The article presents a dynamic analysis of the sorting process of load units transported on conveyor belts. The process is realized by means of an active fence with one freedom degree. During analytic research the manipulated loads were treated as undeformable bodies, or in the case of load impact against the fence as the bodies with nonlinear springy-damping properties. A flexible element, described by Kelvin linear model, was used in the drive of the fence of a rotatably fixed beam. Appropriate choice of construction parameters makes it possible to mitigate the dynamic interactions of the sorted loads.