  Aims. We present the results from a comprehensive spectroscopic survey of the
WINGS (WIde-field Nearby Galaxy-cluster Survey) clusters, a program called
WINGS-SPE. The WINGS-SPE sample consists of 48 clusters, 22 of which are in the
southern sky and 26 in the north. The main goals of this spectroscopic survey
are: (1) to study the dynamics and kinematics of the WINGS clusters and their
constituent galaxies, (2) to explore the link between the spectral properties
and the morphological evolution in different density environments and across a
wide range in cluster X-ray luminosities and optical properties. Methods. Using
multi object fiber fed spectrographs, we observed our sample of WINGS cluster
galaxies at an intermediate resolu- tion of 6-9 A and, using a
cross-correlation technique, we measured redshifts with a mean accuracy of
about 45 km/s. Results. We present redshift measurements for 6137 galaxies and
their first analyses. Details of the spectroscopic observations are reported.
The WINGS-SPE has about 30% overlap with previously published data sets,
allowing us to do both a complete comparison with the literature and to extend
the catalogs. Conclusions. Using our redshifts, we calculate the velocity
dispersion for all the clusters in the WINGS-SPE sample. We almost trip- licate
the number of member galaxies known in each cluster with respect to previous
works. We also investigate the X-ray luminosity vs. velocity dispersion
relation for our WINGS-SPE clusters, and find it to be consistent with the form
Lx proportional to sigma^4.
