  We obtain ratchet effect in inertial structureless systems in symmetric
periodic potentials where the asymmetry comes from the nonuniform friction
offered by the medium and driven by symmetric periodic forces. In the adiabatic
limit the calculations are done by extending the matrix continued fraction
method and also by numerically solving the appropriate Langevin equation. For
finite frequency field drive the ratchet effect is obtained only numerically.
In the transient time scales the system shows dispersionless behaviour as
reported earlier when a constant force is applied. In the periodic drive case
the dispersion behaviour is more complex. In this brief communication we report
some of the results of our work
