Estimation of Unbalance of Piston Engines

Various criteria for assessing harmonic and nonharmonic unbalanced forces and their moments are considered. The disturbance of the resulting second-order inertial force of reciprocating masses (RMs) is assayed. Partial balancing of the overturning reactive torque in an in-line four-cylinder reciprocating internal combustion engine (RICE) by installing two additional balancing shafts offset vertically relative to each other, which also balance the resulting second-order inertial force of the RMs is considered. © Allerton Press, Inc. 2025.