Hydraulic coupling device

A hydraulic coupling device comprising:

• an inner sleeve having a tapered outer surface,
• an outer sleeve having a tapered inner surface mounted on the tapered outer surface of the inner sleeve,
• a nut screwed onto the inner sleeve, and
• a cylinder formed separately from the outer sleeve and secured to the outer sleeve, the cylinder having a frontal face axially abutting against a frontal face of the outer sleeve to form a joint,
• wherein at least part of the nut extends into the cylinder,
• wherein a surface of the cylinder forms a first wall of a chamber, a surface of the nut forms a second wall of the chamber and a surface of the outer sleeve forms a third wall of the chamber,
• wherein the chamber is fillable with a hydraulic fluid,
• wherein the chamber is radially defined by the tapered outer surface of the inner sleeve and the surface of the cylinder and axially defined by the surface of the nut and the surface of the outer sleeve,
• wherein the cylinder, the nut and the outer sleeve are configured such that a fluid pressure increase in the chamber presses the outer sleeve axially away from the nut, and
• wherein a) the frontal face of the cylinder and/or the frontal face of the outer sleeve is provided with a coating having a coefficient of friction higher than a coefficient of friction of the frontal face of the cylinder and the coefficient of friction of the frontal face of the outer sleeve, and/or b) at least one protrusion extends from the frontal face of the cylinder into a complementary recess in the frontal face of the outer sleeve or at least one protrusion extends from the frontal face of the outer sleeve into a complementary recess in the cylinder.