a conveyor device , in particular for an automatic packaging machine for paper rolls , having a horizontal plane of advance , at least one pair of motorised flexible transmission members extending along a closed loop and bearing a plurality of transverse bars fastened to said flexible transmission members , a plurality of thruster elements borne by said bars , and a stationary adjustment station provided with at least one adjustment assembly having a grip organ movable in transverse direction and arranged in such a way as to displace in the transverse direction along the respective bar a thruster element positioned at the grip organ .