US Patent 7748720 Vehicle roll control system

A roll control system comprising a front torsion bar; a front first hydraulic actuator; a front second hydraulic actuator; a rear torsion bar; a rear first hydraulic actuator; a rear second hydraulic actuator; and control means connected to the hydraulic actuators and controlling the operation thereof on detection of a predetermined vehicle condition; wherein each hydraulic actuator comprises a first fluid chamber and a second fluid chamber; wherein the control means comprises a source of fluid pressure, a fluid reservoir, a pressure control valve fluidly connected between the pressure source and the reservoir, and at least three pressure relief valves each having two positions to fluidly connect the fluid chambers of the hydraulic actuators either to the pressure source or to the fluid reservoir; wherein the pressure relief valves are positioned on detection of the predetermined vehicle condition to apply a fluid pressure to the first fluid chamber of the first front hydraulic actuator and to the second fluid chamber of the second front hydraulic actuator, and/or to apply a fluid pressure to the second fluid chamber of the first front hydraulic actuator and to the first fluid chamber of the second front hydraulic actuator, and/or to apply a fluid pressure to the first fluid chamber of the first rear hydraulic actuator and to the second fluid chamber of the second rear hydraulic actuator, and/or to apply a fluid pressure to the second fluid chamber of the first rear hydraulic actuator and to the first fluid chamber of the second rear hydraulic actuator.