This clutch spring provides the clamping force that engages the seed-drive system on the parent drill. It sits between the clutch plate and the pressure plate; when the spring is compressed, it transmits torque from the drive shaft to the metering mechanism. A spring that has lost its free height or shows surface cracks will allow clutch slip, causing intermittent seed delivery and uneven row spacing. The manufacturer machines this spring to the same wire diameter and coil count as the original assembly, so the installed preload matches the design specification. On replacement, inspect the pressure-plate face for wear and replace the retaining hardware if corroded.