Abstract: The invention relates to a closed system. It consists of a spirally-wound elastic pipe (1), inside which a fluid flows, and a straight rubber pipe (2) extending in the center of the spiral, inside which pipe the fluid is so arranged as to flow in the opposite direction, i.e. the fluid circulates inside a closed circuit formed in this way. The system is so arranged as to be extended and compressed so that the internal forces therein enter into a state of imbalance during the actual extension and compression process, and so that the system is thereby so arranged as to begin to move because of the internal forces, which can be utilized as an energy source.