Dimensionless follower load
= Dimensionless follower load
{title2=$\Sigma=\Gamma\ell/k$}
The <dimensionless follower load> compares the moment scale $\Gamma\ell$ of a tangential tip force with a <torsional spring> constant $k$. In the equal-link two-degree-of-freedom model, straight motion loses stability through a Hopf bifurcation at $\Sigma=3$.