  We investigate doping of a two-orbital chain with mobile $S=1/2$ fermions as
a valid model for $\rm Y_{2-x}Ca_xBaNiO_5$. The S=1 spins are stabilized by
strong, ferromagnetic (fm) Hund's rule couplings. We calculate correlation
functions and thermodynamic quantities by DMRG methods and find a new hierarchy
of energy scales in the spin sector upon doping. Gapless spin-excitations are
generated at a lower energy scale by interactions among itinerant polarons
created by each hole and coexist with the larger scale of the gapful
spin-liquid background of the S=1 chain accompanied by a finite string-order
parameter.
