VLBI observations of a complete sample of radio galaxies: 10 years later

A complete sample of 27 radio galaxies was selected from the B2 and 3CR cat alogs in order to study their properties on the milliarcsecond scale. In th e Appendix of this paper we present new radio images for 12 of them. Thanks to the present data, all the sources in this sample have been imaged at mi lliarcsecond resolution. We discuss the general results. In particular we s tress the evidence for high-velocity jets in low-power radio galaxies, comp are high- and low-power sources, and discuss the source properties in light of the unified scheme models. We conclude that the properties of parsec-sc ale jets are similar in sources with different total radio power and kilopa rsec-scale morphology. From the core-total radio power correlation, we esti mate that relativistic jets with Lorentz factor gamma in the range 3-10 are present in high- and low-power radio sources. We discuss also the possible existence of a two-velocity structure (fast spine and lower velocity exter nal shear layer).