ectors 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_{x,{\rm F}} \sin \left( \psi