Abstract: The coupling means according to the invention consists of an insertion member and a receiving member, as the arms of the insertion member by coupling engage a sliding bolt, which is loaded by a leaf spring against a locking position. The leaf spring is angular bent, and has one short leg resting in a slit facing the inside of a tube member, making up the outer part of the receiving member. By mounting the spring in this way, the long leg of the spring is stretching between the tube member and an insert, and fixation of the spring is obtained without use of additional means.