NACHI 1211 KC3 Pendelkugellager (55x100x21)

As a self-aligning ball bearing, this bearing compensates for misalignment and shaft deflection. The principal dimensions are 55x100x21 mm at a weight of 0.71 kg; the further technical details are listed in the specification table. This variant features increased radial clearance (C3). If the self-aligning ball bearing is set onto a plain shaft by way of an adapter sleeve, the drive-up distance expands the inner ring — increased clearance (C3) holds the initial play needed for that available.

Increased clearance (C3) has a very concrete reason in this design. Self-aligning ball bearings are frequently supplied with a tapered bore and set onto a plain, unstepped shaft by way of an adapter sleeve — the method with which long shafts are built up in plummer block housings. During drive-up the inner ring is deliberately expanded, and the mounting is controlled by the clearance remaining in the process; without a sufficiently large initial play, too little of it would be left after drive-up.

If too little play remains at the end, the ball set is braced against the raceways; frictional torque and temperature rise, and the additional heat reduces the play further. The larger clearance class changes nothing about the properties of the design: the inner ring unit remains able to swivel in the outer ring, the bearing position compensates for misalignment and shaft deflection, the load rating stays tied to the low conformity of the spherical outer raceway, and axial forces are permissible only to a modest extent.

Rings and balls are made of through-hardened standard bearing steel. The open form presupposes sealing and lubricant supply by the surrounding construction. For the layout, the type of seat, the drive-up distance or fit, and the temperature profile to be expected should be assessed together.