Fabric advancement device for sewing machines

Fabric advancement device for sewing machines, comprising a first bar at one end of which a first jaw is fixed, a first U-shaped body, open downwards, being arranged on the opposite end of the first bar, a first elongated seat being formed in the first bar, a square pin is received in said seat and is designed to act as a fulcrum for the first bar and as a runner so as to translate in the first seat, so that the first bar can move according to a horizontal oscillatory and translational movement, a rotating pin being included to which a first cylindrical body is fixed to which a first cylinder is associated which is eccentric with respect to the axis of the pin, the first cylinder being received in a homologous cylindrical seat formed in a first square block adapted to translate vertically in the first U-shaped body, characterized by the fact of comprising a second bar at one end of which a second jaw is fixed, a second U-shaped body, open towards the rear part of the second bar, and a third U-shaped body, open downwards, being comprised at the opposite end of the second bar, a second elongated seat being formed in the second bar, the square pin is received in said seat and is adapted to act as a fulcrum for the second bar and as a runner so as to translate in the second seat, so that the second bar can move according to a horizontal oscillatory and translational movement, a second cylindrical body being comprised and fixed to the rotating pin and to which a second cylinder is associated which is eccentric with respect to the axis of the pin, the second cylinder being received in a homologous cylindrical seat formed in a second square block adapted to translate vertically in the third U-shaped body, a cylindrical eccentric element being comprised and fixed to the rotating pin, received in a cylindrical seat formed in a third square block adapted to translate horizontally in the second U-shaped body.