Electromechanical translation apparatus provides power-off clamping because each clamp assembly comprises pressure means and clamp actuator means acting in opposition. The pressure means is arranged, when the actuator is de-energized, to apply clamping force to releasably clamp the associated movable...http://www.google.fr/patents/US7045932?utm_source=gb-gplus-shareBrevet US7045932 - Electromechanical translation apparatus
