The invention relates to an actuating device comprising: —a first element (7), —a second element (8) able to move translationally with respect to the first element (7), and —a locking device (6) comprising a catch (18, 20) able to move between a deployed position and a retracted position, the catch (18-20) being positioned with respect to the first element (7) in such a way that when the catch (18-20) is in a deployed position, the catch (18-20) allows the second element (8) to move with respect to the first element (7) in a first range of movement (A) and prevents the second element (8) from moving with respect to the first element (7) in a second range of movement (B), and when the catch (18-20) is in the retracted position, the catch (18-20) allows the second element to move with respect to the first element (7) in the second range of movement (B). This device is particularly suited to allowing actuation of a thrust reverser system and of a system that regulates air flow through an aircraft propulsion unit.