Abstract: A power absorbing device according to the present invention is a device for absorbing the mechanical energy of reciprocating motion of pistons of a reciprocating adiabatic expansion engine, comprising a cylindrical cam having a hollow space therein and converting the reciprocating motion of the pistons into rotatory motion, a speed-increasing gear disposed in the hollow space to increase the speed of the rotary motion and having an output shaft to rotate at an increased speed, and an electric generator including a rotor mounted on the output shaft to rotate and an electric generating section operating jointly with the rotor to supply an external load with electric power.

Abstract: An expansion engine fixed to a flange so as to extend into a vacuum tank comprises an outer cylinder inserted in said vacuum tank and having its proximal end opening into the atmosphere, an inner cylinder removably inserted from its distal side into said outer cylinder through said opening, a piston capable of reciprocating inside said inner cylinder and having an exhaust valve, an intake valve mechanism disposed on the distal side of said inner cylinder and capable of moving together with said inner cylinder, and O-rings disposed between said inner and outer cylinders to seal the interface between said cylinders airtightly.