Electro-hydrostatic servo-actuators with unilateral rod cylinder

The replacement of the classical hydraulic servo-actuators on the aircraft with the new electro-hydrostatic servo-actuators raised many technical problems. One of these is the necessity of a unilateral rod cylinder. Such cylinder needs different flow ratios in his chambers. So it is necessary to provide the servo-actuator with some systems which ensure the correct functioning. It is not desired to use a bilateral rod cylinder on the aircraft because of supplementary space required on board.