Load sharing based maximum fillet stress analysis of asymmetric helical gears designed through direct design — A parametric study

• The bending load capacity is more in the directly designed asymmetric helical gear.
• The area of existence gives all the possible design solutions for required gear drives.
• As the gear parameters of k, i, Lapt and zp increases the area of existence decreases.
• We found the worst load line of asymmetric helical gear for various gear parameters.
• The LSR based fillet stress is lesser for the higher values of k, i, Lapt and zp.

Direct gear design method is one of the most effective gear design approaches, which provides the high performance gears without concern for any predefined tooling parameters. In the present work, the load sharing ratio (LSR) and the corresponding LSR based maximum fillet stresses in terms of non-dimensional stress number have been estimated for the conventionally designed and direct designed symmetric helical gears. It is also extended for direct designed asymmetric helical gears. The area of existence procedure is developed and using the same, the possible existence of design solutions for a drive of required constant transverse contact ratio and different addendum pressure angles is chosen to develop the rack dimensions. Finally, the influence of a few parameters such as gear ratio, transverse contact ratio, top land thickness coefficient and the pinion teeth number on area of existence, load sharing ratio and the corresponding values of non-dimensional stress number in the asymmetric helical gear drives designed through the direct design method has been carried out and discussed.