Abstract: Hardened concrete is removed from the drum of a concrete-transporting truck by applying strong vibrational force to the exterior of the drum. Apparatus for applying the vibration includes a vibration impact device suspended from the end of a laterally oriented holding arm. The opposite end of the holding arm is pivotably attached to a vertical post. A control arm, pivotably attached to the post has a hydraulic cylinder adapted to cause raising or lowering of the suspended impact device.