Device for decreasing or increasing a gas volume by means of forced displacement

The device (1) has a set of pistons oscillated in a set of displacer cylinders (3, 5), respectively, and a set of connecting rods is arranged on the pistons, respectively. The connecting rods are flexibly connected with a crank shaft drive, and the cylinders are provided with openings that extend from inner chamber of the cylinders through cylinder outer wall. The cylinders are arranged such that flow channel directly passes an operating medium between the cylinders through the openings, and axles (A, B) run through the cylinders.