This paper presents a workpiece moving unit with parallel kinematics, where its kinematic model is described. Based on the Chebyshev-Grübler-Kutzbach mobility equation the mobility properties of the mechanism are examined. Using the modified Chebyshev-Grübler-Kutzbach criterion the number of degrees of freedom of the workpiece tilting table is determined, after this the screw theory will be presented. As the Chebyshev-Grübler-Kutzbach criterion does not take into account the geometrical characteristics of the examined structure, using the screw theory the workpiece tilting unit will be reanalysed, to take geometrical characteristics into account in determining the degrees of freedom of the structure. Finally, the results of the two theories will be compared in the study of the given kinematic model.