A balance shaft is a small shaft inside certain types of internal combustion engines that spins in order to cancel out the engine's inherent vibration tendency caused by reciprocating masses. By offsetting the rotating mass from the crankshaft, the balance shaft generates force that counters the rotational vibration produced by inertia forces in the pistons and connecting rods. This a... https://articlescad.com/how-vehicle-balance-shafts-help-reduce-vibrations-251063.html