  The branching fractions of $\tau \to \pi^+ \pi^-\pi^- \nu_\tau$ and $\tau \to
\pi^- 2\pi^0\nu_\tau$ are calculated within the chiral NJL model. Features of
the axial-vector $a_1$ meson which plays an important role in describing the
$\tau$ decays are discussed. Permissible values for the mass and width of the
$a_1$ meson are considered in accordance with the latest experiments.
