  Dynamics of a classical particle in a one-dimensional, randomly driven
potential is analysed both analytically and numerically. The potential
considered here is composed of two identical spatially-periodic saw-tooth-like
components, one of which is externally driven by a random force. We show that
under certain conditions the particle may travel against the averaged external
force performing a saltatory unidirectional drift with a constant velocity.
Such a behavior persists also in situations when the external force averages
out to zero. We demonstrate that the physics behind this phenomenon stems from
a particular behavior of fluctuations in random force: upon reaching a certain
level, random fluctuations exercise a locking function creating points of
irreversibility which the particle can not overpass. Repeated (randomly) in
each cycle, this results in a saltatory unidirectional drift. This mechanism
resembles the work of an escapement-type device in watches. Considering the
overdamped limit, we propose simple analytical estimates for the particle's
terminal velocity.
