\documentclass{scrbook}
\usepackage{pst-plot}
\begin{document}
\psset{yunit=1.5}
\begin{pspicture}(-1,-1)(5,3)
\psaxes[arrows=->,showorigin=false,Dy=1.5,dy=2,Oy=0.75,labels=x](0,0.75)(-0.5,0.5)(4.5,2.5)
\psyTick(1){1}\psyTick(2){2}
\end{pspicture}
\end{document}