Patent ID: 8739679

Claim:
An apparatus for eliminating back drive in a push pull type control system, the apparatus comprising: a control rod including a rod end assembly comprising a pair of spaced apart piston displacement members, each piston displacement member having a check valve aperture configured to receive a check valve; a first check valve of a set of opposite-facing check valves having a body connected to a first of the pair of piston displacement members and having an aperture extending through a piston-facing surface of the first check valve for receiving hydraulic fluid; and a second check valve of the set of opposite-facing check valves having a body connected to a second of the pair of piston displacement members and having an aperture extending through a piston-facing surface of the second check valve for receiving hydraulic fluid; wherein the first check valve body is oriented so that when the first of the pair of piston displacement members is retracted into a direction of a piston head positioned between the set of opposite-facing check valves and the piston-facing surface of the first check valve lands upon an opposing surface of the piston head, the aperture of the first check valve forms an at least substantially sealed pathway through an aperture in the piston head; and wherein the second check valve body is oriented so that when the second of the pair of piston displacement members is extended into a direction of the piston head and the piston-facing surface of the second check valve lands upon an opposing surface of the piston head, the aperture in the second check valve forms an at least substantially sealed pathway through the second aperture in the piston head.