Abstract: This invention relates to a roll mill comprising hydraulic clamping devices acting on at least one roll (2) with adjustable level, and devices for measuring the position of the adjustable roll, comprising, at each end (42) of the roll, a measuring rod (4) going through a tubular sleeve (5) with a certain clearance for insulating the pressure chamber (33). According to the invention, the clamping jacks (3) are single-action and the insulating sleeve (5) connected to each jack is extended by a sheath (53) going through the roll standard of the stand up to an external end on which rest devices for restoring the jack (3), in the direction opposite the clamping direction, while resting on the standard of the stand.