This brake disc is the rotating friction component in the tractor's service brake system. It mounts on the axle shaft and is clamped between stationary friction pads to convert kinetic energy into heat during braking. The disc's thickness and hole pattern match the original hub and caliper geometry, ensuring the correct clamping force and pad-to-disc clearance. A worn disc reduces braking torque and can cause uneven pad wear or pedal fade. The manufacturer machines the disc to the same runout tolerance as the original assembly, which prevents vibration and maintains consistent contact with the pads. On installation, clean the hub mounting face and torque the wheel bolts to specification.