PURPOSE: To prevent abrasion of a belt and prevent removal of the belt by bearing a drive pulley, a V-belt pulley just under each roller, and a transmission pulley by pulley shafts directed almost perpendicularly, and disposing the pulleys to be positioned almost in the same plane.

CONSTITUTION: A V-belt pulley 9 having a transmission pulley 10 to get in contact with a straight cylinder-like roller 5 and a tapered roller 4 is disposed just under the rollers 5, 4, and it is borne by a pulley shaft 8 directed almost perpendicularly. A drive part 11 is positioned on the inner side of a curved part 2, and it is composed of a drive pulley 12 and tension pulleys 13, 13 capable of horizontal displacement toward the shaft of the tapered roller 4. These pulleys 9, 12, 13 are disposed in the same plane, and a V-belt 25 is applied. In this constitution, the V-belt can be run horizontally, and the tension can be equalized.