Abstract: The device comprises two paddles 1 each one of them being connected to a bar 3, the extremities of which are placed within a cam track. The cam track is formed in the surface turned towards the working zone of support 18 which is located corresponding to both the lateral extremities of the device. The motion of the bars 3 and therefore of the paddles 1 along the cam track 8 which has a rectilinear section 8' and a section of circular sector 8", is determined for each bar by a pair of connecting rods 7 which has a slit 7. The two ends of the bars 3 close to the extremities are placed in the slit. The four connecting rods 7 rotate synchronously, the rods corresponding to the same paddle being in the same direction, the rods corresponding to the same side of the device being opposite to the other.

Abstract: The device comprises two paddles (1), each one of the paddles being fixed to a bar (3), the ends of which are located within a cam path (8) formed on the surface turned towards the working zone of support (18) located corresponding to both the lateral heads of the device. The motion of the bars (3) and obviously also of the paddles (1) along the cam path (8) which presents a rectilinear working section (8') and a portion of a circular section (8"), is determined for each bar by a pair of rods (7), each rod having a slot (7'). Two sections of the bars close to their extremities are placed within the slot (7') and all four rods rotate synchronously, the bars placed corresponding to the same paddle rotating in the same direction while the rods corresponding to the same head of the device rotating in the opposite direction.