Abstract: Compacting rod retainers are disposed on both sides of a web of the compacting rods and consist each of a bushing mounted on a drive shaft eccentrically, on which a carrier is slidably engaged, and cooperating with an associated clamping wedge. The opposite side of the clamping wedge cooperates correspondingly with the web of the compacting rod, so that upon an appropriate rotary motion of the shaft the carrier is moved translating the clamping wedge pressing against the web of the compacting rod, or releasing it. Thereby area pressure is attained, which makes possible the utilization of very heavy compacting rods.