Abstract: Rotary disk saw is adapted to be mounted on an earth excavator or the like, having an articulating and rotatable member for a boom. To this excavating boom, which normally carries a shovel, the saw carrying unit is attached and includes a compound pivot means adapted for orthogonal and transverse rotation about the bucket, the same carrying a saw carrying boom and a carriage which travels up and down the boom, hydraulically driven, to locate a sub-carriage which transversely locates a rotary disk saw. By a relative rotating of compound pivot means and the boom and by locating the carriage and sub-carriage, as required, the saw may be positioned onto a working piece which is to be cut. Such devices are especially suitable for demolition of highway bridges and the like.