A rear tractor suspension for a tractor includes a suspension arm pivotally coupled to the chassis of the tractor, and a hydraulic cylinder coupled to the suspension arm to support it. The hydraulic cylinder conveys only longitudinal forces in a first mode of operation in which the suspension is not substantially loaded. When a substantial load is placed upon the suspension and the suspension arm begins to bend within normal operational and design limits, the hydraulic cylinder counteracts the load applied to the suspension, the torsional moment it produces, and the torsioning of the suspension arm by automatically applying a counteracting torsional moment to the suspension arm.