AGMA 11FTM09 PDF

The load distribution measurement of gear teeth and the determination of the face load factor for contact stressK_Hβ are of fundamental importance for the gear manufacturing industry. The factorKHß is ameasure for the uniformity of the load distribution along the face width. The closer this factor is to one the more uniform is the load distributed along the face width. During the design phase this factor is determined with the help of approximation equations as well as finite element analysis and is used to dimension the flank modifications. In addition K_Hß is used in the lifetime calculations according to DIN 3990 and ISO 6336 required by the certification societies. In the testing phase this factor is experimentally determined by strain measurements of tooth fillets in order to verify the load distribution calculations and the suitability of the used modifications.

For spur gears with no helix angle the interpretation of the measurements to a face load factor is intuitively easy. For helical gears, more frequently used in big gearboxes, the determination of the factor gets tougher. The line of contact of these gears runs inclined over the face width of the tooth flanks. In this context the question arises whether the face load factor is evaluated along the face width or along the path of contact.

The evaluation of the measured values and the interpretation to a face load factor is a complex challenge and is not standardized. Alarge number of publications make suggestions; however, these suggestions differ to a large degree. The standardisation of the load distribution evaluation and a uniform definition of K_Hß for helical gears enable a safer design for themanufacturers and an easier comparability of the results for the customers.

The paper compares the different suggestions to the K_Hß definition and will derive a suitable definition for the calculation methods in DIN 3990 and ISO 6336.