SKF NKX20-Z Nadel-Axialkugellager (20x30x30)

As a combined needle/thrust bearing, this bearing carries radial and axial loads simultaneously. The principal dimensions are 20x30x30 mm at a weight of 0.085 kg; the further technical details are listed in the specification table. Splitting the duty into needles radially and balls axially keeps the frictional torque of the longitudinal direction low and suits moderate axial loads at high radial load.

The combined needle roller / thrust ball bearing brings two kinds of rolling element together in one assembly: the needle roller assembly carries the radial load through line contact, the ball set the axial load through point contact. The application profile follows from that split — high radial capacity at a low section height, plus an axial stage for the moderate longitudinal forces that arise when locating and positioning a predominantly radially loaded shaft.

Each of the two ratings applies only to its own direction; a high radial rating says nothing about the permissible axial force. The ball set requires a permanently acting minimum axial force so that the balls roll rather than slide, and its seating face is to be made square to the shaft axis. Depending on the version the raceways are enclosed as washers or are to be provided hardened and ground by the surrounding design; standard bearing steel covers the usual operating-temperature range.