Correct coupling selection guide 3 #DriveLineHarmony Technical Information Mechanical Power Transmission Couplings Axial misalignment Radial misalignment Angular misalignment Ka Kr Kw Shaft Misalignment Shaft misalignment is the result of displacement during assembly and operation and where machines constructed with two radial bearings each are rigidly coupled causing high loads to be applied to the bearings. Elastic deformation of base frame, foundation and machine housing will lead to shaft misalignment which cannot be prevented, even by precise initial setup alignment. Furthermore, because individual components of the drive train heat up differently during operation, heat expansion of the machine housings causes shaft misalignment. Poorly aligned drives are often the cause of seal, rolling bearing or coupling failure. Alignment should be carried out by specialist personnel in accordance with operating instructions. Couplings can be categorized into one of the following groups: Single-Joint Couplings Couplings with flexible elements mainly made of elastomer materials. Shaft misalignment results in deformation of the elastomer elements. The elastomer elements can absorb shaft misalignment as deformations in an axial, radial and angular direction. The degree of permissible misalignment depends on the coupling size, the speed and the type of elastomer element. Single-joint couplings do not require an adapter and are therefore short versions. Example: In the case of a RUPEXRWN 198 coupling with an outer diameter of 198mmand a speed of 1500 rpm, the permitted radial misalignment is ΔKr = 0.3mm. Depending on the direction of the effective shaft misalignment a distinction is made between: Kr