  We measure the central stellar velocity dispersion function for quiescent
galaxies in a set of nine northern clusters in the redshift range $0.18 < z <
0.29$ and with strong lensing arcs in Hubble Space Telescope images. The
velocity dispersion function links galaxies directly to their dark matter
halos. From dense SDSS and MMT/Hectospec spectroscopy we identify $231 - 479$
spectroscopic members in each cluster. We derive physical properties of cluster
members including redshift, $D_{n}4000$, and central stellar velocity
dispersion and we include a table of these measurements for 3419 cluster
members. We construct the velocity dispersion functions for quiescent galaxies
with $D_{n}4000 > 1.5$ and within $R_{200}$. The cluster velocity dispersion
functions all show excesses at $\sigma \gtrsim 250 km s^{-1}$ compared to the
field velocity dispersion function. The velocity dispersion function slope at
large velocity dispersion ($\sigma > 160 km s^{-1}$) is steeper for more
massive clusters, consistent with the trend observed for cluster luminosity
functions. The spatial distribution of galaxies with large velocity dispersion
at radii larger than $R_{200}$ further underscores the probable major role of
dry mergers in the growth of massive cluster galaxies during cluster assembly.
