NTN 4T-3478/3420 Kegelrollenlager (34,925x79,375x29,771)

As a tapered roller bearing, this bearing carries high combined radial and one-directional axial loads and is usually adjusted in pairs. For this NTN bearing, 34.925x79.375x29.771 mm and a weight of 0.74 kg apply; the specification table holds the further technical particulars. The contact angle of the series determines what share of the total load is supported axially, which makes it the first selection criterion for an adjusted arrangement.

Tapered roller bearings transmit load through tapered rollers between tapered raceways whose extended surface lines meet at one point on the bearing axis; this is where the combination of high radial and one-directional axial capacity that characterises the design comes from. Because axial force is supported in one direction only, the bearing normally works against a second bearing adjusted against it in a back-to-back or face-to-face arrangement.

Operating clearance is therefore not preset in the bearing but established during mounting as the two units are adjusted against each other; the adjustment travel, the preload and the thermal behaviour of the surrounding design determine it jointly. The inner ring with its roller and cage assembly and the outer ring are separable, so both rings can be fitted with an interference fit.

For the design, the contact angle, the chosen adjustment method and the equivalent load resulting from the axial share should be drawn upon.