Abstract: The present invention relates to an arrangement for an internal combustion engine. The engine is of the kind which has a number of working cylinders (1, 2, 3, 4), each of which communicating with a corresponding auxiliary cylinder (5, 6, 7, 8). Each working cylinder has a working piston (9, 10, 11, 12) which is so arranged as to execute a reciprocating motion and, via a connecting rod (9a, 10a, 11a, 12a), the working piston is operatively connected to a first crankshaft (17). Each auxiliary cylinder (5-8) has an auxiliary piston (13, 14, 15, 16) which is so arranged as to execute a reciprocating motion and via a connecting rod (9a-12a), the auxiliary piston is operatively connected to a second crankshaft (18). Acting between the aforementioned crankshafts is a device (19, 20, 21) to ensure that the motion of the auxiliary piston (13-16) occurs in a relation to the motion of the working piston (9-12), and to provide angular displacement between the shafts (20, 21).