Abstract: A heat powered linear force generator and a heat engine embodying a plurality of the force generators for driving a rotary output shaft. The linear output force of the force generator is a periodic linear force acting continuously in the same direction and produced by exposure of linearly expandable and contractible means, such as one or more wires, having a relatively high coefficient of thermal expansion and contraction alternately to hot and cold working fluids. The several force generators of the heat engine are operatively coupled to the engine output shaft in such a way that the generators operate in timed relation to produce a relatively continuous driving torque on the shaft.