Balance shaft
Balancer shafts are used to reduce or eliminate the free inertia forces of a reciprocating piston engine in order to reduce operating noise and vibrations . For this purpose, imbalances ( eccentric weights) are attached to the balance shaft. The inertia forces thus generated counteract those of the crank drive . The balance shafts are driven synchronously by the crankshaft using toothed wheels , chains or toothed belts . Depending on the type of engine, one or two balance shafts are usually used, which run at single or double crankshaft speed .