This spring applies tension or returns a component to its rest position within the header or threshing unit of a self-loading forage trailer. It is installed between a fixed anchor point and the moving part it controls, such as a flap, latch, or tensioning arm. A spring that has lost its free length or shows surface cracks will fail to maintain the required preload, allowing the connected mechanism to drift or rattle during operation. The manufacturer produces this spring to match the original's coil diameter and wire thickness, so it fits the existing mounting points without modification.