Abstract: A suspension system for a tracked vehicle has a hull provided with double crawler tracks positioned on either side of the hull. Each crawler track runs around a track drive wheel, track roller assemblies and a take-up idler. A torsion unit assembly connects each track roller assembly to the hull. The torsion unit assembly includes a plurality of torsion units mechanically connected in series, with the torsion unit at one end of the series being fixed to the hull and the torsion unit at the other end of the series being connected to and suspending the respective track roller assembly in order to obtain a large amount of suspension travel for the track roller.