NTN NK1A5905 A Nadellager (25x42x23)

As a needle roller bearing, this bearing carries high radial loads in a very compact section. This NTN bearing measures 25x42x23 mm and weighs 0.133 kg; the specification table carries the supplementary technical details. The needle roller bearing carries high radial load at the smallest section height of any rolling bearing type — slender rollers need little room above the shaft.

Needle rollers are long in relation to their diameter; they carry on a line while occupying very little radial space. Hence the defining property of this type: high radial capacity in the smallest section, paid for by being restricted to radial load — axial force is not carried and must be taken by an adjacent position. The solid design with its own rings differs from a needle cage or drawn cup in bringing its raceways with it, so it does not require hardened and ground running surfaces on shaft and housing.

Misalignment is critical: long rollers are sensitive to angular error because load then migrates to the roller ends, so seats must be aligned, accurate and stiff. The open version leaves sealing, initial filling and relubrication to the surrounding design, while keeping the rolling chamber accessible for a directed supply of lubricant. Rings and rolling elements are made of through-hardened standard bearing steel.