The properties of matrix operations and the properties of Hartenberg-Denavit's co-ordinate system's transformation matrices were used for deriving a dependence facilitating an easier determination of the links' angular velocity vectors in the link-related co-ordination systems. The use of derived dependence does not require determining products of transformation matrices nor inverse matrices. The numbers of necessary algebraic operations for previous and simplified dependences was set up. The use of a simplified dependence was illustrated by a numerical example.