Novel gear train transmission type engine

The invention discloses a novel gear train transmission type engine. The novel gear train transmission type engine structurally comprises a vertically-symmetrical piston body arranged on the center axis, a cylinder sleeve used for restraining a piston along the center axis, an engine body shell arranged outside a cylinder and used for supporting and fixing the cylinder sleeve, and a plurality of power output shafts arranged on the engine body shell. A rack which is symmetrical with respect to the center axis is arranged on a piston stretching-out rod. The axial direction of a pair of center mesh gears is perpendicular to the center axis, and the pair of center mesh gears is arranged on the engine body shell. The axis of the cylinder sleeve coincides with the center axis, and the cylinder sleeve is fixed to an engine body. Fuel supply systems and air intake and exhaust systems are arranged at the two ends of the cylinder separately. Cooling air can pass through the space between the engine body shell and the c