r t with the desired transport speed v soll and generates therefrom an auxiliary voltage u hilf t and an auxiliary frequency f hilf t for a control element connected downstream i e the frequency converter 21 the frequency converter 21 operating as a control element transforms the auxiliary voltage u hilf t and the auxiliary frequency f hilf t into a voltage u ist t and a frequency f ist t for the drive motor 22 the drive motor 22 assumes under the actual load torque m r t an actual rotation speed n ist which drives the conveyor belt 60 70 with an actual transport speed v ist the motor rotation speed n ist depends on the load torque i e the actual transport speed v ist is a function of the voltage u ist t and the frequency f ist t which was determined by the controller 19 as a function of the articles 5 to be transported by the conveyor belt 60 70 the estimated or calculated load torque m e t of each control path can hereby be determined by different methods if the individual weights of the articles 5 on a conveyor belt 60 70 are known then the total weight can be easily determined from the sum of the individual weights if only some of the weights are known while others are unknown average values are assumed for the weights of the articles 5 whose weight is not known whereafter the sum is computed if none of the weights of.