  The mechanism of backbending in $^{48}$Cr is investigated in terms of the
Projected Shell Model and the Generator Coordinate Method. It is shown that
both methods are reasonable shell model truncation schemes. These two quite
different quantum mechanical approaches lead to a similar conclusion that the
backbending is due to a band crossing involving an excited band which is built
on simultaneously broken neutron and proton pairs in the ``intruder'' subshell
$f_{7/2}$. It is pointed out that this type of band crossing is usually known
to cause the second backbending in rare-earth nuclei.
