  Traditionally the charge ratchet effect is considered as a consequence of the
extrinsic spatial asymmetry engineered by external asymmetric periodic
potentials. Here we demonstrate that electrically and magnetically driven
dissipative systems with spin-orbit interactions represent an exception from
this standard idea. The charge and spin ratchet currents appear just due to the
coexistence of quantum dissipation with the intrinsic spatial asymmetry of the
spin-orbit coupling. The extrinsic spatial asymmetry is inessential.
