This brake disc is the outer friction element in the tractor's clutch pack. It transmits torque from the engine flywheel to the input shaft of the transmission when the clutch is engaged. A worn disc reduces clamping force, leading to slip under load and gradual loss of drive. As an original-manufacturer component, it is machined to the same thickness and friction-surface finish as the original assembly, which the pressure plate relies on for consistent engagement timing. On reinstallation, ensure the disc is seated squarely in the splined hub and that the pressure plate bolts are torqued to specification.