The present invention is a self-contained hydraulic hammer which is mounted on a hydraulically mobile frame. The hydraulic hammer is capable of travelling in either forward or reverse directions and is provided with liftable weights to which a tool for digging or breaking up a surface is attached. The hydraulic hammer is equipped with time delay controls which: 1) momentarily stop the travel of the hydraulic hammer as the weights and the attached digging tool free fall from a raised position until the digging tool impacts the surface to be busted up, and 2) cause the hydraulic hammer to resume travel as the weights are again raised in preparation for another impact. The hydraulic hammer rapidly repeats these cycles of impact and travel to break up a surface. Adjustments are provided on the hydraulic hammer for regulating the force of the impact and the distance travelled between impacts in order to match the hydraulic hammer's impact and travel cycles to the break characteristics of the surface to be removed.