Abstract: A balance shaft unit for internal combustion engines consists of at least one balance shaft (6, 7) supported in a balance casing (5) and counterweights (8) connected onto it. In order to achieve maximum precision, reliable fastening and minimum external dimensions at minimum manufacturing costs, the counterweight (8) is essentially a cylindrical ring with two end surfaces (61) normal to the axis and with a cutout (55) in the longitudinally central region, so that the counterweight consists of two ring parts (60, 61) abutting the two end surfaces (61) and an intermediate segmental part (62). One of the end surfaces (61) of the counterweight (8) forms, jointly with a machined surface (33) of the balance casing (5), a thrust bearing (32).

Abstract: A device for compensating the inertia forces in reciprocating piston machines consists of a balance shaft housing (5) and of balance shafts (6, 7) mounted in the latter in friction bearings (30) and having compensating weights (8), the balance shaft housing (5) being fastened in one part and to the engine block. In order to achieve the highest possible sufficient lubrication along with minimal production costs and simple assembly, a) the friction bearings (30) of the balance shafts (6, 7) are arranged, together with the main bearings (3) of the crankshaft (2), in a plane (9) perpendicular to the crankshaft axis, b) the friction bearings (30) are cylindrical bores in the balance shaft housing (5) which are machined as bearing surfaces (31), c) the balance shafts (6, 7) are cylindrical shafts of essentially constant diameter, on which the compensating weights (8) are fastened individually.