This adapter sleeve mounts a bearing with a tapered bore onto a cylindrical shaft, transmitting the clamping force needed to fix the inner ring in position. It has a bore diameter of 50.0 mm and a net mass of 358.05 g, with a standard design suited for general mounting arrangements. The sleeve is a mechanical, complete accessory component, designated H311, used together with a locknut and lockwasher to secure the bearing on the shaft. Using a tapered adapter sleeve allows the bearing to be positioned at any point along a plain cylindrical shaft rather than requiring a stepped or tapered seat, simplifying shaft machining. Tightening the sleeve against the shaft sets the internal clearance of the bearing, so the fit must be adjusted according to the specified clearance reduction during mounting. This arrangement is suitable where ease of mounting and dismounting on a straight shaft section is required.