FIELD: internal combustion engines or pumps for handling liquids of gases. SUBSTANCE: depending on required operating conditions of piston machine, positions of dead centers of piston reciprocating in cylinder are changed; as a result, amount of its stroke is changed, thus making it possible to control cylinder displacement and degree of compression. Change of position of piston dead centers is effected through shift of hinge of link connecting rod which converts reciprocating motion of piston into rotation of output shaft away from cylinder axis and return of hinge to cylinder axis. Shift of hinge from and to cylinder axis is effected under action of lever whose one end acts on hinge and other end where its axis of oscillation is located is engageable with drive. During motion of piston from dead center, axis of oscillation of lever is moved by means of drive and reversible member over straight line intersecting cylinder axis from fixed position to next fixation. EFFECT: enhanced efficiency. 10 cl, 13 dwg
