utilized that opens sliding valves 18 when a pressure in piston cylinder unit 21 is lowered thus sliding valves 18 may be automatically opened in the absence of this hydraulic pressure fig4 illustrates an alternative design for drain valves 15 which may include a stopper 27 that may be guided into opening of drain channel 14 in the manner of a reciprocating plug fig4 illustrates drain valves 15 in an open position stopper 27 may be pushed into its open position by a pressure spring 28 and hydraulic fluid may be drained from drain channel 14 i e around stopper 27 into a chamber 29 from which it reaches the reservoir 17 between roll sleeve 2 and support beam 4 in a manner that is not illustrated here stopper 27 may be actuated by an inclined plane 30 formed within slider 31 that may slide substantially parallel to support beam 4 in an axial direction e g as shown by arrows 32 33 when slider 31 is moved in a direction of arrow 32 drain valves 15 are closed conversely when slider 31 is moved in a direction of arrow 33 drain valves 15 are opened to close the drain valves 15 a left end of slider 31 may be equipped with a piston cylinder unit 21 which may be pressurized with hydraulic fluid i e in a manner similar to that discussed with regard to fig3 when slider 31 is then moved to the right the inclined surfaces 30 of slider 31 and stopper 27 move stopper 27 radially inward thus closing the opening of drain channel 14 in an alternative embodiment stopper 27 may also act on a front surface that surrounds the opening of drain channel.