Abstract: A clutch assembly for connecting a shaft to a rotary member mounted on said shaft in a rotationally fixed manner comprises: a sliding sleeve which is rotationally fixed to the shaft, is axially slidably mounted on said shaft and is provided with a first gearing. A clutch body is rotationally fixed to the rotary member and provided with a second gearing which can mesh with the first gearing to connect the shaft and the rotary member in a rotationally fixed manner. And, a locking synchronization unit having a synchronizer ring with a friction surface the ring permitting the speeds of the shaft and the rotary member to be synchronized before the meshing of the first and second gearings. The locking synchronization unit further comprises a locking member which is coupled to the sliding sleeve by a detent groove and to the synchronizer ring in the rotational direction (D) by a pair of locking surfaces.