the axial direction for example by rotating inwards in the roll the regulation rod 23 at the same time pivots the cam member 21 around the articulation pin 22 in which connection as the cam member 21 pivots it is supported with a greater force against the inner face 12 b u2032 of the middle part 12 b of the axle while at the same time increasing the distance between the end part 12 a and the middle part 12 b of the axle at the side of the cam member 21 in this connection the axle bends fig3 shows an alternative embodiment of the mechanism of regulation of bending of the roll in fig3 the regulation mechanism is denoted with the reference 20 a the end area of the roll is in the other respects identical with that described in relation to fig2 so that in the following the construction shown in fig3 will be described in respect of the regulation mechanism only in the embodiment of fig3 the regulation mechanism 20 a is hydraulically operated in the axial direction the inner end of the end part 12 a of the axle is closed by means of a wall 22 a and a piston 24 a has been fitted inside the tubular end part 12 a so that said piston 24 a and the end 22 a define a.