A modular release mechanism (30) disclosed herein comprises a release sleeve (40) which is slideably disposed on a driven shaft, the release sleeve has an axis of rotation, a first end (50) and a second end (60). The release sleeve has a bearing housing portion (65) disposed at the second end for receiving the bearing (70). The bearing housing portion has a shoulder (67) for locating the bearing therein. The bearing housing portion has a retainer for securing the bearing therein by limiting the axial travel of the bearing relative to the release sleeve when the outer race of the bearing is disposed between the shoulder of the bearing housing portion and the retainer. The retainer may be selectively engageable in that the retainer is moveable from a first radial position to a second radial position it comprises at least one radially extending detent portion (82) which is moveable by rotating a radially extending lever (88), from a first angular position to a second angular position relative to the release sleeve.