EXZENTER-SPANNVORRICHTUNG

The invention relates to an eccentric tensioning device for tensioning a traction mechanism that is for example designed as a flat belt or gear belt in a power transmission belt drive. The aim of the invention is to provide advantageous options for bringing a tensioning device into a pre-tensioned assembly state. This aim is achieved by an eccentric tensioning device for a power transmission belt drive that comprises a roller unit with a roller surface and an anti-friction bearing that is provided to support the same, a working eccentric cam for supporting the roller unit in such a way that said unit can be displaced in a radial direction in relation to the revolving axis of the anti-friction bearing, in accordance with the pivoting of the working eccentric cam, a bearing journal for supporting the working eccentric cam, a torsion spring for pre-tensioning the working eccentric cam, a fixing device for securing the working eccentric cam in an assembly position, in which the torsion spring is pre-tensioned and an adjusting eccentric cam for supporting the bearing journal, said adjusting eccentric cam having a rim that overlaps the bearing journal on an end face that faces away from a flange side and a passage being formed in the vicinity of said rim, through which an end region of the bearing journal is accessible. This permits the advantageous provision of a tensioning device, in which an axial force that is used to axially displace the working eccentric cam in relation to the guide journal, is exerted on the end face of the bearing journal without dismantling the adjusting eccentric cam of the bearing journal. This enables a tensioning device that is released by the unlocking of the fixing device to be brought into a pre-tensioned assembly state and to be advantageously reconfigured for correct assembly.