Coupling part for a hydraulic coupling

A coupling part (1), in particular a coupling sleeve, for coupling to a corresponding coupling part, in particular a coupling connector (9), of a coupling for pressure medium lines, in particular hydraulic lines, comprising

• a housing (2) having a continuous first passage that runs in the axial direction,
• a valve tappet (5) that is coaxially arranged in the first passage of the housing (2),
• an inner sleeve body (3) that is coaxially arranged in the first passage of the housing (2), lying against it in certain regions, and having a cylindrical guide section (32) by means of which a central second passage is delimited, which is arranged coaxial to the first passage,
• a valve bushing (4) that is arranged to be displaceable in the axial direction, between a first position and a second position, relative to the inner sleeve body (3), through the guide section (32) of which body the bushing is guided, wherein the valve bushing (4) forms a seal relative to the inner sleeve body (5) both in the first position and in the second position, and in the first position forms a seal on the valve tappet (5) and in the second position delimits a gap between the valve tappet (5) and the valve bushing (4),
• wherein in the first position of the valve bushing (3), a flow channel is delimited by the inner sleeve body (3), the valve bushing (4), and the valve tappet (5), wherein the valve bushing (4) has a circumferential shoulder (46) on the inside, which leads into a hollow-cylindrical end section (43), wherein the inside diameter (d3) of the hollow-cylindrical end section (43) is slightly smaller than the outside diameter (d1) of the sliding section (41) of the valve bushing (4).