A matematical model of electrohydraulic drive system with hydraulic cylinder and steering system was developed. Torsion flexibility of the drive shaft, its torsion vibration consideration, viscous and dry friction, were included in the model. There was analysed the problem of increase in dry friction in consequence for out-of-alignment positioning of hydraulic cylinder rotational couplings with cylinder axis as affecting its mechanical efficiency. It was assumed that friction forces appear between piston rings and cylinder and also betwen piston rod and the seal. The friction force was iteratively computed from the static balance condition. The mechanical efficiency for the loader lifting-mechanism was computed.