Hydraulic device

A hydraulic device comprising a housing, a shaft which is mounted in the housing and rotatable about a first axis of rotation, wherein the shaft has a flange extending transversely to the first axis, a plurality of pistons which are fixed to the flange at equiangular distance about the first axis of rotation, a plurality of cylindrical sleeves including sleeve bottoms and sleeve jackets, respectively, and cooperating with the pistons to form respective compression chambers of variable volume, wherein the cylindrical sleeves are rotatable about a second axis of rotation which intersects the first axis of rotation by an acute angle such that upon rotating the shaft the volumes of the compression chambers change between bottom dead center and top dead center of the pistons within the cylindrical sleeves, wherein each piston has a piston head including a circumferential wall of which an outer side is ball-shaped, hence forming a sealing line within the cooperating sleeve jacket, and an inner side surrounds a cavity, each sleeve jacket has such a thin wall and/or is elastically movable with respect to the sleeve bottom such that at an elevated fixed pressure in the compression chamber at which radial deformation of the sleeve jacket occurs, 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 a 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.