A suspension system has a base, mountable to the floor of a vehicle, and a frame above the base. The base and frame are coupled by a linkage, for example two, spaced pairs of crossed links. A mechanical spring, preferably in the form of a torsion bar, is mounted in one of the base and frame. A lever...http://www.google.fr/patents/US4880201?utm_source=gb-gplus-shareBrevet US4880201 - Constant natural frequency, mechanical spring seat suspension
Constant natural frequency, mechanical spring seat suspension
