Abstract: The invention relates to a ball collector for a device for returning balls for the cleaning of the tubes of cooling systems operated with a fluid, namely water, comprising a casing which is subdivided into an upper chamber with an inlet for the balls and a lower chamber with an outlet for the balls, in which between the upper and the lower chambers is provided an opening which can be closed by a movable flap in the closed position thereof and can be opened in the open position thereof, the upper chamber having a strainer screen being connected to the lower chamber by a bypass line having a pump, through which water can be pumped from the upper chamber into the lower chamber.