Provided is a coupling (12) including: a housing (60) with a cutout (61); a cylindric shaft (62) extending transversely to the cutout through aligned openings (75); a hook (63) having a width which is less than the width of the cutout (61) and which has a receiving opening (64) with a diameter corresponding to the shaft diameter, and which is intended for receiving the shaft (62) and an insertionopening (65) having a width which is less than the shaft diameter and which is oriented at an angle relative to a direction of pull (66) by loading the hook (63), where the shaft (62) at a part (70) for disposition in the cutout (61) is provided with opposing flats (67) with mutual spacing which is less than the width of the insertion opening (65), wherein the shaft (62) is arranged for manual displacement in its longitudinal direction against the action of a spring (71), from a first position (69); where the flats (67) are located outside the cutout (61), and to a second position (68) where the flats (67) of the shaft are displaced into the cutout (61).