  We analyze electron transport through a quantum shuttle for the applied
voltage below the instability threshold. We obtain current-voltage
characteristics of this system and show that at low temperature they exhibit
pronounced steps. The temperature dependence of the current is calculated in
the range from 2K to 300K and it demonstrates a wide variety of behavior - from
1/T decreasing to an exponential growth - depending on how deep the shuttle is
in quantum regime. The results obtained are compared to experimental data on
electron transport through long molecules.
