Paper stacking apparatus

A device for arranging sheets of paper (32) in a stack (33), comprising:

• a frame (2) to be mounted fixed in place, with an inlet opening (62) for introducing the sheets (32) to be stacked,
• an arm (4) pivotably seated at its rear end on the frame (2) and containing a conveyor belt (45) driven by a motor (43) for conveying the sheets (32), the arm (4) having a rail (51) above the conveyor belt (45), in which a plurality of spheres (53) are maintained freely rotatable, which rest on the conveyor belt (45),
• a container (3) for receiving the sheets (32), with a vertically displaceable carriage (12) and a drive member (15) for displacing the carriage (12), wherein the front end of the arm (4) is pivotably connected with the carriage (12),
• a sensor (68) at the front end of the arm (4) for detecting the upper edge of the stack (33), and
• a control device (67), connected with the sensor (68) and the drive member (15), for maintaining the front end of the arm (4) at the height of the stack (33) being formed,
• wherein a guide rail (54), which is pivotably seated on a vertical shaft (55) in the vicinity of a rear end of the arm (4) and which can be displaced by means of a lifting member (56) into two pivot positions, is disposed on one side of the conveyor belt (45), and wherein the conveyor belt (45) extends inclined in a direction of the guide rail (54) in such a way, that in the two pivot positions of the guide rail (54) the rail and the conveyor belt (45) converge in a direction of travel of the belt.