Design factor for permissible tooth root stress

The design factor Y_d takes into account the influence of load reversing on the tooth root strength, relative to the tooth root strength with unidirectional load as defined for the endurance limit for bending stress σ_FE.

The following options are available:

1. User specified
   Direct numerical specification
   
   
2. General
   General operation without alternating loads, Y_d = 1.0
   
   
3. Alternating partial loads
   For gears with part load in reversed direction, such as main wheel in reversing gearboxes, Y_d = 0.9
   
   
4. Reverse load
   Alternating loads; e.g., for idler gears, Y_d = 0.7