www.jbj.co.uk/couplings.html#flender 2 #DriveLineHarmony Technical Information Mechanical Power Transmission Couplings Axial misalignment Radial misalignment Angular misalignment Ka Kr Kw Shaft misalignment Couplings can be categorized into one of the following groups: Single-joint couplings Example: 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. Shaft misalignment is the result of displacement during assembly and operation and, where machines constructed with two radial bearings each are rigidly coupled, will cause high loads being placed on the bearings. Elastic deformation of base frame, foundation and machine housing will lead to shaft misalignment which cannot be prevented, even by precise 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. 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. Two-joint couplings Two-joint couplings are always designed with an adapter. The two joint levels are able to absorb axial and angular misalignment. Radial misalignment occurs via the gap between the two joint levels and the angular displacement of the joint levels. The permitted angular misalignment per joint level is frequently about 0.5°. The permitted shaft misalignment of the coupling can be adjusted via the length of the adapter. If there are more than two joint levels, it is not possible to define the position of the coupling parts relative to the axis of rotation. (The less frequently used parallel-crank couplings are an exception). Example: N-ARPEXARN-6 NEN 217-6 with a shaft distance of 140mmwith a permitted radial misalignment of ΔKr = 2.2mm (angle per joint level 1.0°). Depending on the direction of the effective shaft misalignment a distinction is made between: Kr G_MD10_XX_00 01 4
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