NTN RNA4905 L/3AS Nadellager (30x42x17)

As a needle roller bearing, this bearing carries high radial loads in a very compact section. This NTN bearing measures 30x42x17 mm and weighs 0.082 kg; the specification table carries the supplementary technical details. Sealed on one side also means: one frictional torque instead of two, but no closure of the needle set on both sides. This version carries a contact seal on one end face while the other remains open.

Mounting is therefore orientation-bound, and the mounting position is part of the layout rather than a matter of assembly convenience: the sealed side faces the side from which dust, splash water or wear debris comes, or the side at which an escape of lubricant is to be avoided; the open side faces where the construction itself closes off — against a locating face, into a blind bore, or against a component that bounds the lubricant space — or where lubricant is deliberately supplied.

In practice this yields two advantages over the version sealed on both sides: only one frictional torque arises, at one lip instead of two, and lubricant can be replenished from the open side. The restriction is just as clear, in that the needle set is protected from one side only. Nothing changes in the requirements of the design: without an inner ring of its own the shaft surface forms the raceway and has to be executed accordingly in hardness, surface finish and tolerance; the bearing takes no axial force; and the long contact line of the needles permits only slight misalignment between shaft and housing bore.

The limits of the seal material for operating temperature and media apply unchanged, as does the permissible speed, which is lower than for the open version. The normal radial clearance is matched to common fits and operating temperatures. The material is not held as a separate catalogue attribute for these items and is to be taken from the specification table.