Abstract: The linear actuator comprises two variable-volume chambers (5) containing an operative liquid, each of the chambers (5) being delimited on one side by one of two mobile elements (4), which mobile elements (4) are solidly constrained one to another. One of the mobile elements (4) is connectable to an external user, for example a gearwheel of a gear coupling. A geared rotary positive displacement pump (10) reversibly transfers the operating liquid from one chamber (5) to the other chamber (5) through an infeed conduit (6), to move the mobile elements (5) selectively in one direction or another. A recycling conduit (7), narrower than the infeed conduit (6), places the two chambers (5) in communication and realizes a closed circuit, in a situation where the mobile elements 4) are stationary and the pump (10) is active.