To solve the following problem that, since a crank converting reciprocating motion into rotational motion is subject to restriction in the radius of a crank connection, linear motion is not sufficiently converted into rotational motion, to use also atmospheric negative pressure, and to efficiently effectively use the thermal energy of an engine.

In a means 1, a crank mechanism is so configured that horizontal opposed type engine air chambers are arranged at the right and left sides, and an oblong crank linear gear 2 or one rod long stroke crank is arranged in a center. In a means 2, steam pressure is cooled and reduced after expansion by a sufficiently long stroke and vacuum negative pressure is also used after dew condensation, in a steam engine. In a means 3, the vacuum negative pressure cooled after expansion by the sufficiently long stroke is also used in a Stirling engine. In a means 4, the vacuum negative pressure turned into water and having a reduced volume after explosion and expansion is also used in an oxygen hydrogen ignition explosive combustion engine.