Abstract: A hydraulic cylinder control unit for gait control of a prosthetic limb which features two cylindrical tubes that are eccentric with respect to each other. The inner tube houses hydraulic fluid and the gap between the two tubes serves as a displacement chamber as a piston, mounted on a piston rod, moves through the fluid in the inner tube. When the outer tube is rotated about the inner tube, the gap between the tubes changes which either increases or decreases the flow allowed between the tubes. This changes the resistance which controls the rate of swing of an artificial limb. The resistance is easily adjustable by a simple rotation of the outer cylindrical tube. A floating sealed piston is additionally provided at the bottom of the inner tube. The sealed piston moves upwards or downwards depending on the balance of forces between the fluid force above the piston and the stored energy force below the sealed piston.