orce vectors at front, rear and semitrailer axles is</p>
% <p>
%     \begin{eqnarray}
%     \nonumber {\bf F}_{\rm F} &=& F_{x,{\rm F}} \, {\bf e}_x + F_{y,{\rm F}} \, {\bf e}_y \\
%     \nonumber {\bf F}_{\rm R} &=& F_{x,{\rm R}} {\bf t}_x + F_{y,{\rm R}} {\bf t}_y 
%     \end{eqnarray}
% </p>
% <p>or</p>
% <p>
%     \begin{eqnarray}
%     {\bf F}_{\rm F} &=& \left[ F_{x,{\rm F}} \cos \left( \psi + \delta_{\rm F} \right) - F_{y,{\rm F}} \sin \left( \psi + \delta_{\rm F} \right) \right] {\bf i} + \left[ F_{