PURPOSE: To reduce the generation of vibration owing to unevenness in rotation of a crank shaft by absorbing a high and a low fluctuation responding to the magnitude of a delivery pressure set according to the magnitude of a pressure in a combustion chamber.

CONSTITUTION: A reciprocating internal combustion engine to have at least two or more output shafts to one of which a hydraulic pump 10 is coupled comprises a pressure control valve 12 to control the delivery pressure of the hydraulic pump 10; an angle sensor 16 to detect the rotation angle of an engine 1; a controller 15 to indicate the set pressure of the pressure control valve 12 according to a rotation angle; and an accumulator 14 arranged in the delivery line of the hydraulic pump 10.