%% 
%%  A DANTE-Edition example
%% 
%% 
%%  Copyright (C) 2011 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 
%% 
%% ==== 
% Show page(s) 1
%% 
\documentclass[]{article}
\pagestyle{empty}
\setlength\textwidth{375.57637pt}
\setlength\parindent{0pt}

\usepackage{pstricks,pst-coil,pst-node}
\SpecialCoor

\begin{document}
\begin{pspicture}(-2,-2)(2,2)
  \pscircle{2}
  \pnode(2;-90){O}
  \pnode(2;10){A}\pnode(2;60){B}
  \pnode(2;190){C}\pnode(2;-60){D}
  \qdisk(A){3pt}\qdisk(B){3pt}
  \qdisk(C){3pt}\qdisk(D){3pt}
  \nccoil[coilarm=3mm,coilwidth=3mm,linecolor=red]{-}{O}{A}
  \nccoil[coilarm=3mm,coilwidth=3mm,coilheight=1.4,linecolor=red]{-}{O}{B}
  \nccoil[coilarm=3mm,coilwidth=3mm,coilheight=.9,linecolor=red]{-}{O}{C}
  \nccoil[coilarm=3mm,coilwidth=3mm,coilheight=.5,linecolor=red]{-}{O}{D}
  \rput(1.6,-.4){$m$}
  \rput(.8,-1){$k$}
  \psline[linecolor=blue,linewidth=1.5pt]{<-}(-2,0)(0,0)
  \rput(-1,.2){$r$}
\end{pspicture}
\end{document}