Cardan Shafts for Industrial Applications - Dana

Technical instructions for applicationSpeedChecking the critical torsionalspeedThe plant or vehicle manufacturerhas to prevent the use of cardanshafts within the critical torsionalspeed ranges of the drive. Therefore,the determination of thecritical torsional speed ranges ofthe drive system is required. Thevalues for the moment of inertiaand torsional stiffness of the selectedcardan shaft can be takenfrom the data sheets or besupplied upon request.Checking the critical bendingspeedExcept for short and rigid designs,cardan shafts are flexible unitswith critical bending speeds andflexural vibrations that have tobe checked. To accomplish this,the first and possibly secondorder critical bending speeds areimportant.For safety reasons, the maximumpermissible operating speedmust be at a sufficient distancefrom the critical bending speed.The diameter is limited becauseof the ratio to the shaft size.Therefore, single cardan shaftscan only be provided up to acertain length. All installationsexceeding this limit have to beequipped with subdivided drivelines.For determination of the criticalbending speed, see thefollowing selection diagrams.These diagrams only apply tocardan shafts that are installedwith solid bearing supports locatedclose to the flange.Different installations (e.g.,units with elastic mountingbearing) must have lower criticalbending speeds.Depending on the type of theplant, excitations of secondorder can cause flexible vibrations.Please contact Danaengineers if the deflectionangle exceeds 3° and for greaterlength dimensions.n perm. max. _~ 0,8 · n crit. [rpm]The critical bending speed fora particular shaft size is determinedby the length and the tubediameter only (see diagram). Forgreater length dimensions, thetube diameter has to be increased.41