A machine is disclosed for the expansion of pipes for heat exchangers, including a machine frame equipped with a drive unit for pressing or pulling an expansion mandrel through a pipe as well as an expansion mandrel. In at least one embodiment, the machine includes at least one drive unit with at least one motor-driven drum as well as a band or wire guide which extends horizontally from an outlet of the drum and forwardly to the pipe, the drive unit including a set of lateral plates. In at least one embodiment, the drum is disposed between the lateral plates of the drive unit and is equipped with a band or a wire and is additionally adapted to press or pull a band or a wire with an expansion mandrel through a pipe, wherein the expansion mandrel is expandable. In at least one embodiment, the drum includes two lateral plates, a hub and a circular guideway, the hub including a driving gearwheel and at least two idling gearwheels arranged internally in and in engagement with a toothed rim in the hub, and wherein the circular guideway of the drum is formed by bearings disposed in a circle between the sides of the drum and along the outermost rim of the sides.