Joint and Cardan Shafts

172 173 Application Guidelines Calculation data Technical Annex Technical Annex  Service Phone Europe  + 49 (0) 71 42 / 353-0  Service Phone North America  + 1 – 2 6 9 / 6 3 7 7 9 9 9  Catalog  Spare parts  Drive-Shaft Calculation  Installation and Maintenance  www.elbe-group.com To size universal drivelines properly, various conditions and factors must be considered. In view of the multitude of possible applications, exact, generally valid rules cannot be provided. The following information is there- fore used for the first rough determination of size. In case of doubt, we will gladly compu- te the required joint sizes for you and, in this context, we like to refer to the technical ques- tionnaires starting on page 189. 6. Fundamental data for sizing of universal drivelines 6.1 Torques The max. permitted torques Md max stated for the individual drive-shaft sizes apply normally only for short-term peak loads. Md nom : Nominal torque for pre-selection on the basis of the operating moment. Md lim : Limit torque that may be transmitted temporarily from the universal-drive-joint at limited frequency without functional damage. The respective permissible torque has to be cal- culated individually depending on the remaining operating data, such as shock loads, angle of de- flection, rotation,etc. (See item 6.2 and 6.3) 6.2 Shock loads Depending on the type of power input or installation, a driveline can be subjected to shock loads considerably above the rated torque. To take those into account, shock service factors must be implemented. Following are some shock-service factors for the most common drives Of course, not only the drives, but, in many instances, also the driven equipment is responsible for shock loads. Because of the magnitude of different possibilities, general data valid for every use cannot be supplied. 6.3 Life expectancy – calculation The decisive factor with regard to life ex- pectancy of universal drivelines is usually the joint bearing. Therefore, in order to determine the individually required joint size, the life expectancy diagram shown later on should be used. This diagram allows to: a) determine the theoretical life expectancy of a selected driveline as a function of prevailing operating conditions, or b) to determine the required joint size for a given life expectancy. Prime mover with flexible coupling without flexible coupling Turbine or electric motor 1 1 to 1,5 Gasoline engine, 4 and more cylinders 1,25 1,75 Gasoline engine, 1 to 3 cylinders 1,5 2 Diesel engine, 4 and more cylinders 1,5 2 Diesel engine, 1 to 3 cylinders 2 2,5 In this case, the rated input torque is multiplied by the appropriate service (shock) factor and the M d such obtained entered in the following diagram. Other factors, such as correction - or deflection angle factor do not have to be considered since they are already incorporated in the diagram. On machines or vehicles with changing ope- rating conditions, at first, the individual life expectancy values (for each condition) must be determined from the diagram. Then the overall life expectancy L hR can be calculated as follows: q 1 , q 2 … = time share in [%] L h1 , L h2 … expressed in 10 3 [Hours] L hR = 100000 q 1 + q 3 + ... + qn L h1 L h2 L hn 6.4 Life expectancy-Diagram In view of the multitude of applications, it is not possible to determine the suitability of a driveline by tests. Therefore, the selection and analysis of the required joint size is done by calculations. These are based on the compu- tation of the dynamic load carrying capacity of full rotation needle - and roller bearings ac- cording to ISO recommendation R 281. The life expectancy diagrams shown in the catalogue are based on this recommendation and also on an equation formula especially suited for obtaining nominal life expectancy on universal joints. The thus obtained life expectancy lists the hours of operation that will be reached or exceeded by 90% of a larger number of equi- valent universal joint bearings. There are also methods of obtaining the mo- dified life expectancy. In this case varying sur- vival probabilities, material quality and ope- rating conditions are taken into account. The present technical know how does not allow statements to be made about variations in life expectancy performance resulting from differ- ences in steel quality (grain, hardness, impu- rities). For this reason, no guidelines have been set in the International Standards. All pertinent operating conditions, such as operating temperature, lubrication intervals, the type of grease used and its viscosity in operation, must also be considered. Since these factors vary from case to case, it is not possible to determine the modified life expectancy and accordingly, a life expectancy diagram valid for universal use. The two following life expectancy diagrams will allow you to roughly determine the nomi- nal life expectancy. If the deflection angle is smaller than ß = 3°, ß = 3 should be used. Otherwise, the obtained result will be less accurate. If it is necessary to determine the life expec- tancy accurately, kindly consult the ELBE Engineering Department. [Hours]