PURPOSE: To maintain sufficiently rigidity between the outside-bush and the inside-bush inserted in the outside-bush rotatably and, at the same time, to facilitate the separation of both the bushes.

CONSTITUTION: A minute gap 11 which is filled with an electroviscous fluid 10 is created between the eccentric outside-bush 4 round which a printing cylinder is fitted and the eccentric insidebush 3 in which bearings 5 are inserted. And a voltage application means 12 for applying a voltage to the electroviscous fluid 10 held in the minute gap 11 is provided.