In this work is presented research about main dynamic parameters that have influence in the efficiency of trapezoid belts (VBelts). Research is done in the testing machine with 3 wheels. Two main parameters analyzed are important dynamic parameters: Force of preliminary belt tightening (Fpr), and Coefficient of elastic slipping (Kes). Last coefficient is important factor for dynamic analysis of belt transporters while it defines clearly level of carrying capacity vs. defined force of preliminary belt tightening. Through laboratory testing has been researched influence of power that is transmitted and force of preliminary tightening in the coefficient of elastic slipping, with the aim to determine optimal limit of this coefficient. In practice it is recommended that values of this coefficient not to be higher than 2%.