The invention relates to a coupling unit (24) for transmitting high-frequency mechanical vibrations from a vibration generator (12) onto a tool (34). Said coupling unit comprises in input part (22) and an output part (30) that are interconnected via two identical vibration bars (26, 28), said bars being off-set from each other. The bars may have the shape of quadrants to provide the output movement in a direction that forms an angle of 90° with the direction of the input movement.