Abstract: A method and apparatus for controlling the tension of flexible drive belts, or a single drive belt, connecting a drive pulley to a driven pulley. The apparatus includes a first idler assembly for engaging the slack run of the drive belts, a second idler assembly for engaging the drive run of the drive belts, and a tension member for adjusting the distance between the first idler assembly and the second idler assembly to a distance sufficient to cause the apparatus to maintain a position between the drive pulley and the driven pulley. The apparatus requires no external support or positioning member to maintain the position of the apparatus on the belts while the apparatus is controlling the tension of the moving belts. The method includes placing a first idler assembly on the slack run of the drive belts, placing a second idler assembly on the drive run of the drive belts, and forcing the assemblies together to increase the tension of the drive belts.