  During the last years there has been an increasing excitement in nanomotors
and particularly in current-driven nanomotors. Despite the broad variety of
stimulating results found, the regime of strong Coulomb interactions has not
been fully explored for this application. Here we consider
nanoelectromechanical devices composed by a set of coupled quantum dots
interacting with mechanical degrees of freedom taken in the adiabatic limit and
weakly coupled to electronic reservoirs. We use a real-time diagrammatic
approach to derive general expressions for the current-induced forces, friction
coefficients, and zero-frequency force noise in the Coulomb blockade regime of
transport. We prove our expressions accomplish with Onsager's reciprocity
relations and the fluctuation-dissipation theorem for the energy dissipation of
the mechanical modes. The obtained results are illustrated in a nanomotor
consisting of a double quantum dot capacitively coupled to some rotating
charges. We analyze the dynamics and performance of the motor as function of
the applied voltage and loading force for trajectories encircling different
triple points in the charge stability diagram.
