Existing commercially available long range piezoelectric actuators have limited load carrying capacity due to the fact that frictions are used as the load bearing mechanism. In order to improve the load carry capacity for long range piezoelectric actuators with nanometer resolutions, a novel design that employs the self-lock concept has been reported. In this paper, we study the input-output displacement relations for this new design. In particular, we investigate the losses of the actuator displacement due to elastic deformations when a large force is applied. For a given load, a minimum value exists for the stroke command to ensure a non-zero output displacement. A positioning strategy was proposed to achieve a nanometer scale positioning process in a long distance. Experimental results were also given to support the analysis.