Series 40 AP Sheave - Acetal Solid Bearing - 40mm(1-9/16")OD. Precision moulded Acetal sheaves running on Acetal or Torlon ball bearings provide high performance & low friction.. Acetal Sheaves:. Choice of bearings. Solid bearing - high strength and durability, utilizing the self-lubricating properties of Acetal. U.V. resistant Acetal sheaves