The present invention refers to a motor assembly for a railway axle (1) comprising: one axle (2) exhibiting at least one driving wheel (2a) and configured for rotating around an axis (A), a main wheel (3) fitted to the axle (2), a first actuating wheel (4) constrained to the axle (2) and configured for rotating with respect to this latter around the axis (A) and actuatable by a first motor (8), a connecting wheel (5) fixed to the first actuating wheel (4) and configured for cooperating with the main wheel (3) for enabling the axle (2) to rotate around the axis (A), a second actuating wheel (6) constrained to the axle (2) and configured for rotating with respect to this latter around the axis (A) and actuatable by a second motor (9), a coupling portion (7) fixed and integral with the second actuating wheel (6) - placed at least partially around the connecting wheel (5) - and which exhibits an inner coupling surface (7a) engaged with the connecting wheel so that this latter is interposed between the main wheel (3) and said inner coupling surface (7a). Moreover, the present invention refers to a railway wagon.