Apparatus for moving supports carrying sensors displaceable inside fixed guides integral with the towers of submarines, and the like, upon operation of an actuator, the actuator consisting of an electric motor coupled to one end of a screw actuator on which a screw nut integral with a rod is movable, the entire assembly being contained inside a housing with seals, from which the free end of said rod protrudes for fastening to the tube. The housing can include a first bearing and a second bearing or bushing for supporting the rod and the screw actuator coaxially within the housing. The housing can include a top chamber above the first bearing and a bottom chamber below the first bearing. One or both of the chambers can be filled with lubricating oil to dissipate heat and/or dampen noise. The bottom chamber can house the motor and include a dielectric oil. The motor can be controlled by an electronic actuating system using an angular position transducer. The system can also include a braking circuit for braking the motor and a circuit that provides resistance or short-circuits the windings of the motor to cause a gradual downward movement of the support in the event of a power failure.