SEALED-CLEAN FOUR-ROW TAPERED ROLLER BEARINGS NSK is specially designed with higher load capacity and greater sealing performance and adopts to Super-TF and WTF™ material. The rollers are made of super-TF or WTF™ steel material with a newly designed bearing internal geometry that ensures wider cage diameter, increased number of rollers & larger rollers. The bearings are introduced to a special helicoidal groove, new type of lateral seal, new bore seal with more compact design in the main seal and seal holder. The newly designed bearing internal geometry and special seal provides with higher load capacity. The introduction of new type of bore seal prevents the build-up of negative pressure that can cause water to enter through the main seals. The new seal also ensures a significantly longer service life under heavily contaminated operating conditions. Introduction of WTF™ steel offers significantly longer service life under water and metallic contamination. The complete sealed-clean solution significantly reduces grease consumption.