SKF 21311 E/C3 Pendelrollenlager (55x120x29)

As a spherical roller bearing, this bearing carries very high radial and axial loads and accommodates misalignment. The dynamic load rating of 156 kN characterises this bearing. The static load rating is 166 kN. The limiting speed is 7500 rpm. This variant features increased radial clearance (C3). The alignment capability is unchanged; what has changed is only the initial radial clearance from which the operating clearance follows.

In this design the clearance is not merely a tolerance class but also the mounting dimension. On a tapered seating surface the inner ring is deliberately expanded during drive-up, and the mounting is controlled by the reduction in clearance rather than by a tightening torque; that presupposes enough initial clearance to absorb the drive-up distance and still retain a residual play.

On a cylindrical seat the same mechanism acts on a smaller scale through the interference fit. Operation adds to this: a two-row roller set under high load releases friction power in the rolling contact, the inner ring runs warmer than the outer ring, and the differential expansion consumes further play. Increased clearance (C3) sets the starting point so that an operating clearance within the intended range remains after fitting and heating; without that reserve the bearing works with a preloaded rolling contact, which raises frictional torque, temperature and lubricant duty, and reinforces itself through the additional heat.

The clearance class changes nothing about the load-carrying behaviour: both roller rows still run on the common spherical outer raceway, the bearing position remains self-aligning, and radial as well as axial force are transmitted as in the standard configuration. Rings and rolling elements in through-hardened standard bearing steel cover the usual operating temperature range.

The open form still requires sealing and lubricant supply by the surrounding construction. For the layout, the type of seat, the drive-up distance or fit, the temperature gradient between the rings and the load direction should be assessed together.