A low-level frame (1) carrying longitudinal and lateral supports (1a,1b) runs on four wheels (2) in axle-boxes (5) with primary springs. The lateral supports (1b) carry secondary springs (6) and oscillation dampers (7). The wheels on each side are coupled by elastic hollow shafts (3d) to a drive unit (3) suspended from the lateral supports. Each drive unit comprises a central three-phase AC motor (3a), two transmissions (3b) and a preferably hydraulic passive brake (3c). The module is attached to the frame by longitudinal elements (9) with resilient transverse buffers (10) and a transverse damper (11).
