  We develop and analyze a model for ratchet-driven macroscopic transport of a
continuous phase. The transport relies on a field-induced dewetting-spreading
cycle of a liquid film with a free surface based on a switchable, spatially
asymmetric, periodic interaction of the liquid-gas interface and the substrate.
The concept is exemplified using an evolution equation for a dielectric liquid
film under an inhomogeneous voltage. We analyse the influence of the various
phases of the ratchet cycle on the transport properties. Conditions for maximal
transport and the efficiency of transport under load are discussed.
