Patent ID: 7168360

Claim:
A fluid-operated linear actuator for power steering systems of vehicles with at least three steered wheels, of a double-acting type, comprising: a cylindrical body, which is closed at opposite ends thereof; a piston, which is accommodated inside said cylindrical body so as to be axially slideable between said opposite ends; a stem, which is rigidly associated with said piston, is substantially coaxial to said cylindrical body, and protrudes from both of said opposite ends of the cylindrical body for articulation to a steering system of a vehicle, said piston dividing said cylindrical body into two chambers, each of which is provided with an opening that is formed proximate to said opposite ends for inflow and/or outflow of a working fluid; said piston comprising at least one pair of one-way valves, which have a respective inlet connected to a respective one of said chambers, and respective outlets that are connected to each other, said valves being each provided with a stem and a flow control element, said stem being accommodated for axial sliding in said respective inlet and having a first end associated with the respective flow control element and a second opposite end that protrudes externally from said piston, said valve stem being adapted to open the respective valve, with the piston being located proximate to the closed end of one of said chambers and the other valve being at least partially opened by a flow of pressurized working fluid acting in another one of said chambers, for a transfer of an amount of fluid from the one of said chambers that is at a higher pressure to the other one of said chambers that is at a lower pressure.