a vehicle wheel, - an oil distributor (9; 209) that rotates as one with the reaction element (6; 206) and brings the ducts selectively into communication with an oil supply line (18; 218) and oil return line (19; 219) depending on its angular position relative to the hydrodynamic element, and - a brake (12; 212) mounted functionally between the two elements (2, 6; 206) in order to selectively prevent said rotational movement, the brake (12; 212) having at least one first braking surface rotationally coupled to the hydrodynamic element, and a second braking surface rotationally coupled to the reaction element (6; 206), - a brake (12; 212) mounted functionally between the two elements (2, 6; 206) in order to selectively prevent said rotational movement, the brake (12; 212) having at least one first braking surface rotationally coupled to the hydrodynamic element, and a second braking surface rotationally coupled to the reaction element (6; 206),