The device comprises drums, which are coaxial and supported by an axle, located below needle beds subjected to a constant torque acting with springs being provided inside the drums as a mechanical connection between them and the axle.Two pressure rollers for each drum are fitted to a number of arms mounted on a bar and holded in contact with the related drum, while electromagnets are provided to rotate one of the rollers by a predetermined amount in order to cause the related drum to be rotated in in synchrony with the formation of a corresponding portion of the last row of the fabric, that runs between the row of drums and related pairs of pressure rollers.