  The generation of valley current is a fundamental goal in graphene
valleytronics but no practical ways of its realization are known yet. We
propose a workable scheme for the generation of bulk valley current in a
graphene mechanical resonator through adiabatic cyclic deformations of the
strains and chemical potential in the suspended region. The accompanied strain
gauge fields can break the spatial mirror symmetry of the problem within each
of the two inequivalent valleys, leading to a fnite valley current due to
quantum pumping. An all-electrical measurement configuration is designed to
detect the novel state with pure bulk valley currents.
