Unbalanced oscillatory pressures, developed on the power piston of hydraulic servoactuator systems cause vibrations on actuator housing supports. An unbalanced oscillatory force results, when two sides of the power piston are subjected to two unequal oscillatory forces induced by a disturbance. The two...http://www.google.com/patents/US5600955?utm_source=gb-gplus-sharePatent US5600955 - Hydraulic servoactuator stabilizer device
