Abstract: A thermodynamic motor of the "sea-saw" type employs water tanks into which opposed ones of low-boiling liquid-containing interconnected tanks on a pivot arm are cyclically immersed. Tank water is maintained at a higher-than-ambient temperature level by a primary heat source. Temperature differential between liquid containing tanks is enhanced by a heat exchanger in the interconnection between tanks. The motor drives fluid compressors and further heat exchanging means communicate with the compressors and tank water to transfer heat of compression into the water to further enhance the temperature differential upon which motor operation depends.