Estimation of tooth form factor for normal contact ratio asymmetric spur gear tooth

• The fillet stress factor has been estimated for asymmetric gear through ISO and FEM.
• The bending strength is more in the case of asymmetric gear than that of symmetric gear.
• The fillet stress is lesser when the high pressure angle side is used as drive side.
• The fillet stress factor decreases with increase in drive side pressure angle.
• The fillet stress factor increases with increase in coast side pressure angle.

To estimate the tooth form factor for a loaded symmetric spur gear tooth, some normalized standards like International Organization for Standardization (ISO) and American Gear Manufacturers Association (AGMA) are available. However, the tooth form factor for a loaded asymmetric spur gear tooth cannot be estimated through the available standards. An asymmetric spur gear tooth is one whose drive side pressure angle is different from the coast side pressure angle. In the present work, the standard ISO B methodology has been adapted suitably for estimating the tooth form factor and the stress correction factor in asymmetric spur gear tooth. Also, the critical root fillet parameters (critical root tooth thickness, bending moment arm and radius of curvature) and the tooth form factor for asymmetric spur gear tooth with several sets of drive side and coast side pressure angles are determined through an adapted ISO method and a comparative study with FEM is also carried out.