PURPOSE: To facilitate operation by oscillating a floating pulley bearing plate, and by converting the mutual phases of the eccentric pendulums of two shafts on the sides of a driven shaft and a driving shaft, with a belt, toothed on both the surfaces via floating pulleys.

CONSTITUTION: A floating pulley bearing plate 22 having floating pulleys 23, 24 formed vertically integrally is set to be oscillated in the front and rear directions of a machine body. After that, around toothed pulleys 18, 20 arranged on a driving shaft 16 and a driven shaft 14 via the pulleys 23, 24, a belt 25 toothed on both the surfaces is applied, and the shaft 13 and the shaft 14 are synchronously rotated in the directions opposite to each other. Then, by oscillating the floating pulley bearing plate 22 in the front and rear directions of the machine body, the mutual phases of the eccentric pendulums 17, 19 of the shafts 13, 14 are converted via the belt 25, and the machine body is moved forward or backward. As a result, a mechanism can be easily manufactured at an economical cost.