The invention relates to a rolling unit (1) having three rollers (3,4,5) with axes arranged at 120°, wherein the main roller shaft (6) derives its motion from a drive (9) and transmits it to the shafts (7,8) of the other two rollers (4,5) through bevel gears (10,11). To simplify the assembly and service procedures, as well as to improve the roller adjustment facilities, the main roller (3) is carried on a supporting body (12) which can be removably positioned on the unit casing (2) to allow axial adjustment of the main roller (3). The respective shaft (6) engages rotatively, but in an axially slidable manner, with a coupling shaft (24) connected to the drive (9). The supporting body (12) may be attached to the casing (2) radially, thereby it becomes possible to assemble the main shaft (6) together with the roller (3), bearings (13) and gears (10), and then secure the supporting body (12) on the casing (2).