A hydraulic device comprises a shaft mounted in a housing rotatable about a first axis. A plurality of pistons are fixed to a flange rotatable about a first axis. A plurality of cylindrical sleeves sleeve bottoms and sleeve jackets that cooperate with the pistons to form compression chambers. Rotation of the shaft causes the volumes of the compression chambers. Each piston head forms a sealing line within the cooperating sleeve jacket. Each sleeve jacket has a thin wall and/or is elastically movable with respect to the sleeve bottom such that at a fixed pressure the radial deformation of the sleeve jacket at the sealing line is substantially constant at piston positions ranging from bottom dead center to a position where the distance between the sleeve bottom and the sealing line is less than 50% of the distance between the sleeve bottom and the sealing line at bottom dead center.