The end of a shaft (1) in a sleeve (2) is adjusted axially into a stop position where the two are fixed together. The axial locking is obtained by a latch (4) on the sleeve external surface. The latch pivots in front of a slot (5) in the sleeve wall (6). It can be inserted in a hole (7) in the shaft when the shaft is stopped in the sleeve. The shaft and sleeve have an axial guide system which enables the shaft hole to be positioned opposite the sleeve slot when the shaft is stopped in the sleeve. The guide system comprises a lug on the shaft which slides in an axial groove (9) in the sleeve internal surface. The latch engages with a locking system comprising a screw (16') which when tightened exerts a force on the latch causing its locking inside the shaft hole.