The invention concerns a hydraulic actuator (10), which includes two or more cylinder parts (11, 12) arranged to nest inside each other, namely an inner cylinder part (12) and an outer cylinder part (11), each of which cylinder parts includes a piston (13.1, 13.2) and a piston rod (14.1, 14.2) arranged to form an operating element (15, 16) and a cylindrical component (17.1, 17.2), inside which the operating element is arranged, and the piston (13.2) of the inner cylinder part is arranged inside the piston rod (14.1) of the outer cylinder part； chambers (A, B) arranged to be formed for each cylinder part； a pressure-medium feed arrangement (19) for creating a work-movement (Ml, M2) in the operating element by the pressure medium led to the chambers, which includes first ducting (63) equipped with a connection (18.1) arranged to the cylindrical component of the outer cylinder part and second ducting connected to the first ducting, which is arranged to run through the pistons in order to arrange a pressure-medium connection to chamber (B) of the inner cylinder part； and control means (20) for controlling the operation of the hydraulic actuator. The control means include a pressure-difference-controlled valve (46) arranged between the first ducting and the second ducting, arranged to control the feed of the pressure medium between the chambers.La présente invention concerne un actionneur hydraulique (10), qui comprend deux parties cylindres ou plus (11, 12) agencées pour s'emboîter l'une dans l'autre, à savoir une partie cylindre interne (12) et une partie cylindre externe (11), chacune de ces parties cylindres comprenant un piston (13.1, 13.2) et une tige de piston (14.1, 14.2) agencée pour former un élément d'actionnement (15, 16) et un composant cylindrique (17.1, 17.2), à l'intérieur duquel est disposé l'élément d'actionnement, et le piston (13.2) de la partie cylindre interne étant disposé à l'intérieur de la tige de piston (14.1) de la partie cylindre externe； des
