Abstract: A machine is constructed from plural elongated elements constructed as tubes or rods with double duct and which are alternatingly cooled and heated past a transition temperature, whereby restauration of the original length occurs during heating under development of force and is effective as work producing stroke, while upon cooling below the transition temperature such element is extended or upset. The elements are resiliently coupled to a crank shaft or to the rotary output of swash plate like machine. Heating and cooling fluid is alternatingly driven through the duct or ducts in the stroke producing elements to obtain periodic extension and contraction which is translated into rotational power.