Chain-drum drive or guidance mechanism in a machine frame of a chain-scraper conveyor, has a shaft (6) of its chain-drum (5), outer bearing parts (8) receiving shaft bearings (7), as well as sealing elements (24, 25) for sealing gaps between the outer bearing parts and the chain drum, all combined in a pre-assembled unit (12), which is fitted into, and removed from the machine frame (1) as a whole. The unit (12) is secured in the machine frame (1) preferably by clamp connections, in particular hydraulic annular clamps (31) or the like, which are seated in the openings (11) of the machine frame side walls (2, 3).