Abstract: For progressively breaking-in-place concrete of roadways or the like, a vertically extending diesel power driver, of a type used as a pile driver, but with a concrete-breaking shoe forming its lower end, is advanced by a towed chassis. Guide angles at the upper portion of the power driver, cooperating with a guide bar vertically disposed, guide the power driver in its conventional rythmic bobbing, with sufficient looseness to permit the power driver to have a pendulum like swinging action. This swinging action results from relatively intermittent movement of the bottom portion of the power driver while the top portion is advanced more steadily by the chassis. Shoe-towing means extend forwardly from the shoe to a hanging link which is resiliently biased forwardly to tow the shoe. The biasing is provided by long-throw cushions. The forwardly extending shoe-towing means is flexible, to prevent damage when the shoe is driven deeply.