A harvesting header on a vehicle such as a combine harvester includesa mounting assembly comprising left and right float elements each for applyingcontrolled left and right lift forces and arranged to allow upward floating ofeach end ofthe header in response to ground contact. Left and right sensors detect theangle oftilt of the header and a control system operates to reduce the left lift forcewhen theleft end is raised and to reduce the right lift force when the right end israised. On acombine harvester this can be done by rotating the face plate of the feederhouse inthe required direction. In other systems the force generated by the left andright floatelements can be directly modified. The changes to the lift force are appliedonly whenthe propulsion vehicle is tilted beyond a predetermined angle.
