Abstract: A self-locking belt reel-in mechanism, especially for the safety belts of motor vehicles. The mechanism includes a belt-winding spindle that is mounted in a housing and is loaded by a rewinding spring. The spindle includes a spindle core and a spindle body, at each end of which are disposed two locking members that operate radially between an inner position and an outer position, are adapted to be surrounded by stops on the housing, and bring about a symmetrical quadruple locking. The locking members are coupled by connecting rods that are parallel to the central axis of the spindle, are disposed within the cross-sectional area of the spindle, and rotate with the latter. When self-locking is initiated via a system that is sensitive to movement of the belt and/or vehicle, the locking members mesh with the housing stops. The connecting rods have ends on which are integrally connected the locking members, which enclose the spindle core symmetrically relative to the respective connecting rod.