Actuator for axial displacement of an object

An actuator for axial displacement of an object, the actuator (1) comprises:

• an actuator piston (4) comprising an actuator piston rod (7) having a first end (8) and a second end (9), wherein the actuator piston (4) is displaceable in the axial direction in a reciprocating manner between a first position and a second position, and
• a hydraulic circuit (20) comprising a liquid filled chamber (21), the first end (8) of the actuator piston rod (7) being arranged to be displaced in the axial direction within said liquid filled chamber (21) in conjunction with axial displacement of the actuator piston (4),
• wherein an axially extending recess (22) mouth in said liquid filled chamber (21) and is arranged to receive the first end (8) of the actuator piston rod (7) when the actuator piston (4) is in said first position,
• characterized in that the actuator piston rod (7) in the area of the first end (8) presents a cylindrical envelope surface (24), and in that the recess (22) presents a cylindrical inner surface (25), the cylindrical envelope surface (24) and the cylindrical inner surface (25) presenting matching shapes, wherein the actuator comprises a passage extending between the recess (22) and the liquid filled chamber (21) when the cylindrical envelope surface (24) and the cylindrical inner surface (25) are located in overlapping configuration, wherein a section of a predetermined maximum overlap is constituted by a braking overlap (35), the passage presenting at said braking overlap section (35) a cross section area (A1) that decrease as a function of increasing overlap between the cylindrical envelope surface (24) and the cylindrical inner surface (25), wherein said cross section area (A1) of the passage at a beginning of said braking overlap section (35) decrease with decreasing derivative and at an end of said braking overlap section (35) decrease with increasing derivative, as a function of increasing overlap.