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Four-row cylindrical roller bearings

Čtyřřadé válečkové ložisko
Four-row cylindrical roller bearings are suitable for very high radial loads due to the large number of rolling elements. They are used almost exclusively for back-up rolls in rolling mills.
Sealed four-row cylindrical roller bearings with extremely high load capacity have a long operating life and significantly extend inspection intervals even in highly contaminated conditions with insufficient opportunity for lubrication.
NSK sealed-clean bearings can be supplied in case-hardened and through-hardened steel. NSK’s various steel specifications are particularly wear and shock resistant thanks to the special heat and surface treatment technology. (Steel STF, WTF.)

Special Resistant Bearing Steels:

STF steel (Super-TF)
Specially developed steel for high-load bearings with higher austenite content and special heat treatment. It has a very fine structure. This combination provides greater durability in dirty environments with insufficient lubrication. Super-TF steel provides a significantly longer service life under heavily contaminated operating conditions
Extends the service life to approximately ten times that of standard steel when grease is contaminated, and two times standard steel when grease is less contaminated.
Of direct relevance to the wind energy sector, international accredited registrar and classification society DNV GL has confirmed that roller and ball bearings made of NSK’s Super-TF material exhibit significantly higher dynamic load rating than the standard bearings.
Such is the effect of the higher load rating that bearing service life is effectively doubled in wind turbine applications.
The verification confirmed NSK's published specifications and, in a Statement of Conformity dated 15 November 2017, certified that when Super-TF material is used, the basic dynamic load rating can be improved by 23% in roller bearings and 26% in ball bearings. This is equivalent to a doubling of bearing fatigue life in comparison with ordinary bearings.
WTF steel (Water-TF)
Super-clean bearing steel developed specially for rolling mills. Advantageous under harsh operating conditions. This material provides higher reliability and longer operating life due to prevention of flaking stage and cracks caused by water infiltration.
These materials increase the bearing life several times, increase reliability in extremely demanding conditions and prevent unexpected accidents. They reduce maintenance costs to less than 50% of those with conventional bearings.
Bearing series: STF-RV

More details in the catalogues:

Čtyřřadá válečková ložiska / Čtyřřadá válečková L - Four-row CRB
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