This PTO O-ring provides the seal between the power take-off shaft and its housing, preventing lubricant leakage from the transmission case. It sits in the groove machined into the PTO housing or shaft hub, where it is compressed during assembly to create a static seal. A degraded or hardened O-ring allows oil to weep past the shaft, which can lead to low lubricant levels and eventual bearing damage in the PTO driveline. As an original AGCO component, its cross-section and durometer match the housing groove geometry, so the seal compresses to the correct squeeze without over-stressing the gland. On reinstallation, inspect the groove for debris or corrosion and apply a light film of clean transmission fluid to the O-ring before seating it.