PURPOSE: To simultaneously carry out the registration and the connection regardless of the fixed position of a roll shaft, by automatically moving the joint back and forth and up and down by mechanical driving.

CONSTITUTION: A couple of connecting parts is provided on the ends 1 and 2 of universal joint and the ends 3 and 4 of roll shaft which is corresponding to the universal joint respectively. Positioning arms 7 and 8 which are independently vertically movable are provided on the ends 1 and 2 of universal joint and positioning guides 9 and 10 on which the positioning arms 7 and 8 are abutted are provided on the ends 3 and 4 of roll shaft. The abutting position of positioning arm 7 and positioning guide 9 is deviated from the abutting position of positioning arm 8 and positioning guide 10 in the front and rear direction of the connecting line of the roll shaft and the outputting shaft of a reduction gear and the positioning arms 7 and 8 are commonly movable back and forth.