PURPOSE: To develop a generating power for emergency, by a method wherein the physical energy of compressed air produced by means of accumulated resilient energy generated through compression of a spring in a cylinder is exerted on a gear train mechanism to convert the energy into mechanical energy which is exerted on a compression device to induce reduction action.

CONSTITUTION: When a spring 2 in a cylinder 1 is compressed according to movement of a compression device, air enters the cylinder 1. Through automatic repulsion of the spring 2, the air is compressed, and the air provides physical energy to urge the action of the gear train mechanism of a crank chamber 12. According to movement of a piston 5 moved from the cylinder 1, rotation of a piston gear 7 is converted into mechanical energy together with movement of a piston pin 6 and is transmitted to an external transmission gear 9, and the force produces a power by means of which a ring gear 8 of the compression device is driven. Namely, physical energy of air is converted into mechanical energy, which is exerted on the compression device to induce reduction action, and reciprocating movement of the aboves produces a power to generate a generating power, and energy can be saved.