Abstract: In a material working (e.g. penetrating, loading, compacting) machine the power and machine weight needed to achieve a given performance can be reduced by making one (50) of two pivots (34, 50) at which a working implement such as a bucket 14 is supported an eccentric pivot and driving it by means of a motor (36). The circular vibration of the bucket at pivot (50) combined with arcuate vibration which results and is permitted at pivot (34) by means of link (30), causes the working portion namely bucket teeth (56), to vibrate on a closed elongate curved path 58. This improves penetration and loading performance of the bucket without requiring excessive power to generate the vibrations.